KJZ Laser Instrument for Oral Cavity, which is specially based on oral cavity characteristics, is a novel medical instrument. It can treat pure gingivitis; flatness lichen in oral cavity, periodontitis, pulpits, pericoronitis, dental caries and diseases of oral mucosa, and the curative effect is wonderful beyond all others. Therefore the application of the instrument is an effective means for diseases in oral cavity. As early as in the 1980s a medical Nd: YAG laser was applied to the oral cavity in USA and the Great Britain. An Nd: YAG laser emits laser with wavelength of 1064nm, which can moderately run through human body and produce the right heat. By means of this type of laser with small energy the blood capillary in oral cavity can effectively be sealed off. The laser can also resolve and vary the protein of bacteria, playing a role of detumescence, homostasis and bactericidal action. It can also kill some nerve cells in teeth, playing a role of desensitization. The machine has many characteristics, such as small volume, light weight, easy operation, stable and reliable performance, fastness therapy, slight heat damage, short period of ulcer healing, no pain, no complications and a wonderful curative effect, so it is popular with clinic surgeons and patients. Compared with the product made in foreign countries, the instrument is not only of good quality, but also of low price. The price is ten times as low as that made abroad, which is about a hundred thousand US dollars per set.