This study sought to characterize the incidence and clinical progression of dentinal hypersensitivity after periodontal surgery. Fourteen patients scheduled for open-flap periodontal debridement participated in the study. Ten subjects completed the study and were evaluated for six consecutive weeks after periodontal surgery. Tactile hypersensitivity was assessed using the Yeaple probe; thermal hypersensitivity measurements were obtained using a blast of air from the air/water syringe; and subjective hypersensitivity measurements were obtained using a visual analog scale (VAS). Measurements were taken preoperatively, one week postoperatively, and once a week for the next five consecutive weeks, for a total of six measurements after periodontal surgery. Depending on the stimuli used, dentinal hypersensitivity at one week after periodontal surgery ranged from 67 to 76%. Preoperative tactile and thermal hypersensitivity incidence combined was 30% at baseline. One week after periodontal surgery, the combined incidence had increased to 79%; at six weeks postsurgery, it had decreased to 45%. This study shows that postoperative dentinal hypersensitivity increases at one and three weeks after open-flap periodontal debridement before spontaneously and gradually decreasing to levels similar to those presurgery, even in the absence of desensitizing therapy.