Dental Anatomy and Occlusion

LINE ANGLES

8 lines per tooth Formed by the junction of two crown surfaces (i.e. mesio-lingual, disto-buccal)

cross section of max. central incisor

A cross section of a central incisor will look somewhat triangular. (Think a triangle with softened corners.) • The root has no grooves or indentations, however the MESIAL aspect of the root can be flattened or slightly depressed.

Anatomical crown Clinical crown Anatomical root Clinical root

ANATOMICAL CROWN: Part of the tooth covered by enamel CLINICAL CROWN: Part of the tooth that is visible in the mouth ANATOMICAL ROOT: Part of the tooth covered by cementum CLINICAL ROOT: Part of the root NOT seen in the mouth

Neurocranium vs Viscerocranium

Neurocranium (houses the brain) Paired bones: Parietal Temporal Single bones: Frontal Occipital Sphenoid Viscerocranium (facial skeleton) Singular bones: Mandible Vomer Ethmoid Paired bones: Maxilla Inferior nasal concha Zygomatic Palatine Nasal Lacrimal **just know maxilla, mandible, and temporal bone locations

What do you notice are missing from primary dentition? (compared to the permanent dentition)

No premolars for primary

CERVICAL LINE :trends

Normally curved toward the apical on the facial and lingual surfaces Normally curved toward the incisal or occlusal on the proximal surfaces Depth of curve is greater on the mesial Depth of curve decreases as you go posteriorly **Curve is higher in mesial surface than distal JUST FOLLOW THE GUMLINE FOR THE ANSWER TO THIS

What change(s) do you observe in the open mouth image of the TMJ?

Note: the articular disc moves with the condyle along the articular eminence. the condyle is posterior in relation to the eminence when mouth is closed but when open its almost anterior to the eminence since it slides anteriorly along the eminence...note the articular disc follows the condyle so they both together do the movement

Occlusal Curvatures

Occlusal Curvatures Arrangement of the arches and the inclinations of the teeth - efficient use of the forces of mastication, stabilizing and protecting the arches. Curve of Spee Curve of Wilson Sphere of Monson (Compensating Occlusal Curvature)

which are the only teeth that arent SUCCEDANEOUS

Only Permanent MOLARS are NOT succedaneous teeth because they do not replace any other tooth

Which teeth have mammelons

Only central and lateral incisors have mammelons (and they wear away with time)

max. lateral incisors : facial view compared to max centrals? what record does it hold vs all incisors?

Overall, the lateral has a rounder outline than the central, with a rounded incisal edge and rounded mesial and distal incisal angles. • Incisal edge curvature is greater than any other incisor.

POSTERIOR TEETH

PRIMARY : Two Molars per quadrant Four teeth per arch (x2) = Eight total PERMANENT: Two Premolars per quadrant Three molars per quadrant Five posterior teeth per quadrant Ten per arch (x2) = Twenty total

ERUPTION STAGES

PRIMARY DENTITION PERIOD: when the patient only has primary teeth (6 months-6 years) MIXED DENTITION PERIOD: when the patient has both primary and some permanent teeth (6 years - 12 years) PERMANENT DENTITION PERIOD: when the patient has only permanent teeth

UNIVERSAL NUMBERING SYSTEM for permanent teeth

Permanent teeth #1 - #32 Upper right third molar = #1 Upper left third molar = # 16 Lower left third molar = # 17 Lower right third molar = # 32

SUCCEDANEOUS TEETH

Permanent teeth that replace primary teeth.

Proximal

Surface that is BETWEEN the teeth (Mesial or Distal)

how many arches and quadrants

TWO ARCHES FOUR QUADRANTS

Incisal view: max. central incisors incisal edge centered over? what does this mean for the view? shape? taper of crown and root? cingulum offset how?

The Incisal edge is centered over the root, and the HOC is in cervical 1/3. Therefore, in this view of the crown, no portion of the root can be seen. From this view the tooth is triangular in shape. The crown and root both taper lingually. Cingulum is offset toward the distal.

