6.0 Flashcards
- Gingival health is protected by the _____________
- FVC is about ____ times as likely to have a pulpal problem as with a PVC.
- ____ should be chosen first over FVC when a cast restoration is needed. A FVC should be chosen only when the coverage or retention afforded by a PVC is found wanting.
- Reluctance to use a three-quarter crown because it has more margin than a full crown is unfounded; the additional margin is vertical, which fits better than a horizontal margin.
- Its use is based on the premise that an intact surface of tooth structure should not be covered by a crown if its inclusion is not essential to the retention, strength, or esthetic result of the definitive restoration. ______
4) An open-faced PVC is more _____ seated completely during cementation, while a full veneer crown tends to act like a hydraulic cylinder containing a highly viscous fluid. - The most commonly used feature is a _______.
- To achieve maximum effectiveness, grooves must have_________________________.
- Resistance to torquing is produced by achieving a ________________________ by directing the bur (and groove) slightly to the opposite corner of the tooth.
- A V-shaped groove, without a definite lingual wall, provides only ____ of the retention and 57% of the resistance of a concave groove with a lingual wall
supragingival margin
2.5
PVC
PVC
easily
groove
definite lingual walls
“lingual hook” or a “lock effect”
68%
- The standard three-quarter crown is a _________________ in which the facial surface is left uncovered. It is the most commonly used partial coverage crown.
- ____________ is the first step in preparing a tooth for a three-quarter crown.
- Final extension to the facial is achieved with the short needle diamond or, in esthetically critical areas, with a ______________ on a maxillary tooth or a ___________________ on a mandibular tooth.
- The ____________ of the finished groove is drawn on the occlusal surface with a sharp pencil.
- The groove is prepared in stages: (3)
- Grooves should be placed as ______ as possible without undermining the facial surface, paralleling the long axis of a posterior tooth.
- Grooves are done first on the more inaccessible proximal (ie, ____) surface of molars and the more esthetically critical (ie, ____) surface of premolars.
- A ____ is a flat plane that removes equal amounts of the facial wall of the groove and the outer surface of the tooth. It is cut from the groove outward with the tip of a flame diamond to prevent overextension.
- The _______, a 1.0-mm-wide ledge on the lingual incline of the facial cusp, is made with a no. 171L bur. It forms an inverted V that lies a uniform distance from the finish line. It provides space for a truss of metal that ties the grooves together to form a reinforcing staple.
- Occlusal reduction: __________________
- Functional cusp bevel: _____________________
- Lingual axial reduction: _________________
- Proximal axial reduction: _________________
- Axial finishing: ________________
- Proximal grooves: __________
- Proximal flares: ______________
- Occlusal offset: _____
- Facial bevel: __________________
partial coverage crown
Occlusal reduction
15-8-8 binangle chisel; 15-8-14 enamel hatchet
outline form
shallow occlusal template (A), extension to half length (B), and completion to full length (C).
facially
distal; mesial
flare
occlusal offset
coarse-grit round-end tapered diamond and no. 171L bur
coarse-grit round-end tapered diamond and no. 171L bur
coarse-grit tapered torpedo diamond
medium-grit short needle and coarse-grit tapered torpedo diamond
fine-grit tapered torpedo diamond
no. 171L bur
flame and diamond bur
171L bur
flame diamond and no. 171L bur
There are several modifications of posterior partial veneer crowns that can be used. (4)
* A ____________________________________ is more retentive than a standard preparation with grooves, but boxes are very destructive. They can be justified only if there has been proximal caries or previous restorations. A less destructive way to augment retention and resistance is to use ________, which is not significantly less retentive than two boxes.
* The _____________________ is a three-quarter crown whose vertical distofacial margin is positioned slightly mesial to the middle of the facial surface. Esthetics are good because the veneered distofacial cusp is obscured by the mesiofacial cusp. With more of the tooth encompassed, ________is better than that of the three-quarter crown.
* The _____________________ is used on mandibular molars to preserve an intact lingual surface.
* The _________________ is a three-quarter crown that is rotated 90 degrees, with the distal rather than the facial surface left intact.
a. Three-quarter crown
b. Seven-eighths crown
c. Reverse three-quarter crown
d. Proximal half crown.
three-quarter crown preparation with proximal boxes
four grooves
seven-eighths crown
resistance
reverse three-quarter crown
proximal half crown
- When a partial veneer is used, it is usually a ___________________________ in which metal coverage is minimized by using pins.
