Longitudinal quantitative radiodensitometric study of treated and untreated lower molar furcation involvements.

38 first or second lower molars from 16 patients showing furcation involvements of degrees 1 and 2 were treated after motivation and hygiene instruction, either by subgingival curettage, or by the modified Widman surgical procedure or by furcation plasty. The plaque index, the gingival index of inflammation and the depth of interproximal and interradicular pockets were recorded before and up to 1 year after the 3 therapeutical procedures. The above clinical indices were also followed for 2 years in 15 lower molars from 7 untreated patients. A quantitative radiographical analysis of the interradicular bone was performed in all patients, by using superposable identical radiographs and a computer-assisted photodensitometric technique. In the 3 groups of treated patients, the clinical scores were, in general, improved by the 3 therapeutic modalities. In the furcation areas, the plaque index was always higher on the lingual side, whereas the depth of "horizontal" pockets was always greater on the buccal side. Except for the lesions treated by furcation plasty, no change could be noticed clinically in the depths of vertical or horizontal penetration of a periodontal probe in the furcation areas. The quantitative radiographic analysis, however, clearly showed a loss in the first 2 mm of superficial bone during the 2 months following the 3 therapeutical procedures: this loss was followed by a statistically significant recovery and, for the group treated by curettage, even by a net gain during the 6 to 12 months following therapy. The radiographical density of the deeper layer of bone did not change in the group treated by curettage only. It showed a loss in the first 2 months following the 2 surgical procedures but a statistically significant recovery in the months thereafter. As for the group of untreated patients, at the examinations performed initially, 6 months, 1 and 2 years later, the number of plaque-free and non-bleeding sites in the furcation areas was lower on the lingual as compared to the buccal side, whereas the frequency distribution of furcation involvements was similar on both aspects. No significant changes were found in the various clinical parameters throughout the 2 years of the study. On the contrary, a significant loss of average density of the superficial layer of interradicular bone was already measured on the superposable radiographs 6 months after the initial examination and was found to increase thereafter. No changes of radiodensity could be measured for the deeper layer of bone.(ABSTRACT TRUNCATED AT 400 WORDS)