Early bacterial accumulation on guided tissue regeneration membrane materials. An in vivo study

THE AIM OF THE STUDY was to compare the in vivo early bacterial plaque colo nization of 3 different guided tissue regeneration (GTR) membrane materials using a morphological (scanning electron microscope) method. Rectangular-s haped strips were cut from 3 periodontal membranes (expanded polytetrafluor oethylene, polyglactin 910, and polylactic acid) and glued to the buccal as pect of removable acrylic devices, which were applied to the molar-premolar region of the upper quadrants in 8 dental students. Each device held 3 str ips: one ePTFE, one polyglactin 910, and one polylactic acid. The surface r oughness of each membrane material was measured by means of a laser profilo meter. During a 24-hour period, the students had to refrain from any oral h ygiene procedures and did not use chlorhexidine mouthrinses. In each subjec t, one device was removed after 4 hours and the other after 24 hours. After removal, the devices were placed in a 2.5% gluteraldehyde solution to fix the membranes, which were then processed for SEM analysis. Fifty-four micro scopic fields (at 200X magnification) were randomly selected and analyzed i n each strip. Magnification was increased to determine the presence of bact erial morphotypes. The presence or absence of bacteria was assessed in a bi nomial fashion. In such a system, the field was bacteria-positive when bact eria constituted the deposits covering the surface of the membrane. The mic roscopic field was considered bacteria-negative when no bacteria were prese nt. Bacteria-positive fields showing rods and filaments as prevalent bacter ial morphotypes were recorded as rod-positive fields. A different pattern o f plaque accumulation was demonstrated on different membrane materials. The 4-hour results indicated a statistically significant difference (P = 0.008 , ANOVA) in the proportion of bacteria-positive fields among the 3 membrane s; a greater amount of bacteria was demonstrated on the ePTFE membrane comp ared to the other 2 membranes. At 24 hours, the difference in the proportio n of bacteria-positive fields was statistically significant (P = 0.002, ANO VA); a lesser amount of bacterial plaque was present on the polylactic acid membrane compared to the ePTFE and polyglactin 910 membranes. No differenc e in the proportion of rod/bacteria-positive fields was demonstrated among the 3 membranes at either 4 or 24 hours. It was concluded that quantitative differences in early plaque accumulation on various membranes seem to be r elated to the textural and structural characteristics of the surface, which is not adequately represented by the surface Ra value measured with a prof ilometric instrument.