- the best candidates for anterior three- quarter crowns. (3)
- Two (2) factors must be controlled successfully to produce a restoration with a minimal display of metal:
- Reduction is done to the depth of the orientation cuts. The lingual reduction of a canine is done in __________, with a slight ridge extending incisogingivally down the middle of the lingual surface.
- A ________________ can be placed in the cingulum to compensate for a very short lingual wall.
- On the facial aspect of each groove, a ____ is started at the gingival end with the thin tip of a flame diamond.
- Lingual reduction: _________________________
- Incisal reduction:______________________
- Lingual axial reduction: ___________________
- Proximal axial reduction: ___________________
- Axial finishing: __________________
- Proximal grooves: __________________
- Proximal flares: _________________
- Incisal offset: ____________
- Incisal bevel: ________________
pin-modified three-quarter crown
(1) Well aligned, (2) thick, (3) square anterior teeth with a large faciolingual bulk of tooth structure
1) Path of insertion and groove placement,
2) Placement and instrumentation of extensions.
two planes
3.0-mm-deep pinhole
flare
small football-shaped and coarse-grit ball-shaped diamonds.
long needle diamond
tapered torpedo diamond
long needle and tapered torpedo diamonds.
fine-grit tapered torpedo diamond.
no.169L and 170L burs
flame diamond and bur
no. 171L bur
fine-grit flame diamond and no. 170L bur
The _________________________ is an esthetic modification that has long been considered the retainer of choice on unblemished teeth used as FPD abutments in esthetically critical areas. Although resin-bonded retainers gained popularity in such situations in the 1980s, the pin-modified three-quarter crown is still an excellent retainer for ____________.
The pin-modified three-quarter crown preserves the ____________ and _______________surface.
The pin-modified three-quarter crown is good for repairing incisors and canines with ___________________. It should not be used on teeth with caries or restorations on surfaces that are not to be covered, or in mouths with extensive caries.
Although this restoration design is ____________ in the amount of enamel that is untouched, a variety of factors could place the pin holes near or even in the pulp. Therefore, pin-modified three-quarter crowns should not be used on teeth that are small, thin, possessed of large pulps, or malpositioned, or that have large pulps.
* Pins are likely to produce less retention, and pin-retained castings are less retentive than standard three-quarter crowns. However, the greater the________________, the greater the retention.
* Pinholes are usually made with a ____________ (Kodex K97 non–depth-limiting twist drills, Coltene/Whaledent).
* Retentive pins are made by using a 0.675-mm twist drill (a) for the pinhole, a _____________ (b) to carefully enlarge the pinhole, and a smaller-diameter _____________ (c) for the impression and as part of the restoration.
* These pins should be ______ deep for optimum retention and resistance.
pin-modified three-quarter crown
short-span FPD
facial surface; one proximal
severe lingual abrasion
conservative
number, depth, or diameter of pins
0.675-mm drill
no. 169L carbide bur
nylon bristle
4 mm
The _________________ is the simplest of the cast restorations and has been used for the restoration of occlusal, gingival, and proximal lesions. It utilizes ______________which exerts some outward pressure on the tooth.
This pressure is exerted first during try-in and cementation, but it occurs again when _____________is applied.
For the restoration to be successful, there must be some form of ___________. When an inlay is placed in a tooth with ample bulk of tooth structure, the tooth structure itself ______ the force.
The indications for an inlay are virtually the same as for an ________________. The inlay simply replaces missing tooth structure without doing anything to reinforce that which remains. If the tooth requires protection from occlusal forces, the protection must be gained by the use of some other type of restoration that incorporates a veneer of casting alloy over the occlusal surface. ______ tend to wedge cusps apart, and a lone- standing unsupported cusp is at risk of fracture.
__________________ is normally equal to anatomic cusp height, measured from cusp tip to the bottom of the central groove.
The recommended isthmus width has been reduced to ____________________.
_________________________, decreased the fracture strength of teeth in another study.
intracoronal inlay
“wedge” retention
occlusal force
counteraction; resists
amalgam restoration
Inlays
Mechanical cusp height
1⁄4 the intercuspal distance
Depth, combined with width
- It is indicated for premolars or molars, with minimal caries or previous restoration, that need a MO or DO restoration.
