Root canal retained restorations: 3. Root-face attachments.

It has been common practice for many years to use retained roots to provide support and stability for partial or full dentures. The retention of such overdentures is greatly enhanced if the remaining roots are modified and restored with posts and root-face attachments. The final article in this series on root canal retained restorations classifies and describes some of the root-face attachments currently available, and also describes a number of prefabricated post systems with integral overdenture attachments. Guidelines for clinical and laboratory procedures are given.

Two-part resin bonded cast metal bridges for use when abutment teeth have unequal effective root surface areas.

Resin bonded cast metal bridges have become a popular method of replacing missing teeth. Such bridges are usually constructed as single castings following modifications to the abutment teeth in order to ensure a distinct path of insertion and to secure maximum metal to tooth contact. Unfortunately, long term retention of resin bonded bridges cannot be guaranteed and many surveys have reported substantial failure rates, particularly in the posterior segments of the mouth. It is the authors contention that many of these failures occur because clinicians are neglecting one of the fundamental principles of fixed bridge prosthodontics, namely that abutment teeth should be matched for effective root surface area (bony support). This article describes how problems created by incompatible abutment teeth can be overcome successfully by the construction of resin bonded bridges in two parts which are cemented separately, but interlock to provide a movable joint. Such an arrangement allows independent movement of the abutment teeth whilst providing sufficient retention and support for the bridge. The two-part design can also overcome problems created by malaligned abutment teeth as well as allowing conventional full crown retainers to be combined with resin bonded retainers.

A screw-connected fixed partial denture.

This technique provides one solution to the problem of using tilted abutment teeth for a fixed partial denture. It provides good retention without excessive tooth destruction and without excessive contour in the completed restoration.