Prosthodontics 2020

Complications of a post

1) Loss of retention may be salvagable, unless associated with root fracture Related to post vs canal anatomy, post surface texture, cement. Leakage or loss of retention result in exposure of RC filling to oral bacteria - risk of RCT failure - re-treatment? Avoid ultrasonic scalers on post-retained crowned teeth 2) Post fractures Occur in isolation or concurrently with root fracture May be retrievable - depending on location of fracture, and post material; coronal fracture may be salvageable Ease of removal - Fibre > Metal >> Zirconia 3) Root fractures Often catastrophic failure; necessitates extraction Ferrule design around sound coronal dentine is protective Two conflicting ideas;Elastic posts; failure occurs earlier, but is often salvagable or Stiff posts; failure occurs later, but may be catastrophic However, following cementation of crown with ferrule, negligible difference 4) Gap under post Risk of reinfection / space for bacteria (weak literature of reduced prognosis) Technical trouble shooting - to avoid can do a resin stop

Retention of complete dentures

1. Adhesion - attraction of unlike molecules; saliva + mucosa / saliva + fitting surface of the denture 2. Cohesion - attraction btw like molecules; hence importance of good saliva flow 3. Interfacial force - therefore we need a thin layer of saliva and a well fitting denture surface 4. Border seal - posterior palatal seal and periphery of denture buccally / labially 5. Atmospheric pressure - creates negative pressure when dislodging forces are applied if good fit 6. Muscle coordination - shape of polished surfaces conform to peripheral tissues (eg denture stability via lips tongue cheek and alveolar ridge; denture support by bony support such as mx tuberosity, palate and ridge)

Auxillary retention / resistance features for a crown / onlay prep

1. Bonding - Zidan(2003) looked at zinc phosphate, GIC and resin bond to abutments of tapers 6, 12 and 24 degrees. Results - crowns luted onto a prep with 6 degrees taper was 2/3 as retentive as a crown adhesively cemented on a prep with 24 degrees of taper. Preps with the same taper were twice as retentive if adhesive cement 2. Increase prep height via... Occlusal lengthening Core restorations Purpose - blockout undercuts, reduce casting weight, assist with retention / resistance (if using for this purpose do not rely on bonding alone, must be mechanically retained), and shade modification. Orthodontic Extrusion Slow extrusion to bring attachment with it - Still requires crown lengthening Rapid extrusion requires severing of pperiodontal fibres Time and $$$ Apical lengthening (sub g margins, crown lengthening) Subgingival margins Problems - isolation, cementation, cleanup, biological width Crown lengthening Increase crown decrease root Aesthetic implications Morbidity / healing time Root contours / constriction 3.Grooves - placed on walls adjacent to short / tapered walls Boxes - fatter / more destructive version of a groove, increased retention Slots Terracing - on very tapered wall, step like Cast pins

What options do we have if inadequate ferrule?

1. Crown lengthening - Disadvantages: Inadequate crown to root ratio (thus cantaleiver forces are greater); compromised aesthetics (eg if high smile line / anterior tooth), potential loss of interdental papilla, compromised periodontal support (may expose furcation areas) 2. Orthodontic extrusion - can reduce crown:root or expose furcation areas, takes time, costly. 3. Extraction and a replacement option

Clinical procedure for full denture making

1. Hx and exam 2. Primary impression - create special tray 3. Secondary impression, registration (recording VDO, CR and orientation relation) 4. Try in wax dentures - ensure correct vertical dimension, centric relation, protrusive reg, aesthetics, phonetics, posterior extension of denture, etc 5. Insertion 6. Post insert visit

Clinical procedure of fabrication of an acrylic denture

1. Primary impression, jaw relation record if cant hand articulate 2. Cast surveying 3. Design + Tooth set up (path of insertion, support, retention, reciprocation, connectors) 4. Insertion

Acrylic RPD designs

1. Spoon Denture - Maximal palatal coverage Relies on palate For retention and support (suction) Relieved gingival margins Relatively hygienic (doesn't touch the teeth much) Not recommended due to the poor retention and the risk of swallowing and inhalation à retained by pt pushing the "spoon" / palate with their tongue so not the most comfortable (1b). Modified Spoon Denture - same but extended and can add some clasps More stable and applicable Reliance on frictional contact between the connector and the palatal surfaces of some posterior teeth Wrought wire clasps can be added 2. "Every" Denture Design à if edentulous areas spread apart can use this Indicated for restoring multiple bounded edentulous areas in the maxillary jaw The connector borders are at least 3 mm from the gingival margins Open design (wide embrasures) between artificial tooth and adjacent teeth Point contacts between the artificial teeth and abutment teeth Posterior wire stops to prevent distal drift of the posterior teeth. Can also contribute to retention Flanges are included to assist the stability of the denture Retention and stability can be obtained following the principles of complete denture occlusion Lateral stresses can be reduced by Relying on natural teeth for occlusal guidance Or obtaining balanced occlusion Can add clasps or distal wires at molars to increase stability 3. Maximal Coverage "Gum stripper" à Least hygienic Covering the interdental papillae and the embrasure areasà Provides friction retention Support is obtained by seating the acrylic above the survey line Retention can be enhanced by wrought wires

Milling procedure for ceramic, precious alloys, and resin composite via CAD/CAM

1. Tooth prep 2. Intra oral scanning 3. CAD software 4. Virtual design 5. CAM processing - milling unit cuts block down into final product via "subtracting" 6. Finishing

Indications, pros and cons of Lithium disilicate

= Emax Glass matrix and crystalline fillers (lithium disilicate fillers) Advantages • good optical refraction index = good aesthetics even with lots of filler • increased compressive strength = shoulder • increased fracture toughness due to randomly orientation of particles = blocks propogation • can bond to enamel Disadvantages • Brittle / low flex • Low tensile strength = no chamfer • Significant tooth reduction • Thicker preps (eg 2 - 3mm+) = greater chance of voids / imperfections = fracture Indications • Inlay, onlay or crowns

What is a cantaliever in prosthesis?

A fixed dental prosthesis in which the pontic is cantilevered, i.e., is retained and supported only on one end by one or more abutments. Can be retained by a wing (RBB) or crown prep.

Advantages vs disadvantages of veneers

Adv • Shape / size / colour change without removing as much tooth as a full crown • More durable than RC, resistant to stain and wear and tear • Quicker than ortho (but carries biological restorative burden) Disadv • Cost • Difficult to temporize → ie nearly impossible to have a temp stick • Colour not completely predictable → dentine colour may show through the veneer as they can be thin/ translucent; hence colour matching quite difficult • Debond risk → more likely to come out than other fixed pros • Limited ability to repair

Advantages and Disadvantages of an immediate denture

Advantages Physiological - Preservation of muscle support, vertical dimension, jaw relationship and face height - Preventing spread of tongue (can widen / spread without prostehsis) - Enhancing adaptation to complete denture (so they don't get used to compensating when eating / speaking etc without teeth so easier to adapt to the denture) - Less post-operative pain due to protection of extraction sites - More rapid healing (protect surgical sites) - Control bleeding Less bone resorption Psychological - must provide something immediately; ideally would wait until patient ridges are healed but doesn't do much for their self esteem. - Preserving social well-being - No interruption of lifestyle (eg work and social interactions) - Maintaining patient image and self-esteem - Maintaining speech - Duplicating the natural shape and position of teeth (making as aesthetic as possible) - Possibly less painful, as the denture will act as a splint (denture protecting the extracted area while it heals) - Easier denture adaptation as the muscle coordination will be maintained To operator - The position, size and appearance of anterior teeth can be accurately re- established (ie if patient is happy with their natural teeth) - The existing occlusion can be utilized as a basis for the registration of jaw relations (But can also copy wrong positions) Disadvantages of immediate denture - More complex than conventional complete dentures: Impression (is harder because we are dealing with teeth) Lack of try-in (cant try in because being made before extraction - so technique must be extremely accurate in guessing how much bone will be removed after the extraction) - More time and cost is associated to complete the treatment as A new denture likely to be needed (needs a reline at the absolute minimum) Extra need for maintenance - Pre-prosthetic surgery might be needed (not very common à try to avoid surgery) - More patient discomfort (ie there will be swelling oedema etc from the extraction) - More patient cooperation is needed (additional visits) / more inconvenience - Functional activities might still be impaired (speech and mastication) - More challenging technically Presence of anterior ridge undercut / the presence of teeth hinder accurate vertical dimension and centric relation records

Pros and cons of CADCAM

Advantages Potentially simpler Faster - same day crowns impossible without it Greater material choice More accurate fit à debated More controlled material / prosthesis fabrication Lab costs cheaper Disadvantages Big initial investment Steep learning curve - ie need training in software / computer Needs updates Ongoing cost eg licensing Case selection important

Materials for primary impressions; their pros and cons

Alginate - impression material commonly used for primaries What is alginate? Irreversible hydrocolloid impression material Setting reaction? Setting time? Advantages - Good physical properties Strength Accuracy Disinfection Dimensional stability Compatibility with gypsum Cheap Disadvantages Poor dimensional stability (dries out quickly) Impression compound - for fully edentulous only. Metal trays are generally used with impression compound. Suitable when alveolar ridges are highly resorbed. Advantages - Thermoplastic Can be adjusted if impression unsatisfactory Technique sensitive Needs a hot water bath to get the compound really soft so it can be malleable into the metal tray Does not dry out Disadvantages - Not an easy material to handle Not pleasant for the patient because it gets hot

Fabrication + troubleshooting of provisional restoration

Allow 1 hour Key of desired shape of provisional Load with provisional material and seat on prep Remove crown from key Trim, check fit, reline Remove flash with soflex Cement and remove excess If marginal deficiency - place flowable composite where needs the repair / place inside the crown, seat it and then cure. Do NOT pour outside the mouth Troubleshooting - Temp stuck on prep Possible causes - Undercuts on prep or adjacent teeth Excess material on adjacent teeth Unset monomer from CR core buildup Retentive prep + polymerization shrinkage Resolution Remove with artery forcep Push it with plastic/ hollenback interproximally / below the margin If wont remove after a minute get help May need to section How to avoid If redoing it - work out why it didn't work the first time Ensure no undercuts Vaseline the prep (usually just in preclin) Block out undercuts with periphery wax / putty / cavit

Define balanced occlusion. Why is it suitable for a complete denture? Pros and Cons?

