Evaluation of Alveolar Bone Changes Associated with Overhanging Restorations via Fractal Analysis

There is limited information in the literature regarding when overhanging restorations should be replaced, and the topic remains underexplored. Therefore, the aims of this study were to investigate, using fractal analysis, whether overhanging restorations cause microtrabecular alterations in the adjacent alveolar bone even in the absence of radiographically visible changes, and to evaluate whether the size of the overhang contributes to the extent of these bone changes.

In periapical radiographic images of 85 individuals with overhanging restorations, regions of interest (ROIs) were selected from the interdental trabecular bone adjacent to the overhanging edge and the normal side of the same tooth. Fractal dimension (FD) values were obtained using the box-counting method developed by White and Rudolph, implemented with ImageJ software version 1.52 (National Institutes of Health, Bethesda, MD, USA). Compliance with the normal distribution was analyzed using the Kolmogorov-Smirnov test. The relationship between FD values was assessed using the paired two-sample t-test and expressed using the Pearson correlation coefficient. The angle between the lines drawn from the cementoenamel junction of the tooth to the mesio-distal extreme point of the overhanging restoration and the contact point with the adjacent tooth was determined. The effect the of overhanging restoration angle on FD value was analyzed using linear regression analysis.

The overhanging restorations were most commonly found in the maxillary molar regions and in disto-oclusal cavity types. The FD obtained on the overhang side was 0.99 ± 0.06, and the FD obtained on the control side was 1.04 ± 0.06. When FD on the overhang side and FD on the control side were compared using the dependent t-test, the difference between them was statistically significant (p < 0.001). The effect of angle on the FD ratio was evaluated using linear regression analysis, and no significant result was found (F = 0.072, p = 0.789).

According to the results of this study, overhanging restorations can cause radiographically undetectable alveolar bone loss, and this effect can be demonstrated using fractal analysis.