Root proximity characteristics and type of alveolar bone loss: a case-control study.

This study assessed root proximity (RP) in patients with and without periodontitis in terms of prevalence, distribution, location along the root, width and severity, and explored the role of RP characteristics in the type of alveolar bone loss (horizontal or angular).Root proximity was studied in the interdental spaces of 250 patients with periodontitis and 80 patients without disease. Linear measurements were performed in digitized radiographs. Root proximity was classified by location along the root, width and severity. Bone defect type (horizontal or angular) at the RP site was recorded.Root proximity prevalence did not differ between periodontitis and non-periodontitis groups. For both groups, most RPs were located at the middle root third. Root proximity width and severity in periodontitis sites were different between horizontal and angular bone loss sites. Root proximity width was greater in horizontal bone loss sites. In periodontitis, a unit (pixel) increase in the RP width decreased the probability to detect an angular bone defect by 20%, while a unit decrease in RP severity increased the possibility to detect angular bone loss by 71%.Root proximity prevalence was similar for both patients with and without periodontitis. The RP location along the root was not related to the existence of periodontitis. Root proximity width and severity differed between horizontal and angular bone loss sites. Root proximities had greater width in horizontal than angular bone loss sites.