The influence of overhanging restoration margins on interproximal alveolar bone levels in general dental practice

Aim To determine the prevalence of restoration overhangs in a general dental practice and investigate if these are associated with an increase in the rate of alveolar bone loss locally. Methods Historical dental records were randomly and anonymously selected from the records of patients in a general dental practice. The most recent bitewing radiographs were examined and any overhangs were recorded along with location. Sequential bitewing radiographs were examined so that the restored tooth with an overhang could be compared over time with a similar but unrestored tooth which acted as a control. Results A total of 111 dental records were audited and an overhang was observed in 67 cases. The prevalence of overhangs was greatest on upper molar teeth. Bone loss was calculated from 35 historical sets of bitewing radiographs over a period of up to 25 years. The mean bone loss on the unrestored control teeth was 0.06 mm/year and on the teeth adjacent to the overhangs it was 0.16 mm/year. This difference of 0.1 mm/year was statistically significant (paired t-test, P = 0.01). There was no significant difference between males and females. The mean size of the overhang was 0.9 mm (range 0.4-2.0 mm) with the bigger overhangs being associated with greater bone loss; however, not all ledges were associated in bone loss. Conclusions Restoration overhangs can be associated with increased bone loss and larger overhangs may be most problematic, although other factors are involved as not all ledges caused bone loss.