Analysis of healing of surgically created bone defects in rat calvaria treated with bovine grafts (Bio-Oss) associated with low level laser. Histological and histometric study

Abstract

With the increase in the utilization of endosseous implants for the rehabilitation of partially or totally edentulous patients, there must be satisfactory quality and volume of soft tissue and bone. Thus, the clinicians often face situations in which implants must be placed in less favorable positions due to the local bone quantity. Therefore, techniques and materials have been developed to promote predictable bone regeneration and allow the placement of implants in ideal position and angulation, which will provide better and more predictable restorations. To histologically evaluate the bone healing process in surgically created critical size defects in rat calvaria treated with Bio-Oss (BO), in isolation or irradiated with low level laser (LL). The study will be conducted on 40 male rats (Rattus norvegicus, albinus, Wistar), weighing 250 to 300 g (University of São Paulo - USP, from the Central Animal Laboratory of Bauru Dental School - SP). For the accomplishment of all experimental procedures, the rats will be anesthetized via an intramuscular injection of xylazine (0.02 ml/kg) and ketamine hydrochloride (0.4 ml/kg). After trichotomy and antisepsis of the dorsal part of the skull of each animal, a half-moon incision will be made on the calvaria for posterior displacement of a full thickness flap. A critical size defect (CSD) with 5-mm diameter will be created with a trephine bur in low speed, under abundant irrigation with sterile saline. The animals will be divided into four study groups: 1) Control Group (Control), 2) Group LL (Low level laser - Thera Lase DMC, São Carlos, São Paulo), 3) Group BO (Bio-Oss®), 4) Group BO + LL (Bio-Oss® + Low level laser - Thera Lase DMC, São Carlos, São Paulo). The animals will be killed at 30 days postoperatively. After decalcification, each specimen will be longitudinally divided into two blocks, exactly through the center of the original surgically created defect. The specimens will then be processed and embedded in paraffin. Longitudinal serial sections with 6-µm thickness will be achieved, initiating from the center of the original surgically created defect. The sections will be stained with hematoxylin and eosin (H.E.) for light microscopy and histomorphometric analysis (AU)