FACIAL (LABIAL) LINE ANGLES

The facial line angles of the anterior teeth and premolars in both arches more prominent than the lingual line angles. They are the facial termination of the facial embrasures, are located in the same location faciolingually, and account for the perceived esthetic shape of the teeth

Crown Surface Form what shapes

The geometric configuration of the crown surfaces of the teeth fall into trapezoidal, rhomboidal and triangular shapes. Facial and Lingual Surfaces: All are roughly trapezoidal - creating interproximal spaces and contact areas. Mesial and Distal Crown Surfaces: Anterior : Roughly triangular Maxillary posterior : roughly trapezoidal Mandibular Posterior : roughly rhomboidal

OCCLUSAL ANATOMY:

The groove and ridge pattern on the chewing surfaces of the teeth. Functional occlusal anatomy must be reproduced to pre-existing form in all restorative procedures.

HEIGHT OF CONTOUR

aka crest of curvature, is the greatest height of contour inciso (occluso)-gingivally on the facial and lingual surfaces when viewed from the proximal. The importance of these contours is critical to the health of the periodontium

How many root canals in #8 and #9

almost always one

with respect to what/who are you talking when you say left or right

always with respect to the Patients left and right not mine

Slightly open: hinge action What boney feature limits opening fully when using only hinge movement?

articular eminance

The condyle (head) meets with the ? to form the ?

base of the skull (cranial base) temporomandibular joint (TMJ) note that the specific bone that the condyle meets with is the temporal bone

Periodontal Ligament (PDL) goes into what

cementum and bone

rotation of condyle and disc during mouth opening and closing slightly what about during full mouth opening/closing or protrusion/retrusion

condyle rotates but stays in place due to eminence first condyle rotates then slides along eminence

Facial view: Cervical line shape for max. central incisor

evenly curves toward the root.

Widely open: hinge and gliding What type of movements are happening here?

first condyle rotates then gliding Occurs after the mandible opens more than 20-25mm condyle slides down (away from the mandibular fossa) to get around the articular eminence

Labial surface shape of max. incisor shape compared to other anteriors?

is less convex (and therefore more flat) when compared to the other anterior teeth. This makes the central incisor look more square or rectangular in appearance.

INCISAL EDGE resembles a

knife edge to allow for cutting/slicing during mastication.

Jawline

outline of the posterior aspect of mandibular ramus and inferior aspect of mandibular body

It is the ?, all or a portion of which, may suffer the consequences of ? forms or dentist induced (?) imperfections.

periodontium anomalous natural tooth forms iatrogenic

CROWN RIDGES: 5 types

Marginal ridges Triangular ridges Transverse ridges Oblique ridges Cusp ridges (Mammelons/incisors) Jeff RIDGES doing MTT in the OC Inclined Planes

Neck also called ? CEJ also called ?

NECK (Cervix) CERVICAL LINE: Cemento-enamel junction (CEJ)

The TMJ boney components include:

1. condyle of the mandible 2. articular eminence of temporal bone 3. Anterior aspect of mandibular fossa Interposed between the temporal bone and the mandibular condyle is an articular disk

International (FDI) Method converted to universal 1-8 (1st quadrant, 8th tooth) = ? (2-8 = ?, 3-8 = ?, 4-8 = ?) Primary 5-5 (5th quadrant, 5th tooth) = ? (6-5 = ?, 7-5 = ?, 7-5 = ?)

#1 #16 #17 #32 A J K T

Which is the widest of the anterior teeth mesiodistally?

#8 and #9, front incisors (right and left).

What is the exception with lobes of premolars

*EXCEPT - the mandibular second premolar which has three buccal lobes and two lingual lobes (mesial and distal) 5 LOBES IN TOTAL

PALMER NOTATION SYSTEM

1 - 8 Permanent A - E Primary 8 teeth in each quadrant Anterior to posterior (from the midline towards the back) Differentiated by quadrant symbols *pretend to be looking at mofoing patient ex. L1 = upper left central incisor 1_I= upper right central incisor

All succedaneous teeth are ? - but not all permanent teeth are ?

