CO2-LASERS AND TEMPERATURE-CHANGES OF TITANIUM IMPLANTS

LASERS MAY BE USEFUL IN UNCOVERING submerged implants or in removing c ontaminants from ''ailing'' implants, The purposes of this study were to record temperature changes at the bone-titanium implant interface w hen using a CO2 laser to: 1) uncover the implant at second stage surge ry; and 2) ''decontaminate'' exposed implant threads. Scanning electro n microscopy (SEM) was used to characterize surface changes of lased i mplants, both uncontaminated or contaminated with blood or saliva. In part one, 28 titanium implants, measuring 3.75 mm by 7 to 20 mm, were placed into room temperature, fresh, resected pig mandibles-and covere d with a flap of gingiva, The overlying tissue was removed with a CO2 laser at different power levels. Bone-implant interface temperatures w ere measured with a thermocouple near the top of the implant, and 5 to 7 mm apical to the osseous crest. The effects of implant size, power level, tissue thickness, and operation time were evaluated. In part tw o, 5 mm by 4 mm bony dehiscences were created on 3 implants in one man dible and the exposed fixture threads lased at varying times and power levels. The results from part one showed temperature increases at the top thermocouple ranged from 4.2 to 16.8 degrees C and increases at t he bottom thermocouple ranged from 2.0 to 11.5 degrees C. The results from part two showed temperature increases at the top thermocouple ran ged from 1.2 to 11.7 degrees C and increases at the bottom thermocoupl e from 0.0 to 5.0 degrees C. If baseline ambient temperatures are 37 d egrees C, then the temperature at the bone-implant interface might exc eed 50 degrees C. SEM revealed no gross surface changes in lased uncon taminated implants, but laser treatment alone of contaminated implants failed to completely remove saliva or blood. Further study is needed regarding temperature increases and surface changes induced by lasers that may adversely affect osseointegration.