An auto matrix is typically used for which class of restoration?

An auto matrix is primarily used for Class II restorations, which involve cavities found in the posterior teeth, specifically in the interproximal areas between teeth. These restorations typically require the use of a matrix band to recreate the missing wall of the tooth structure to ensure proper shaping and contouring of the dental material being placed. The auto matrix system allows for a more efficient and effective application because it helps to secure the matrix band tightly around the tooth without manual adjustment, ensuring the restoration is formed correctly.

In the case of Class I restorations, no matrix is needed as these cavities occur in pits and fissures on the chewing surfaces of teeth. Class III and Class IV restorations are used on anterior teeth and usually involve facial and incisal surfaces, where the aesthetic requirements are different, and often different materials and techniques are applied. Therefore, the use of an auto matrix is most suitable for the specific challenges presented in Class II restorations.