Assessment of thermal damage in precooled CO2 laser wounds using biological markers

Precooling of the tissues was investigated as a possible means of reducing the thermal damage during CO2 laser surgery of the oral mucosa. Standard wounds 5 mm long were created with the CO2 laser, with and without precooling, or the scalpel on the dorsum of tongues. Tissue damage was evaluated by studying changes in mast cells and in the activity of lactate (LDH) and succinate (SDH) dehydrogenase. Cooled unoperated tongues acted as controls. The area of thermal damage, indicated by loss of SDH activity, was significantly smaller in precooled tissues (p < 0.001). Although a similar pattern was detected using LDH, the difference was not significant. At both 0 and 6 h normal mast cell numbers were significantly different between groups (p < 0.02). Furthermore, at 0 time, there were significant differences in the numbers of degranulated mast cells between surgical treatment groups (p = 0.001), although not at 6 h. Total numbers of mast cells (normal and degranulated) did not differ between treatment groups or between 0 and 6 h sampling times. Positive significant correlations were observed between the cross-sectional areas and widths of non-reactive succinate and lactate dehydrogenase and the number of degranulated mast cells around the laser wounds. Analysis of the data demonstrated that (i) uncooled laser wounds but not precooled laser wounds were associated significantly with greater levels of immediate mast cell degranulation than scalpel wounds (p = 0.03).(ABSTRACT TRUNCATED AT 250 WORDS)