Balanced Occlusion - all teeth in contact during occlusion (does NOT occur naturally) Bilateral, simultaneous, anterior and posterior occlusal contacts of teeth in working and non-working sides Not a feature of the natural dentition, but it is thought to increase denture stability during non-functional jaw movements Appears more important when no food is in the mouth However, lacking evidence to support the validity of balanced occlusion during chewing In centric occlusion, all the teeth are interdigitating Facilitated by anatomic teeth use On the working side: teeth to glide evenly over each other from central incisor to second molar No single tooth must interfere and cause others to lift out of articulation On the non-working side (balancing side): contacts should exist but not interfere with smooth gliding movement of the working side (no single tooth dictating movement, no friction from any single tooth) Protrusive balancing contacts exist when the mandible is protruded When the patient incises there is simultaneous contact on molar teeth on each side Prevents distortion / mobility of the denture Rationale in a complete denture any force applied to a single denture tooth will be directly transferred to the entire denture (as opposed to natural teeth where each tooth will respond individually. Hence balancing forces between one side and the other are ideal Enhance denture stability Allows maximal intercuspation Applies aesthetic and naturally looking teeth Advantages Reported slightly more efficient in chewing tests Posterior teeth appear more natural Disadvantages Most time consuming to set; most complex Restrictions of setting posterior teeth Needs at least semiadjustable articulator

Primers required for bonding to base metals, noble alloys, ceramic and zirconia

Base metals - phosphate primers eg 4META or MDP Noble alloys - sulfur primers eg VBATDT, MEPS, MTU6, MDDT, MDTP Ceramic - Silanization (silane) Zirconia - cannot truely bond as no glassy matrix thus luting cement used. but - can use particle abrasion to increase roughness, silica coated particles to abrade (cojet) as silica is receptive to silane, or selective infiltration etching to allow bonding. Currently use APC (airblast, prime w MDP and cement with resin cement)

3 Broad principles of tooth prep

Biological, Mechanical, Aesthetic

What is ceramic veneer

Bonded ceramic restoration: anterior Path of insertion: buccal Boundary between crown and veneer can be loose eg 360 veneers/creneers --> Anterior equivalent to a posterior onlay

Types of rests + preparation guidelines

Categories of rests - Occlusal rest - rounded confined to enamel inverted triangle. 3mm wide and long, 1.5mm deep, floor inclined so seat cant slip - Lingual (cingulum) rest - inverted V or rounded - Incisal rest - for anteriors, but poor aesthetics. - Overlay - covers entire occlusal surface, useful to build VDO - Intracoronal (precision) rest - placed within a crown, a manufactured attachment of fixed pros

Check the laboratory work prior to your appointment

Check the laboratory work prior to your appointment to ensure it is of a satisfactory standard. If there are laboratory-related issues with the crown, these need to be resolved before seeing the patient What you should receive the following from the laboratory (as well as master impression and occlusal registration) Crown Inspection checklist Correct shade Correct contour and morphology No visible cracks within porcelain/ceramicà small cracks will become larger in pt mouth No defects in metal Other instructions as stated in your lab sheet have been followed Working die Used for Waxing up copings for PFM crowns Initial ceramic build up Inspection checklist Die spacer à creates space for cement thickness, lack of spacer = open margin as cement will push the crown up. No die spacer on the margin Margins have been trimmed correctly Crown fits to margins satisfactorily No abrasion of the working die Working model A full arch model with the preparation present. Used to build the occlusal surface and interproximal contacts of the crown Inspection checklist Interproximal contacts - no open contacts. Hold up - can you see daylight interproximally? If so = open contact No abrasion of model on adjacent teethà if this has happened may not fit in mouth properly Crown fits on this model satisfactorily Virgin model A model that is left untouched throughout the crown fabrication process, which the final crown is checked against Ensures margins are correct Ensures interproximal contacts are correct à Reference incase unintentional changes were made to the working model and die Opposing model Used to build occlusal surface of the crown Used to ensure correct occlusal contour and contact of the crown Ensure no air bubbles on occlusal surfacesà effectively rasising the bite in the area so the bite reg / occlusion will be off Check the crown contacts the opposing model

Kennedy Classification System

Class I - Bilateral edentulous areas located posterior to the remaining natural teeth. Class II - A unilateral edentulous area located posterior to the remaining natural teeth. Class III - A unilateral edentulous area with natural teeth remaining both anterior and posterior to it. Class IV - A single, but bilateral (crossing the midline), edentulous area located anterior to the remaining natural teeth. Edentulous areas other than those determining the classification are referred to as modification spaces and are designated by there number

Post insertion problems of dentures

Common complaints in the mandibular arch 1. Peripheral area soreness Over extension - Denture adjustment Unpolished sharp edge - Polish denture border 2. Soreness of the crest of ridge Bony spicules-Provide relief over area. Pressure spot during time of impression - Disclosing paste to locate spot, adjust accordingly. Premature occlusal contact - Probably the main cause. Correct occlusal error, check VDO. 3. Generalised discomfort with / without pain. Patient cannot eat comfortably. Increase in VDO - May need to redo lower denture or reset teeth of /F to correct VDO. Locked occlusion - Provide smooth movement from centric relation (long centric). 4. Looseness of lower denture Retracted tongue position - Patient education about normal tongue position. Incorrect centric occlusal position - If minor, remount and adjust on articulator. Under-extension of flanges - Reline denture providing correct extensions. Over-extensions - Can cause excessive movement during movement. 5. Cheek biting Inadequate horizontal overlap. Gross decrease in VDO Common complaints in relation to the maxillary denture. 1. Denture loosens occasionally. Underextension-Add green stick compound to suspected areas and check. When retention achieved cure in acrylic. Occlusal errors - Check occlusion and correct. 2. Denture loosens when eating. Incorrect tooth position, teeth set too far buccal - Reposition teeth. Non-displaceable tissue in the palate - Need to provide relief in the areas. Chewing hard foods - Instruct patient to maintain soft diet until conditioned to new dentures. 3. Denture loosens when yawning or opening of mouth. Denture base too thick in the buccal posterior area - Reduce thickness to provide space for coronoid process to move during opening of mouth. Over-extended in hamular notch - Shorten denture flange until pterygomandibular ligament does not exert tension on the posterior border of the denture. 4. Denture loosens when talking or singing. Inadequate posterior palatal seal - Diagnose by first adding compound. Overextended in posterior region - Adjust posterior area until soft palate movement does not interfere with retention. Interference in occlusion - Check anterior relation of teeth. Picture right - Compound (thermoplastic material) 5. Food collects on tissue surface of denture. Labial and/or buccal flanges are under- extended Problems in speech Loose dentures - Find the cause/s, may need relining of dentures (fitting surface does not adhere closely to the tissues) Change in the contour of the speech area - Anterior palatal area too thick and may need thinning of the denture. Maxillary anterior teeth improperly placed - Replace teeth in proper position. Excessive salivation Common complaint when an oral prosthesis is first inserted - Normal physiological action to a foreign body and is usually controlled in days. Gagging related to complete dentures Over-extension - Determine correct posterior extension of maxillary and mandibular dentures. Borders too thick (posterior) - Thin borders. Posterior of maxillary denture (palatal area) too thick touching dorsum of tongue - Appropriately reduce the thickness of denture base. Over-extension of retromylohyoid flange-Reduce length of mandibular flange. Follow up Treatment - Re-appoint patient and continue adjustments until patient is comfortable. Sometimes complete denture issues may not be resolved completely. Complete dentures are a poor substitute for the natural dentition unless supported by implants Over denture abutments

Treatment options for fully edentulous

Complete denture - Very few teeth remaining / No strategic teeth The remaining teeth are in compromised situation Uncontrolled caries and periodontal problems Implants - Prosthodontic anchorage units Implant supported prosthesis - In many cases, ideal treatment option Indicated if the adjacent teeth are not restored or minimally restored Suitable if there is no distal abutment Closest replacement to natural teeth Costly Overdenture - eg full lower denture difficult for pts to adapt as less retention. Hence by giving 2 implants with ball attachments we create frictional resistance and retention. The implant provides duality of support because the soft tissue compressible, axis of rotation on implant balls = can rotate forwards and backwards. Fixed bridge - Full arch cases - maxilla = 6 implants, mandible = 4 implants.

