Evidence for healing of periodontal defects 5 years after conventional and regenerative therapy: digital subtraction and bone level measurements.

Objective: The aim of the present study was to compare radiographic assessment of bony fill by digital subtraction analyses (DSA) after periodontal surgery of infrabony and furcation defects with bone level measurements.

Methods: For 19 patients with 19 infrabony lesions and 20 degree II furcation defects, five defects were treated conventionally and 34 defects were treated by regenerative periodontal surgery. At baseline and 60 +/- 3 months after surgery, clinical measurements (GI, PPD, PAL-V, PAL-H, PlI) and standardized radiographs were obtained. Furthermore, intrasurgically after reflection of a mucoperiosteal flap and 60 months after surgery after local anesthesia without flap reflection, the distance from the cementoenamel junction (CEJ) to bottom of the bony defect (BD) was measured vertically (PBL-V) and, in furcation defects, horizontally (PBL-H). Pre- and postsurgical radiographs were analyzed by digital subtraction. Bone level gain and DSA results were compared by simple regression analysis.

Results: Surgical treatment revealed significant PPD reduction (- 3.45 +/- 1.56 mm; P < 0.001), PAL-V gain (2.84 +/- 1.36 mm; P < 0.001), and PBL-V gain (1.68 +/- 1.20 mm; P < 0.001) in infrabony defects, as well as PPD reduction (- 1.68 +/- 1.73 mm; P = 0.001) and PAL-H gain [1.43 +/- 1.70 mm (P = 0.001)] in furcation defects after 5 years. A correlation could be found in furcation defects between PBL-H gain and DSA (R2 = 0.34, P = 0.003), whereas the study failed to demonstrate a consistent correlation between PBL-V and DSA in infrabony defects (R2 = 0.12, P = 0.149).

Conclusions: DSA correlates significantly with PBL-H measurements in furcation defects. Thus, either method is a sufficient tool to evaluate bony fill within furcation defects. On the other hand, DSA did not correlate significantly with PBL-V measurements in infrabony defects. This discrepant contribution of DSA in the evaluation of these two types of defects may be explained by the fact that DSA primarily evaluates change in a buccolingual direction.