Class V tooth preparation for amalgam restoration

1. Class V Tooth
Preparation for
Amalgam Restorations
MARYAM ARBAB

2. Tooth Preparation
 It is defined as the mechanical alteration of a tooth to receive a
restorative material, which will return the tooth to proper anatomical
form, function and esthetics.
 The procedure of preparing the tooth by removal of defective or
friable tooth structure.
 Any remaining infected or friable tooth structure may result in further
caries progression, sensitivity or pain or fracture of the tooth and/or
restoration.

3. Classification for restoration

4. Class V restorations
Class V restorations ,by definition, include
the gingival one third (i.e., cervical area) of
the facial and lingual surface of the tooth
crown

5. Amalgam
 Amalgam is an alloy in which mercury occurs as a main
component.
 Dental Amalgam is an alloy of mercury with silver, tin and varying
amounts of copper, zinc and other minor components.

6. Advantages of amalgam
1. Ease of manipulation
2. Satisfactory marginal adaptation
3. Wider range of application
4. Physical characteristics are comparable to enamel and dentin
5. Less technique sensitive
6. Self sealing
7. Biocompatible
8. good wear resistance
9. Low cost
10. Can be completed in 1 dental visit

7. Disadvantages of Amalgam
1. Less aesthetic
2. Extensive preparation to hold an amalgam filling
3. Amalgam filling can corrode or tarnish over time, causing
discoloration
4. Does not bond to tooth
5. No-insulating
6. Does not support weakened tooth structure
7. Poor tensile strength, thus brittle
8. Results in galvanic current with gold restorations or even same
restoration with non-uniform condensation

8. Contraindications of Amalgam
 When aesthetics is the prime concern
 Small to moderate class I and II preparations

9. Class V Tooth
Preparation for
Amalgam Restorations

10. Principles of tooth preparation
 There are 2 steps
 Initial tooth preparation
 Outline form
 Primary resistance form
 Primary retention form
 Convenience form
 Final tooth preparation
 Management of remaining caries
 Secondary resistance and retention form
 Pulp protection, if required
 Finishing of enamel margins
 Final inspection of preparation

11. Initial Tooth Preparation
 The same general principles for tooth
preparation apply for all other tooth
locations .
 Using an inverted cone bur of suitable size,
enter the carious lesion (or existing
restoration) to a limited initial axial depth of
0.5 mm inside the DEJ .

12.  The depth is usually (1-1.25mm) total axial depth, depending on the
incisogingival/occlusogingival location.
 The enamel is considerably thicker occlusally and incisally than
cervically.

13.  Extend the preparation incisally,gingivally,
mesially and distally until the cavosurface
margins are positioned in sound tooth
structure to establish an initial axial depth
of 0.5 mm inside the DEJ( if on the root
surface, the axial depth is 0.75mm) .
 The axial wall should be in sound dentin,
unless there is remaining infected caries or
old restorative material .

14.  Preparation of the axial wall depth 0.5 mm inside the DEJ results in a
uniform depth for the entire preparation .
 A depth of 0.5 mm inside the DEJ will permit placement of necessary
retention grooves without undermining the enamel .

15. Final Tooth Preparation
 Final tooth preparation involves removal of any remaining infected
dentin, pulp protection, retention form, finishing external walls, and
final procedures of cleaning, inspecting, and desensitizing.
 Remove any remaining infected axial wall dentin with a No. 2 or
No. 4 bur.
 As the mesial, distal, gingival, and incisal walls of the tooth
preparation are perpendicular to the external tooth surface, they
usually diverge facially.

16.  Consequently, this form provides no inherent retention, and retention
form must be provided .
 Use a No.1/4 bur to prepare two retention grooves, one along the
incisoaxial line angle and the other along the gingivoaxial line angle.
 The depth of the grooves should be approximately 0.25 mm, which is
half the diameter of the bur.
 Finally, clean the preparation using air-water spray and evacuation.

17.  use the air syringe to remove visible moisture
(do not desiccate tooth structure), and
inspect the preparation for completeness.
 If the preparation is complete, either apply :
 desensitizer (for a non-bonded
restoration)
or
 begin the bonding procedures (for a
bonded restoration).

18. Condensation and Carving
 Using the amalgam carrier, insert the mixed amalgam into the
preparation in small increments and condense it into the retention
areas first with an appropriately sized condenser.
 Next, condense the amalgam against the mesial and distal walls of
the preparation
 Finally, provide sufficient bulk in the central portion to allow for
carving the correct contour .

20.  Carving may begin immediately after insertion of the amalgam

21.  the side of the carving instrument should always rest on unprepared
tooth surface adjacent to the prepared cavosurface margin. This
prevents overcarving.
 Begin the carving procedure by removing excess amalgam to
expose the incisal (or occlusal) margin.
 Continue removing excess to expose the mesial and distal margins.

22.  Finally, carve away excess at the gingival margin

23. Finishing and Polishing
 If carving procedures were performed correctly, no finishing of the
restoration should be required.
 However ,additional finishing and polishing of amalgam restorations
may be necessary to correct a marginal discrepancy or improve
the contour.

24.  Care is required when using stones or any rotating cutting instruments
on margins positioned below the cementoenamel junction (CEJ).
 This is because of the possibility of removing cementum or notching the
tooth structure gingival to the margin or both

25. References
• Art and Science of
Operative dentistry
• Textbook of Operative
Dentistry
• Internet

26. Questions

27. Thank You!