Consequences of tooth loss

Compromised function and comfort Aesthetic limitations - (Facial aesthetics (eg lack of lip support) + Dental aesthetics (particularly missing anterior teeth)) Compromised phonetics Further loss of residual ridge; Loss of ridge height and width (without form of prosthesis to maintain it); Rendering the rehabilitation treatment more complicated Reduction in facial height (VDO) Partial edentulism: Tooth movement: tipping, rotation, migration and over-eruption Increased risk of tooth wear (as a result of overloading the remaining teeth) - can lead to loss of inter / intra arch relationship, teeth can tilt / move / overerupt to try fill gaps - harder to fit prosthesis after this happens; also can lead to difficulties with mastication hence trauma to dental tissues; can lead to splaying and destruction of PDL Full edentulism Bone Resorption of residual ridges - differences between maxilla and mandible Maxillary - more buccal resportion à narrower arch width Mandibular - more lingual resoption à appears wider arch Gum shrinkage

What is CADCAM + its components?

Computer aided design, computer aided manufacturing (design/milling) Digital dentistry - Model free, no impressions Two types of digital workflow; Fully digital workflow - I/O scanner Combined work flow - conventional / physical impressions then lab scanner CAD/CAM Components Scanner / digitalization tool to convert shape into digital data that can be processed by computer (CAD) Software to process the data / further produce a data set and manipulate it (CAD) Production unit / milling device that transforms data into desired product (CAM)

Onlay vs crown?

Conservation of tooth structure is important when there is little tooth structure remaining. Edelhoff (2002) - in mx FPM, full coverage crown involves the removal of around 70% of the available tooth structure compared to 30-40% for an MOD onlay. Further adhesive type restorations conserve more tooth structure than full coverage crowns. Therefore onlay / adhesive preparations can conserve more tooth structure from already compromised tooth, HOWEVER, need to clinically assess if saving tooth structure is worth the potential downside of adhesively retaining the restoration (relying solely on bond) Onlay preparations should be the go to option. - Allows for retreatment - Onlay preparations should have some degree of resistence form (e.g boxes etc). - Adhesive onlay preparations should have enamel margins - Crown preparation may require the placement of core. Need enough retention for the core. If unable to achieve resistance form or no enamel margins, need to consider full crown

Biological factors of tooth prep

Conservative Avoid iatrogenic damage to teeth - wrt soft tissue and pulp via thermal, chemical, bacterial and physical means Marginal design / integrity - smooth margins, must be able to be closely adapted to finish line. be wary of marginal gap (vertical discrepancy) and marginal seal (horizontal discrepancy). - Supragingival - easier, but aesthetics, reduced preparation height - Sub gingival - aesthetics, increased prep height, but harder - Equigingival - best / worst of both worlds Cement escape - bevel shown to improve seal, but cement thickness is limiting factor (steeper bevel = worse seating as prevents cement escape), improve cement escape via low viscosity cement, die spacing, venting of crown, use greater force to seat crown

Define curve of Spee and Wilson

Curve of spee - describes curvature of occlusal plane where a 2.5" radius circle will touch incisal edges, buccal cusps of posterior teeth and anterior of condyle Curve of wilson - extension of curve of spee, not just a curve but a sphere hence inclination of cusps in coronal plane

Deciding on technique, material and size of post

Deciding on technique and material - Controversial • Look at canal shape - If narrow straight round shape; can do direct; If tapered, ovoid shape canal - doesn't really fit direct thus indirect • Most of the time custom cast post / core for severely broken down teeth - Plastic burn out post Deciding on size • Strength of post vs strength of the tooth • Smallest size that fits passively • Direct post = cut to fit requires bigger size • Tooth coloured post may require bigger size, especially ceramic • Most of the time brown

Definition and purpose of provisional restorations

Definition - a prosthesis designed to enhance aesthetics, provide stabilization and/or function for a limited period of time Purpose - worn while permanent is being made; should be a copy of the permanent crown; need to hold them in the same standard in terms of fit and shape Function Basic Protect pulp (ie reduce sensitivity) Caries protection Prevent abutment migration (ie ortho retender) Maintain perio health Interim restoration of aesthetic and function Diagnostic Prep check - can detect problems such as undercuts / under reduction Checks phonetics Aesthetics - width and shape? Occlusal change Other Periodontics Orthodontics Endodontics Formation of ovate pontic site

What is the aim of surveying a diagnostic cast?

Determines the most suitable path of insertion, identifies parallel surfaces that can act as guide planes and determines undercuts

Parapost drill

Do not put in slow speed handpiece → perforation • Parallel sided twist drill • Shape the canal to fit the parapost • Use with your hand +/- a handle • Remove debris, rinse with hypochlorite and repeat

Determinants of dynamic occlusion

Dynamic occlusion - movement of mandible, protrusive or excursive contacts. Anterior determinants - teeth Teeth guide mandibular movements Lateral excursive guidance - ant / post teeth, non working side contacts. Purely guided by teeth Protrusion guidance - incisal relationship, cuspal inclines Dictates VDO Posterior determinants - joint TMJ Head of condyle Articular eminence Intra articular disc Glenoid fossa

Trying in the crown

Ensure tooth is asymptomatic à if symptomatic do not try tooth in because may think the crown is uncomfortable Administration of local anaesthesia (if required) Removal of provisional crown Avoid levering against margin when removing temporary crowns à don't want to damage the margins. Try keep intact incase crown doesn't fit and need to reuse it Use artery forceps/haemostats Removal of temporary cementà need to ensure all removed or will change the fit of the crown Check interproximal contacts Use floss and shimstock If the crown is not fully seated, tight interproximal contacts could be preventing the crown from fully seating In this case - adjust interproximal contacts with articulating paper. Don't over adjust or will result in open contact Once adjusted, recheck margins to ensure the crown is fully seated Open contacts need to be closed. Addition of porcelain if all-ceramic / PFM crown, or gold solder if full gold crown Check resistance form of crown in the mouth Ideally should have been done with provisional crown prior to impression Check retention form; a well fitting crown does not need to be tight in the mouth without cement present Check the crown margins Use an explorer to check that crown margins are satisfactory360 degrees No open margins/crown extends to the correct margins No ledges or overhangs Negative ledge - needs to be remade / adjusted Overhang - can be polished down Check crown is fully seating. If the crown is not fully seating Check for retained temporary cement Tight interproximal contacts Fitting surface abnormalities or binding within crownà eg bubble Trapped gingival tissueà eg in subgingival margins; use retraction cord If the crown is still not fitting, check whether the seating of the crown in the mouth matches that on the model to determine if there's a distortion in the impression or a problem with the crown. à ie if you identify that its not fitting in the pt, & same problem occurs on the model = crown fault. If fits model = impression fault. New impression will need to be taken or New crown will need to be made Check occlusal contactsà only once we know it fits. Check intercuspal position, followed by protrusive and lateral movements Use articulating paper and shimstock Any high occlusal contacts need adjustment and repolishing Crowns that are not in occlusion risk overeruption of the opposing tooth predisposing to potential occlusal interferences A patient that is not anaesthetised will have greater proprioception to detect occlusal changes à listen to pt feedback, they have detect occlusal problems better. May make minor adjustments For tooth coloured crowns: - check the shade If shade is not correct, check whether it matches your laboratory prescription If a shade adjustment is required, the crown will need to be returned to the laboratory for shade adjustment or remake/relayering Show the patient to ensure they are aesthetically satisfied

Errors with impressions

Errors In selection of trays Mixing of Material Did it set to early Placement of impression in the mouth (eg if don't press impression in place properly no mechanical retention) Drag - triangle voids Where impression material falls off while you seat the tray Vacuum voids Usually have a triangular shape follow the flow of the material Moisture Inadequate light body wash Avoid via moisture control, more light body, seating gently as the material sticks to the tooth better so wont drag off. Bubble - round voids Air filled voids Inadequate syringing technique Pre existing bubbles within the material If longer bubble its due to poor technique On the body is ok but cannot have on the margin Tear - if taken out too early Delamination - poor coordination between light and heavy body (ie they didn't mix because one was already set) Separation from tray - lack of adhesive / taking out too early

Cementation of veneers

Etch prime bond Conventional self adhesive resin cement only Strict bonding protocol and moisture control Colour of cement - may effect colour of veneer. Watch out for colour stability; cement changes colour over time, particularly chemical cure turns yellow / orange - Light cure only as much more stable, still discolours a little bit though. New generation dual cured claim to be colour stable still waiting for data

List aesthetic parameters

Facial harmony (horizontal alignment - harmony btw interpupillary and incisal plane; vertical alignment - dental midline w/in 2mm of facial midline) Display zone - low, average or high smile line (re amount of gingival / crown display) Parallelism between incisal curve and lower lip Number of teeth displayed (most commonly 4 - 4 or 5 - 5) Tooth morphology - shape (round / blunt), size (MD to gingival length ratio ~.75), intraarch relationships (embrasures, axial inclination), shade + surface character

How to set up occlusion in fixed, RPD or complete denture

Fixed - consistent with existing occlusion RPD - typicaly use existing occlusal scheme unless opposing complete denture or if only anterior natural teeth remain in which case we use balanced occlusion Complete denture - MIP must occur at centric relation; use balanced occlusion

