Dentures book end-of-chapter questions

Question 1

What is the primarv’ difference in requirements between an acceptable diagnostic cast used for treatment plarming for tiie average patienL and one used for complete denture patients?

Answer 1

Diagnostic casts with inaccurate or partially missing vestibules are often acceptable when creating a treatment plan for the routine dental patient. Diagnostic casts for the complete denture patient should have all vestibules present and have accurate extensions. Accurate vestibular extensions ai-e necessary for the creation of acceptable custom impression trays.

Question 2

How does the clinician know if a partictUar stock impression tray is the correct size for a patient

Answer 2

The impression tray is the correct size if it provides coverage of all desired tissues without being overextended and provides a uniform space of approx- imately 5-6 mm (1/4 inch) between the tissues and impression tray.

Question 3

3. What is the puipose of periphery wax?

Answer 3

Periphery wax is used to change the internal contour of an impre.ssion tiay as necessary to ensure proper spacing between the tray and the tissues and also to gain additional flange extension. Occasionally it may be placed on the borders ofa stock tray if the flanges have shai’p edges. Periphery wax should not automatically be placed on all stock trays; it should be used only wben necessaiy

Question 4

In what situation can a clinician leave an impres.sion unattended in a patient’s mouth?

Answer 4

Never

Question 5

5. How quickly should an irreversible hydrocolloid impression be poured?

Answer 5

W’ithin 10 minutes. Once removed from the mouth, the impression is quickly rinsed, di.sinfected, and wrapped in wet paper towels until it can be poured.

Question 6

6. Wliat are the goals when making a final impression?

Answer 6

The goal when making a final impression is to make as exact a replica of the soft and hard tissues as possible, bave maximum acceptable coverage of supporting tissues, and have minimal extension onto the surrounding movable tissues and muscle attachments

Question 7

7. What are the physical characteristics of a correctiy formed impression tray?

Answer 7

7. Il must be fabricated ofa material that is rigid and stable, easily adjusted as necessary, and not bulky.

Question 8

8. What are three final impressions techniques?

Answer 8

8. Mucostatic, functional, and selective pressure.

Question 9

9. How does the selective pressure technique differ from the other two tech- niques?

Answer 9

With the selective pressure technique, the clinician attempts to place light- to-moderate pressure on speciik areas of the arches and minimal-to-no pres- sure on other areas. With the mucostatic technique, an attempt is made to place minimal-to-no pressure on the supporting structures. With the func- tional technique, pressure to the supporting suiictures is desirable.

Question 10

10. What are primary, secondary, and nonstres.s-bearing areas?

Answer 10

The primary and secondary stress-bearing areas ofthe arches are those areas that are best able to withstand the functional forces that are applied to a denture. The nonstress-bearing areas are those that are least able to with- stand tiiose forces. With the selective pressure technique, an effort is made to direct these functional forces to the primar)’ and secondary stress-bearing areas and eliminate them from the nonstress-bearing areas

Question 11

1. What feature of a cotnpleted denture routinelv increases the factors of retention?

Answer 11

1. Maximum tissue co\erage

Question 12

2. What is the distal extent of a maxillary complete denture?

Answer 12

2. Vibrating line

Question 13

3. What is border molding?

Answer 13

S. Border molding is the technique of properly extending the fiange length of an impression tray prior to making the final impression.

Question 14

4. Why is the “relief wax” removed from an impression tray just before making the final impression?

Answer 14

4. Removal ofthe relief wax creates a chamber, or relief area, within the impression tray that reduces the chance of physical pressure from the impression tray to the underhing nonsuess-beaiSng tissues.

Question 15

5. Why are multiple #6 or #8 round but r-sized holes cut into the impression tray just prior to making the fmaJ impression?

Answer 15

5. To reduce the hydraulic pressure that builds up within the impression caused by the viscous impression material being trapped between the impression tray and the underlying tissues.

Question 16

6. What is the location of the posterior palatal seal area, and what is its ante- rior and posterior limits?

Answer 16

(). Anterior limit is nonspecific and depends upon the available displaceable tissue. The posterior limit is the \ibrating line.

Question 17

7. How does the clinician minimize the capturing of the roll of tissue, seen in many paüents in the masseter muscle areas, within the impression?

Answer 17

7. By pulling the tissue from beneath the impression tray while seating the tray.

Question 18

8. What are some of the characteristics of a good impression material?

Answer 18

8. Is minimally viscous, polymerized intraorally within 2-3 minutes, is hydrophyllic, is thixotropic, will not fiow once removed from the mouth,
   is not excessively rigid, is not excessively expensive, is well tolerated by the tissues, is very exacting in recording and maintaining tissue detaiis, and can be poured in a dental stone more than once.

