Steps for Class II Cavity Preparation in Deciduous Teeth for Amalgam

Restoring deciduous teeth with amalgam requires proper cavity preparation to ensure durability and functionality. Here are the steps involved in preparing a Class II cavity in deciduous teeth:

1. Diagnosis and Treatment Planning

• Clinical Examination: Assess the extent of caries through visual inspection and radiographs.
• Treatment Plan: Decide on the need for amalgam restoration based on the tooth’s condition and patient’s oral hygiene.

2. Anesthesia

• Local Anesthesia: Administer local anesthesia to ensure patient comfort during the procedure.

3. Isolation

• Rubber Dam: Use a rubber dam to isolate the tooth, providing a dry working field and preventing contamination.

4. Access Opening

• Initial Cut: Use a high-speed handpiece with a round or pear-shaped bur to create an initial access opening, removing carious enamel and dentin.

5. Outline Form

• Cavity Shape: Extend the cavity outline to include all carious areas and unsupported enamel, ensuring smooth and rounded internal line angles to reduce stress concentration.
• buccal and lingual wall should converge occlusally.
• width of isthmus is about 1/3 occlusal table.
• gingival floor is just beneath contact area with no bevel on gingival margin.

6. Resistance and Retention Form

• Cavity Depth: Ensure the cavity is deep enough to provide resistance against occlusal forces but not so deep as to risk pulp exposure.
• Retention Grooves: Place retention grooves or undercuts in the dentin to help retain the amalgam.

G. V. Black class II amalgam cavity preparations. A, Maxillary right second and first primary molars (occlusal view). B, Mandibular second primary molar (proximal view); note occlusal convergence of proximal walls. C, Mandibular right second and first primary molars (occlusal view).

7. Removal of Carious Dentin

• Excavation: Use a slow-speed handpiece or spoon excavator to remove all infected dentin, preserving as much healthy tooth structure as possible.

8. Finishing Enamel Walls

• Smooth Walls: Smooth and refine the enamel walls and margins to ensure a good seal with the amalgam.

9. Cavity Cleanliness

• Debris Removal: Thoroughly clean the cavity with water spray and dry it with air to remove all debris and moisture.

10. Base or Liner Placement (if needed)

• Protective Layer: Place a base or liner, such as calcium hydroxide or glass ionomer, if the cavity is deep and close to the pulp(the best cement to be placed is zinc polycarboxylate cement ).

11. Matrix Band Placement

• Matrix Band: Place a matrix band around the tooth to help shape the amalgam and restore the proper contour of the tooth(T band should be used ).

A, The T-band matrix. B, The T band is formed into a circle, and the extension wings are folded down to secure the band. C, The T band is adapted to fit the tooth tightly , and the free end is bent back.

12. Amalgam Condensation

• Condensation: Condense the amalgam into the cavity incrementally, ensuring there are no voids and achieving a dense restoration.

13. Carving and Finishing

• Carving: Carve the amalgam to reproduce the tooth’s natural anatomy and ensure proper occlusion(shallow carving).
• Finishing: Smooth the surface of the amalgam to reduce roughness and enhance the longevity of the restoration.

14. Final Check

• Occlusion: Check the occlusion and make any necessary adjustments to ensure the restoration does not interfere with the patient’s bite.

15. Post-Operative Instructions

• Care Advice: Provide the patient with instructions on how to care for the restoration and maintain good oral hygiene.

for more information on class 1 cavity preparation check this link : 

https://oraloasis.blogspot.com/2024/10/steps-of-class-i-cavity-preparation-in.html