Reduction guidelines

Follow anatomical planes - Remember second plane reduction and functional cusp reduction Minimum 3mm tooth height for incisors, canines and premolars at 10 degrees Minimum 4mm tooth height for molars at 10 degrees All ceramic Ceramics like compressive forces = no chamfer as tensile, need flat butt joints Shallow and rounded favorable; avoid sharp corners = stress concentration (3mm thickness MAX for ceramic preps as more chance of voids / fracture) Never put margins on any structure other than tooth. (ie not on resto) 1mm reduction minimum buccal / palatal, 1.5mm incisal edge / functioning cusp Metal Chamfer margin Strength in thinner sections .5mm buccal / palatal, 1mm incisal / non functioning cusp, 1.5mm functioning cusp PFM Shoulder on buccal, chamfer in non aesthetic areas. Although palatal is thinner, buccal is thicker hence overall about the same amount of destruction as all ceramic 1.2mm buccal, .5mm palatal, 1.7mm functioning cusp

Casting procedure of metals / alloys

For metal / alloy 1. Tooth prep 2. Impression - Must capture crown margin and extension 3. Master model / die fabrication 4. Wax up of crown 5. Sprueing (provides channel for molten material to flow) 6. Investing (like an impression) 7. Burnout furnace to remove wax from investing 8. Casting - Casting defects due to inadequate vacuum, air trapped, fracture (dropped, rapid heating, or excessive casting force), or short rounded margins (too cold, insufficient casting force) 9. Trimming, polishing and finishing - ensure fits on die. Occlusal contact adjustment, interproximal adjustment, polishing. 10. → if PFM - veneering of porcelain

Consequences of RPD

Full denture Chewing efficiency of complete denture wearers much less than that of dentate persons - Biting force of dentate persons reported as 6 times more than patients with complete dentures Consequences of RPD Plaque accumulation - plaque builds up in crevices of teeth and the prosthesis "protects" bacteria by preventing saliva flow to this area / harder to clean / trapping plaque Caries - usually youll see caries where the prosthesis covers the natural teeth (6 times increase in caries rate with RPD) - hence before being fitted with prosthesis must control oral hygiene. Related to the amount of tissue coverage; Excessive coverage affects the self-cleaning abilities and facilitates plaque accumulation, Increase risk following root exposure - aim to reduce amount and extension of tissue coverage it is more hygienic Periodontal complications - Inflamed gingiva is greatly associated with RPD coverage Mucosal inflammation Trauma from RPD components - Trauma = mobility and orthodontic movement Maintenance Occlusal stability Occlusal interferences- Teeth mobility Loss of denture retention Pain and discomfort Excessive pressure on edentulous ridge

Benefits of tooth replacement

Functional improvements Aesthetics restoration Phonetics restoration Arch stability Prevention of tooth movements Improving distribution of occlusal loads Preparation for complete dentures Psychological improvements

Define guide planes and undercuts

Guide plane - two or more parallel axial surfaces on abutment teeth which can be used to limit the path of insertion and improve stability of RPD (via frictional retention). if parallel guide planes exist there are multiple paths of insertion hence decreased stability Undercuts - area under the survey line that are suitable for retention.

Pros and cons of high noble alloys, noble alloys and base alloys

High noble alloys Advantages - Tarnish / corrosion resistant Good working characteristics ie easy to cast / finish Good aesthetics - yellow hue = warmth / vitality Varying mechanical properties depending on additives Disadvantages - Cost Adhesive and Porcelain bond not as strong as with base metal alloys Examples Gold palladium - full cast / metal ceramic, can add oxide forming elements to promote adherence Gold platinum - full cast / metal ceramic; no palladium sensitivity Gold silver copper - full cast only, melting temp too low for porcelain applications Noble alloys Advantages Higher % of Pt / Pd increases strength, hadness, sag resistance hence useful for long span bridges / high stress areas Some tarnish / corrosion resistance Lower cost than gold alloys Disadvantages White / blue / light grey oxide colour = less warmth Reduced corrosion resistance vs high noble Reports of palladium sensitivity Examples Palladium silver - full cast / metal ceramic, highest elastic modulus of non-base metal alloys, but silver = green Palladium copper gallium - full cast / metal ceramic, gallium lowers melting point for high casting accuracy, copper = yellow / red hue Palladium silver gold - full cast / metal ceramic, higher ultimate tensile strength and elastic modulus than high noble alloys Base alloys Advantages Superior mechanical properties; high elastic modulus, hardness, sag resistance, ultimate tensile strength Better castability Readily forming oxide layer = excellent porcelain bond Cheap Disadvantages Difficult to work - hard / stiff Dark oxide layer - porcelain colour issues Metal sensitivity / allergies Corrosion Examples Nickel chromium - softer than co-cr, nickel lowers melt temp = smoother. But nickel sensitivity = contact dermatitis Cobalt chrome - high strength, hardness and elasticity, technique sensitive casting due to porosities Titanium - mainly used in implants

Indications and contraindications of ceramic veneers

INDICATIONS Changing shape and sizes - Peg laterals Traumatic damage Minor alignment issues --> not common but alternate to ortho; quicker but carries biological restorative burden Colour change - however they aren't very good at changing colour, attempt bleaching first. eg useful in surface defects / hypocalcification or tetracycline staining (ie these cannot be completely resolved with ext bleaching) Largely intact tooth with abundant buccal enamel Less destructive than crown; and More durable than RC, resistant to stain and wear and tear CONTRAINDICATIONS Caries, perio and other Unresolved disease Heavily restored broken down tooth lacking enamel Labially proclined teeth àveneers will make them thicker Moderate to severe alignment issues Severe discolourations Parafunction / bruxism Unrealistic expectation / body dysmorphia "Direct (cant do directly with porcelain, would need RC veneers)"

Indications and Contraindications of RBB

INDICATIONS - Missing incisors Missing premolars - abutment tooth prepared for conservative 3/4 crown Patient factors FPD (rather than rpd) health, space, age, cost Provisional; pre-implant young pt (ie 5 - 10 years) Apprehensive pts à eg nervous about surgery / implants Pt expectations Abutment tooth selection Pulpal/perio health Sufficient enamel Minimally restored à don't bond well to composite Minimal wear Minimal incisal translucency à eg backed by metal = will see this through a translucent tooth = poor aesthetics Ovoid/square form. Avoid triangular/conical form à youll see the metal travelling through triangular space Occlusal features à ~10 kg of forces at incisors, 40kg at pm, up to 80kg on molars; hence not a good option for molars Minimal overbite Increased overjet Consider static and dynamic occlusion Consider dx wax-up Adjust opposing teeth? Avoid parafunction Ridge form Either, low smile line Or, no horizontal ridge defect Ideally papilla present Ovate pontic, Or modified ridge lap CONTRAINDICATIONS - must exclude cases likely to fail to increase your success rate. Parafunction (bruxism, nail biters, pen chewers) Deep overbite (occlusal forces on pontic, loss of enamel) Short clinical crowns (reduced surface area) Triangular abutment teeth (reduced sa, aesthetics) Cervical constriction with loss of papilla (perio) Apical contact zones with pointed cuspsheavily restored teeth (consider conventional crown w cl) Horizontal ridge defect and exposed gingival margin à shadows / problems masking transition from neck of pontiff to bridge. May consider grafting /bulking up the bridge, or a rem pros with a flange

Indications of acrylic RPD

Indicated as immediate partial denture, transitional denture or provisional denture. Primarily indicated to replace missing anterior teeth, Provide aesthetic, phonetic and functional convenience. Works much better for the maxilla, Very compromised on the mandible Immediate denture Following tooth/teeth extraction Anticipated alterations and relines Accommodate further residual ridge resorption Transitional denture Preparation for complete edentulism Very few teeth present Completely mucosa supported denture If the remaining teeth have poor prognosis Future extraction is inevitable Training for complete denture Diagnostic denture Part of treatment planning Evaluation of increasing vertical dimension Evaluation of phonetics Provisional (interim or temporary) denture Minimal period of function Young patient - Accommodate growing jaws / Dentition development

Indications, contraindications, pros and cons of PFM restorations

Indications Teeth that require complete coverage Aesthetic demands Extensive tooth destruction; eg caries, trauma, RCT teeth, cast postcores Durability; eg bruxers / wear cases Implant supported restorations Bridge abutment Indirectly restored denture abutments Contradictions Active caries or periodontal disease Young patietns with large pulp à need more conservative option If suitable for other more conservative treatment Advantages Combines best of metal + porcelain - metal fit / strength and porcelain aesthetics /hardness Strength of case metal but aesthetic of all ceramic Excellent aesthetics with good preparation / lab technique Superior marginal fit Correction of axial form High success and survival in general - 90%+ success over 10 years Hence done well / careful case selection = 1% failure rate per year. (Metal > PFM >> Ceramic) Disadvantages Significant reduction for material requirements; Need 1 - 1.2mm of porcelain for aesthetics; ie opaque layer to mask metal and translucent porcelain for "depth". Insufficient space = grey, lifeless. 2mm + = easily fracture Subgingival margins for aesthetics All ceramic better aesthetics Cost Aesthetic considerations Excellent aesthetics are achievable. Compromised appearance is due to Insufficient porcelain thickness (axial / marginal reduction) Poor margin placement Gingival recession post treatment (hence must arrest perio before treatment)

Indications and contraindications of denture reline

Indications - Loose denture Poor retention and stability Food accumulation under denture Easy dislodgement during normal function Under extended denture peripheries Traumatized mucosa Following immediate denture insertion In conjunction with denture repair (eg denture fracture) Acceptable denture appearance (ie if ugly / patient unhappy - remake denture) Contraindications - The following are better off with anew denture / will not be corrected via reline. Very old denture Gross occlusion errors Worn out dentition Severe discrepancy between centric relation and maximal intercuspation Loss of vertical dimension of occlusion (more than 7 mm) Unacceptable denture appearance Denture related speech problems

Indirect vs direct posts

Indirect Pros • Fits any shape canals • Good retention • Anti rotation → prep not perfectly round hence post locks in with prep • Reduce the requirement to prep → its made to the existing prep Cons • Extra appointment (leakage?) • More technique sensitive • Higher cost → cost more because you need to pay lab to cast alloy Direct Pros • Matching shape drills • Non metal post • Metal post • Passive vs active Cons • Round cross section (no anti rotation) → no anti rotation resistance / it can spin

What maintenance / repairs of RPD may be needed? How can we complete the repair?

