Commentary

Currently all evaluations of the success of the process of osseointegration seem unequivocal, a plethora of literature confirming the long-term survival of osseointegrated implants. There is, however, a paucity of evidence from RCT to support the routine use of implant-retained prostheses in edentulous patients. From a clinical perspective, there is an inherent attraction in using implants to retain a prosthesis, particularly in the mandible. Fund providers and patients alike nevertheless need to be convinced that substantial benefits accrue from this procedure before committing the significant extra funds for treatment and, indeed, undergoing surgical procedures to place implants.

A group at McGill University, Montreal, Canada, have published reports from a number of RCT1,–3; these showed that patients receiving implant-retained overdentures report substantial improvement on more outcomes than patients who received conventional treatment. The periods of follow-up were relatively short, so the evidence provided here by MacEntee et al. is timely.

The present study differs from the previous ones in that there are no conventional denture control groups. In this RCT, 100 edentulous patients were randomised into one of four treatment groups (either ball-retained mandibular overdenture with or without reinforced framework, or bar-clip retained mandibular overdenture with or without reinforced framework), and between-group comparisons are made. The primary outcomes of interest are patient-rated satisfaction and maintenance requirements. The authors based their sample size on detecting, “a differential of 25 percentage points or more between the proportions requiring repairs in the two attachment groups,” but details of the power calculation and rationale for it are vague. It is also unclear whether this power calculation was appropriate for detecting differences in VAS.

In addition, the authors appear not to have adjusted the VAS outcomes for multiple comparisons. Consequently, the data need to be interpreted cautiously. Despite these caveats, the follow-up time is 3 years for 68 subjects, and long-term satisfaction with implant-retained overdentures is confirmed. Eleven subjects were lost to follow-up, and a further 19 had not completed 3 years in the study at the time of publication. There is nothing to suggest that this undermined the conclusions of the study. Satisfaction at 2 years is comparable with VAS scores at 1 month post-insertion, and this finding contrasts with studies of conventional dentures. The mode of the attachment of the overdenture does not appear to significantly influence satisfaction.

A common problem with overdentures is the relatively high maintenance requirement, and an important finding from the study is that ball-retained overdentures require much more maintenance than do bar-clip retained overdentures. This may influence clinical practice in general, and is perhaps the most important outcome from this study.

Practice point

  • Patients are highly satisfied with implant-supported dentures at 2 years, although ball-retained overdentures require more maintenance than bar-clip retained overdentures.