In traditional partial dentures, metal clasps (hooks) are used to hold the prosthesis in place on the existing natural teeth. Besides being aesthetically unappealing, these clasps apply significant horizontal stretching and bending forces to the abutments during eating; this can lead to the loosening and eventual loss of the abutments. In precision attachment (snap-on/sliding) systems, the abutments are first bonded together with porcelain veneers, and hidden male and female sockets (sliders) are machined into these veneers. The prosthesis sits vertically in these sockets. Biomechanically, precision attachments transmit chewing forces completely parallel (vertically) to the long axis of the abutment. This breaks the horizontal destructive lever arms acting on the tooth, and the abutments are protected much more securely compared to clasp systems.
