Stud vs Bar Attachments for Maxillary Four-Implant-Supported Overdentures: 3- to 9-year Results from a Retrospective Study.

Abstract

The aim of this study was to compare the clinical outcomes of four-implant-supported overdentures retained by stud or bar attachments for patients with an edentulous maxilla. From January 2008 to December 2014, patients with maxillary edentulism were enrolled in this retrospective study. The insertion of four maxillary dental implants was followed by restoration with either stud-retained or bar-retained overdentures. The characteristics of the subjects and implants were recorded. Implant survival rates, marginal bone loss, peri-implant clinical parameters, and prosthetic maintenance efforts were evaluated at the last follow-up time. Furthermore, patients were asked to complete a satisfaction questionnaire using a modified Denture Satisfaction scale at their last follow-up visit. The data were statistically analyzed, and the level of significance was set at α = .05. A total of 132 implants were placed in 33 patients, of whom 18 were restored with four-implant-supported overdentures retained by stud attachments, and the other 15 with four-implant-supported overdentures retained by bar attachments. Thirty-one patients and 124 implants were available for the entire follow-up. During a mean follow-up period of 77 months (range: 36 to 111 months), five among 72 implants failed for three patients in the stud-retained group and two among 60 implants failed for two patients in the bar-retained group, resulting in estimated cumulative implant survival rates of 81.4% and 86.2% for the stud-retained group and the bar-retained group, respectively. Except for the modified Plaque Index (mPI, P = .035), no significant differences were indicated between the two attachment groups in terms of implant survival rate, marginal bone loss, or peri-implant clinical parameters. Peri-/inter-implant gingival hyperplasia occurred only with implants under bar attachments. Over the entire observation period, the incidence of prosthetic maintenance treatments was 2.12 per patient per study for the stud-retained group and 2.29 per patient per study for the bar-retained group. Patients in both groups reported a high degree of satisfaction. Within the limitations of this study, no significant differences were indicated between the clinical outcomes of maxillary four-implant-supported overdentures with either stud or bar attachments, although a higher modified Plaque Index was observed for the bar-retained group. Furthermore, prostheses with stud attachments were advantageous for their convenient cleaning and repair. Patients with compromised systemic and periodontal conditions should be treated with caution. Further clinical studies with larger sample sizes and stricter epidemiologic designs are still needed.