Piezoelectric device vs. conventional rotative instruments in impacted third molar surgery: relationships between surgical difficulty and postoperative pain with histological evaluations

Purpose: To investigate and compare the influence of surgical difficulty on postoperative pain after treatment of impacted mandibular third molars by rotatory osteotomy or Piezoelectric surgery. Materials and methods: A prospective, randomized, split-mouth study was performed of 52 patients with bilateral and symmetrically oriented impacted mandibular third molars, who were surgically treated using a burr (Group A) on one random side of the lower jaw and a Piezoelectric device (Group B) on the contralateral side. Surgical difficulty was evaluated using a modified version of the Parant scale to cate- gorize “simple extractions” and “complex extractions”. Primary outcome parameters were the comparison of the postoperative pain evaluation rated on the Visual Analogue Scale from day 0 to day 6 postsurgery, and the assessment of differences in surgery time between the groups. Bone biopsies were taken during surgery to assess differences in bone tissue damage levels between the two different techniques. Results: In “complex extractions” lower pain evaluation and significantly shorter surgery times were recorded when rotatory instruments were used. In “simple extractions”, similar surgery times were observed for both techniques, but pain was greatest on the day of surgery when the burr was used. Bone heat osteonecrosis was observed only in the rotatory group and a high level of alkaline phosphatase was noted only in the Piezoelectric group. Conclusion: Pain after extraction of a mandibular third molar increases with increased surgical difficulty and especially in longer interventions. The integrity of the bony structure observed after the ultrasonic technique may favour the bone healing process.