In Part I of this two-part study, the authors investigated heat production during osteotomy drilling at three different speeds, and determined that high-speed drilling produced the least heat when using 700 XL carbide burs. Part II of the study histologically examines the rate and quality of healing after drilling osteotomies at the three speeds in the mandible. Osteotomies were histologically examined 2, 4, and 6 weeks postoperatively. Histologic findings suggested that in the initial 6 weeks, the rate ofhealing and quality of new bone formation were higher after high-speed drilling than after low-or intermediate-speed drilling. These results, when considered wi th the results reported in Part I in which a 4.3 degrees C difference in heat production was observed between the speeds, seem to imply a relationship between heat production and healing for osteotomy drilling.