Marginal bone loss around implants retaining hinging mandibular overdentures, at 4-, 8- and 12-years follow-up

Aim: The aim of the present study was to study the effect of occlusal factors, oral hygiene, gender and age on the long-term maintenance of alveolar bone height around screw-shaped machined surface commercially pure (c.p.) titanium implants retaining hinging mandibular overdentures. Method: In this retrospective study a long-term (4-, 8-, up to 12-years) follow-up of such implant-retained overdentures was performed. From the population of patients so treated at the University Hospital of the Catholic University Leuven, Department of Periodontology and Department of Prosthetic Dentistry, 158 patients were selected on the basis of being treated before March 1994, and the availability of intra-oral radiographs (paralleling technique) present at abutment connection (baseline) and at years 4, 8, and 12. For each patient, all relevant clinical data were recorded, and measurements of marginal bone height around the implants were performed on intra-oral radiographs by means of a digital sliding calliper. Results: Results indicated that only the factor "time" had a significant influence on marginal bone loss. The age and gender of the patients, dental/prosthetic status in the antagonistic jaw oral hygiene variables, and location of the implants had no significant effect. Conclusion: The very high cumulative success rate (97.2%) and limited marginal bone loss (on average 1.7 mm) after 12-years, encourage this kind of treatment using this type of implants.