Effects of premature contact in maxillary alveolar bone in rats: relationship between experimental analyses and a micro scale FEA computational simulation study

Forastero cacao bean extract gel decreases IL-6 positive osteoblasts, osteoclasts, and osteocytes on OIRR model: A primitive study

Background

Malocclusion can be corrected with orthodontic treatment to improve function and aesthetics. Orthodontic treatment patients have the potential to produce greater Reactive Oxygen Species (ROS), as evidenced by an increase in the Oxidative Status Index (OSI) a week after treatment. As a result, oxidative stress may induce an imbalance of bone remodeling through intensifying osteoclastogenesis by expressing pro-inflammatory cytokine, namely Interleukin-6 (IL-6). The worst pathological condition that can occur is Orthodontic-Induced Root Resorption (OIRR), a resorptive area on the root that is unwanted from orthodontic treatment. OIRR incidence is reported to be more than 90 % asymptomatic. Using Forastero cacao bean (Theobroma cacao L.) extract gel as a natural antioxidant and anti-inflammatory compound is expected to be able to prevent excess ROS, which triggers an increase in various pro-inflammatory cytokines, especially IL-6, which plays a role in the bone resorption pathway, thus reducing the incidence of OIRR and making orthodontic treatment successful through balanced bone remodeling.

Aim

This study aimed to investigate the effect of Forastero cacao bean (Theobroma cacao L.) extract gel on the decrease of IL-6 cytokine expressed by osteoblasts, osteoclasts, and osteocytes in the OIRR model of male Wistar rats.

Results

IL-6 positive osteoblasts, osteoclasts, and osteocytes decreased significantly after 8 % Forastero cacao bean extract gel-treated, as seen in T7 and T14 groups compared to C-7 and C-14 groups (p < 0.05).

Conclusions

8 % Forastero cacao bean extract gel decreased IL-6-positive osteoblasts, osteoclasts, and osteocytes in the tension side of the alveolar bone.

Does Ovariectomy Affect the Mechanics of the Mandibular Alveolar Bone Structure of Wistar Rats Subjected to Tooth Loss and Modified Diet?-A FEA Study

The aim of this study was to evaluate the mechanical effect of ovariectomy, diet, and tooth extraction on the bone structure of the mandible of Wistar rats. Mandibles from 40 female Wistar rats were used, divided into rats with ovariectomy surgery or surgical simulation. Half of the rats had the right upper incisor extracted and a soft diet was introduced for half of the animals for 30 days. After euthanasia, microtomography of the mandibles was performed for bone segmentation to construct three-dimensional models. Each mandible was subjected to a three-point bending test. The simulation by finite element method was configured according to the protocol for positioning the part on the support and force action by the load cell defined in the mechanical tests. Stress dissipation was described qualitatively on a color scale distributed in ranges of stress values. All models showed a higher concentration of stresses in the regions of force action and in the support regions, with differences in stress values and locations. Diet and dental condition interfered in the distribution of stresses, with the lateral surface of the mandible being more influenced by diet and the medial surface of the mandible by diet and dental condition.

Fenestration and Dehiscence in Human Maxillary Alveolar Bone: An In Silico Study Using the Finite Element Method

INTRODUCTION

Fenestration and dehiscence are alveolar bone defects. Although not considered a pathology, these alveolar bone defects end up influencing dental treatment, such as surgeries, mainly periodontal, and therefore must be considered during treatment planning. However, currently, little is known about the biomechanical origin of these bone formations. The aim of the study was to use the finite element method (FEM) to test hypotheses of predictive factors for fenestrations and dehiscence in human alveolar bone.

METHODS

A FEM simulation of the action of functional, parafunctional, and orthodontic occlusal loads on the upper central incisor and upper canine was performed. For the simulation, a three-dimensional model of an adult human skull, fully dented and with intact bone structure, was constructed from computed tomography images. The buccal alveolar bone lamina was evaluated considering the calculation of equivalent stresses, as well as maximum principal stresses.

RESULTS

The action of functional and parafunctional forces on the incisal edges and the orthodontic force on the buccal face of the upper central incisor and upper canine teeth generated tensions at different levels of magnitude in the buccal bone lamina, varying in regions, at all levels of strength. Changing levels of force magnitude resulted in variations in relation to the level of deformation.

CONCLUSION

The computational simulation using the FEM was able to identify a difference in stress in the alveolar bone tissue in each of the applied forces. The difference in stresses obtained may suggest the formation of dehiscence or fenestration in the region studied.