All succedaneous teeth are permanent teeth - but not all permanent teeth are succedaneous teeth

LOBES Anterior teeth VS Premolars vs Molars

All teeth in the human dentition are comprised of four or more lobes. Anterior teeth : three labial lobes (mesial, middle and distal) and one lingual lobe Premolars - three buccal lobes (mesial middle and distal) and one lingual lobe Maxillary molars Four lobes : Two buccal (mesial and distal) and Two lingual (mesial and distal) Mandibular first molar: Mandibular First Molars : Five cusps and five lobes (four standard and a distal lobe) Mandibular second molar: Four cusps and four lobes

Roots - Anterior teeth and premolars

Anterior teeth normally have single roots Premolars have one root, except the maxillary first premolar which has two roots - Buccal and Lingual

Directional vocab of TOOTH SURFACES of anterior vs posterior teeth

Anterior: Mesial Distal Labial (Facial) Lingual (Palatal) Incisal (edge) Posterior teeth Mesial Distal Buccal (Facial) Lingual (Palatal) Occlusal

Features of temporal bone

Articular Eminence Mandibular fossa External acoustic meatus Zygomatic process The mandibular fossa (also called glenoid fossa) is a depression or "valley" in the temporal bone in which the head of the mandibular condyle sits (articulates) The articular eminence is a "ramp" or raised area in the temporal bone, anterior to the mandibular fossa. It limits and guides movements of the condyle (and articular disc) The external acoustic meatus is the external ear canal The zygomatic process is an extension of the temporal bone that helps to form the zygomatic arch, which contributes to the prominence of the cheek.

eruption stages TIMING

Calcify in utero eruption of deciduous mandibular central incisor~6 months of age. eruption of permanent First mandibular molars at ~6 years old exfoliation of deciduous maxillary canine at ~12 years old

ROOT THIRDS

Cervical Middle Apical Mesial Middle Distal

Cervical line vs gingival margin vs epithelial attachment

Cervical Line is a stable entity - separates the anatomical crown from the anatomical root Gingival margin is a variable entity - separates the clinical crown from the clinical root Epithelial attachment - actual attachment of the soft tissue of the oral cavity to the tooth

Contact area movement as you move posteriorly

Contact areas move slightly to the facial and slightly to the gingival as you move posteriorly.

Curve of Wilson for both arches is

Convex for maxillary arch Concave for mandibular arch

Max central incisors: mesial view shape? incisal edge in line with what? cervical line? record it holds? HOC?

Crown is wedge or triangular in shape, with base of the triangle towards the cervix and the apex toward the incisal edge. • The incisal edge of the crown is in line with the center of the tooth. A line drawn through the crown and the root from the mesial aspect through the center of the tooth will bisect the apex of the tooth and also the incisal edge of the crown. • The cervical line curvature is greater on the mesial aspect than any other tooth in the mouth. • Height of Contour on both labial and lingual is in the cervical 1/3.

Crown elevations 4 examples

Cusps Tubercles Ridges Cingula(um) ELEVATE in RaC CiTy bitich

Mandibular Movements

Depression: opening the mouth Elevation: closing the mouth Protrusion: sliding lower jaw (mandible) anteriorly (forward) Retrusion: sliding the mandible posteriorly (backward) Lateral excursion: sliding mandible to the right or to the left

HETERODONT

Different TYPES OF TEETH Example: incisor, canine, premolar, molar

vital vs nonvital dental tissue

Enamel and cementum=non vital (don't have blood supply nerves lymphatics etc) Dentin, pulp etc= vital

HEIGHT OF CONTOUR facial vs lingual surfaces

Facial surfaces - the height of contour on the facial surfaces of all the anterior and posterior teeth is located in the cervical third. Lingual surfaces the height of contour in the anterior teeth is in the cervical third. In posterior teeth it is in the middle or occlusal third

POINT ANGLES

Formed by the junction of three crown surfaces (i.e. mesio-linguo-incisal, disto-bucco- occlusal) 4 points per tooth

CROWN DEPRESSIONS 4 examples

Fossa Developmental (Primary) Groove Supplemental (Secondary) Groove Pit

ROOT OF THE CENTRAL whats the problem with the root?

From labial aspect the root is cone-shaped. Blunt apex The root is 2-3mm longer than the crown. This means there is poor CROWN TO ROOT RATIO. • Crown to root ratio = the ratio of the length of tooth structure below the alveolar bone versus the length of the tooth structure which appears above it. A line drawn through the center of the root and crown tends to parallel the mesial outline of the root and crown.

