Lec 7

Question 1

The acceptable abutment tooth!

Answer 1

1. Endodontically treated and is asymptomatic,with radiographic evidence of a good seal and complete obturation of the canal.
2. A tooth with some sound,surviving coronal tooth structure to ensure longevity.

Question 2

A tooth that shouldn’t be used as a fixed partial denture abutment!

Answer 2

The one that has been pulp capped in the process of preparation

Question 3

Factors the are taken into consideration with the roots and the surrounding tissues of the abutment teeth.

Answer 3

1. Crown_root ratio.
2. Root configuration.
3. Periodontal ligament area.

Question 4

Crown_root ratio

Answer 4

It is the measure of the
crown (from the occlusal to the alveolar crest of bone)compared with the length of root embedded in the bone.

Question 5

What is the optimum crown_root ratio for a tooth to be used as a fixed partial denture abutment?

Answer 5

2:3

Question 6

Root configuration

Answer 6

1. Roots that are border labiolingually than they are mesiodistany are more preferred
2. In multi-rooted posterior teeth, widely separated roots are better in periodontal support than fused roots.

Question 7

Note about conical roots!

Answer 7

The tooth with conical roots can be used as an abutment for a short_span fixed partial denture if all other factors are optimal.

Question 8

What is ante’s law ?

Answer 8

The tooth surface area of the abutment Teeth
had to equal or surpass that of the teeth being replaced with Pontiacs.

Question 9

What are the situations where the mobility of the abutments can be maintained?

Answer 9

When:
1. They are free of inflammation.
2. The patient is aware of the oral hygiene and proficient in plaque removal.

Question 10

Double abutments

Answer 10

Used when we have unfavourable crown_root ratios and long spans.

Question 11

Note about double abutment!!

Answer 11

A secondary abutment must have at least as much root surface area and as a crown_root ratio as the primary abutment.
For example: a canine can be used as a secondary abutment to a first premolar primary abutment, but we cannot use lateral incisor as a secondary abutment to a canine primary abutment.

Question 12

How the arch curvature has its effect on the stresses occurring in a fixed partial denture?

Answer 12

When poetics lie outside in the inter- abutment axis line, the Pontic act as a lever arm, which can produce A torquing movement.
For example: when replacing all four maxillary incisors with a fixed partial denture