The influence of altered occlusion on pro-inflammatory cytokine levels in the TMJ synovial tissues of rats

Sidney R Figueroba; Marina Passarela Desjardins; Luiz E N Ferreira; Luciana A Berto; Heloisa Cristina Valdrighi; Francisco C Groppo

doi:10.1016/j.archoralbio.2014.07.003

The influence of altered occlusion on pro-inflammatory cytokine levels in the TMJ synovial tissues of rats

Arch Oral Biol. 2014 Nov;59(11):1164-71. doi: 10.1016/j.archoralbio.2014.07.003. Epub 2014 Jul 22.

Authors

Sidney R Figueroba¹, Marina Passarela Desjardins¹, Luiz E N Ferreira¹, Luciana A Berto¹, Heloisa Cristina Valdrighi², Francisco C Groppo³

Affiliations

¹ Department of Physiological Sciences, Piracicaba Dental School, UNICAMP, Av. Limeira, 901, CEP 13414-903 Piracicaba, São Paulo, Brazil.
² Department of Orthodontics, Araras Dental School, FHO/UNIARARAS, Av. Maximiliano Baruto, 500, Jd Universitário, São Paulo, Brazil.
³ Department of Physiological Sciences, Piracicaba Dental School, UNICAMP, Av. Limeira, 901, CEP 13414-903 Piracicaba, São Paulo, Brazil. Electronic address: fcgroppo1@yahoo.com.br.

PMID: 25103542
DOI: 10.1016/j.archoralbio.2014.07.003

Abstract

Objective: The aim of this study was to evaluate whether altered occlusion affects both the condylar cartilage thickness and the cytokine levels of the TMJs of rats.

Design: Thirty adult-male rats (n=30) were randomly assigned to three experimental conditions: a control group that underwent sham operations with unaltered occlusion; an FPDM group that underwent functional posterior displacement of the mandible that was induced by an incisor guiding appliance; and an iOVD group in which the increased occlusal vertical dimension was induced in the molars. The rats were subjected to the FPDM or iOVD model for 14 days and then killed. Both the right and left TMJs were removed and randomly assigned to examination with staining or immunoassay techniques. Toluidine blue staining was used to measure the thicknesses of the four layers of the articular cartilage (i.e., the fibrous, proliferating, mature, and hypertrophic layers). ELISA assays were used to assess the concentrations of the pro-inflammatory cytokines IL-1α, IL-1β, IL-6, and tumour necrosis factor (TNF-α). The measurements of the articular cartilage layers and cytokine concentrations were analyzed with ANOVA and Tukey's tests and Kruskal-Wallis and Dunn tests, respectively (α=5%).

Results: The thickness of articular cartilage in the FPDM group (0.3±0.03mm) was significantly greater than those of the control (0.2±0.01mm) and iOVD (0.25±0.03mm) groups. No significant difference was observed between the control and iOVD groups. The four articular cartilage layers were thicker in the FPDM group than in the control and iOVD groups, and the latter two groups did not differ one from each other. Both the FPDM and iOVD groups exhibited higher cytokine levels than did the control (p<0.05) group. Compared to the FPDM group, the iOVD group exhibited significantly higher levels of IL-1β and TNF-α.

Conclusion: Both models induced inflammation in the TMJ and caused significant structural changes in the TMJ and surrounding tissues.

Keywords: Animal model; Cartilage; Cytokines; Dental occlusion; Endochondral ossification; Temporomandibular joint.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Animals
Cartilage, Articular / metabolism*
Cartilage, Articular / physiopathology*
Cytokines / metabolism*
Dental Occlusion*
Enzyme-Linked Immunosorbent Assay
Male
Mandibular Condyle / metabolism
Mandibular Condyle / physiopathology
Random Allocation
Rats
Temporomandibular Joint / metabolism*
Temporomandibular Joint / physiopathology*

Substances

Cytokines