One-Year Prosthetic Outcomes With Implant Overdentures: A Randomized Clinical Trial

One-Year Prosthetic Outcomes With Implant Overdentures: A Randomized Clinical Trial J. N. Walton, M. I. MacEntee, N. Glick, Int J Oral Maxillofac Implants. 2002;17:391–398 The use of implants to stabilize and support removable prosthodontic restorations for edentulous patients has long been associated with marked improvement in comfort and function. Surgical placement of two implants in the anterior mandible and construction of an attachment-retained overdenture is a conservative and cost-effective alternative to conventional, complete denture therapy. A wide variety of attachment systems are available for implant-retained overdentures. Originally, it was considered beneficial to connect the two implants with a screw-retained metal bar. The denture could then be attached to the bar using nylon or metal clips processed into the denture base. More recently, numerous stud attachments have appeared on the market offering both simplicity and easy access for hygiene as major advantages. However, there is a lack of consensus in the literature as to the most appropriate attachment system from both patient and practitioner perspectives. The present article reports on a randomized clinical trial that evaluates implant overdenture fabrication, maintenance, and patient satisfaction. Sixty-four edentulous patients were treated using two dental implants (Nobel Biocare) placed in the anterior mandible and restored with an overdenture. Two attachment systems were compared, including the 2.25-mm ball abutment with titanium alloy cap (Nobel Biocare) and the bar and clip system incorporating a round gold bar and two metal clips (Nobel Biocare). Additionally, an all-resin overdenture design was compared to a metal-reinforced overdenture. Patients were surveyed to ascertain satisfaction with their restorations relative to pain, comfort, appearance, function, stability, speech, hygiene, and overall satisfaction. Patients were followed for at least 1 year noting all treatment provided during this maintenance period. Results indicate that there were no differences between ball attachment and bar and clip overdentures with regard to the time required during fabrication, the number of postplacement adjustments, or overall patient satisfaction. The incorporation of a metal reinforcing framework, the amount of ridge resorption, or gender of the patient did not influence the incidence of postplacement adjustments. The most interesting result was that ball attachment overdentures required nine times more repairs than the bar and clip overdentures. Most of the repair made on ball attachment overdentures involved the titanium denture-borne matrix. The authors conclude that metal reinforcement of overdentures supported by two dental implants is not indicated and the 2.25-mm ball attachment with a titanium matrix should be used with caution. This last conclusion is most inconsistent with both existing literature and common clinical experience. The use of only one stud attachment system may have limited the practical value of this study. Future investigations comparing stud attachments and bar and clip systems should incorporate a greater number of attachment systems, including, but not limited to, the ERA (Sterngold), Locator (Zest Anchors), ZAAG (Zest Anchors), magnetic, and standard ball and ring systems.