Class III Composite Preparation
#8 ML
![](https://mydentalkey.com/wp-content/uploads/2023/11/Class-III_edited-e1713032771267.png)
Overview
-
Outline Form
preparation outline is determined by the extent of the carious lesion, defects, or old restorative material
-
Retention Form
obtained through micromechanical bonding of tooth structure to restoration material
*beveling increases tooth structure available for bonding -
Resistance Form
rounded box form provides greater resistance to fracture of the restoration and tooth from masticatory forces
-
Convenience Form
appropriate access to the interproximal lesion is gained from the lingual or buccal surface
Armamentarium
Instruments and Materials
![](https://mydentalkey.com/wp-content/uploads/2024/04/Class_III_Prep_Arm-edited.png)
Video Demonstration
![](https://mydentalkey.com/wp-content/themes/MDK/assets/images/404-img.png)
Procedures
- Clinical note: Perform shade selection with natural light prior to isolation of the tooth
![](https://mydentalkey.com/wp-content/uploads/2023/02/shade_guide.png)
- Clinical notes:
- Preparation measurements are determined by the extent of the carious lesion or existing, faulty restoration
- Class III procedure is performed when caries extends past enamel into dentin. Therefore, the mesial-distal width of the preparation will be at least 0.2 mm into dentin
*Radiographic caries superimposed on preparation
![](https://mydentalkey.com/wp-content/uploads/2023/11/Class-III-caries-2_edited.png)
![](https://mydentalkey.com/wp-content/uploads/2023/11/Untitled_Artwork-18-2-scaled-e1701876343275.jpg)
![](https://mydentalkey.com/wp-content/uploads/2023/11/Untitled_Artwork-7.jpg)
![](https://mydentalkey.com/wp-content/uploads/2023/11/indirect-vision.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/DSC_0010-copy-1_edited.jpg)
- Clinical note: Position the bur over the carious lesion or existing, faulty restoration
Bur options: pear shaped carbide bur (330)
![](https://mydentalkey.com/wp-content/uploads/2023/11/Untitled_Artwork-3-2-scaled-e1699611774904.jpg)
![](https://mydentalkey.com/wp-content/uploads/2023/11/F7D21D94-D688-46B8-AB75-ED2F75860BAE_1_105_c.jpeg)
- Facial wall is at least 90º relative to the axial wall
- Optional:
- Leave a small “enamel shell” interproximally
- Break the enamel shell with a hand instrument
- Clinical note:
- Extension should remove the carious lesion or existing, faulty restoration
Hand instrument options: enamel hatchet, enamel hoe
![](https://mydentalkey.com/wp-content/uploads/2023/11/Untitled_Artwork-20-1-scaled.jpg)
- Inciso-gingival length: 2-2.5mm, no greater than 3mm, depending on the length of the contact
- Gingival floor width: 1-1.25mm
- Incisal floor width: 1.25-1.5mm
![](https://mydentalkey.com/wp-content/uploads/2023/11/09CED662-9CE9-4C05-A3FE-F9CC538D061A_1_105_c.jpeg)
![](https://mydentalkey.com/wp-content/uploads/2023/11/7D29ECC4-FBF0-495B-B476-4A4A70DCED77_1_105_c.jpeg)
- Assess for remaining caries using the explorer or spoon excavator
- Remove remaining carious tooth structure using the largest round bur that fits into the preparation with rotary instruments (slow speed) or a spoon excavator
Bur options: round carbide burs (4, 6)
![](https://mydentalkey.com/wp-content/uploads/2023/11/Untitled_Artwork-90.png)
Bur options: pear shaped carbide bur (330)
![](https://mydentalkey.com/wp-content/uploads/2023/11/Untitled_Artwork-191-scaled.jpg)
- Remove major unsupported enamel
- Remove steps/ledges
Bur options: straight fissure or pear shaped carbide (556, 330)
Hand instrument options: enamel hatchet, enamel hoe
![](https://mydentalkey.com/wp-content/uploads/2023/11/Untitled_Artwork-20-1-scaled.jpg)
- Do not bevel in areas subject to masticatory forces (e.g. incisal contact)
Bur options: coarse diamond bur (flame)
![](https://mydentalkey.com/wp-content/uploads/2023/11/Untitled_Artwork-182-scaled.jpg)
![](https://mydentalkey.com/wp-content/uploads/2023/11/Untitled_Artwork-19-scaled.jpg)
- Use the explorer to check for smoothness
- Use the probe to check for appropriate depth and width
- Clinical note: The final depth of the preparation is determined by the extent of the carious lesion or existing, faulty restoration
![](https://mydentalkey.com/wp-content/uploads/2023/11/Untitled_Artwork-181-scaled.jpg)
Checklist
![](https://mydentalkey.com/wp-content/uploads/2023/11/C3-com-prep-1.jpeg)
![](https://mydentalkey.com/wp-content/uploads/2023/11/8_CIII_RC_Outline-1.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