Elimination of epithelium from healing postsurgical periodontal wounds by ultra-low temperature. Initial observations

Prevention of epithelial migration into healing postsurgical periodontal wounds may enhance connective tissue attachment. This study attempted to destroy selectively epithelium on gingival flap surfaces by ultra-low temperature. Sixteen sites in four young adult cats received subcrestal reverse bevel incisions followed by sulcular incisions. Full thickness periodontal flaps were reflected, the remaining supracrestal soft tissue surrounding the teeth was removed, and exposed root surfaces were curetted. Narrow zones measuring about 4 mm along the coronal margins of the flaps were exposed to ultra-low temperature for 5 seconds using a gas expansion cryoprobe cooled to -81 degrees C and placed at the oral gingival aspects of the flaps. Flaps were then repositioned and sutured. Control sites were sham-operated with the cryoprobe kept at room temperature (25 degrees C). Gingival biopsies were taken at 1 hour and at 2, 4, 8 and 12 days following surgery. Microscopically, 1-hour postfreezing and control specimens appeared similar. At 2 and 4 days, large surface areas of corium were denuded of epithelium or were covered by necrotic debris. Mild inflammatory responses were noted within the corium. At 8 days, the epithelium almost completely covered the corium with some initial formation of crevicular epithelium. After 12 days, crevicular epithelium was observed in all tissue sections. No significant morphologic damage to the connective tissue was noted at any time. We, therefore, concluded that low cryodoses can effectively destroy oral gingival epithelium without causing significant morphologic damage to the underlying lamina propria at this level of observation.