Effects of Antibiotic Treatment on Clinical Conditions and Bacterial Growth With Guided Tissue Regeneration

Mucogingival flaps were reflected over pairs of mandibular molar teeth with Class II furcation invasions. The dimensions of the furcations were measured. The teeth were debrided and an expanded polytetrafluoroethylene (e-PTFE) membrane was placed and retained over one furcation of each pair (test site) for 4 weeks. The second site served as a control. Eight patients (group 1) with 12 e-PTFE sites received no antibiotic. Seven patients (group 2) with 12 e-PTFE sites were administered amoxicillin/clavulanate potassium for 10 days. Paper-points were used to collect bacterial samples and clinical indices were recorded at baseline and weekly for 4 weeks. Paper-point samples and the e-PTFE collected at week 4 were sonicated and analyzed by DNA probes for seven putative pathogens. At baseline no parameter showed statistical differences between groups or sites. At week 1 significantly greater levels of Prevotella intermedia type I (P < 0.05) and Fusobacterium nucleatum (P < 0.01) were found in group 1. At week 4, paper-point samples from test sites (P < 0.05) and e-PTFE materials (P < 0.001) showed significantly higher presence of Bacteroides forsythus in group 1. No significant microbial changes were found for control sites over time or between groups. The total bacterial load at test sites over time increased similarly for patients administered or not administered the antibiotic. Clinical signs of inflammation were significantly greater in group 1 and associated with the presence of B. forsythus (P < 0.01).