Occlusal Contrasters are designed to give contrast to your images and eliminate those elements not required in the picture.
They allow occlusal photos to be taken with a completely black background. This obscures either the inside of the mouth or the lips to make image more presentable for patient before and after presentations and publications.
When using the Contraster for the upper or lower occlusal images, the curved end is designed to simplify taking occlusal mirror views and as it acts as retractor for the upper or lower lip. The curved end lifts the lip to keep it away from the teeth and prevent it from folding over the incisal edge. It also prevents nostrils and moustaches from appearing in the upper occlusal photo.