This study aimed to investigate the marginal bone changes beneath overhanging restorations. The study group consisted of 250 archived panoramic radiographs that had at least one overhanging restoration, examined by two observers. The distance from the cementoenamel junction (CEJ) to the marginal bone crest beneath the overhang was measured with ImageJ software. The same distance was measured from the control sites (the intact surface of the same tooth with overhang, and the same tooth on the contralateral side) to assess bone loss. To evaluate bone density, two regions of interest (ROIs) were chosen: one in the marginal bone beneath the overhang, and the other was in the marginal bone adjacent to the intact surface of the same tooth. Wilcoxon paired t test and Mann-Whitney U test were used for comparisons (P < .05). The prevalence of overhangs was 4.3%. Molar teeth (80.8%) and the disto-occlusal cavities (54%) were the most common sites for overhangs. The average bone loss beneath the overhangs was 2.77 ± 1.20 mm, which was significantly different from the control sites (P < .05). The bone density beneath the overhang was significantly lower than at control sites (P < .05). The frequency of overhangs was higher in areas that are difficult to reach, and the height and density of the marginal bone beneath the overhang were decreased compared to control sites.
