Abstract:

BACKGROUND: Some studies have reported that there exist two kinds of ossification ways, intramembranous ossification and endochondral ossification in the distraction gap. Others also reported that there will be only intramembranous ossification when the tensions forces axial without other direction of external interference.
OBJECTIVE: To investigate the level of stress of different occlusal conditions suffered by new tissues, and to verify whether the environment can induce and promote endochondral ossification in order to explain the issue of osteogenesis inconsistent.
METHODS: We established a clinical bilateral mandibular distraction osteogenesis model and set the distance of 1 cm. After consolidation for 4 weeks, we exerted muscle force in the site of masticatory muscles’ attachment in order to simulate the actual chewing movement. We selected three basic occlusion statuses, namely clenching in the intercuspal position, left unilateral molar clenching and incisal clenching. The three-dimensional finite element analysis was used to investigate the level of stress (stress/tensile stress, shear stress, the stress paradigm).
RESULTS AND CONCLUSION: ①Status of clenching in the intercuspal position: the value of Von Mises stress and shear stress was increased from lingual lateral to the buccal. The compression stress was gradually turned into a tensile stress from lingual and distal lower edge to buccal and distal upper edge. ②Status of incisal clenching: the value of Von Mises stress and shear stress was decreased from lingual lateral to the buccal. Pressure stress was gradually turned into a tensile stress from lingual lateral to the buccal. ③Status of left unilateral molar clenching: the stress distribution of left distract region was very similar to that of the intercuspal position status, but the maximum values were lower than the intercuspal position status. The maximum value of Von Mises stress existed at the upper and lower edge of distal lateral. The minimum value existed at the buccal and mesial lower edge. There is a transition zone between the maximum and minimum value. The characteristics of shear stress were similar to that of Von Mises stress. Compression/tensile stress mainly exited at the mesial lower edge. This indicates that masticatory movement can create a mechanical environment promoting the cartilage formation especially when the fixation is not stable enough and provide a accurate solution to the issue of osteogenesis inconsistent.