CAD/CAM Chairside Review and Seating Flashcards
What is the sequence of clinical procedures for a CEREC restoration? (13 steps!!)
- Case Selection
- Preparation
- Powder
- Optical Impression
- Bite Registration
- Powder
- Optical Impression
- Design
- Milling
- Try-in
- Cementation
- Finishing
- Polishing
The exit angle for an inlay/onlay preparation is between ____ and ____ degrees.
90 to 120 degrees (closer to 90 is better)
Where do restorations typically fracture (internally) due to sharp angles?
the axio-pulpal line angle
Occlusal reduction depth is typically evaluated at the ______ but the critical dimension is at the ______.
wall margin (typically evaluated) central fossa (critical)
The basic design rule for CEREC optical impressions states that “all preparation surfaces must be ______ by the camera when oriented along the prospective line of insertion”
clearly visible
Which image (of the 3) will give you the path of insertion?
the first image
Images must overlap _____ with each other (which is approximately equal to 1/3 the camera lens length).
8 mm
What are you able to do in Master Mode that cannot be done in basic mode?
select the position of the sprue
Which CEREC mode can be used for 4-unit temporary FPDs?
Master Mode only
Which CEREC mode can be used for posterior teeth?
Both modes (basic and master)
Which CEREC mode can be used for anterior teeth?
Master Mode only
Which CEREC mode can be used for inlays and onlays?
Both modes
Which CEREC mode can be used for 3/4 crowns?
Both modes
In the “Normal” mill setting, the bur moves in increments of _____ microns. In the “Fast” mill setting, the bur moves in increments of _____ microns. Why not use “Fast” mode all the time?
25
50
Fast milling saves about 30% on milling time but the margins are prone to CHIPPING
What are the three considerations with shade selection?
- shade of prepared tooth
- shade of the restoration
- shade of the cement
(For example: the natural tooth is A3, the cement is yellow, and you want the final result to be A2 because the original tooth was too dark….make the crown color choice A1 because the yellow cement will darken the results)
True or False: Multishade blocks allow for differences of translucency in the crown.
True
True or False: The MZ100 blocks are round instead of square which allows easy identification.
True
What is the strongest block material?
zirconia
What is the strongest chairside block material?
eMAX (lithium disilicate)
What is the most esthetic block material?
empress
Are repairs on ceramic easy to make?
no, must etch with hydrofluoric acid which is very dangerous in a patient’s mouth
True or False: Lava Ultimate (the block material we practiced CEREC with) has a similar/higher compressive strength than other leading chairside materials.
True (compressive strength only, its elastic modulus is similar to dentin)
After retrieving the restoration from the milling unit, you would try it in, polish/glaze it, isolate the patient’s tooth, prepare the restoration surface, prepare the tooth surface, and apply a luting agent. What are the two steps for “preparing the tooth surface?”
apply acid etch
apply silane coupling agent
What is the ideal contact measurement?
25 to 75 microns
How do you remove the sprue?
- use a football diamond (small contact point) to remove the sprue
- use porcelain polishing wheels to remove the buildup of material that held under the sprue
Sof-Lex Discs are used to polish composite. Rubber wheels are used to polish ceramic restorations. What is the order (colors) in which to use wheels?
Coarse (blue)
Medium (Red)
Fine (Gray/White)
After using the rubber wheels, what can you use to gloss the porcelain?
- Robinson bristle brush
- DiaShine Polishing Paste
Polishing should take _____ mins.
3-5
What are luting agents?
agents that bond, seal, or cement particles or objects together
How do luting agents work?
- Mechanical retention (fills gaps)
- Chemical retention (bond/adhesive)
What are the issues with Zinc Phosphate cement?
- mixing must take place on a cold slab and its messy
- causes high sensitivity**
True or False: Glass Ionomer bonds to dentin but has lower strength compared to RMGI.
True
What are the three most commonly used types of cement?
- GI
- RMGI
- Resin
Which cement type can be used with every restoration type?
Resin
Which is better for a METAL restoration: Resin or Glass ionomer?
Glass Ionomer (or RMGI) -resin can be used but it is more difficult to seat
True or False: Resin generally cannot be used under zirconia.
True
Unicem RelyX is a _____ cement that has been modified to work under ______ crowns.
resin
zirconia
Of the cement types, which has the highest tensile strength?
resin
Weak restoration materials should have ______ cements.
strong
Give three examples of “weak restoration materials.”
- glass/ceramic/porcelain
- composite
- resin nano ceramic
Give three examples of “strong restoration materials.”
- metal/PFM
- Glass infiltrated zirconia
- Core strengthened zirconia and alumina
Empress, Lave Ultimate, Sirona, and eMAX would be used with ______ (weak or strong?) cement.
Strong
Lava Plus, Bruxzir, Cercon, and Vita In-Ceram AL would be used with _____ (weal or strong?) cement.
weak
What are the three “generic” adhesive bonding system steps?
- Etchant
- Primer
- Adhesive Resin
What is the purpose in using an etchant?
HF dissolves the glass matrix and leaves a rough filler for microMECHANICAL bonding
What is the purpose of using a primer?
improves wettability of resin
-hydrophilic to enhance penetration to depth of demineralization
On which surface of the restoration is the HF acid etch applied?
the intaglio (inside)
True or False: It is not critical that you match bonding systems with cement types.
False, match ‘em up!
True or False: All bonding agents require etching.
False, read the directions to know for sure
_______-Cure resin cements have predictable curing, easy cleanup, and maximum adhesive retention.
Dual
NX3 Nexus Third Generation is a ______-cure system. MulitLink is a ______-cure system. How does this influence the seating procedure?
Nexus: Dual cure
MultiLink: Self cure
*During seating: Nexus requires one sec of light exposure on buccal and lingual prior to seating. MultiLink does not require cure until after crown is seated (no fear of seating-difficulties)
What type of curing reaction does Unicem RelyX use?
Dual cure (mostly VLC-visible light)
What type of curing reaction does VarioLink II use?
Dual cure
True or False: MultiLink is a dual cure resin cement.
False, self cure
Silane Coupler improves the wettability and contributes to __________ formation between porcelain and composite resin.
covalent bond
Porcelain limits light transmission to cement because it absorbs _______% of light energy. Why does this matter?
40 to 50%
cements need 30 to 40% light in order to get the initial set; could cause incomplete polymerization which would:
- reduce physical properties
- decrease bond strength
- cause post-op sensitivity
Using the MultiLink system, the ceramic is etched (60 sec. for empress vs 20 sec. for emax), the intaglio is treated with Silane, then rinsed and dried. What is next?
- mix multilink PRIMER (A+B 1 drop of each)
- apply to TOOTH
- air thin to dry
- apply cement into restoration intaglio
- seat restoration
- remove excess
- cure each surface for 40 seconds
Silane goes on the _______, Primer goes on the _______, and Cement goes on the ______.
Silane = restoration Primer = tooth Cement = restoration
True or False: The restoration should be finished with dry disks.
False, copious amounts of water with microfine diamonds and rubber points (green, red, yellow, white)
True or False: Carbide and preparation diamond burs should be used to remove minor imperfections from the porcelain.
FALSE
carbide “chatter” causes fractures
prep diamonds cause surface damage
True or False: Porcelain can be polished with finishing paste.
True
True or False: Ceramic margins can be finished with an Axis Super-fine 889 bur.
True, its a very small, super-fine diamond bur
_____ _______ Finishing strips are used for ceramics.
Axis Diamond