PERIODONTIUM supporting structures (both hard and soft tissues) include

Gingiva Periodontal Ligament (PDL) Alveolus (the bony socket for the root of a tooth) Alveolar Bone (Alveolar Process)

MARGINAL RIDGES: height, etc

Height is equal to that of the adjacent tooth Shaped to create a small embrasure Symmetrical in nature and its relation to the adjacent tooth impacts greatly on the health of the teeth and supporting structures.

What are contact points and Why are contact points so important

In a complete arch each tooth touches or contacts two adjacent teeth (except the third molars) These are the CONTACT points. Normally the mesial surface of one tooth makes contact with the distal surface of the tooth immediately anterior to it. Central incisors make contact mesial surface to mesial surface why so important? Teeth need to have contact points so that food doesn't get between teeth (proximal surfaces) otherwise decay will set in ONE ABERRANT TOOTH CONTOUR CAN LEAD TO THE BREAKDOWN OF THE ENTIRE DENTAL MECHANISM OVER TIMEfperiod

Contact Area

In a complete arch each tooth touches or contacts two adjacent teeth (exception: the most posterior tooth)

PERMANENT DENTITION per Quadrant

Incisors (2) -- Central, Lateral Canine (1) Premolars (2) Molars (3)

PRIMARY DENTITION per Quadrant

Incisors (2) -- Central, Lateral Canines (1) Molars (2)

MAXILLARY CENTRAL INCISOR DEVELOPMENT

Initiation of Calcification 3-4 months Enamel Completion 4-5 years Eruption 7-8 years Root Completion 10 years ****no 69 for centrals

LECTURE #2

LECTURE #2

What are two ways to call a split down the middle sagitally

MIDLINE MIDSAGITTAL PLANE

Axial position - Mandibular arch root inclinations

Mandibular Anterior Teeth Roots have great lingual inclination and a very minor mesial inclination Mandibular Premolars Roots show some distal inclination and a slight lingual inclination for the first premolar and slightly to the buccal for the second premolar Mandibular Molars Moderate to great buccal and distal inclinations

Axial position - Maxillary arch root inclinations

Maxillary Anterior teeth: The root inclination is toward the lingual and slightly toward the mesial (Canine toward the distal) Maxillary premolars: Root inclinations are slightly toward the lingual and slightly toward the distal Maxillary Molars: Root inclinations are greatly toward the lingual and moderately toward the distal.

Roots - Molars

Maxillary Molars normally have three roots, one lingual and two buccal Mandibular molars normally have two roots, one distal and one mesial which usually has two canals.

Directional vocab for ROOT SURFACES

Mesial Distal Buccal, Labial (Facial) Lingual (Palatal) Apical

Contact points of max central incisors

Mesial: incisal 1/3rd Distal: junction of incisal and middle 1/3rd

TMJ movement guided by what Synovial joint:

Movement is guided by functional surfaces: 1. Articular eminence 2. Condylar process Interposed between the functional surfaces is the articular disc The position of the articular disc creates a superior cavity and inferior cavity within the joint Inferior cavity: between articular disc and mandibular condyle, allows for hinge/rotation around an axis Superior cavity: between articular eminence and articular disc, allows for gliding/translation This ability to perform both translation and rotation makes the TMJ a *ginglymo-arthrodial joint. Ginglymus = hinge Arthrodial = gliding two boney elements articulating, surrounded by a capsule, lined by synovial membrane

UNIVERSAL NUMBERING SYSTEM for primary teeth

Primary Teeth #A - # T Upper right second molar = # A Upper Left second molar = # J Lower left second molar = # K Lower right second molar = # T

ANTERIOR TEETH

Primary and Permanent Incisors and Canines Three per quadrant Six per arch (x2) = Twelve total

FEDERATION DENTAIRE INTERNATIONAL (FDI)

Quadrants labeled 1 - 4 permanent teeth 1: UR, 2: UL, 3: LL, 4: LR 5 - 8 primary teeth 5: UR, 6: UL, 7: LL, 8: LR Teeth labeled from midline 1 - 8 permanent teeth 1 - 5 primary teeth

translation and hinge around a vertical axis i.e. left lateral excursion (moving jaw to the left...What is happening at the right and left joints?)

