Abstract: A dental system comprises a dental prophy angle and an adjustable angle adapter. The prophy angle includes a housing and a guard with a concave inner surface. The adapter is configured to drive the prophy angle and the adapter includes a body, a nose, and an outer joint. The nose is configured to receive a portion of a prophy angle. The body is adjustably connected to the nose. The outer joint includes a ball portion connected to the nose, and a ball receiver positioned on the body. The ball receiver includes a first portion coupled to a first end of the body and a second portion attachable to the first portion. The nose is rotatable relative to the body into at least a first configuration and a second configuration. The concave inner surface of the guard engages a convex outer surface of the ball receiver.