3.0 Replacement of Missing Teeth

Question 1

constant pushing of the dental arch

Answer 1

State of dynamic equilibrium

Question 2

When a tooth is lost, the ___________ of the dental arch is disrupted, and there is a subsequent realignment of teeth as a new state of ______ is achieved. Teeth adjacent to or opposing the edentulous space frequently move into it.

Answer 2

structural integrity
equilibrium

Question 3

Opposing tooth or teeth may ______ into the vacated space.

Answer 3

supra-erupt

Question 4

MISSING TEETH MAY BE REPLACED BY 3 TYPES OF PROSTHESES

Answer 4

1. RPD
2. FPD
3. IMPLANT SUPPORTED FPD

Question 5

FACTORS INVOLVED WHEN CHOOSING PROSTHESIS (5)

Answer 5

1. Biomechanical
2. Periodontal
3. Esthetic
4. Financial factors
5. Patient’s wishes

Question 6

it is indicated for:
(1) Spaces greater than 2 posterior teeth.
(2) Anterior spaces greater than 4 incisors.
(3) Spaces that include canine and 2 other contiguous teeth i.e. CI, LI & canine; LI, canine, and 1st PM; canine & both PM.
(4) Edentulous space with no distal abutment exception with cantilever FPD.
(5) Bilateral edentulous spaces with more than 2 teeth missing on one side.

Answer 6

REMOVABLE PARTIAL DENTURE (RPD)

Question 7

FPD is preferred by majority and can provide long life of function if: (3)

Answer 7

1. Abutment teeth is sound periodontally.
2. Span is short and straight.
3. Retainers are well designed and executed.

Question 8

• There should be no gross soft tissue defect in the edentulous ridge. If there is, it may be possible to augment the ridge with ____ to enable the construction of a fixed prosthesis.
• This treatment is reserved for patients who are both highly motivated and able to afford this special procedure. If the patient does not meet these criteria, a __________ should be considered.

Answer 8

grafts
removable partial denture

Question 9

• It creates a poor environment for any crown. The margins of the retainers will be at great risk from recurrent caries, limiting the life span of the prosthesis. However, it can also hinder the success of a removable partial denture.
• In either case, the patient must be made aware of the high risk involved. The risk may be minimized through home fluoride application and frequent recall, but it cannot be eliminated.

Answer 9

Dry mouth

Question 10

a conservative restoration that is reserved for use on defect-free abutments in situations where there is a single missing tooth, usually an incisor or premolar.

Answer 10

RESIN-BONDED TOOTH SUPPORTED FPD – Maryland Bridge

Question 11

ideally suited for use where there are insufficient numbers of abutment teeth or inadequate strength in the abutments to support a conventional fixed partial denture and when patient attitude and/or a combination of intraoral factors make a removable partial denture a poor choice.

Answer 11

IMPLANT SUPPORTED FPD

Question 12

This prosthesis utilizes a standard pontic form, accommodating an edentulous ridge with moderate resorption and no gross soft tissue defects. Because it requires a shallow preparation that is restricted to enamel, it is especially useful in younger patients whose immature teeth with large pulps are poor candidates for endodontic-free abutment preparations.

Answer 12

RESIN-BONDED TOOTH SUPPORTED FPD – Maryland Bridge

Question 13

________ can be accommodated only if there is enough tooth structure to allow a change in the normal alignment of axial reduction. This is limited by the need to restrict most of the reduction to enamel.

Answer 13

Tilted abutments

Question 14

It is limited only by the availability of alveolar bone with satisfactory density and thickness in a broad, flat ridge configuration that will permit implant placement.

Answer 14

Span length

Question 15

A single tooth can be replaced by a single implant, saving defect-free adjacent teeth from the destructive effects of retainer crown preparations. A span length of two to six teeth can be replaced by multiple implants, either as single unit restorations or as implant-supported fixed partial dentures.

Answer 15

SINGLE TOOTH IMPLANT FPD

Question 16

In cases in which the choice between a fixed partial denture and a removable partial denture is not clear cut, two or more treatment options should be presented to the patient along with their advantages and disadvantages. The dentist is in the best position to evaluate the physical and biologic factors present, while the patient’s feelings should carry considerable weight on matters of esthetics and finances.

