Using a Matrix to Build the Lingual Shelf for Class IV Restorations

Creating a solid lingual layer for composite bonding is critical to achieving natural, long-lasting results. Here’s a step-by-step guide based on Dr. Corky Willhite’s method for using a template (or putty index/matrix) and Renamel Microhybrid to form the lingual layer.

Step 1: Prepare the Template

Create and Trim the Template: Once the template is made, trim it carefully along the facial incisal line angle. This ensures you avoid trapping air bubbles or leaving too much material, which can affect the thickness of the incisal edge.

Check the Fit: Try the trimmed template in the patient’s mouth to ensure it fits well and lines up correctly.

Step 2: Score the Lingual Margin

Mark the Lingual: Gently score the lingual margin of the template with a light mark with your IPC instrument. This helps guide the placement and thickness of the composite material.

Step 3: Load the Template with Composite

Use Renamel Microhybrid Composite: Dr. Wilhite recommends using Renamel Microhybrid for its adaptability and lower viscosity. Slowly extrude the composite into the template, avoiding air pockets.

Distribute Evenly: Spread the composite across the template to avoid lumps or trapped air bubbles, especially when working with multiple teeth.

Step 4: Adapt the Composite to the Lingual Surface

Smooth the Base: Use a multi-use instrument to smooth the composite where it will adhere to the lingual surface of the tooth. Avoid creating a large ledge or leaving excess material that might trap air.

Check Thickness: Ensure the composite isn’t too bulky; it should be adapted smoothly to the tooth but not paper-thin.

Step 5: Seat the Template

Monitor the Lingual Margin: As you seat the template, watch the lingual margin to ensure it’s positioned correctly. Adjust as needed before fully seating the template.

Step 6: Thin and Refine the Composite Layer

Achieve the Proper Thickness: After seating, press the composite from the facial side to thin the layer. The goal is to make it thin but durable, ensuring there’s enough room for the final layers without the composite being too fragile.

Avoid Proximal Thickness: Clear any excess composite from the proximal areas, as the final facial enamel layer will form the proximal surface later.

Step 7: Cure the Composite

Cure Carefully: When curing through the tooth, double the curing time to ensure the material sets properly. If some areas remain uncured, blend them in before curing the lingual surface.

Check and Blend: After removing the template, check for any uncured composite on the lingual side. Blend these areas smoothly before finishing the cure.

Step 8: Final Touches

Cross-section Shape: The composite should resemble the shape of the letter “L” in cross-section, providing enough space to add the remaining layers, including those for incisal translucency and color blending.

Following these steps you’ll create a well-formed lingual layer that ensures a strong bond and a natural appearance for composite restorations.

About the AuthorDr. Corky Willhite

Dr. Corky Willhite has achieved Fellowship from the Academy of General Dentistry, the American College of Dentists, and the American Academy of Cosmetic Dentistry. He is one of less than 100 Accredited Fellows in the AACD worldwide. He has served on their Board of Governors (currently the American Board of Cosmetic Dentistry) and spent years as an Examiner for Accreditation. He is an Assistant Clinical Professor in the Department of Prosthodontics at L.S.U. School of Dentistry. He is on the faculty of the Center for Esthetic Excellence in Chicago. He has been published and feels honored to have so many opportunities to lecture nationally and internationally. Over the years, his private practice in suburban New Orleans—The Smile Design Center—has become limited to Cosmetic Dentistry. His experience is based on a dedication to the belief that “excellence” and “esthetics” are not only compatible but can take dentistry to a new level of satisfaction and success.