CLINICAL, MICROBIOLOGICAL, AND HISTOLOGICAL FACTORS WHICH INFLUENCE THE SUCCESS OF REGENERATIVE PERIODONTAL THERAPY

THE PRIMARY OBJECTIVES OF THIS DOUBLE-BLIND, controlled clinical trial were to assess factor(s) which affect the success of guided tissue re generation (GTR) procedures in mandibular Class II buccal furcation de fects. Thirty subjects, with mandibular Class II furcation defects, we re randomly assigned to one of two treatment groups; patients in Group A received oral hygiene instructions with scaling and root planing, w hile subjects in Group B received similar treatment but without subgin gival scaling and root planing at the affected site. After initial ora l hygiene instructions and scaling and root planing, GTR surgery was p erformed using ePTFE barrier membranes. Membranes were retrieved at 6 weeks and subjected to histological examination. Twelve months after r egenerative therapy, clinical measurements and re-entry surgical measu rements were repeated. Probing reduction (2.61 mm), horizontal probing attachment gain (2.59 mm), and vertical probing attachment gain (0.95 mm) were all significantly better compared to baseline. Likewise, sig nificant improvements in furcation volume (8.0 mu l) and in bone measu rements were observed at re-entry. There was no discernible difference between subjects for whom complete anti-infective therapy was deferre d to the time of the surgery (Group B) compared to subjects in whom co mplete anti-infective therapy was performed as part of the hygienic ph ase of therapy (Group A). Pre-operative pocket depth was directly corr elated with the magnitude of attachment gain as well as the amount of new bone formation in the furcation area. Subjects who maintained good oral hygiene and who had minimal gingival inflammation throughout the study demonstrated consistently better regenerative response. The pre sence of connective tissue cells along the inner surface of the retrie ved membranes also correlated with better healing. This suggests that the presence of connective tissue cells, as opposed to bacterial plaqu es or epithelial remnants, on the membranes is predictive of enhanced healing. Subjects who did not harbor Actinobacillus nctinomycetemcomit ans at the site of regenerative therapy showed a better clinical respo nse with significantly greater bone regeneration than in A. actinonlyc etemcomitans infected subjects. Hence, monitoring for A. actinomycetem comitans, and antimicrobial therapy for A. actinomycetemcomitans-infec ted sites is proposed as an adjunct to periodontal regeneration. In su mmary, shallow initial probing depth, poor oral hygiene, gingivitis, A . actinomycetemcomitans infection, and absence of connective tissue ce lls on retrieved membranes are associated with less favorable results for regenerative therapy.