Objective: Ultrasonic osteotomy devices (UODs) are reported to have many clinical benefits; for example, they cause little damage to adjacent tissues in oral surgery. However, the difference in the tissue repair process between rotary osteotomy devices (RODs) and UODs is still unclear. This study aimed to compare bone healing after osteotomy with UODs versus RODs in a rat calvarial defect model.Methods: Calvarial bone defects were made in male Wistar rats with a UOD on the right side and an ROD on the left side. Bone and morphological changes were quantitatively evaluated for 4 weeks by micro-CT, light microscopy and electron microscopy. Furthermore, after calvarial bone osteotomy, osteoblastic cells were collected from the bone chips and cultured for 2 weeks, and their proliferation and differentiation activities were analysed.Results: Scanning electron microscopy (SEM) showed that UOD cuts had smoother surfaces than ROD cuts. In HE-stained sections and micro-CT images, the bone wound gap was closed earlier on the UOD side than on the ROD side. Bone thickness, the quantity of newly formed bone, and the number of osteocytes were greater on the UOD side than on the ROD side. Cultured osteoblast-like cells harvested from bone chips cut by the UOD had greater proliferative activity than those harvested from ROD-cut bone chips.Conclusions: The use of a UOD may assist bone regeneration, presumably because osteoblasts differen-tiated from mesenchymal cells are activated by ultrasonic microvibration and because UODs cause less damage to the bone than conventional RODs. (C) 2021 Asian AOMS, ASOMP, JSOP, JSOMS, JSOM, and JAMI. Published by Elsevier Ltd. All rights reserved.