Question 19

9. What are some of the disadvrantages of itsing modeling compound as a botder-molding material?

Answer 19

9. Planned preparation and the usage of several pieces of equipment and materials are required. Only rea.sonably small areas of the horders can be corrected at a time before the material cools and becomes too rigid to be used properly. Once cooled, because of itsrigidity,it is very difficult to place and remove from bilateral undercut areas—particularly the retromylobyoid areas—^without causing trauma to the tissues and discomfort to tlie patient.

Question 20

10. Why should a maxillary denture not be extended onto the movable soft palate?

Answer 20

10. Retention of the denture may be compromised, and the denture may cause irritation and trauma to the soft movable tissues.

Question 21

1. Wiiat are some of the procedures that require the use of a record base and an occlusion rim?

Answer 21

1. The record base and occltision rim are necessary for establishing facial contours; as an aid in tooth selection, in establishing and maintaining the vertical dimension of occlusion during record making; for making interoc- clusal records; for tiae arrangement of the denture teeth; for the verification of the collect master cast mounting on the articulator; at the esthetic trial insertion appoinmient; and as a wax-up mold for the external surface of the complete denture.

Question 22

2. List some of the characteristics of a satisfactory record base.

Answer 22

2. A satisfactory record base must be stable on both the master casts and intraorally, be rigid; be accurately adapted to the casts; be comfortable to the patient and esthetic; and fully cover the entire supporting tissues of the arches.

Question 23

3. Why is it important to properly block out undercuts on the master cast prior to fabricating the record base?

Answer 23

3. Because of the possibility of cast breakage when initially separating the record base from tlie master cast, which usually necessitates making a new final impression and creating a new master cast.

Question 24

4. What area is a possible exception to complete block out of an undercut prior to record base fabrication, and why is this area an exception?

Answer 24

4. An exception is the undercut on the labial or anterior portion of tlie maxil- lary cast. It need not be completely eliminated because the completed record base and occlusion rim can be placed and removed at an angle from an anterior direction.

Question 25

5. WTiy is tiie blocked-out master cast soaked in water for five minutes prior to fabricating the record base?

Answer 25

5. The cast is soaked in room temperature water for five minutes to minimize the foiTnation of bubbles in llie completed record base.

Question 26

6. Can the drying time of the titifoil substitute be expedited by drying with air tuider pressure?

Answer 26

6. Do not attempt to expedite the drying time by blowing it dry with air under pressure because the separating medium may be blown off the cast

Question 27

7. What material and laboratory technique is itsed to create the record base?

Answer 27

7. The record base is fabricated with an autopolymerizing acrylic resin using a “spinkle-on” technique.

Question 28

8. Other than over-reduction, why must care be taken when trimming the poly- merized record base with an arbor band or acrylic burr?

Answer 28

8. Because the record base may warp if excessively heated, care must be taken when trimming the resin.

Question 29

9. Can any average position of the natural central incisor be used as a guide in fabricating ihe maxillan’ occlusion rim?

Answer 29

9. Studies indicate that the labial surface of the natural central incisors average 6-8 mm anterior to the middle of the incisai papilla. This should be kept in mind when forming tlie occlusion rim.

Question 30

10. The record bases and occlusion rims will eventually be destroyed. So, why should the laboratory technician spend time properly shaping them and making them neat and clean?

Answer 30

10. The record bases and occlusion rims must be neatly constioicted because patients often begin to fonn opinions about their new dentures based on the appearance and feel of these record bases and occliision rims.

Question 31

The collection of information for use in denture tooth selection begins: a) during contouring and marking of the occlusion rims.

b) at the esthetic try-in appointment.
c) with the introduction of tlie dentist and patient.
d) after the casts have been mounted on the articulator.

Answer 31

c

Question 32

Sources of information for anterior tooth mold selection include: a) patient photographs.

b) diagnostic casts of tlie patient’s natural dentition.
c) existing dentures.
d) record bases and occlusion rims. e) all of the above.

Answer 32

e

Question 33

The high smile line scribed into the wax of the maxillary occlusion rim usually indicates the minimum incisogingi'al height of the maxillary anterior teeth to avoid a “gummy” smile.

a) true
b) false

Answer 33

a

Question 34

The factors of age, sex, and persotiality can be useful in developing an esthet- ically pleasing denture. This has been proven in several scientific studies.

a) both statements are true.
b) both statements are false.
c) the first statement is true, and the second is false. d) the ftrst statement is false, and the .second is true.

Answer 34

c

Question 35

The selection of molds for denture teeth is the responsibility of the: a) dental assistant.

b) patient.
c) detitist.
d) laboratory technician.

