Class II Amalgam Preparation
#29 DO
![](https://mydentalkey.com/wp-content/uploads/2023/04/Class_II_Amalgam_Preparation-e1713034062456.png)
Overview
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Outline Form
extent of preparation on tooth surface
*amalgam preparations are typically larger than comparable composite preparations due to material requirements -
Retention Form
form, shape, and configuration of the tooth preparation that resists the displacement or removal of restoration from the preparation under lifting and tipping masticatory forces
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Resistance Form
internal form of tooth preparation that allows restoration to resist forces of mastication
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Convenience Form
form of tooth preparation that allows for physical and visual accessibility to preparation
Armamentarium
Instruments and Materials
![](https://mydentalkey.com/wp-content/uploads/2023/04/Class_ii_A_Prep_Arm.png)
Video Demonstration
![](https://mydentalkey.com/wp-content/themes/MDK/assets/images/404-img.png)
Procedures
- Clinical note: The final preparation dimensions are determined by the extent of the carious lesion or existing, faulty restoration
![](https://mydentalkey.com/wp-content/uploads/2023/04/Class_II_Amalgam_Caries.png)
![](https://mydentalkey.com/wp-content/uploads/2023/11/11DADC94-E25D-4799-831A-C6D322DE2E97.jpeg)
![](https://mydentalkey.com/wp-content/uploads/2023/11/Untitled_Artwork-21-scaled.jpg)
- Optional: Place a matrix band or metallic fender wedge interproximally to protect the adjacent tooth from iatrogenic damage
![](https://mydentalkey.com/wp-content/uploads/2023/11/Untitled_Artwork-20-scaled.jpg)
- Bur options: pear shaped carbide bur (330)
![](https://mydentalkey.com/wp-content/uploads/2023/11/8AC18DB3-5BA5-4FCF-83C2-6CB4A0FC3E8E.jpeg)
![](https://mydentalkey.com/wp-content/uploads/2023/11/Untitled_Artwork-18-scaled.jpg)
Clinical note: The final preparation depth is determined by the extent of the carious lesion or existing, faulty restoration
![](https://mydentalkey.com/wp-content/uploads/2023/11/57C8E000-C3B4-46EC-8B9E-363D8029466C_1_105_c.jpeg)
- Always keep the bur perpendicular to the long axis of the tooth
- Follow the anatomical grooves of the tooth
- Leave a small “enamel shell” interproximally to protect the adjacent tooth from iatrogenic damage
![](https://mydentalkey.com/wp-content/uploads/2023/11/Untitled_Artwork-22-scaled.jpg)
- BL width of occlusal outline: at least 1mm
- BL width of isthmus: 1-1.5mm
- BL dimension must accommodate the smallest condenser
![](https://mydentalkey.com/wp-content/uploads/2023/04/IMG_3895.jpeg)
- Follow the anatomy of the grooves
Bur options: pear shaped carbide burs (330, 245)
![](https://mydentalkey.com/wp-content/uploads/2023/11/DF81B957-BF7A-4B76-AB51-FD192BAEFE7F_1_105_c.jpeg)
![](https://mydentalkey.com/wp-content/uploads/2023/11/906543FD-FC58-4A31-9F28-4A6AB1BA2DFB_1_105_c.jpeg)
Bur options: pear shaped carbide burs (330, 245)
![](https://mydentalkey.com/wp-content/uploads/2023/11/D43A0BE3-04BA-4CCA-BD5A-B1166ACC9376_1_105_c.jpeg)
- The gingival contact is broken <0.5mm
- When the gingival contact is broken, the tip of the explorer will pass through the broken contact
Drop the box = creating the proximal box!
![](https://mydentalkey.com/wp-content/uploads/2023/11/Untitled_Artwork-22-scaled.jpg)
![](https://mydentalkey.com/wp-content/uploads/2023/11/D43A0BE3-04BA-4CCA-BD5A-B1166ACC9376_1_105_c.jpeg)
- Position the flat side of the instrument against the enamel shell and push the instrument outward toward the adjacent tooth
Hand instrument option: enamel hatchet
![](https://mydentalkey.com/wp-content/uploads/2023/11/41A88801-285E-40E4-B802-F799D10CB3CC_1_201_a.jpeg)
Bur options: pear shaped carbide burs (330, 245) <br>
Hand instrument options: enamel hatchet
![](https://mydentalkey.com/wp-content/uploads/2023/11/B3FC3193-88F0-4F64-A6B5-7485751148DC_1_201_a.jpeg)
- The exit angles are 90º degrees to the tooth surface, following the direction of the enamel rods
- The buccal and lingual walls are occlusally convergent
- The axial wall is occlusally divergent
![](https://mydentalkey.com/wp-content/uploads/2023/11/Untitled_Artwork-17-scaled.jpg)
- The tip of the explorer should pass through buccal, lingual, gingival contacts
![](https://mydentalkey.com/wp-content/uploads/2023/11/6B6BB797-AF56-4488-9A59-A6DD4CA093CC_1_201_a.jpeg)
Bur options: pear shaped carbide burs (330, 245)
![](https://mydentalkey.com/wp-content/uploads/2023/11/D43A0BE3-04BA-4CCA-BD5A-B1166ACC9376_1_105_c.jpeg)
![](https://mydentalkey.com/wp-content/uploads/2023/11/EB784DA4-9983-4617-AF89-B4A19373629B_1_201_a.jpeg)
Bur options: round carbide burs (4, 6)
![](https://mydentalkey.com/wp-content/uploads/2023/11/IMG_3075-scaled.jpeg)
- Remove unsupported enamel
- Remove steps/ledges
- Bevel the axiopulpal line angle
![](https://mydentalkey.com/wp-content/uploads/2023/11/B2624D5A-1FB6-4ACE-A50E-D2640AF47FA5_1_105_c.jpeg)
Hand instrument options: enamel hatchet, enamel hoe, gingival margin trimmer
![](https://mydentalkey.com/wp-content/uploads/2023/11/565A376B-F53F-4651-899F-27F4B2D44149_1_201_a.jpeg)
![](https://mydentalkey.com/wp-content/uploads/2023/11/6852E0CC-98DC-4810-8C27-376BCE84FF81_1_105_c.jpeg)
- Use the explorer to check for smoothness
- Use the probe to check for appropriate depth and width
- Clinical note: The final dimensions of the preparation are determined by the extent of the carious lesion or existing, faulty restoration
![](https://mydentalkey.com/wp-content/uploads/2023/11/Class-II-a--scaled.jpg)
Checklist
![](https://mydentalkey.com/wp-content/uploads/2023/11/c2-am-prep.jpg)
![](https://mydentalkey.com/wp-content/uploads/2023/11/c2-am-labeled.jpeg)
Common Mistakes
![](https://mydentalkey.com/wp-content/uploads/2023/11/ddd.png)
![](https://mydentalkey.com/wp-content/uploads/2023/11/dde.png)
References
Hilton, T. J., Ferracane, J. L., & Broome, J. C. (2013). Summitt’s fundamentals of operative dentistry a contemporary approach. Quintessence Publishing Co. Inc.
Ritter, A. V., Boushell, L. W., Walter, R., & Sturdevant, C. M. (2019). Sturdevant’s art and Science of Operative Dentistry. Elsevier.
Congratulations
You’ve reached the end of this lesson