The apical location of calculus within the intrabony defect.

Although several studies have concluded that calculus removal becomes more difficult as pocket depth increases, few have examined the clinical location of calculus within the intrabony defect. This study evaluated the relationship between apical calculus position and the depth and morphology of the intrabony defect. As part of an on-going study of new attachment procedures in humans, 260 intrabony defects were surgically entered in 39 patients. Using magnifying loops and fiber optics in all defects, the most apical level of calculus was grooved to serve as both a clinical and histologic reference point. Clinical measurements made prior to root debridement included the alveolar crest to base of calculus, and the base of calculus to base of defect. The type of defect was classified by the number of remaining osseous walls. Calculus has not been found apical to the groove in any histologic section. The mean distance measured clinically between the base of the calculus and the base of the defect was found to increase with the depth of the defect. This relationship did not vary with either tooth type or number of remaining osseous walls in the defect. Data analysis of this group of patients (N = 39) showed a positive correlation (r = .83) between increasing depth of intrabony defect and the distance of the most apical calculus from the defect base.