Right condyle: protracted Left condyle: retracted and rotated around vertical axis it will be vice versa if moving jaw to the right

ROOT SHAPE :

Shape and number are directly related to the function of the particular tooth Normally widest at the cervical area and tapered toward the apical area

Axial Position

The inclination of a tooth in the vertical axis in a mesiodistal and faciolingual direction

Lingual surface: maxillary central incisors which thirds of the tooth from the lingual fossa? HOC? cingulum offset how? cervical line?

The middle and incisal portion of the tooth is concave and forms the lingual fossa. Mesial and distal marginal ridges make up the lateral borders of the lingual fossa. The cingulum is a convexity in the cervical 1/3 of the lingual surface. • HOC (height of contour) on the lingual surface of ALL anterior teeth is in the cervical 1/3. WHY? Cingulum is offset to the distal (not central). Cervical line is convex towards the apex.

EMBRASURES

The open space between two adjacent teeth, between proximal surfaces, where they diverge facially or lingually, incisally or cervically from the contact area, and are named according to location.

Interproximal Space

The triangular area between adjacent teeth and cervical to the contact area. Usually filled with that portion of the periodontium called the Gingival tissue, specifically the " Gingival Papilla". It has the alveolar bone at the base, the proximal surfaces of the teeth at the sides and the contact point (area) at the apex. The size and shape of the interproximal area depends on the form and location of its boundaries. The maintenance of this area is critical to the health of the entire periodontium

max. lateral incisors : lingual view whats bad about this view? what record does it hold with anterior teeth? cingulum?

There is a developmental groove (which is deep so this can make it easy to build plaque and therefore lead to decay) visible at the junction of the lingual fossa and the cingulum. • Deepest lingual fossa of any anterior tooth . • Cingulum is centered.

Incisors do have an incisal edge but DO NOT have

They do not have an OCCLUSAL TABLE, the wider, flatter surface of ridges and cusps of posterior teeth which functions as a food grinder.

Sphere of Monson

This curvature is combination of the curve of spee and curve of wilson

Embrasure spaces have 2 main physiological purposes:

To act as a spillway for food material during mastication To server as an integral part of the self cleansing process These two purposes are inter-related and tend to compliment each other in the protection and stimulation of the periodontium In the anterior part of the mouth embrasure form is a factor in the esthetics of facial appearance cervical or gingival embrasure=interproximal space

DIPHYODONT

Two separate SETS OF TEETH Example: primary and secondary

TOOTH TRAITS

Type Traits- Central Incisor vs. Lateral Incisors Arch Traits- Maxillary vs. Mandibular Set Traits- Permanent vs. Primary

Thirds of crown : Viewing from the Proximal vs Facial

Viewing from the Proximal : Labial, Middle, Lingual Buccal, Middle, Lingual Viewing from Facial: Mesial, Middle, Distal -Incisal, Middle, Cervical (anterior teeth) -Occlusal, Middle, Cervical (posterior teeth)

Purpose of incisors

slice/cut esthetics phonetics

What movements of the mandible might result from translation of the condyle? What movements of the mandible might result from rotation of the condyle around an axis?

sliding the mandible forward or backwards (protrusion and retrusion)=translation (gliding) depression and elevation

Diastema

space between teeth (usually b/w central incisors)

Terms of Relationship and Anatomical Planes:

superior, inferior, lateral, medial, anterior, posterior, sagittal, transverse (axial plane), frontal (coronal plane), median plane (aka midsagittal), occlusal view

View from the facial: max. incisor characteristics all angles/sides? dev lines?

the incisal edge is straight, the mesial edge is straight, the mesial-incisal angle is almost a right angle, the distal edge is curved, and the distal-incisal angle is more rounded. Developmental lines on the labial surface divide the surface into three vertical parts: distal, middle and mesial.

When we chew or speak, what part of our skeleton is actually moving?

• Movements of the mouth are driven by movements of the mandible • The mandible articulates with the base of the skull at the temporomandibular joint to allow for movement

Cervical line trend from anterior to posterior

• The cervical line curvatures decrease from anterior to posterior.