BACTERIAL-COLONIZATION OF BIOABSORBABLE BARRIER MATERIAL AND PERIODONTAL REGENERATION

THE OBJECTIVE OF THE STUDY WAS TO evaluate bacterial colonization of t he tooth-facing surface of bioabsorbable membranes and to determine it s effect on the clinical outcome of membrane supported reconstructive periodontal surgery. Twenty systemically healthy subjects affected by chronic adult periodontitis were enrolled in the study. One non-furcat ion tooth site per patient, associated with an angular bony defect and a probing attachment loss of > 5 mm, was selected to be treated by me ans of a guided tissue regeneration procedure using a polyglicolactic membrane. Antibiotics (amoxicillin/clavulanate potassium 1 g per day) for 2 weeks were prescribed, in addition to the use of chlorhexidine f or post-surgical plaque control. All patients were recalled once a wee k for 5 weeks for professional tooth cleaning. At 5 weeks sites with c linically exposed membranes underwent a second surgery to harvest resi dual barrier material which was analyzed by scanning electronic micros copic (SEM) for bacterial colonization. Sites with no membrane exposur e at 5 weeks were allowed to heal without any other surgical intervent ion. Professional tooth cleaning and reinforcement of self-performed o ral hygiene measures were given at 1 month intervals for the duration of the study. For each treated site the difference in probing attachme nt loss between baseline examination and a follow-up examination made 6 months after the second surgery was calculated. Gain of probing atta chment was statistically (P < 0.001) greater in sites with no membrane exposure when compared to sites with partially exposed barrier materi al (4.2 +/- 0.5 vs. 3.3 +/- 0.6). The results of SEM analysis revealed that bacterial colonization was evident in all the microscopic fields of the exposed areas of the membranes. In the mid-part of the membran es 16 out of 39 microscopic fields (41%) demonstrated microbial coloni zation, while no bacteria-positive field was observed in the most apic al portion of the membranes. Regression analysis indicated that gain i n probing attachment level was negatively correlated to microbial colo nization of the mid-part of the membranes. It was suggested the midpor tion of the tooth-facing surface of polyglicolactic membrane is a crit ical area for the healing process since its bacterial colonization was detrimental to the outcome of the GTR surgery.