Keep in mind not all repairs are possible and not all repairs ensure longevity - consider if it is worth repairing or replacing instead Pick up impression - ALWAYS take a pick up impression w alginate To relate the partial denture to the dental arch Ensure the RPD is fully positioned on teeth and tissues Opposing Arch Impression - Not needed for every repair; Required whenever the repair will influence the occlusion of the RPD. eg Rest repair Occlusally approaching clasp repair Tooth/teeth addition / repair 1. Resin Repairs - Resin fracture can be related to accident, occlusal overloading or inadequate thickness If the broken part is available, it can be reassembled back. Preferably sent to the laboratory (more durable if done by technician). a) flange fracture - relieve 1 mm of resin fitting surface. Broken flange built with green compound material. Reline + pick-up impressions taken + Sent to laboratory Clinic repair Can be built chairside by self-cured acrylic b) Denture tooth fracture - Can be caused by Inadequate framework design Poor occlusion scheme Poor handling by the patient (eg bruxism) If the tooth is detached from the denture, a rapid chairside repair can be performed using self cured acrylic resin - just make some holes / grooves but not as predictable as other repairs Mechanical retention can reinforce the chemical bond Alternatively can be sent to laboratory for repair or new tooth placement 2. Metal Repairs - Occurs for thin framework sections- eg major connector is rarely effected usually Clasp Rest minor connector a) Fractured clasp arm - For most cases, clasp fracture can be repaired by wrought clasp addition Embrasure clasps are more difficult to repair Circumferential clasp can be replaced by gingivally approaching bar - Incorporated in the resin without affecting the occlusal surface; Pick-up impression is mandatory but no opposing impression Replacement of failed circumferential clasp (akers clasp) - Opposing impression is needed - can have a discussion with the technician if not sure what can and cant be done as difficult procedure. Fractured component wax-up, Casting the component separately, Laser welding or soldering the component to the original framework. Can be costly, and making a new framework is indicated b) Occlusal rest fracture - Due to inadequate tooth preparation or over adjustment / very thin metal (minimum 1mm thickness). Rest seat should be reprepared Wax and cast new rest seat Soldered or laser welded to the original framework c) Tooth addition - Fill a space created by denture tooth loss or extracted natural tooth Pick-up impression Opposing arch impression Jaw relation record Laboratory addition The metal connector can be modified to establish mechanical retention d) Fractured Major Connector - Rarely worth the effort of repairing as usually a sign of a bigger design problem. Mandibular sublingual bar can be repaired by soldering or laser welding Plates are almost impossible to repair If the major connector is bent Can be sectioned and repaired after pick-up impression 3. Relines Indications Ridge resorption Following recent extraction or surgery Increased denture mobility Poor denture fit The metal framework should be properly fitting; if not fitting or broken then don't reline Can be laboratory or clinical (but clinical difficult must be very experienced) Ensure even space is available (1-2 mm) for reline resin Options - Temporary (tissue conditioner) Improve the fit temporarily or diagnostically Allow for healing of mucosal injury Following surgery Prior to definitive denture treatment Permanent (hard acrylic) - good option if area is stable enough Steps chairside reline - avoid unless very experienced Relief the acrylic fitting surface Mix the resin according to manufacturer instructions Apply the resin on the fitting surfaces Correctly seat the denture in position All rests should be well positioned Pressure should be applied on indirect retainers Border mould the peripheries Avoid undercut engagement with hard resin otherwise denture will get stuck in the mouth / traumatise patient. Remove excesses and polish the resin surfaces Steps (laboratory reline) Relieve the acrylic fitting surface Ensure the borders are relieved (2 mm) Apply PVS adhesive on the fitting surfaces Correctly seat the denture in position All rests (and indirect retainers) should be well positioned Border mould the peripheries Keep in mouth until fully set. Jaw relation record Pick-up impression Opposing arch impression 4. Occlusal adjustment - Loss of occlusal contacts due to occlusal wear and sinking of the denture following alveolar ridge resorption Do in conjunction with reline. The fitting surface should be relined first, followed by Jaw relation record Pick-up impression Opposing arch impression New acrylic teeth placement

List and describe pros and cons of different cements for a permanent indirect restoration

LUTING - Relies upon mechanical resistance and retention form to retain crown Cement is space tfiller to prevent microleakage. Luting agents commonly used: Polycarboxylate cement Zinc phosphate cement Glass ionomer cement Composite resin Zinc phosphate cement Advantages Long controllable working time Thin cement thickness Easily removed Disadvantage Potential irritant to the pulp Short setting time Opaque Polycarboxylate cement Advantages Adhesive properties Thin cement thickness Low irritant to pulp Disadvantages Opaque Can be difficult to mix Low compressive strength Glass ionomer cement à we tend to use it for gold Advantages Good biocompatibility Low solubility Releases fluoride Relatively non-irritant to the pulp Adheres to dentine and enamel Disadvantage Prone to moisture contamination Can sometimes irritate pulp because acidic in nature BONDING Bonding Utilises chemical bonding to help retain crown Requires enamel for bonding Mechanical resistance and retention form is advantageous Resin-based cements Advantages: Can be used as a luting and/or bonding agent Low solubility Can bond to enamel with good bond strength Disadvantages: Prone to moisture contamination Difficult to remove once fully polymerised Can be difficult to handle

Challenging dentitions that may warrant referral

Large overjets Shallow over-bites Steep curves of Spee Anterior open bites Shallow condylar inclinations Steep curves of Wilson

Types of dynamic occlusion

Lateral excursive movements - canine guidance; all teeth except canines discluded as move up the slope of the canine. ideal occlusal scheme as canine roots are robust / designed to take this force - group function: in absence of canine guidance lateral movements guided by slopes of cusps of posterior teeth; hence both posterior and anterior contact during movement. leads to fracture as teeth not designed for these angled forces Protrusive movements - incisal guidance: overbite / overjet of incisors influences forward movement of the mandible - condylar guidance: lack of teeth results in protrusion being limited by the angle of the articular eminence

Outcome of veneers

Layton and Walton Feldspathic only (weakest but most aesthetic) 96% at 5 to 6 years, 93% at 10 - 11 years, and 73% at 15 to 16 years à best case scenario though because they are the best 2 in Australia so their success rate is higher. Good up to 10 years but goes down hill after that Reasons for failure - aesthetics 31% (à problem since the reason people get them is for aesthetics), mechanical complications 31%, periodontal support 12%, loss of retention 12.5%, caries 6%, aand tooth fracture 6% Keep in mind above data is per veneer so if you do 8 veneers it will be 0.93 to the power 8 = 56% at 10 years. à Must discuss this with patients. Say best case scenario for 10 years is 92%; can fail due to ______

Pros and cons of metal and acyrlic RPD

Metal RPD advantages (ie. major advantages of metal vs acrylic hence always try to recommend metal if patient can afford it) Hygienic (the metal is less plaque retentive than acrylic) 50% survival in 10 years Favourable support: tooth or tooth and soft tissue supported More comfortable More resistant to fracture Less bulk Transmission of heat Support Stability Patient comfort is more likely Disadvantages of metal RPD- more costly, time consuming and more complex Advantages of Acrylic RPD Low cost (can be ½ - 1/3 of the cost of a cobalt chrome / metal denture) Ease of fabrication / less steps are involved for acrylic RPD - only need 1 acceptable impression Quicker fabrication Ease of adjustment Ease of tooth/teeth addition No tooth preparation Problems of Acrylic RPD - discouraged as first line of treatment 50% survival in 3 years Unfavourable support: soft tissue supported Poor support - The RPD support is obtained from the underlying mucosa and gingival tissues, No or minimal tooth support, Can lead to poor occlusion stability / gingival and mucosal trauma Periodontal damage - Gingival margins coverage, Physical stripping of the gingiva Damaging lateral forces: due to limited bracing Interdental wedges Unhygienic (more coverage of gingival margins and more plaque retentive) Not self cleansable Enhance plaque formation on teeth Enhance food impaction Increase risk of oral fungal infection Rigorous maintenance and oral hygiene are mandatory Acrylic partial dentures excessively cover the gingival margins and primarily supported by soft tissues Commonly poorly designed (due to limited design options) Residual ridge resorption Made of weaker and less rigid material More likely to flex and fracture during function More bulky than metal RPD Compromised patient tolerance

Materials for CAM

Metals - limited to less precious metals due to subtractive nature of milling, eg titanium cobolt chrome, and their alloys. Resin Bondable ceramics - leucite and lithium discilicate (empress / emax) Infiltration ceramics - porous ceramic structures are milled and subsequently infiltrated with ianthanum glass Oxide ceramics - extremely dense high purity copings, aluminum oxide or zirconium oxide

