Читать книгу Fundamentals of Fixed Prosthodontics - James C. Kessler - Страница 109

Fixed partial dentures supported by implants are ideally suited for use where there are insufficient numbers of abutment teeth or inadequate strength in the abutments to support a conventional fixed partial denture and when patient attitude and/or a combination of intraoral factors make a removable partial denture a poor choice. Implant-supported fixed partial dentures can be employed in the replacement of teeth when there is no distal abutment. Span length is limited only by the availability of alveolar bone with satisfactory density and thickness in a broad, flat ridge configuration that will permit implant placement.

A single tooth can be replaced by a single implant, saving defect-free adjacent teeth from the destructive effects of retainer crown preparations. A span length of two to six teeth can be replaced by multiple implants, either as singleunit restorations or as implant-supported fixed partial dentures. In fact, an entire arch can be replaced by an implant-supported complete prosthesis, but that type of restoration lies outside the realm of this discussion.

The retainers used for most implant systems require a great degree of abutment alignment precision, as do the retainers for a tooth-supported fixed partial denture. If implants are placed by someone other than the restorative dentist, implant/abutment alignment demands close coordination between surgeon and restorative dentist. The abutments should be positioned so that the occlusal forces will be as nearly vertical to the implants as possible to prevent destructive lateral forces.

Implants should be better able than natural teeth to survive in a dry mouth. Implants may be a better choice for fixed partial denture abutments if prospective tooth abutments would require endodontic therapy with or without dowel cores, periodontal surgery, and possibly root resections to support a long-span, complex, and expensive prosthesis.