[Observations on the effects of Nd-YAG laser irradiation in the canine tongue].

Recently, the Nd-YAG laser has been widely applied for head and neck surgery. This medical instrument provides several advantages, including hemostatic efficacy and cutting capability which are dependent on manipulation. The purpose of this study is to discuss the clinical application of Nd-YAG laser in the field of oropharyngeal surgery. For this reason, the canine tongue is used in this study. After irradiation by Nd-YAG laser, observations were performed on histological findings, measurement of tissue temperature and changes in blood vessels. The results obtained are as follows: 1) Irreversible tissue changes were found in the center of the irradiated area, with other tissue degeneration occurring in the surrounding areas. 2) Within the coagulated degenerative area, blood vessels were completely embolized. 3) Temperature measurements revealed that there were minimal effects on the surrounding tissues. 4) The coagulated degenerative area was replaced by granulation tissue subsequently occurring after wound healing. 5) The Nd-YAG laser was useful for oral and paranasal surgery, because these diseases are localized in the cavity. 6) Non-contact type Nd-YAG laser was indicated for vaporization of the lesions and was particularly useful for vaporizing superficial benign lesions. In this case, close range, low power vaporization is recommended. Conversely, vaporization for hemangioma and/or malignant lesions were most effective with high power irradiation. 7) Contact type Nd-YAG laser might be suitable for cutting and excision of lesions, but careful attention must be given determining the safety margin for application in malignant lesions, because tissue degeneration when using contact type Nd-YAG laser is less reactive than in non-contact type.