The effect of chlorhexidine mouthrinses on early bacterial colonization ofguided tissue regeneration membranes. An in vivo study

Background: Different membrane materials accumulate varying amounts of bact eria when exposed in the oral cavity, due to their textural and structural surface characteristics. The aim of the study was to evaluate the effect of chlorhexidine mouthrinses on the in vivo early bacterial colonization of 3 different guided tissue regeneration membrane materials. Methods: Rectangular-shaped strips cut from 3 periodontal membranes (expand ed polytetrafluoroethyl ene, polyglactin 910, and polylactic acid) were glu ed to removable devices adapted to the 2 upper quadrants in 8 dental studen ts. In each student 1 quadrant was randomly selected as test side while the other served as control side. The experiment was divided in 2 phases: in t he first phase plaque accumulation was followed for 4 hours while the secon d accumuation was followed for 24 hours. During the 4-hour experiment, stud ents rinsed the test device twice (immediately following device application and after 2 hours) with 0.12% chlorhexidine solution. The control device w as rinsed with saline. In the second phase, students rinsed the test device with chlorhexidine and the control devices with saline 3 times (after devi ce application and at 8 and 16 hours). Both the 4-hour and the 24-hour spec imens were processed for scanning electron microscopy analysis. Fifty-four fields (at 200x magnification) were randomly selected and analyzed on each strip. Magnification was increased to determine the presence and morphotype of bacteria. The presence or absence of bacteria was assessed in a binomia l fashion: the field was bacteria-positive when bacteria constituted the de posits covering the membrane surface. The microscopic field was negative (b acteria-negative) when no bacteria were observed. Bacteria-positive fields showing rods and filaments as prevalent morphotypes were recorded as rod-po sitive fields. Results: The results of data analysis suggest that bacterial contamination of membrane materials is significantly reduced by treatment with chlorhexid ine. They also suggest that other variables affect plaque accumulation as w ell; i.e., the time allowed (4 versus 24 hours) and the different membrane materials. The interaction between these 2 variables is also highly signifi cant, thereby indicating a different rate of plaque accumulation on differe nt materials, irrespective of the treatment with chlorhexidine. Conclusions: It was concluded that chlorhexidine mouthrinses may be effecti ve in reducing and delaying the early bacterial accumulation on membrane ma terials although they are not able to fully prevent it. Membrane surface ch aracteristics seem to be a more critical factor than the use of chlorhexidi ne, in influencing bacterial adhesion and colonization of barrier materials .