Topical and systemic antimicrobial therapy in guided tissue regeneration

Background: Bacterial contamination of membrane material negatively affects healing after guided tissue regeneration (GTR) procedures; conversely, fla p connective tissue integration on barrier material improves the clinical o utcomes. The objective of this study was to evaluate the effect of topical application of antibiotics on: 1) clinical outcomes of GTR surgical procedu res using titanium reinforced expanded polytetrafluoroethylene (ePTFE) peri odontal membrane; 2) bacterial colonization of membrane material; and 3) fl ap connective tissue-membrane integration. Methods: Fifty-six deep interproximal bony defects were treated with GTR su rgical procedures using titanium reinforced ePTFE periodontal membranes. Pa tients were randomly assigned to 1 of the 2 antimicrobial treatment groups: the test group received weekly topical application of 25% metronidazole ge l and the control group received systemic antibiotics (amoxicillin plus cla vulanic acid 1g/day for 14 days). Clinical outcomes were assessed at 1 year ; the amount of bacterial contamination and connective tissue integration o n membrane material was evaluated at time of membrane removal by means of a morphological (SEM) method. Results: No statistically significant difference was found between test and control groups in terms of clinical attachment (CAL) gain (baseline CAL - 12 months CAL; P = 0.2) and probing depth (PD) reduction (baseline PD - 12 months PD; P = 0.6). A greater increase in gingival recession (REC) (12 mon ths REC - baseline REC) was found in the test group compared to the control group (P = 0.003). The SEM analysis revealed no statistically significant (t test) difference between test and control groups in the number of fields positive to integrated connective tissue (P = 0.82), while the number of f ields positive to bacteria was statistically higher (P < 0.001) in the cont rol group. Conclusions: Local antibiotic administration is more effective than systemi c use in preventing membrane contamination, but it does not improve clinica l outcomes due to an interference of the vehicle (gel) with gingival tissue s which may reduce the potential benefits derived from better control of th e bacterial load.