The purpose of the present study was to evaluate the effect of root planing on the reduction of probing pocket depth and the gain of clinical attachment depending on the pattern of bone resorption (vertical versus horizontal bone loss) in the interproximal aspect of premolar teeth that showed an initial probing pocket depth of 4-6 mm.

In this study, we analyzed 68 teeth (15 from the maxilla and 53 from the mandible) from 32 patients with chronic periodontitis (17 men and 15 women; mean age, 53.6 years). The probing pocket depth and clinical attachment level at all six sites around each tooth were recorded before treatment to establish a baseline value, and then three months and six months after root planing.

The reduction in interdental pocket depth was 1.1 mm in teeth that experienced horizontal bone loss and 0.7 mm in teeth that experienced vertical bone loss. Interdental attachment was increased by 1.0 mm in teeth with horizontal bone loss and by 0.7 mm in teeth with vertical bone loss. The reduction of probing pocket depth and the gain of clinical attachment occurred regardless of defect patterns three and six months after root planing.

The reduction of pocket depth and gain in the clinical attachment level were significantly larger in horizontally patterned interproximal bone defects than in vertical bone defects.