MECHANICAL AND BIOLOGICAL RESPONSE OF ALVEOLAR BONE WITH TOOTH UNDER TRAUMATIC OCCLUSION IN RATS: EXPERIMENTAL ANALYSIS ASSOCIATED TO COMPUTER SIMULATION
Authors: Rossi Ana Cláudia , Freire Alexandre Rodrigues , Okamoto Roberta , Costa Sarah Teixeira , Botacin Paulo Roberto , Prado Felippe Bevilacqua 
Published: November 2023

The aim of this study was to evaluate the bone remodeling activity and microarchitecture associated to the computational strain analysis of the maxillary alveolar bone with tooth under traumatic occlusion in rats. A total of 50 male rats (Rattus norvegicus albinus), 2 months old, Wistar lineage were used. The experimental group (N=40) received a unilateral (right side) resin cementation on the occlusal surface of first maxillary molar, featuring a traumatic occlusion. Then, these animals were distributed in 4 subgroups according the euthanasia periods: 7, 14, 21 and 28 days after cementation (N=10, each period). For the control group (N=10), the teeth were kept without occlusal changes. The pieces including the upper molars, alveolar bone and periodontal tissue were subject to immunohistochemistry evaluation of OPG and RANKL protein expression (scores). For the three‐dimensional morphometric analysis, the head of animals were scanned using a SkyScan 1174 micro‐tomography and analyzed using CTAnalyzer software. For the computer simulation by finite element analysis, the three‐dimensional geometry and finite element mesh of rat head were constructed using Mimics v18 software and the simulation of normal and traumatic occlusion were performed using Ansys v17 software. Both normal and traumatic occlusion were simulated with the same masticatory forces once only the premature contact in the geometry was considered as difference in the simulations. All periods with traumatic occlusion presented higher scores of RANKL expression compared to the control group, both the periodontal ligament and bone tissue. The RANKL expression presented higher scores compared to the OPG expression in all groups. The three‐dimensional morphometry showed bone volume decrease in the traumatic occlusion, with significant values between control and 7 days and 14 days groups (P = 0,007). In association to computer simulation, the traumatic group presented a small increase of bone strain compared to the control group located at the interradicular septum. Traumatic occlusion also presented a small increase of compressive strain in this region. The traumatic occlusion caused changes in the bone remodeling, which the protein expression was associated to bone resorption, as well as the morphometry indicated decrease of bone volume at the first and second week with premature contact. This biological response shows association to changes in the tissue strain features, which presented small difference between the groups, involving the strain quantity and compressive strain. However, this small difference in the normal and traumatic occlusion suggests that the premature contact is not the only factor in the mechanical effect; the effects can be associated to the increase of masticatory forces.Support or Funding InformationSão Paulo Research Foundation – FAPESP (grant number: 2014/14409‐0).