1. The Role of Wedges

Wedges not only help in stabilizing the matrix band but also serve two main functions:

• Separation: Creating slight tooth separation for a tighter proximal contact.
• Adaptation: Ensuring the matrix band adapts closely to the cervical margin, reducing the risk of overhangs.

Types of Wedges

Wooden wedges:

• Provide better separation, especially useful for pre-wedging.
• Can support the rubber dam.
• Sometimes require customization if they cause unwanted convexity inside the cavity or when dealing with concavities at the cervical margin (e.g., mesial of upper first premolar, mesial of lower first molar, or distal of upper first molar).

Plastic wedges (V-shaped, hollow):

• Easier and faster to place.
• Do not compress the gingival papilla.
• More flexible, allowing better adaptation of the matrix band.

read our guide about Snow Plow vs Injection Molding Technique in Class II Composite Restorations

Diamond wedges (Bioclear system):

• Available in different sizes and shapes.
• Expand once placed, providing strong fixation and preventing overhangs.
• Especially useful in deep margin cases.

2. Separation Rings

Separation rings provide stronger stabilization and contact creation compared to wedges alone.

Material:

• Stainless steel (SS): weaker separation, loses tension quickly.
• NiTi: stronger, more durable.

Design:

• Angled rings for better stability.
• Prongs may be made of SS, NiTi, glass fiber plastic, or soft silicone.
• V-shaped prongs give better adaptation, reducing overhangs.

Limitations of Separation Rings

• May cause straightening of the matrix band in the occlusal third, reducing natural occlusal embrasure.
• Sometimes, the cervical margin opens, requiring Teflon or other sealing methods.
• Using two rings simultaneously (mesial + distal) in MOD cavities is not recommended, as their separation forces cancel out.

💡 Clinical Tip: In back-to-back Class II cavities, restore one box completely before moving to the second to ensure proper contact and contour.

3. Teflon Tape

Teflon tape is extremely valuable in Class II restorations:

• Seals gaps at the gingival margin.
• Provides additional matrix stabilization when rings are not used.
• Useful in deep Class II cases with difficult sealing.

While complete prevention of overhangs is impossible, Teflon significantly reduces their occurrence and simplifies finishing.

4. Flowable Composite for Stabilization

Flowable composite can be used as a temporary block-out material:

• Applied at the gingival margin or cavity floor to stabilize the matrix band.
• Particularly helpful when rings are not used.
• Should be removed or carefully integrated into the restoration during finishing.

Clinical Considerations

• Always aim for tight proximal contacts: studies show that initially strong contacts may weaken over time, while weaker contacts remain unchanged. This highlights the importance of maximizing contact tightness from the start.
• Overhangs cannot be avoided 100%, but if they are small, well-adapted, and smooth, their clinical impact on the periodontium may be negligible.
• In MOD restorations, prioritize one box with a ring and wedge, then complete the second box separately.

Successful stabilization of matrix bands in Class II restorations depends on proper selection of wedges, separation rings, Teflon tape, and flowable composite. Wooden wedges and NiTi rings remain gold standards, while advanced options like diamond wedges and Bioclear systems provide additional control. Mastering these techniques ensures well-contoured restorations with tight contacts and minimal overhangs, ultimately improving the longevity of posterior composite restorations.