Laser-assisted surgery with different wavelengths: a preliminary ex vivo study on thermal increase and histological evaluation.

Since the introduction of laser in clinical practice, different wavelengths have been used for oral surgery on the basis of the different characteristics and affinities of each one. The aim of this study was a comparison of different laser wavelengths in relation to both thermal increase and "histological quality" in a model of soft tissue surgery procedures. Thermal evaluation was realized, during laser-assisted surgery excision performed on a bovine tongue, by a thermal camera device to evaluate thermal increase on the surface of the sample and with four thermocouples to evaluate thermal increase on the depth of the specimen; temperature was recorded before starting surgical procedure and at the peak of every excision. The quality of excision, in terms of tissue damage and regularity, was realized by two blind examiners on the basis of established criteria. The highest superficial thermal increase was recorded for Superpulse 5-W CO2 laser, the lowest one for Er:YAG laser. The highest in depth thermal increase was recorded for 5 W Diode laser, the lowest one for Er:YAG laser. The best quality of incision was obtained with a 3-W CO2 laser and 3-W diode laser; epithelial, stromal, and vascular damages were evaluated with different degrees for all the used wavelengths with the best result, in terms of "tissue respect," for Er:YAG laser. In all the surgical procedures performed, thermal increase was evaluated until the end of the procedure; at remaining tissue level, thermal decrease was evaluable in the few seconds after surgery. The Er:YAG laser was the device with a lower influence on thermal increase; CO2 and diode lasers revealed a good histological quality. Further studies may be necessary to test the reliability of laser devices for the excision of all the types of specimens needing histological evaluation and diagnosis.