fixed pros Flashcards
When would you provide extra coronal restorations
To protect weakened tooth structure
To improve or restore aesthetics
For use as a retainer for fixed bridgework
When indicated by the design of a RPD
-Rest seats
-Clasps
-Guide planes
To restore tooth function
What are the principles of tooth prep
1- Preservation of tooth structure
2- Retention and resistance
3- Structural durability
4- Marginal integrity
5- Preservation of the periodontium
6- Aesthetic considerations
What is meant by retention and resistance
Retention:
Prevents removal of the restoration along the path of insertion or the long axis of the tooth preparation
Resistance:
Prevents dislodgement of the restoration by forces directed in an apical or oblique direction and prevents any movement of the restoration under occlusal forces
How is resistance and retention achieved
Taper:
Ideal inclination of opposing walls 6º.
Long walls not short to prevent tipping
Extra means of retention
-Grooves
-Slots
Parallel walls
limiting paths of insertion
What must the margins of the restoration be
- Smooth and fully exposed to a cleansing action
- Placed where the dentist can finish them and the patient can clean them.
- Placed at gingival margin whenever possible
What is the prep needed for a metal crown
axial reduction 0.5m
Functional cusp 1.5mm
Non-functional cusp 0.5mm
0.5-1mm Chamfer
What is the prep needed for a porcelain crown
axial reduction 1m
Functional cusp 1.5mm
Non-functional cusp 1mm
1mm Shoulder
What is the prep needed for a metal ceramic crown
axial reduction 1.3mm
Functional cusp 1.8mm
Non-functional cusp 1.3mm
Chamfer where the metal is
Shoulder where the ceramic is
What is the tooth prep needed for a all ceramic crown
axial reduction 1.5m
Functional cusp 2mm
Non-functional cusp 1.5mm
1mm Chamfer
When would you plan veneers
Improve aesthetics
Change teeth shape and/or contour
Correct peg-shaped laterals
Reduce or close proximal spaces and diastemas
Align labial surfaces of instanding teeth
When would you NOT plan veneers
Poor OH
High caries rate
Gingival recession
Root exposure
High lip lines
If extensive prep needed (>50% of surface area no longer in enamel)
Labially positioned,severely rotated and overlapping teeth
Extensive TSL/insufficient bonding area
Heavy occlusal contacts
Severe discolouration
When would you plan inlay or onlay
Tooth wear cases
-Increase OVD
Fractured cusps
Restoration of root treated teeth
Replace failed direct restorations
When would not plan inlay or onlay
Active caries and perio disease
Time consuming
Cost
When would you plan the use of crowns
To protect weakened tooth structure
To improve or restore aesthetics
For use as a retainer for fixed bridgework
When indicated by the design of a RPD
To restore tooth function
When would you not use crowns
Active caries and periodontal disease
More conservation options available
Lack of tooth tissue for preparation
Unable to provide post and core
Unfavourable occlusion
