What is reverse curve in class 2 cavity prepration?

A reverse curve in a Class 2 cavity preparation refers to a specific design feature where the internal walls of the cavity exhibit a concave curve, transitioning from a wider opening at the top to a narrower base. This design helps to enhance the retention of the restorative material and provides better access for cleaning and shaping the cavity. It also aids in minimizing stress concentrations and optimizing the distribution of forces on the restoration, ultimately contributing to its longevity and effectiveness.