1. Decreasing the crown-root ratio in the posterior segment will
A. Result in an increased vertical dimension
B. Have no effect on facial height
C. Decreased vertical dimension
D. None of the above
C. Shortening the crown to root ratio in the posterior segment can potentially decrease the primary holding or supporting cusps and result in a closed bite.
2. Hemisection means
A. The separation and removal of the roots of a teeth
B. Separating the roots of a tooth
C. Sectioning the roots of a tooth in half
D. Sectioning both the root and the crown of a tooth
D. Hemisection means dividing the tooth essentially in half, sectioning both the root and the crown. Separation and removal of any part of a root or roots is usually referred to as root amputation.
3. A telescopic retainer is
A. A special type of overcastting for crowns
B. An additional casting underneath the crowns of a bridge
C. An undercasting for posterior abutments only
D. Used grimarily under partial denture abutments
B. telescopic retainer is an additional casting underneath the crowns of a fixed bridge or a removable partial denture. It is usually constructed of gold alloy which is very thin in dimension. After the preliminary undercasting is made,impressions are taken to fabricate overcastings for a fixed bridge or a removable partial denture.
4. A major limitation to the use of the telescope in anterior teeth is
A. Its added thickness
B. Its cool
C. The length of treatment
D. Esthetic
A. A major limitation in the use of telescopic retainer, especially in anterior teeth, is that it will provide additional thickness. Consequently, it is imperative that, in a construction of telescopic retainers, additional tooth structure is removed to provide space to accommodate both an undercasting and an overcastting.
5. To cement the telescopic retainer to the abutment tooth
A. A weaker cementing medium should be used than that for the overcase and retainer
B. A stronger, cementing medium than that for the overcase and retainer is advantageous
C. The same type of cement is used as that for both overcase and telescope
D. None of the above
B. It is generally advisable to cement the undercasting directly to the abutment tooth with permanent cement. If this is not done the undercasting can, potentially, be dislodged. Other possible sequelae are marginal leakage, sensitivity, recurrent caries and loss of tooth vitality.
6. The use of floss under a ridge lap pontic
A. Is an irritant when there is inflammation present
B. Adequately removes plaque
C. Improves the ridge tissue
D. Seldom is necessary
A. The use of loss under a ridge lap pontic will cause irritation to the tissue whether there is existing inflammation or not. The floss under a ridge lap pontic would rest upon the buccal and lingual extension
of the cervical portion of the pontic; consequently the use of floss would further insult the ridge tissue.
7. More important than the material used for a pontic is
A. The shape of the ridge
B. The position of the abutment teeth
C. The design of the pontic
D. The number of missing teeth
C. The design of the pontic is of utmost consideration in the fabrication of a fixed bridge because improper pontic design can result in chronic inflammation of the infrapontic space area which ultimately will involve the abutment teeth. Any material can be used for pontics provided that the modified ridge lap concept is employed, the surface of the pontic is highly polished and does not exert on the residual ridge.
8. The buccal and lingual shunting mechanism of a pontic
A. Can be narrower than that of the adjacent teeth
B. Should conform to those of the adjacent teeth
C. Can be disregard in short span bridges
D. Should be designed differently in the anterior segment as opposed to the posterior segment
B. The buccal lingual shunting mechanism of a pontic should conform to those of adjacent teeth to prevent food impactions at the abutments. Food impaction will result if the pontic has a narrower buccal/ lingual dimension than the adjacent abutment teeth.
9. In cases where the shape of the ridge is grossly aberrant
A. Compensate by the design of the pontic
B. Don’t consider fixed prosthesis
C. Consider the use of implants
D. Consider surgical correction
. D. Grossly aberrant ridge tissue should be surgically corrected prior to the final impression. A pontic designed to aberrant ridge tissue will trap plaque and debris in the infrasurface portion, resulting in inflammation.
10. Where there is a decrease by half or less of the inter-tooth space
A. Make the pontic half size
B. Use orthodontics to enlarge it
C. Recontour adjacent teeth with inlay, onlay, or crowns
D. Extract a tooth to provide additional space
C. it is very important that one avoid match stick type pontics for this design usually causes plaque and food entrapment. It is more desirable to recontour adjacent teeth with inlays, onlays or crowns to close up a space that has been decreased by half or less of the intertooth space originally prpvided. These can be single, unsoldered units to allow for maintenance.
