Overview of the Clear Custom Matrix Technique
The Clear Custom Matrix Technique for light-cured composites utilizes a clear, fast setting, PVS bite registration material to take a pre-operative impression of the tooth surfaces to be restored. This small, extremely accurate impression is used to reform the unset composite, like a die, and then allows light through for curing. This technique can be used with any light cured restorative material to shape any class of composite restoration leaving a surface that is NOT air- inhibited and in many cases needs NO finishing or polishing, saving 5 to 10 minutes of chair-time, materials and effort.
The vast majority of light-cured restorations can benefit from the Clear Custom Matrix Technique.
If the surface is defective due to caries or tooth fracture, these defects can usually be restored quickly with a very small amount of red border molding wax. A small amount of red wax is rubbed into the defect with a gloved finger and the excess carved away with an explorer or another instrument, and then the custom matrix impression is made. If replacing a fractured cusp, the red wax is shaped with gloved fingers and the excess removed as above. To see a demonstration of using red wax, please see the video on this web site "Gross Caries Restoration - A Time Saving Technique."
The most difficult aspect of the custom matrix procedure is knowing the amount of composite to place for the restoration. You only want to place a slight excess. Since most dentists have been trained to place more composite than is needed and grind away the excess, it is a difficult habit to break.
There is a training-wheels approach. Coat the composite side of the custom matrix with a separator such as your bonding resin. This will allow the custom matrix to be removed without distorting the surface. Then you can see the excess composite flash. After removing the flash, the matrix is replaced and the composite is cured through the clear custom matrix. Bonding resin as a separator works about 80% of the time. I have tried every type of separator, and they are all equally successful. Consequently, I would recommend a bonding resin since it is conveniently available.
After curing through the matrix for the normal amount of time, the matrix is removed, and if there is any gross flash, it is removed prior to curing the composite again for the normal amount of time.
This technique allows the quick, easy placement, contouring and "finishing" of any light-cured material, while allowing the reproduction of anatomy, contour and surface texture that is many times impossible to do freehand.
If you have any questions or problems with this technique, please email me. I have used the Clear Custom Matrix Technique successfully for 15 years.
James C. Hamilton, DDS
Associate Clinical Professor (retired)
University of Michigan School of Dentistry, Ann Arbor, MI