Objectives: The aim of the present study was primarily to relate marginal bone loss around osseointegrated dental implants to gender, jaw and loading time. Our secondary aim was to evaluate if marginal bone loss was associated with individual implants or with a patient associated trait.

Methods: The study population comprised 586 implant cases (318 upper and 268 lower jaws, 245 in males, 341 in females,) ad modum Brånemark. Consecutively treated patients with at least 1 year of loading and at least 2 radiographic examinations of implants were selected. A total of 2767 fixtures were studied. The mean functional loading time was 4.8 years (range 1-15 years). Marginal bone level was recorded as the mean number of exposed fixture threads above the marginal bone crest. Marginal bone loss was calculated in each patient by the comparison of 2 radiographic examinations. Worst bone loss (WBL), the mesial or distal fixture surface showing greatest amount of bone loss, and the modified mean bone loss (MMBL), the mean marginal bone loss excluding the fixture with greatest bone loss, observed in each patient were registered.

Result: Twenty-four fixtures were lost (0.9%) in 12 cases of 11 patients. 6 patients showed multiple fixture losses. All fixtures lost during function were lost in the upper jaw. A correlation between WBL and MMBL was observed (r=0.56, p=0.00). Significantly higher MMBL was observed in patients who experienced fixture loss after loading compared to those without fixture losses. A statistically higher MMBL was observed in upper jaws compared to lower jaws. No correlation was found between duration of functional load and WBL or MMBL. Bone gain was observed in 22.5 % of the cases.

Conclusion: The bone loss observed may support the hypotheses that late marginal bone loss around fixtures relates to patient associated factors.

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