Monolithic vs layered ceramic

Monolithic • One piece, pressed or CAD CAM • better strength • Easier and faster to fabricate • Poor translucency / aesthetics, poor marginal fit • Indications - high loads/ parafunction, low aesthetic area, bridges Layered • Core ceramic and outer layers, pressed, CAD CAM, conventional layering • Poorer strength • Longer to fabricate • Better translucency / aesthetics, better marginal fit • Indications - high aesthetic demand, translucent / unusual appearing teeth

Indications, pros and cons of Zirconia

No glass matrix, only fillers Advantages • Strength comparable to steel = can be thin prep • Aesthetic • Good fracture toughness due to crystals changing phase and compressing the crack • Biocompatible • increased hardness • wear resistant Disadvantages • No bonding • 25% shrinkage on cooling • not etchable

Metal alloys classifications

Noble metals - gold or platinum group • High noble - at least 60% noble metal content • Noble - at least 25% noble metal content • Predominantly base metal - less than 25% noble metal content Classification of alloys • Precious = high noble • Semi-precious = noble • Non-precious = predominantly base metal

Types of clasps and indications

Occlusally approaching clasps (Only one third of the clasp is engaging the undercut, Generally more hygienic because not touching soft tissue, Less aesthetic. Good for molars, hard for premolars because shorter arm) 1. Circumferential (Aker's) clasp - Most simple and versatile clasp The retentive arm begins above the height of contour and curves and tapers to its terminal tip The distal 1/3 of the arm engages the undercut Advantages Excellent bracing qualities Easy to design and construct Less potential for food accumulation below the clasp Disadvantages More tooth coverage Metal display 2. Ring clasp - Encircles nearly the entire / majority abutment tooth Used for tilted molars when undercut next to edentulous area The undercut is next to the edentulous area Supporting strut on the non- retentive side and auxiliary rest seat on the opposite side are highly recommended Advantages Excellent bracing Allows use of an available undercut adjacent to edentulous areas Disadvantages Covers a large area of tooth surface Needs additional rest Very difficult to adjust If poorly designed the mechanics will be compromised 3. Embrasure (double Aker's) clasp - Used in quadrant when no edentulous area exists Composed of 2 rests, 2 retentive arms and 2 bracing arms Double rests are needed to prevent weakening of clasp arms, separation of teeth and food impaction Buccal and lingual occlusal proximal areas must be reduced to provide room and avoid occlusal interferences The proximal contact should not be opened Should be used with discretion (only if there is not other option) Advantages Allows for direct retainer placement where none could otherwise be placed Disadvantages Extensive interproximal reduction Covers large area of tooth surface 4. C-clasp (reverse action clasp) The retentive area is adjacent to the occlusal rest As alternative to ring clasp Advantages Uses undercut adjacent to edentulous space Disadvantages Difficult to adjust Not aesthetic Difficult to fabricate Covers extensive tooth surface Food trapping Limited flexibility Gingivally approaching clasps (anterior or PM only, Contact the tooth at its tip, Less influence on occlusion Less hygienic More aesthetic. need sufficient depth ~4mm e.g. not suited if shallow sulcus or prominent frenal attachment) Usually I bar but variations possible (T or Y) Specially designed clasping system 1. RPI system - R: Occlusal rest P: Distal guide plate I: Gingivally approaching I bar Difference between RPI and normal I bar - the rest. Allows vertical rotation of the distal extension saddle into the denture bearing mucosa under occlusal loading without disengaging the supporting structures of the abutment tooth As the saddle is pressed in to the mucosa, the denture rotates about the point close to the mesial rest seat The plate and the I bar disengage the tooth Eliminating the potentially harmful torque on the abutment tooth Indications: Free-end saddle area (class I and II) Premolars Presence of buccal or mesiobuccal undercut Compromised abutment tooth Contraindications Insufficient vestibular depth (4 mm from gingival margin) No labial or buccal undercut on the abutment Severe soft tissue undercut Distobuccal undercut (less than 180 degree encirclement) 2. RPA system Same principles to RPI but Aker's clasp 3. Combination clasp - similar location to the cast circumferential clasp The retentive arm is fabricated from a round wrought wire (platinum-gold-palladium alloy) Wrought wire is round in cross section (more adjustable than 1⁄2 round) Better aesthetics (round and small diameter) Can be placed in deeper undercut (0.5 mm). I.e. allows for lower placement Engage deeper undercut, less lateral forces on the tooth

Considerations of overprepping and underprepping

Over preparation o Biological - risk of pulp degradation / biological width violation o Mechanical - compromised mechanical or chemical retention and resistance o Aesthetics - plenty of room for aesthetics Under preparation o Biological - over contour of axial surface / embrasure - risk of perio o Mechanical - structural durability issues, insufficient thickness for functional occlusion or material strength o Aesthetics - insufficient thickness to develop shade / translucency

Pros general treatment objectives

Preserve remaining teeth and supporting structures Restore aesthetics and phonetics Restore and/or improve mastication Restore health, comfort and quality of life

RPD Construction Steps

Primary impressions Diagnostic casts Surveying RPD design Tooth preparation Definitive impression Framework casting Framework try-in Jaw relation record Teeth set-up RPD try-in RPD Processing RPD insertion RPD review

What are the criteria for a satisfactory primary impression?

Proper extensions Well rounded borders / margins Adequate detail of tissues (particularly frenum) Tray or border wax minimal or not showing through The material should be firmly attached to the tray No significant contact between the tray and soft tissues or teeth No large voids or tears in the impression All critical anatomy should be well recorded Well-recorded sulcus Full denture fabrication MUST have fully extended borders however for other purposes depending on function it may not matter as much

Material of provisional restoration

Protemp (bis acryl) Most common, more of a composite than acrylic Autocures via base activator system Brittle Surface hardness Polymerization shrinkage Oxygen inhibited layer Limited ability to make additive changes Leave in mouth for 1.40, sets at 2.50 so if leave long à polymerisation shrinkage may make it difficult to remove the prep PMMA Exothermic reaction High polimerisation shrinkage Difficult to handle Has good flexure strength Readily adheres to itself Composite resin High conversion rate Hard to cure the thickness of material

Recording occlusion

Recording vertical jaw relationship: (ie VDO / freeway space) using pre extraction records, or physiological methods such as willis gauge (records VDO at rest from nose to bottom of chin) Recording horizontal relationships: (MIP or centric relation); if enough teeth present can hand articulate (need tripod / 3 widely spaced points), otherwise use registration rim Recording dynamic relationships: Record transverse hinge axis (ie pure rotational movement of md) via facebow. Simulating funcitonal relationships + mandibular movements - Articulator

Advantages of resin bonded bridges

Relatively minimally invasive (potentially reversible) → usually pt driven, eg no prep if pt is planning on getting an implant but need to wait .• Cost effective → 1/3 of cost of implant • Long lasting - but only with good; o Case selection/treatment planning o Preparation design o Laboratory techniques o Clinical technique

Tooth replacement options

Removable partial denture Fixed prosthesis (bridges?) Implant prosthesis Shortened dental arch Complete dentures Combination

Assessing restorability of a tooth for fixed:

Remove all restorative materials from tooth and assess remaining structure If minimal structure inform pt of questionable prognosis and alternative tx options. If adequate tooth structure discuss restorative options (must have adequate ferrule, and adequate structure to build in resistance and retention) Other factors that might influence your decision include: pt expectations aestehtics finances perio - PD mobility abscess bone loss furcation involvement endo concerns systemic factors eg smoking use of BP (less likely to exo) etc

Biological factors of tooth prep

Retention form - resists dislodgement vertically / along path of placement - Angle of convergence - Parallel walls ideal; large loss of retention in first 10 degrees of taper. Aim for a taper ~6degrees to reduce undercuts, enhance access and facilitate cement escape - Surface area - increase height and diameter increases retention. Hence posteriors / full coverage better retention than anteriors / partial coverage - Cement factors - cohesion / adhesion, elasticity, film thickness, handling properties, aesthetics, sensitivity Resistance form - enhance stability / resist dislodgement in any other axis but the path of insertion or resistance to rotational movement - Parallel walls ideal; large loss of resistence in first 10 degrees of taper - Height:width ratio - greater the height:width ratio the greater resistance - Can add resistance via auxiliary features Increasing retention and resistence - Bonding - found crowns adhesively bonded with poor retention vs good retention features displayed comparable survival. Bond strength to enamel / resin did not deteriorate after 4 years but dentine bond strength did - hence importance of enamel margin as poor dentine - resin bond - Increase prep height... Occlusal lengthening: Core restorations Purpose - blockout undercuts, reduce casting weight, assist with retention / resistance (if using for this purpose do not rely on bonding alone, must be mechanically retained), and shade modification. Orthodontic Extrusion - Slow extrusion to bring attachment with it. Time and $$$ Apical lengthening: Subgingival margins Problems - isolation, cementation, cleanup, biological width Crown lengthening Increase crown decrease root Aesthetic implications Morbidity / healing time Root contours / constriction

Techniques of tissue management and moisture control in secondary impressions

Retraction- Sometimes the gingival margin will interfere with accurate impression of margin of prep; so may need to create space / push the soft tissue away. Intelligent margin placement - best if avoid retraction. Aim for supragingival margins, must be justified in sub gingival; eg short crown needs more height Displacement Removal Retraction cord (double cord technique - 000 then 0) - Classic technique of making way for impression material Vary in sizes Impregnated vs non impregnated - soaked in medicaments / hemostatic agent Braided vs knitted Retraction/hemostatic paste Expasyl Aluminium chloride containing injectable clay Good hemostatsis, average retraction Gum removal - More aggressive tools of soft tissue removal à risk of recession Trichloroacetic acid (TCA)- corrodes / quarterises gum tissue. Electrosurgery Laser High speed ceramic bur These could lead to bleeding à cant take impression anyway Saliva/tongue control Wash and dry Cotton roll Dry guard Suction Dry it like you are about to do composite on it... But the most important tissue management strategy is healthy soft tissue à much easier to move / less bleeding than inflamed tissue. Hence promote good OH.