11. Moisture contamination of a zinc containing dental alloy causes
A. Decreased flow
B. Excessive setting expansion
C. Accelerated setting
D. Excessive delayed expansion
D. Delayed expansion usually begins three to five days after the amalgam restoration is placed. It is caused by the reaction of water inadvertently being incorporated during manipulation with the zinc and the alloy. Hydrogen gas is produced under sufficient pressure to produce expansion of the restoration as high as 500 microns.
12. Which of the following agents are designed to prevent pit and fissure caries?
A. Acidulated phosphate fluoride prophylaxis
B. An adhesive resin caused by ultraviolet light
C. Dextranase
D. Gottlieb’s solution
B. The new adhesive resins cured by ultraviolet light are designed to prevent pit and fissure caries. The rationale behind this approach is to cover those areas that are susceptible to pit and fissure decay with a material that is insoluble in saliva. This material adheres to the enamel surface by an acid etch process. Pit and fissure caries are prevented by virtue of the fact that carbohydrates cannot come in contact with these susceptible areas on the tooth.
13. As a restoration ages, which material minimizers marginal microleakage?
A. Composite resin
B. Silicate cement
C. Glod foil
D. Silver amalgam
E. Polymethyl methacrylate resin
. D. Silver amalgam gradually oxidizes which is deposited on the wall of the restoration and acts as a mechanical plug. This mechanical plug minimizes the microleakage phenomena.
14. A silicon restoration is unique in its anticariogenic properties in that it
A. Has low solubility
B. Contain fluoride
C. Is bacteriostatic
D. Seals the margins effectively
. B. Silicate restorations are unique in their anticariogenic properties because many of them contain fluoride. As the material solubilizes, it deposits fluoride on the tooth surface, which aids caries prevention.
15. A temporary crowns margin should
A. Conform to the gingival margin of the preparation without pressure
B. Be in contact with the attachment
C. Be 0.5 mm. short of the gingival margin of the preparation
D. Be at least 1.0 mm. above the marginal gingival
A. A temporary crown margin should conform to the gingival margin of the preparation without pressure on the surrounding tissue to prevent irritation and plaque entrapment.
16. The function of most articulators is to
A. Set up teeth
B. Simulate masticatory movements
C. Reproduce jaw relations
D. Reproduce jaw movements
C. The primary function of most articulators is to reproduce jaw relationships; that is, the ways a mandible relates to maxilla. The more sophisticated articulators attempt to duplicate the movements of the mandible.
17. Which is most desirable for maximum retention of the retainer?
A. Long coronal preparation with minimal convergence
B. Proximal grooves
C. Tightly fitted casting
D. Medium length coronal preparation with a 20” taper
. A. The greatest amount of retention will be provided by a preparation that is no more than 8 to a12 degrees from vertical on the proximal and lingual surfaces, and has a good coronal extent.
18. Which of the following pontics lend themselves to the most modification for adaptation to the ridge?
A. Sanitary pontic
B. Long pin facing
C. Flatback
D. Trupontic
. B. The long pin facing is adapted to a cast gold backing that is waxed and cast to the ridge. The other pontics must be ground to the ridge and then glazed because they are porcelain.
19. Drying a crown preparation with alcohol will
A. Improve the crushing strength of the cement
B. Reduce sensitivity because of its anodyne effect
C. Possibly cause pulpal damage
D. Increase the setting time of the cement
C, Drying a crown preparation with alcohol will results in desiccation which may result in some form of pulpal damage. Alcohol has no influence on cement whatsoever as far as setting or crushing strength and is not an anodyne medicament.
20. A temporary crown is often constructed to protect a prepared tooth. Such a restoration must follow which of the following criteria?
A. The restoration may displace the gingival tissue slightly
B. The restoration should stop approximately 0.5 mm. short of the gingival margin of the preparation
C. The restoration should conform to the terminal extent of the gingival margin of the preparation
D. The restoration should stop approximately level with the gingival crest
C. A temporary restoration should conform to the terminal extent of the gingival margin of the preparation. Over-extension will result in gingival inflammation and possible tissue loss. Under-extended margins will foster plaque accumulation with the similar sequelae
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