Tooth Preparation

Question 1

What are the purposes of tooth preparation?

Answer 1

• Provided positive location for rests which will not interfere with occlusion or impose non-axial loading on abutment tooth
• Reduce undesirable undercuts
• Alter position of survey line
• Remove abrupt chagnes in direction of denture components resulting in sharper angles (e.g. clasp arm moving from buccal to proximal surface)
• Restore occlusal plane in tilted/over erupted teeth
• Create space for denture components (e.g. connectors or clasp arms need to pass through occlusal embrasures but opposing teeth interfere)

Question 2

What rules guide tooth preparation in rem pros?

Answer 2

• Minimal modification of natural tooth structure
• Modification restricted to enamel
• Modified teeth must be treated with fluoride
• If restoration placed on proximal surface, should minimise undercut (but would not prepare proximal surface of natural tooth)

Question 3

How should occlusal rest seats be prepared?

Answer 3

• Spoon shaped
• Slope apically away from proximal surface
• Blend with occlusal surface
• Provide adequate rest thickness
• Ensure rest does not intefere with occlusion

Question 4

How should cingulum rest seats be prepared?

Answer 4

• Axial surface parallel to or slightly parallel but not undercut to the path of insertion
• Floor no greater than 90 degrees to axial wall of seat (as rest can slip off since there is only one wall and one floor, the other side is open)
• Floro should be less than 1mm wide

Question 5

What speed handpiece should be used to prepare the tooth?

Answer 5

-Intermediate