EVIDENCE FOR HEALING OF CLASS-II AND CLASS-III FURCATIONS AFTER GTR THERAPY - DIGITAL SUBTRACTION AND CLINICAL MEASUREMENTS

IN 21 PATIENTS WITH ADVANCED PERIODONTITIS, 39 teeth exhibiting class II (n = 21) and class LU (n = 18) furcations were treated by the guide d tissue regeneration technique using expanded polytetrafluoroethylene (ePTFE) membranes (n = 20) or bioabsorbable barriers (n = 19), respec tively. Clinical parameters were assessed before and 6 months after su rgery, Presurgically and 6 months postsurgically, 35 pairs of standard ized bitewing radiographs were taken, Using subtraction radiography, g ain of bone density within furcation areas was assessed. Eighteen radi ographs showed sufficiently accurate geometry to be analyzed by subtra ction. Within the defects suitable for subtraction, the average gain o f vertical attachment assessed was 1.35 +/- 1.27 mm in the class II fu rcation group and 1.58 +/- 1.37 mm in the class III furcation group. T he average horizontal attachment gain in the class II furcation group was 1.96 +/- 0.59 mm. No statistically significant differences were ob served between results after GTR therapy using non-resorbable and bioa bsorbable barriers. Radiographic bone gain as assessed by subtraction analysis correlated with vertical (r = 0.458, P < 0.025) and horizonta l (r = 0.734, P < 0.005) attachment gain. A statistically significant number of more radiographs for maxillary molars were not suitable for subtraction analysis than mandibular molars (P < 0.05), Further, stati stically more radiographs that were taken with potentially unstable su pport of the: filmholder were not suitable for subtraction analysis th an those with stable support (P < 0.05). There is a statistically sign ificant correlation between clinical improvements and bony fill within furcation defects. Only 18 of 35 pairs of radiographs were suitable f or subtraction analysis. Subtraction analysis of maxillary molars seem s to be more difficult than assessment of radiographic bone changes in mandibular molars, Potentially stable support of the filmholder seems to be a condition to provide radiographs suitable for subtraction ana lysis.