Intrusion phenomenon in combination tooth-implant restorations: a review of the literature.

STATEMENT OF PROBLEM: Controversy regarding the connection of implants to natural teeth in fixed partial dentures has emerged in response to clinical reports of intrusion of the natural teeth. Although theories have been proposed to explain this phenomenon, the cause of the intrusion remains unknown. Numerous longitudinal studies have demonstrated that teeth can be successfully connected to implants. The use of rigid connectors, or nonrigid connectors with the keyway on the implant, are described as mechanisms to prevent intrusion of the natural tooth. PURPOSE: This article reviews the literature that pertains to this subject and includes treatment modalities that may be helpful in preventing intrusion.