Changes of the condylar cartilage and subchondral bone in the temporomandibular joints of rats under unilateral mastication and expression of Insulin-like Growth Factor-1 - 16/10/21

Doi : 10.1016/j.jormas.2021.09.013

Ziyang Liu ^a,^b,^c, Yali Hou ^b,^c,^d, Pengfei Zhang ^a,^b,^c, Haiyan Lu ^a,^b,^c, Wen Wang ^a,^b,^c,^{^{⁎
These authors are co-corresponding authors, they contributed equally.}}^⁎ , Wensheng Ma ^a,^b,^c,^{^{⁎
These authors are co-corresponding authors, they contributed equally.}}^⁎
^a Department of Orthodontics, School and Hospital of Stomatology, Hebei Medical University, Shijiazhuang, 050017, PR China
^b Hebei Key Laboratory of Stomatology, School and Hospital of Stomatology, Hebei Medical University, Shijiazhuang, 050017, PR China
^c Hebei Clinical Research Center for Oral Diseases, School and Hospital of Stomatology, Hebei Medical University, Shijiazhuang, 050017, PR China
^d Department of Oral Pathology, School and Hospital of Stomatology, Hebei Medical University, Shijiazhuang, 050017, PR China

^⁎Corresponding author.

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ABSTRACT

Objectives

This study aimed to define changes in the rat condylar cartilage and subchondral bone using the unilateral mastication model.

Materials and Methods

In this study, forty 4-week-old Wistar rats were randomly divided into experimental (n = 20) and control group (n = 20). In the experimental group, unilateral dental splints were placed on the occlusal surface of left maxillary molars. The rats were sacrificed at 1, 2, 3, and 4 weeks after placement of the splint. Micro-CT scanning and histological staining were performed to observe the changes in the mandibular condylar cartilage and subchondral bone. Levels of insulin-like growth factor-1 (IGF-1) were determined via immunohistochemistry to analyse the occurrence of osteogenic changes.

Results

Micro-CT scanning findings demonstrated the occurrence of asymmetric growth of condyle in the experimental group. The condylar cartilage and subchondral bone exhibited degradation on the chewing side of the experimental group and showed decreased bone mineral density, thinner cartilage thickness, and increased degree of degeneration and osteoclast activity. Compared with the control group, the expression of IGF-1 was remarkably higher on the non-chewing side.

Conclusion

Long-term unilateral mastication can lead to the occurrence of degenerative changes in the condylar cartilage and subchondral bone during growth and development. IGF-1 may play a role in promoting the process of osteogenesis.

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Keywords : Unilateral mastication, Temporomandibular joint, Condylar cartilage, Subchondral bone, Insulin-like growth factor-1, Micro-CT scanning