COMPARISON OF THE THERMAL TISSUE EFFECTS PRODUCED BY AGED SAPPHIRE AND SILICA HEMISPHERICAL TIPS

This study evaluated the performance of sapphire and fused silica hemi spherical tips under the same exposure conditions. Lesions produced in the chicken breast and a blood field were sectioned for light and tra nsmission polarizing microscopy. Lesion size and thermal damage area w ere recorded as a function of the tips accumulated exposure. The tips transmission was measured after every 1,000 J of exposure. Fused silic a tips lasted for similar to 5,000 J and experienced significant surfa ce and transmission deterioration. The sapphire hemispherical tips las ted for > 12,000 J with no surface and transmission deterioration. Les ions produced with the fused silica tips generally increased in depth with use, and depths of 6 mm were common. Lesions produced by the sapp hire tips were subsurface spherical areas of coagulation with the tiss ue surface relatively intact. This difference in resulting lesions may be attributed to the higher thermal conductivity of sapphire. (C) 199 4 Wiley-Liss, Inc.