Answer 16

CASE PRESENTATION

Question 17

• The question for treatment should be left to the patient’s wishes – if he or she perceives no functional, occlusal, or esthetic impairment, it would be a dubious service to place a prosthesis.
• Teeth adjoining an edentulous space usually move, but not always. When occasional has beaten the odds, recognize it, congratulate patient for being fortunate, and tend to his or her other needs.

Answer 17

NO PROSTHETIC TREATMENT

Question 18

Every restoration must be able to withstand the constant occlusal forces to which it is subjected. This is of particular significance when designing and fabricating a fixed partial denture because the forces that would normally be absorbed by the missing tooth are transmitted, through the pontic, connectors, and retainers, to the abutment teeth. Abutment teeth are therefore called upon to withstand the forces normally directed to the missing teeth in addition to those usually applied to the abutments.

Answer 18

ABUTMENT EVALUATION

Question 19

Roots and supporting tissues should be evaluated for 3 factors:

Answer 19

1. Crown-root ratio
2. Root configuration
3. Periodontal ligament area

Question 20

a measure of the length of tooth occlusal to the alveolar crest of bone compared with the length of root embedded in the bone. As the level of the alveolar bone moves apically, the lever arm of the portion out of bone increases, and the chance for harmful lateral forces increases.

Answer 20

Crown-root ratio

Question 21

The optimum crown-root ratio for a tooth to be used as a fixed partial denture abutment

Answer 21

2:3

Question 22

maximum ratio that is acceptable for a prospective abutment under normal circumstances.

Answer 22

1:1

Question 23

Occlusal force exerted against prosthetic appliances has been shown to be considerably less than that against natural teeth: (3)

Answer 23

o 26.0 lbs for RPD
o 54.5 lbs for FPD
o 150.0 lbs for natural teeth

Question 24

• an important part of the assessment of an abutment’s suitability from a periodontal standpoint.
• Roots that are broader labiolingually than they are mesiodistally are preferable to roots that are round in cross section.

Answer 24

ROOT CONFIGURATION

Question 25

Different root configurations (4)

Answer 25

Normal (Cynodont)
Hypotaurodont
Mesotaurodont
Hypertaurodont

Question 26

• ________ have a greater surface area and are better able to bear added stress.

Answer 26

Larger teeth

Question 27

• In addition to increased load placed on the periodontal ligament by a long-span FPD, longer spans are less ____.
• Bending or deflection varies ____ with the cube of the length and ____ with the cube of the occlusogingival thickness of the pontic.
• Compared with a FPD single tooth pontic, a two-tooth pontic will bend __ as much, while a three-teeth pontic will bend ___ as much as a single pontic.

Answer 27

rigid
directly
inversely
8x
27x

Question 28

• Preparations should be modified accordingly to produce ____________ and _____________.

G ____________, including some on the facial and lingual surfaces, are commonly employed for this purpose.

Answer 28

greater resistance
structural durability
Multiple grooves

Question 29

G ___________ are sometimes used as a means of overcoming problems created by unfavorable crown-root ratios and long spans.
G There are several criteria that must be met if a _____ (remote from the edentulous space) abutment is to strengthen the fixed partial denture and not become a problem itself.

Answer 29

Double abutments
secondary

Question 30

G __________ has its effect on the stresses occurring in a fixed partial denture.
G When pontics lie outside the __________________, the pontics act as a ____ arm, which can produce a ________ movement.
G This is a common problem in replacing all four maxillary incisors with a fixed partial denture, and it is most pronounced in the arch that is pointed in the anterior.

Answer 30

Arch curvature
interabutment axis line
lever
torqueing

Question 31

FPD with the pontic _____ fixed to the retainers provides desirable strength and stability to the prosthesis while minimizing the stresses associated with the restoration

Answer 31

rigidly

Question 32

A problem that occurs with some frequency is a mandibular second molar abutment that has tilted mesially into the space formerly occupied by the first molar.

Answer 32

TILTED MOLAR ABUTMENTS

Question 33

Replacing canines can be difficult because the canine often lies outside the interabutment axis.

Answer 33

CANINE-REPLACEMENT FPD

Question 34

• has an abutment or abutments at one end only, with the other end of the pontic remaining unattached.
• This is a potentially destructive design with the lever arm created by the pontic, and it is frequently misused.

Answer 34

CANTILEVER FPD