Implants in Partially Edentulous Patients; The UCLA Experience

John Beumer, D.D.S., M.S.

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We use 2 basic types of abutments at UCLA. The conical type shown here, and the UCLA type shown here .

The UCLA type is used in most patients because it is simple and the most cost effective. We use the conical type in large fixed cases with a lot of anterior posterior spread such as the case in this patient or in patients where the implant fixture is 4-5mm below the gingival margin. In such cases the use of the conical abutment facilitates impressions and try-in procedures.

With respect to occlusion, we use a modification of the lingualized occlusal scheme depicted here .

We attempt to center occlusal contacts from opposing teeth over the screw access channel as shown here.

In addition, we try to minimize the width of the occlusal table as shown here. We feel it is advisable to restore the anterior guidance, and flatten the cusp angles of the posterior teeth of the implant retained prosthesis so as to ensure occlusal contact only in centric relation or centric occlusion in order to minimize lateral torquing forces.

When restoration is extended anteriorly to restore the cuspid, we design the prostheses to create group function so as to distribute the lateral occlusal loads to all implants in as equitable a manner as possible as is shown in this case.

Here 4 implants were used to restore this patient. Group function was chosen in order to distribute the nonaxial forces generated during occlusion as widely as possible.

When designing these restorations, embrasure spaces and spaces between implants should be wide enough to accept a proximal tooth brush as is shown here. There should be no ridge lapping in the posterior quadrants for this will impair hygiene access and lead to periimplantitis and there should be steady, smooth emergence profiles.

In this case note the wide embrasure for hygiene.

Again in this patient with this large full arch restoration, embrasure spaces have been designed which ensures hygiene access but do not compromise esthetics.

In this third patient proper embrasure spaces and emergence profiles have not been developed and hygiene in this area between the implants is prevented. Eventually, lack of hygiene access leads to periimplantitis.

Occlusal surfaces of porcelain have about a 5% fracture rate in our experience, and resin surfaces shown here have demonstrated an over 60% fracture rate requiring either repair or remake of the restoration.

In addition, we recommend that the metal framework be fabricated in individual units or that they be sectioned after casting and that solder relation records be obtained intraorally in order to ensure a passive fit as is shown here.

To summarize my technical recommendations for the design of implant supported fixed partial dentures that restore posterior quadrants of the maxilla or mandible, let us review this slide.

First, restore anterior guidance so that the implant supported prosthesis comes in occlusal contact only during centric relation or centric occlusion. Avoid group function if possible. Occlusal contacts should be centered over the screw access channel, and lingualize the occlusal relationships when possible. Reduce the width of the occlusal table and provide wide embrasure spaces between the implants for hygiene access.

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