Implant-Related Tooth Intrusion and Migration

Osseointegrated implants have proven to have a high degree of success in the edentulous arches. This success has been applied to single teeth and partially edentulous arches. When natural teeth are present, it can be tempting to fabricate splinted restorations using support from both implants and natural teeth. The mechanism of attachment and the perceived problem of the differential support provided by the implant and the tooth have been discussed by many authors. Connecting teeth to osseointegrated implants presents a biomechanical challenge. This is due to the implant being rigidly fixed to the bone in a similar manner to teeth that ankylose and a healthy tooth being attached to the bone with periodontal ligaments that allows relatively more mobility than an implant. In addition, when teeth are connected to implants, the teeth often intrude into the supporting bone—thus, no support for the fixed partial denture will be provided by the tooth. It has also been reported that when the connection to an implant is severed, the tooth can rebound coronally. This issue of tooth intrusion is not a known reason of why or how it happens—this chapter describes the various proposed issues in more detail. Another aspect of tooth migration related to implants is that open proximal contacts often present when teeth are adjacent to implants; this is due to mesial or distal drift of teeth, but again it is unclear about why this phenomenon occurs.