SUMMARY: In the scientific literature the adverse effects of Low Level Laser (LLL) are not precisely described, neither is their safety. The aim of this study was to evaluate the effect of different protocol doses of laser on the mandibular condyle of rabbits. Sixteen rabbits randomly divided into four experimental groups (EG) of 4 animals were used in this study. We carried out a cone beam computed tomography (CBCT) examination of both temporomandibular joints (TMJs) of all animals which were used as control. Subsequently, we radiated each TMJ with LLL (Ga-Al-As 904 nm), 100mW, spot 0.2 cm2, two points, 3 times/week, totaling 10 times, with doses of 15 J/ cm2 (EG-1), 45 J/cm2 (EG-2), 60 J/cm2 (EG-3) and 90 J/cm2 (EG-4). After 20 days of the last irradiation we performed a new CBCT exam and then the measurement of the condyles on the coronal and sagittal planes was obtained. In the analysis of the results ANOVA and t-student for correlated samples was used. The average values found for the EG were higher than those found for CG for both the coronal and sagittal planes. There was a significant statistical difference for group 1 and between the groups 1 and 2. We concluded that the average values found in the measurements of the mandibular condyles, submitted to doses of LLL used in this study, were higher than those found for the control group in both the coronal and sagittal planes. Furthermore, the CBCT proved to be an effective method for analysis of condylar dimensions.

KEY WORDS: Cone-beam computed tomography; Temporomandibular joint; Rabbit; Animal model; Low-level laser.