Detail on class i amalgam preparation

1. Class I Amalgam Preparation
I.M.C

2. Outline form
Smooth cavosurface margin
Maintains as much tooth structure
as possible (goes around cusps,
narrow isthmus, MR intact)
Follows grooves

3. Retention form
Prevents restoration from being
dislodged
B-L View
correct incorrect
M-D View

4. Resistance Form
Prevents fracture

5. Convenience form
Convenient for the provider!
Can you see/access everything?
Convenient for the patient!
Can they maintain it? caries

6. Steps…

7. EXAMPLE: CLASS I CAVITY PREPARATION
#36-O Amalgam Preparation:
(Mandibular Left First Molar)
Armamentarium:
Restorative cassette
Sharp pencil
330 Bur
245 Bur
Slow and high-speed handpieces
Guidelines:
Isthmus width: 1.0-1.5 mm (1.2mm)
Pulpal floor depth: 1.5-2 mm
Marginal ridge width: 1.5-2 mm measured from an imaginary line drawn tangent to the height of contour of the
proximal surface to the proximal margin of the preparation
5 degree convergence of the buccal and lingual walls
5-10 degree divergence of the mesial and distal walls

8. Outline form:
Prepare a smooth,flowing curve, around the cusps and centered over grooves and fissures. Keep the isthmus
narrow at 1.0-1.5 mm. Bur orientation should be perpendicular to the occlusal plane.
Resistance form:
Pulpal floor depth: 1.5-2.0 mm, relatively flat pulpal floor, slightly divergent mesial and distal walls.
Retention form:
Slightly convergent buccal and lingual walls.
Toilet of the cavity:
Clean and dry the tooth with the air/water spray prior to evaluation.
Self-Evaluation Form Instructions:
Record all errors and describe them precisely in the self-evaluation form, then go over project and form with
your preclinical instructor.

9. a
BUCCAL
LINGUAL
a

10. THANK YOU FOR YOUR ATTENTION