Classification of RBB

Rochette bridge - macromechnical perforations; used pre predictable resin bonding to metal; Maryland - bonded to 2 teeth, opposing forces = wobble = one of them debonds leading to decay occurring underneath one of the wings Resin bonded bridge - macromechanical retention / grooves and slots. Like a half crown

Treatment options for partial edentulism

Shortened dental arch - An occlusion with no molars PM to PM. Can function well / aesthetics not effected. A minimum of 8 occluding pairs (up to first premolars) RPD is not necessarily indicated No implications on Masticatory efficiency, Oral comfort, Signs & symptoms of mandibular dysfunction Most patients can function with shortened dental arch RPD does not usually improve function if minimal occlusal units are restored Prosthetic replacement should be left to patient preference Removable partial denture - Lengthy edentulous span > 2 posterior teeth > 4 incisors One canine and 2 other contiguous teeth No posterior abutment for fixed partial denture Bilateral edentulous areas Excessive alveolar bone loss Complete denture treatment can be postponed Reduced periodontal support to support bridge Need for immediate tooth replacement Affordable Fixed partial denture (bridge) - For few teeth replacement Requires sound abutments at both ends of the edentulous area Adequate ridge and bone level in the edentulous area Much more hygienic than RPD More expensive Invasive to teeth Indicated if the abutment teeth are restore Implants - Prosthodontic anchorage units Implant supported prosthesis In many cases, ideal treatment option Indicated if the adjacent teeth are not restored or minimally restored Suitable if there is no distal abutment Closest replacement to natural teeth Costly Implant retained bridge à issues with differential movement also apply to implants; likely to debond and lead to caries if there is a tooth and an implant as abutments as the tooth can move but the implant will not. Hence for fixed - implant + tooth = NO. Or any of the above in combination with eachother

RPD design principles

Simplicity - Repairable Maintainable + Easily handled by the patient Excessive use of clasps should be avoided Conservative - Aim for comfortable RPD; Less coverage and less RPD bulk are preferred, Minimal interference with patient occlusion Strategic - Should consider prognosis of remaining teeth and accommodate for future modification of the patients dental condition, eg Loss of more teeth / Future reline / Implant placement Hygienic - Minimise consequences of RPD (increased likelihood of Plaque accumulation Caries Periodontal complications Mucosal inflammation) Aesthetic

Reline Methods

Static (closed-mouth technique) - denture sent to the lab - rubber-based material (PVS or polyether) - functional (send patient home with conditioner so they eat with the denture) then denture sent to the lab - Tissue conditioner Chairside - Self-cure resin (acrylic)

Types of static occlusion

Static occlusion - occlusion at rest. Divided into ... Maximal intercuspal position (MIP) The complete intercuspation of opposing teeth, independent of condylar position; aka position where the teeth fit best with opposing arch MIP is reproducible Dependant on teeth - where they fit / wheres comfortable Occurs at specific VDO Centric relation à key points; free from teeth, guided by joints, reproducible Maxillomandibular relationship, independent of tooth contact, in which condyles articulate in the most anterior superior position against the slopes of the articular eminence. In this position the mandible is restricted to purely rotary movement. à aka advantage - can reproduce EVEN when no teeth, based purely on features of the condyle Centric relation Is a border position It is a reproducible position; particularly useful if minimal / no tooth contacts Centric relation serves as a reference position for establishing the occlusal relations. Guided by jaw and ligaments

List the components of RPD

Support (resistance of vertical movement towards tissues) - Rest seats - Ridges - Palate Retention (resistance of vertical dislodging forces) - Direct - clasps, muscular control, adesion - Indirect - free ends, rests, palatal coverage, lingual plate Bracing and reciprocation (resistance to horizontal forces applied to the denture during function. Controls lateral forced delivered to the PDL) - Reciprocating arms - Minor / major connectors - Flanges Major connectors (unifies the denture) - Maxillary - palatal plate, mid palatal strap, ring plate, anterior palatal strap - Mandibular - lingual bar, sublingual bar, lingual plate, dental bar, labial bar Minor connectors (connects components to major connector)

Types of temporary cement and their features

Temp bond (zinc oxide eugenol) Pulp sedative / settles pulp Not adhesive - just a space filler; can only use in retentive preps Sets faster with water Cannot use with resin material Durelon (Polycarboxylate - zinc oxide / polyacrylic acid) Similar chemically to GIC Adhesive - use with non retentive preps Difficult to handle, avoid use Moisture sensitivite Long setting time Difficult to remove à hence if planning on reusing the crown do not use duralon

Define ferrule, what are factors influencing the success of a ferrule?

The ability of the definitive restoration to brace solid and sound remaining tooth structure Critical for long-term success - Ferrule height - For effective ferrule, a minimum height of 2.0mm dentine is recommended. The more remaining core height, the higher the fracture resistence - Ferrule width (remaining dentine thickness) - >1.0mm dentine wall thickness - Number and location of walls and ferrule; ie BL more important than MD; if two adjacent walls missing higher risk. - Type of tooth (shape and location) and the extent of resultant lateral loads

Purpose of post

The sole purpose of the post is to retain the core. If it is not possible to retain the core restoration using conventional means (mechanical locks, pins, adhesion etc), additional core build up may benefit from a post for retention from the pulp space within the tooth Does NOT retain crown or strengthen the tooth The intra radicular anchorage (post) supports the core build-up, which in turn supports the eventual coronal restoration à post does not directly retain the crown . The core (residual coronal tooth structure +/- core restorative material(s)) is designed with retention and resistance form for the crown. A post does not retain the crown. A post does NOT strengthen a tooth - Has the potential to weaken the tooth due to root dentine removal. Changes its fracture behaviour - fractures deeper and increases the risk of vertical root fracture.

Sequencing of a pros TP

Three phases involved: 1) Stabilization - Pre prosthetic phase, Primarily concerned with relief of pain and disease control. Failure of prosthodontic treatment can be, in many cases, due to inadequate mouth stabilization. eg Extraction, RCT, Periodontal debridement, OHI, etc 2) Rehabilitation - Prosthetic phase - Primarily concerned with consolidation of existing teeth and replacement of missing teeth, or Treatment related to aesthetic improvement such as indirect restorations 2a) Preliminary phase Involves treatment that will allow provision of definitive phase treatment e.g. Orthognathic surgery, pre-prosthetic orthodontics, implant placement Involves treatment to ensure patient is pain- free, comfortable and satisfied prior to definitive phase e.g. Adaptation to increased occlusal vertical dimension, aesthetic expectations 2b) Definitive phase: Involves provision of definitive restorations or treatment e.g. Tooth-supported restorations, removable prosthesis, implant-borne restorations What comes first? If both rem and fixed; removable pros treatment is designed first; but the fixed pros treatment is undertaken first as some aspects of the rem pros treatment will guide the fixed treatment (eg elements of fixed are undertaken in anticipation of the rem pros afterwards) Removable prosthodontics Features of rem pros treatment that will guide fixed pros treatment Tooth shade - It is important ot pick the shade (and mould) of the denture teeth first so that the fixed pros can be matched It is easier to match the shade of fixed to denture teeth than vice versa The selected denture teeth can be sent to the lab to help ensure colour matching Tooth mould Tooth position It is important to know the future denture tooth position so that any fixed crowns can be positioned accordingly (buccolingually, antero posteriorly, cervico incisally) Occlusal vertical dimension Similar to tooth positing, the OVD may need to be determined by the proposed denture tooth setup This may be necessary where the retained teeth need to be built up or reduced in height à eg think about rest seats in advance, best not to have porcelain where youre placing a rest seat, porcelain can wear and chip Path of insertion / removal The path of insertion determines how the denture will be inserted into the patients mouth. It needs to be determined prior to tooth preparation to ensure RPD features such as guide planes and undercuts can be accurately positioned on the fixed restorations Implants Can provide additional support stability and retention to a rem pros Implant positions are guided by the proposed denture tooth positions The position of the implants needs to be such that any attachments are contained within the outlines of the proposed denture design Removable and fixed prosthodontics Removable prosthesis design features that can be incorporated into fixed pros treatment Rest seats Guide planes Undercuts Precision attachments / bars à easier for the technician to put them in the crown and bridge for you than to do them in the mouth Considerations Care must be taken during tooth preparation to ensure adequate reduction for any features required for the planned removable prosthesis Fixed prosthodontics Material selection Removable prosthesis features required in teeth needing fixed prosthodontic treatment may also influence material selection - eg metal rest or guide planes; best not to have porcelain where youre placing a rest seat, porcelain can wear and chip What happens when the removable pros is not designed first? Failure to design the removable prosthesis first can lead to unnecessary complications Required removable prosthesis features not incorporated into fixed restorations Fracture of porcelain during rest seat preparation Perforation of crowns during rest seat preparation Incorrect guide planes re: path of insertion Incorrect tooth contour re: undercuts and/or aesthetics Shade mismatch between denture teeth and crowns 3) Recall / Maintenance Primarily concerned with monitoring and review of patient. Can include: Recall examinations Periodontal review Supportive periodontal therapy Oral hygiene/diet reinforcement

