Peripheral occluding effects of non-absorbable membranes on ingrowth of cultured gingival connective tissue cells.

Abstract

The success of periodontal regenerative procedures, i.e., using regenerative cells to repopulate wounds, is enhanced by using barrier materials, such as expanded polytetrafluoroethylene (ePTFE) membranes, to provide a barrier to the proliferation of epithelial cells and gingival connective tissue cells at the healing site. However, several animal and clinical studies have demonstrated the difficulties of avoiding thin connective tissue ingrowth under the ePTFE membrane used for bone regeneration procedures. We investigated the peripheral occluding effects of ePTFE membranes on ingrowth of cultured gingival connective tissue cells in vitro. The ePTFE membrane was divided into 4 pieces, fixed, and immobilized on a culture dish. Human connective tissue cells from clinically healthy gingiva were isolated and cultured. Low passages (2 through 3) of these cells, 5 x 105, were seeded and cultured in each dish. At weeks 1, 2, and 4, the ingrowth cells under the membranes were stained with Giemsa and photographed. The percentage of cell ingrowth as an area measurement and the cell ingrowth score as a linear measurement were determined using computer-assisted interactive image processing. There were no measurable spaces between the membranes and the dishes at x40 magnification using the stereomicroscope. However, the percentage of cell ingrowth under the membrane gradually increased from 1 to 4 weeks, reaching approximately 70% by week 4. There was a statistically significant difference between the 1 - and 4-week percentage of cell ingrowth (P <0.05). The cell ingrowth score also increased gradually, and cells invaded the center from all peripheral borders. There was a statistically significant difference for the lower right and left margins of the membrane between the 1-week and 4-week cell ingrowth scores. Furthermore, there was a statistically significant difference for the 4-week cell ingrowth score between the upper and lower margins (P <0.05). The use of ePTFE membranes placed over the culture dish plate cannot prevent ingrowth of cultured gingival connective tissue cells in vitro.