This paper describes the relation between differences in output power and tissue repair in Nd:YAG laser contact irradiation. Conventionally, pathological research is carried out on tissue repair, but, this paper additionally reports the cell kinetic index measured quantitatively. For irradiation conditions, the output power at the end of the handpiece was set at 3 W, 5 W, 7 W and 9 W and exposure time for all of these was set at 1 second. The following results were obtained: 1) A difference was found between the 3 W group and the other 3 groups pathologically in the early period of wound healing. In the 5 W, 7 W and 9 W groups the output power made no particular difference. 2) Pathologically, the epithelial junction was complete in the 3 W group on the 4th day after irradiation, in the 5 W group on the 7th day and in the 7 W and 9 W groups on the 14th day. 3) Pathologically, the effect of the laser irradiation appeared to end in the 3 W group on the 14th day, in the 5 W group on the 21st day, and in the 7 W and 9 W groups on the 28th day. 4) On the 1st day after irradiation in all groups, the cell kinetic index was maximum at 0.5 mm-2.0 mm away from the wound and not at the regenerated epithelial edges. 5) In all processes for the 3 W group, the cell kinetic index was lower than the other 3 groups. But, among the 5 W, 7 W and 9 W groups there were no particular differences. 6) The cell kinetic index returned to the normal range in all fields in the 3 W and 5 W groups on the 21st day and in the 7 W and 9 W groups on the 28th day. A difference was seen between the 3 W group and the other 3 groups as a result of the cell kinetic index and pathological study. Differences related to the output power in the 5 W, 7 W and 9 W groups were not observed.