Bonding of veneers to enamel and to ceramic

To enamel Predictable - very little fluid / protenease that will break down bond to enamel; dentine more likely to break down Durable Good seal Preferably 100% margin Stiff substrate - eg ceramic tile glued to concrete (enamel) difficult to break bond; glue onto carpet (eg dentine) vulnerable to bending forces To ceramic Etchable ceramic only Lithium disilicate Leucite reinforced Feldspathic - ie need a ceramic that can bond really well; cant rely on non bonding ceramics eg zircona Strict protocol to achieve - silane bonding

Treatment options for single tooth replacement

Treatment options for single missing tooth - Denture 3 unit bridge - lifespan 10 years; failure due to debond, caries, or overload. Destructive. Maryland bridge - common, used because failure non catastrophic (debond - put back on every 5 years) Implant

Post cementation; try in, cement type procedure

Try in and cementation • Fit - via visual inspection or fit checker/PVS • Adjustment - Softlex disc or Sandblaster • Aim for passive seating Cement type • GIC • RMGIC Want GIC or RMGIC as impossible to have good dentine bonding down the canal but RMGIC expands when in contact with moisture • Self adhesive resin eg relyx unicem Clean the canal • Sodium hypochlorite may interfere with bonding • Saline/sterile water final rinse + dry with paper point • Specialised tip • Dip and seat • Don't use lentulo spirals because the cement will set before you put the post in → un fixable mistake, cannot clean out

Veneer preparation guidelines

Varies in shape Goal is to achieve enough space while removing as little as possible - Depth cut / Depth wheels / Additive approach (if making more than one veneer; we cut less and add more thickness) Stay in enamel as much as possible Space requirement (0.3 - 0.8mm) depends on - Material selection - Colour correction require 0.3mm per step (eg A1 - A2 = 1 step. A3 to a1 = 2 steps = .6mm. in these cases crown is a better choice; or you do something about the colour befre you prep) Margin - Light rounder shoulder or deep chamfer (0.3 - 0.5mm) No incisal reduction, or if you do must be at least 2 mm - usually only if trying to add to the incisal edge Decision about interproximal contacts - eg if just changing the shape buccally don't need to push interprox contact, if changing colour more likely to need to break it and hide the margin in the palatal; or if already has an interproximal resto more likely to break through it Buccal path of insertion Crown prep vs veneer prep: Palatal coverage Buccal path of insertion Lack of resistance form à ie requires bonding Structural removal à 16.6% removed if just buccal reduction 30% if incisal edge very conservative compared to crown = min 60%

Secondary impression materials, their pros and cons

Zinc Oxide impression paste (ZOE) - only used for edentulous patients or for relining Pros - Can record soft tissues at rest, sets in 5 minutes cheap, stable when set Cons - sticky, messy, difficult to manipulate, not elastic hence cannot be used in impressions with undercuts (ie for fully edentulous only), can be a problem for gaggers because needs to be in patients mouth for a decent amount of time Polyvinyl siloxane (PVS) PVS (regular or medium body used only) Indications - edentulous, RPD, or fixed. Pros - excellent physical and mechanical properties, accurate detail reproduction, good dimensional stability, Widely used, cannot mess up mixing as self dispense, only loading / impression taking Cons - polymerisation shrinkage and hydrophobic

Define immediate denture

any removable dental prosthesis fabricated for placement immediately following the removal of a natural tooth/teeth

Common materials used in fixed pros

• Cast Metal Alloys - Base, Noble, High Noble Alloys • Ceramics - Lithium Disilicate, Glass Infiltrated, Oxide (Alumina / Zirconia) • Acrylic / Composite Resin Reinforced • Combination of Ceramics and Metal (i.e. Porcelain fused to metal - PFM) • Combination of Resin and Cast Metal

Procedure of post

• Check restorability (ie if already had RCT / if tooth is suitable for endo) • Prepare canal to right shape - gently and hand turn • Verify length → perio probe down to the GP to measure where the post should end; control length and ensure the post reaches the GP (prepared adequately / no gap between post and GP) • Create a stop • Mold the post / canal portion - build a pattern in acrylic, ensure canal is instrumented properly / lubricated with hypochlorite or saline / use pumping action to avoid acrylic locking / getting stuck • Finish the core - trim into crown prep. Remove for investing and burning out • Temporize with cotton pellet and 2mm of cavit • Provisional - suck down since not enough structure to retain a temp • Stick gold in with cement • Then make a crown

Failure of resin bonded bridges

• Debonding; poor resistance/retention form? o Recement, or remake; o Consider why it debonded → over prepare = no macromechanical lock, into dentine = less reliable bonding than enamel • Wear-in vs wear-out • Colour issues; o Retainer - abutment discolouration o Pontic at gingival interface - shadows, cement staining • Biological; caries (2 wings), perio • Structural damage • Porcelain chipping/fracture,

Case selection of post

• Does it need a post? → if tooth doesn't have enough dentine height to retain a crown you'll need a post and core • Is it restorable with a post? • RCT. If not you're either bonding to dentine which is poor; or doing elective endo / not preserving tooth vitality • Does it have a ferrule effect common exam - "cuff", stops tooth from splitting; 2mm height of tooth structure, Ideally circumferential

How long should the post be

• Equal or greater than the crown length - Shorter posts (particularly shorter than crown length) have a greater risk of fracture .• 4mm apical seal • Modify your obturation length accordingly

Classification of posts

• Indirect - custom vs direct - prefabricated • Active or passive (active not used - drives / screws in; high risk of root fracture, passive = passively fits in canal and cemented) • Different material • Shape (parallel vs tapered)

Recementing resin bonded bridges

• Restoration surface metal wing must be air-abraded back to metal (lab) • Tooth surface residual cement must be removed remove "resin tags"? • Air abrasion ideal, but gingival bleeding inevitable; consider rubber dam placement, or tofflemire band • Repeated debonding common; design or bonding issue?

Design concepts of resin bonded bridges

• Single wing - more successful than double abutments o Cantilever design • Avoid double abutments • M-d pontic space o Normal dimension o Less than abutment Retainer wing coverage • Maximal sa/coverage • 80o+ degree wraparound • Replace old (stale) fillings • Consider crown lengthening subgingival margin/cord electrosurgery Technical features • Adequate material thickness o Non-precious metal - occlusal clearance (0.7mm) o All-ceramic - occlusal clearance (1.5mm) → if needs ortho can get them to set up this much clearance / space. Connector dimensions, min. POI/max. Retention Aesthetics • Retainer o Avoid incisal 2.0mm - translucent enamel o NP; opaque cement → helps mask effect of non precious alloy which will decrease the value • Careful shade selection o Involve lab/try-in → may overcompensate to camouflage the shadow • Pontic design o Ovate o Adequate ridge form o Ridge preparation • Modified ridge lap o Reduced buccal bone • Crown and root form o Vertical bone loss → may build in some pink porcelain or some root form to look like its just recession Ultra-conservative palatal chamfer • 0.3mm, remaining in enamel, metal can also be additive • Maximum palatal coverage • Palatal open bite ideal or 0.5 - 0.7mm prep clearance • Proximal groove (adjacent to pontic) - path of insertion → must have the grooves at the exact same inclination to ensure a single path of insertion • Additional grooves for retention and resistance - grooves w fine tapered bur Think about proximal groove and where it will be - will put it interproximally where circled - ensure metal cant be seen facially (not too close to the buccal + not too close to the incisal edge) Maximum palatal coverage • Except what is visible through incisal embrasure • Avoid incisal 2.0mm (translucent enamel) Palatal preparation • Remain in enamel • 0.7mm at occl contact • Metal may also be additive • Ideal is open bite, i.e. No prep Palatal open bite ideal. Or, 0.5-0.7mm prep clearance Proximal groove (adjacent to pontic) - poi additional grooves for retention and resistance Grooves w fine (0.8mm diam) tapered bur

Define mechanical properties tension, compression, stress, strain, flexure, elastic, proportional limit, modulus elasticity and strength

• Tension - "stretch" → most dent materials will fail under tensile stress; flexural strength more important • Compression - "squeeze" • Stress = force x unit area • Strain = how much deformation a body undergoes when subject to stress • Flexure - opposing forces at ends vs centre • Proportional limit - max stress after which permanent deformation takes place • Modulus elasticity - measurement of stiffness. Elastic materials will return to normal shape in response to stress, but stiff materials permanently deform • Strength -max stress material can withstand before fracture / permanent deformation

Materials of posts

• Type 4 gold alloy or PFM bonding alloy - strength in thin sections; but then you'll need a core that is opaque (ideal post is white) • Fibre post - Modulus of elasticity matching dentine • Stainless steel • Titanium • Zirconia

Gates glidden

→ used to remove GP when canal is filled • Side cutting intra canal drill • Removes GP mostly by heat (friction) • Make sure canal is dry • Depth control down to desired length • Most of the time use it up to size 3 • Do not push it