Predictive value of Periotest® assessment for failure of Mini Dental Implants supporting maxillary overdentures: a pilot study

Objective: This prospective cohort study assesses the long-term (5 years) clinical outcome of mini dental implants (MDIs) supporting maxillary overdentures with Periotest® and explores the applicability of Periotest® values (PTV) to predict implant failure.

Materials and methods: Included patients were edentulous in the maxilla, dissatisfied with their conventional dentures, and reluctant to undergo augmentation procedures. Per patient, 5 to 8 MDIs (ILZ, Southern Implants Inc., Irene, South Africa) were placed flaplessly. Provisional loading occurred after one week, functional loading after 4–6 months. Periodical assessment up to 5 years after placement was performed with Periotest® (Gulden Medizintechnik, Bensheim an der Bergstraβe, Germany). Statistical analysis compared subgroups nonparametrically, while Pearson correlation analyzed covariance of continuous variables. Linear regression analysis identified predictors for MDI failure. Significance level was set at p < 0.05.

Results: Placement of 204 MDIs in 31 patients resulted in a 5 years cumulative failure rate of 23.2%. Successful implants yielded a PTV of 5.87 (SD 5.717) at baseline and 5.37 (SD 6.294) at 5 years respectively (p = 0.336). Failed implants demonstrated elevated last Periotest® measurement 3 months (21.55; SD 8.694; p = 0.007) and 12 months (18.86; SD 10.612; p = 0.007) before failure. A regression analysis with survival time as the dependent factor, identified the last available PTV as a significant predictor of implant failure (p < 0.001; R²=0.451).

Conclusion: MDIs are a viable treatment option for supporting maxillary overdentures in last-resort cases with severe atrophy. Periotest® measurements aid monitoring long-term stability in MDIs and attribute to prediction of implant failure.