- _______________ should be used in mouths that have shown a low caries rate for some time preceding the placement of the restoration.
- Those walls should have a minimum degree of ________ of the facial and lingual walls to promote optimum retention and resistance. As taper ________, stress rises and retention decreases.
- This gingivoaxial groove, sometimes referred to as the ______________, is placed to enhance resistance to displacement by occlusal forces.
- _______ are flat planes added to the facial and lingual walls of the box using a flame diamond or an enamel hatchet. The hatchet is reserved for use in those areas where esthetics is an important consideration.
- The bevel must be __________ because compressive stress increases as the inclination of the bevel increases.
- Occlusal outline: _______
- Undermining marginal ridge: _________
- Proximal box: ____________
- Gingivoaxial groove: ____________
- Proximal flares: ______________
- Gingival bevel: _________________
- Isthmus bevel: ____________
- Bevel and flare finishing: _________
PROXIMO-OCCLUSAL INLAYS
Class 2 inlays
divergence
increases
Minnesota ditch
Flares
minimal
no. 170L bur.
no. 169L bur.
169L and 170L burs
gingival margin trimmer.
coarse-grit flame diamond.
coarse-grit flame diamond.
fine-grit flame diamond.
flame bur.
- A ____________ can be used to restore a moderately sized occlusal lesion in the mouth of a patient with predominantly gold restorations in other teeth.
class 1 inlay
- A ____________ can be used to restore a moderately sized occlusal lesion in the mouth of a patient with predominantly gold restorations in other teeth.
- The __________ shows metal, making it unacceptable for incisors. However, it is useful for restoring the distal surface of canines if a slight display of metal is acceptable to the patient. A well-done inlay in a canine will look better than an amalgam restoration, last longer than a composite resin restoration, and be much less destructive than a porcelain crown.
- The ___________ is used to restore severe abrasion or erosion as well as large caries on the gingivofacial aspect of molars. It cannot tie into other restorations without producing a poor marginal seal.
- Occlusal forces applied to an ___________ produce stresses that tend to separate the cusps
- When the same force is applied to an __________, it dissipates over a wide area in less destructive pattern.
- There are two acceptable occlusal finish lines for the functional cusp of an MOD onlay: (2)
- Planar occlusal reduction: __________________________________
- Functional cusp bevel: __________________________
- Occlusal shoulder: _____________
- Isthmus: ________
- Proximal box: ______________________
- Proximal flares: ________________________
- Gingival bevel: ____________________
- Facial and lingual bevels: ___________________
class 1 inlay
class 3 inlay
class 5 inlay
MOD inlay
MOD onlay
o occlusal shoulder and a
o heavy chamfer.
round-end tapered diamond and no. 171L bur.
round-end tapered diamond and no. 171L bur.
no. 171L bur.
no. 171L bur.
no. 169L and no. 170L burs.
flame diamond and flame bur.
flame diamond and flame bur
flame diamond and no. 170L bur.
It is capable of producing the best cosmetic effect of all dental restorations. However, since it is made entirely of ceramic, a brittle substance, it is more susceptible to fracture.
The development of dental porcelain reinforced with _______ in the 1960s created renewed interest in the restoration. In recent years, this interest has mushroomed with the use of new reinforcement materials such as ____________________________
An overshortened preparation will create stress concentrations in the labiogingival area of the crown, which can produce a characteristic ________________ in the labiogingival area of the restoration.
It should be avoided on teeth with an _____________________ that will produce stress in the incisal area of the restoration.
- Depth orientation grooves __________________
- Incisal reduction: ______________
- Labial reduction _________________
- lingual reduction: __________________
- Lingual axial reduction: ______________
- Axial walls and radial shoulder finishing ________________________
ALL-CERAMIC CROWNS
alumina; lithium disilicate and zirconia.
“half-moon” fracture
edge-to- edge occlusion
flat-end tapered diamond.
coarse-grit flat-end tapered diamond.
flat-end tapered diamond.
Small wheel diamond bur/ coarse-grit football-shaped diamond.
coarse-grit flat-end tapered diamond.
radial fissure bur/ fine-grit flat-end tapered diamond.