Answer 35

c

Question 36

The overall mesiodistal width of the mandibular posterior teeth is governed by the amount of space available from the distal end of the canine tooth to the beginning of the slope to the retromolar pad.

a) true
b) false

Answer 36

a

Question 37

Recently extracted teeth may be unreliable sources of shade information due to the effects of drying or storage in disinfectant solutions.
a) true b) false

Answer 37

a

Question 38

The most important source of shade information is the: a) tootli manufacturer.

b) dendst.
c) patient.
d) photograph

Answer 38

c

Question 39

The shade that stands out most strongly when the operator squints the eyes is the best choice for harmony with tlie patient’s complexion.
a) true b) false

Answer 39

b

Question 40

The most common errors in denture tooth selection are too light in shade and too small in size.
a) true b) false

Answer 40

a

Question 41

1. For most padents, when considering the arrangement of the maxillary ante- rior teeth, what determines esthetics? What determines the fullness of the lips (lip support)?

Answer 41

For most patients, the position of the incisai edge of the maxillary anterior teeth determines esthetics, while the cer\ical portion, or necks, ofthe teeth and the fullness of tlie maxillary denture base determine lip suppon (fuU- ness of the lips).

Question 42

2. Most padents desire symmetrical arrangement of the anterior teeth with minimal variations that might provide a more natural look. Which two groups of paùents might he an exception to this statement?

Answer 42

2. The exceptions are those patients with existing dentures, who would like the arrangement of the teeth of the new denture to mimic tiiose of the existing denture. Occasionally patients receiving immediate complete dentures also desire that the arrangement of the denture teeth match the arrangement of tiie natural teeth.

Question 43

3. Alterations of the maxillary lateral incisors can he made to help create a more natural-appearing denture. What changes might he considered?

Answer 43

3. Changes include; (1) inclination of the long axis, (2) leiationship to tlie incisai edges of the central incisor, (3) tooth width, (4) levels of the gingival margins, (5) tooth shade, and (6) shapes of incisai edges, angles, and proxi- mal surfaces.

Question 44

4. The alignment of the canines is important from an esthetic standpoint. How shottld canines he arranged in comparison to the central and latei^al incisors?

Answer 44

4. The long axis of the maxillar)’ canine should be vertical or distally inclined with the cervical portion (neck) prominentiy oriented because of its labial position in relation to the lateral incisor. For esthetic purposes. Uie canine should be rotated so that the distal half of the facial surface of the tooth is not visible when \iewed for the anterior.

Question 45

5. WTiy is it itnportant to minimize the vertical overlap of the anterior teeth when arranging these teeth for a halaiiced occlusion?

Answer 45

5. Decreasing the steepness of the incisai guidance minimizes the separation of the posterior teeth during excursive movements, and hence the require- ment for excessively steep cusp heights, compensating curves, and/or effec- tive cusp angles. This i eduction simplifies the an angement of the teeth and eliminates prematurities in both the laboratory and clinic remount phases of treatment.

Question 46

6. In what direction do the crests of the residual ridges resorb following extractions, and what might tiiese resorptive patterns result in?

Answer 46

6. Long-term studies indicate that, when the natural teeth are lost, the mandibular residual ridge resorbs downward and outward, while the maxil- lar)’ residual ridge resorbs upwaid and inward. Becatise of these resoiptive patterns, it is often necessary to create a reverse articulation (crossbite) for the posterior teeth.

Question 47

7. What anatomical feature limits the most posterior position of a mandibuiar molar?

Answer 47

7. The most distal mandibuiar molar should be set no further posteriorly than the beginning of the incline leading to the retromolar pad.

Question 48

8. Ideally, how should the plane of occiusion relate to the retromolar pad,
   the interocclusal space between the ridges, and the ridge crests themselves?

Answer 48

8. The plane of occltision should ideally split the distance between the maxil- larv’ and mandibular ridges, be parallel to both ridges, and be at the level of the middle to upper one-tiiird ofthe tetromolar pad.

Question 49

9. If an adjustment is necessary to the vertical position of the plane of occlu- sion, which arch should he favored and why?

Answer 49

9. If interarch space or esthetics are significant problems, the position of the plane of occlusion may be adjusted either superiorly or inferiorly to a small degree. When making adjustments to tile height of the occlusal plane, tlie mandibular arch should be favored whenever possible because of the decreased stability ofthe mandibular denture.

Question 50

10. How should the buccal surfaces of the opposing, primarily second molars be aligned and why?

Answer 50

10. A buccal horizontal overlap ofthe posterior teeth, especially second molars, is required when airaiiging the opposing teeth. An airangement that results in the buccal surfaces of both the maxillar)’ and mandibular teeth being aligned vertically is contraindicated becau.se of the possibility of creating a cheek-biting situation.