Replacement of missing cusps: an in vitro study

One of the commonest methods of replacing a missing cusp, a pinned amalgam restoration, was compared with three adhesive restorative techniques, two of them with additional pin retention. All the teeth were subjected to occlusal/lateral forces and loaded to fracture in an Instron testing machine. A layered restoration of glass ionomer cement replacing the dentine, and resin composite replacing the enamel, without pins required more force to fracture than any of the other techniques including the pinned amalgam restoration. A composite restoration with dentine bonding agent and additional pin retention was second best and significantly better than the pinned amalgam restoration. A cermet restoration with additional pin retention required slightly less force to fracture than pin-retained amalgam restorations, but not significantly so.