CD5, CAD/CAM in Operative Dentistry:

We need to avoid what things in our preps when using a cad/cam for our restorations? (think about what we have said we need)

-Avoid ferrule margins -Avoid sharp corners -Avoid spikes (it won't fully seat) -Avoid ski jumps/J-margins

According to Guy Fieri, what is the recipe for restorative fracture?

-Bad preparation design -Sharp cusp tips -Not enough reduction -Overmilling -Small ceramic thickness -Increased cement space -Sharp internal angles

What is the process of ceramic firing?

-Requires 2 stages -the milled block is put into a ceramic furnace under a vacuum to complete the crystallization process and achieve full flexural strength (500MPa, 70% crystal volume) -also at the same time, the color of the restoration changes to tooth color -zirconia undergoes further processing (sintering and glazing)

Principles for a cavity prep?

-Spend time getting an excellent prep rather than fair or poor and lot of editing -do not hesitate to go back and re-prepare some more -prep is the foundation for a good restoration -use vision magnification to evaluate the prep prior to final optical impression

What is the axial reduction in mm for a monolithic ceramic crown?

1-1.2mm

In a CAD/CAM there are 3 sequences involved: Digital Impression, Restoration Design, and Restoration milling. What occurs in each phase?

1-Digital impression: you take an intraoral scanner/camera to record hard/soft tissues 2-Restoration design: software is used to create a virtual restoration through biogeneric calculations 3-Restoration milling: computer-controlled device produces the restoration by drilling a block down

A CEREC system includes what parts?

1-Intraoral scanners (Bluecam, LED based) 2-OmniCam (3D scan, color-stream, powder-free, you can show these photos and videos to patients) 3-Chair-side computer with software and LCD monitor 4-Milling Unit (dry milling, wet milling, diamond milling burs)

What does a crown prep for a cad/cam restoration need to have?

1-Rounded internal line angles 2-Occlusal and Axial Reduction 3-Avoid undercuts so get rid if any are present (can block with a dentin substitute)

How does the bluecam CEREC intraoral scanner work?

1-Sprinkle powder on a brush and rub it through the patient's mouth 2-Take the LED-based scanner and run it through the mouth

What are some advantages to using a CAD/CAM?

1-not having to use traditional impression materials (especially severe gaggers) 2-Can digital send things to a lab 3-Single appointment for delivery of ceramic restorations 4-Esthetic restorations 5-The intraoral scanner can take videos and photos to document the patient's mouth and educate them

Is an inlay/only prep divergent or non-divergent?

Divergent with rounded internal angles and no sharp divots or concavities and a uniform reduction, no bevels

A (dry/wet) milling is used for zirconia blocks. A (dry/wet) milling is used for other blocks like an E.Max.

Dry-Z Wet-E. Max

T/F: You can only use a CAD/CAM to make a permanent restoration for teeth and implants

False you can also make provisionals

What is the clinical application of cad/cam?

Inlays, Onlays, Crowns, Veneers, FPD, Implant Abutments, Orthodontic appliances

How does the provider make sure to prevent overmilling?

Making sure that their preparation geometry has smooth contours, good flowing curves, and good transition angles

What is the difference between Overmilling and Undermilling?

Overmilling: machine cuts away more restorative material than needed to ensure it seats properly Undermilling: the machine removes less geometry, leaving more material that will prevent complete seating of the restoration

Guidelines for tooth preparation all-ceramic restorations are generally based on what?

Specific geometries and thickness dimensions to provide the best strength of selected material

Summary of steps so far:

Step 1: Scan Step 2: Design Step 3: Produce Step 4: Sinter and Glazing

How do inlay and only restorations stay on a prep?

They are primarily adhesive style preparations that rely on the adhesion of resin cement to dentin and enamel for retention (so a non-mechanical retentive design)

The smoothness of the prep's contour, rounded transition, and uniform pulpal floor plays a role in determining the restoration produced? T/F

True

________-________ is the largest cause of ceramic failures, so we need a minimum of 1.5mm of porcelain.

Under-Reduction (if you cant reduce 2mm, you need to choose another material like zirconia)

The proximal box shape of an inlay/only with cad/cam should have what requirements:

Walls taper 6-8° -nothing sharp, all rounded and smooth -no undercuts

Some cad/cam softwares require firing the milled restoration inside a furnace prior to the delivery of the restoration. What are two examples of this?

Zirconia Sirona & IPS Ivoclar E. Max

A zirconia crown only needs an occlusal thickness of _mm without compromising the strength of the crown.

1mm

When doing an anterior crown preparation and you are going to be making the restoration with a cad/cam you need to make sure you prep is reduced by how much?

1mm and flatter than normal -the labial by .5mm -0.5mm shoulder or chamfer margin

An inlay only has an occlusal reduction of __mm for functional cusps and __mm for non-functional cusps. They also have a prep isthmus depth of __mm to avoid fractures B-L.

2mm functional 1.5mm non-functional 2mm isthmus

We need an occlusal reduction of ___mm in functional cusps of glass-ceramic preps and ___mm in nonfunctional and central fossa

2mm functional cusps 1.5mm central fossa and non-functional cusps

For an anterior crown preparation, how many different incisal edge prep types are allowed?

3

Examples of chairside CAD/CAM systems:

CEREC OmniCAM MCX Milling PlanFit (D4D tech)

With the use of a CAD/CAM, you can deliver ___________ restorations in one day

Ceramic

What does CEREC stand for?

Chairside Economical Restorations Esthetic Ceramic

What does CAD/CAM stand for?

Computer-Assisted Design or Computer-Assisted Machining