Root trunk concavities as a risk factor for regenerative procedures of class II furcation lesions in dogs.
BACKGROUND: The purpose of this study was to evaluate the influence of root trunk concavities on guided tissue regeneration. METHODS: The second, third, and fourth mandibular bicuspids of 4 healthy mongrel dogs were used. Full flaps were elevated and furcation lesions (5 mm in height and 2 mm in depth) were surgically created. One mm deep concavities were prepared on the root trunks and part of the crown of all teeth. The second bicuspids remained as controls (C); the left third and fourth bicuspids received normal expanded polytetrafluoroethylene (ePTFE) membranes (NM) and the right bicuspids received modified ePTFE membranes (MM). The MM were made by removing the collar from an NM, cutting it into 2 mm segments, and suturing each of the segments to the collar of each MM. Normal and modified membranes were sutured to their corresponding teeth and the flaps sutured. After the healing period, the mandibles were removed and the teeth processed for histomorphometry. RESULTS: The results showed that the junctional epithelium measured a mean of 0.71 mm for C, 0.64 mm for NM, and 0.14 mm for MM. The differences between C and MM and between NM and MM were both statistically significant at the 5% level (Kruskal-Wallis test). Mean bone height measurements for the buccal surfaces from the furcation roofs were 2.79 mm for C, 2.60 mm for NM, and 1.06 mm for MM and for the mid-portion 1.10 mm for C, 1.23 mm for NM, and 0.30 mm for MM. Differences were statistically significant at the 1% level between C and MM and between NM and MM for the buccal measurements, and at the 5% level between NM and MM for the mid-portion measurements. CONCLUSIONS: Root trunk concavities are important risk factors for regenerative procedures. The collars of the membranes should be modified to improve results when concavities are present.