Success and failure in partial edentulism treated with implant-supported bridges.

This report describes success and failure in the use of fixed bridges supported by Brånemark implants, placed in the mandible bilaterally in one patient and unilaterally in the other. The non-intrusive nature and excellent functional characteristics of such bridges make them an attractive alternative to a removable partial denture in making good the loss of posterior mandibular teeth. However, there are biomechanical principles which must be considered in the design of such appliances. In particular, designs which minimise bending moments should be chosen to avoid the type of failure described in one of our patients. Repeated loosening of screw components should be considered as a possible indicator of bending overload. Where space permits, this problem is most easily overcome by placing three implants in staggered formation.