Mandibular condylar process remodeling in rats with different bite-altering devices
1 Department of Oral and Craniofacial Sciences, School of Dental Medicine, University of Pittsburgh, Pittsburgh, PA 15261, USA
2 Center for Craniofacial Regeneration, University of Pittsburgh, Pittsburgh, PA, 15261, USA
3 Department of Bioengineering, Swanson School of Engineering, University of Pittsburgh, Pittsburgh, PA 15261, USA
4 Department of Neurobiology, School of Medicine, University of Pittsburgh, Pittsburgh, PA 15261, USA
5 McGowan Institute of Regenerative Medicine, University of Pittsburgh, Pittsburgh, PA, 15261, USA
Abstract
The objective was to compare different dental splint models and materials for inducing abnormal loading on the gross morphology and histological appearance of the mandibular condylar processes of Sprague Dawley rats. Three different types of dental splints (resin molar, aluminum incisor, stainless-steel incisor) were placed unilaterally to induce occlusal perturbation for 4 weeks. At that time, mandibular condylar processes were assessed by gross appearance and histology. Quantitative measurements were also conducted on the hematoxylin & eosin images for condyle shape. The results showed that although the condylar cartilage was affected by all splint types, the resin molar splint was associated with the most extensive mandibular condylar process remodeling, which was primarily a slant (skewness) of the lateral aspect of the condylar process. Additionally, quantitative measurements on the histological specimens demonstrated that the split and tilt angle of the left (ipsilateral) condylar processes in the resin molar group (124.8 ± 12.7° and 104.1 ± 12.7°, respectively) increased significantly (p < 0.05) when compared to right (contralateral) condylar processes (104.7 ± 5.8°and 91.6 ± 4.4°, respectively). However, no changes were noted on the thickness of the fibrocartilage layer at medial, central, and lateral regions of the condylar process. Another major finding is the high variability of morphology of the naïve animals. Future studies will assess the impact of longer durations of splinting, age, and sex on the remodeling of the mandibular condylar process, allowing for the development of diagnostics and therapies.
Graphical Abstract

Keywords
- Temporomandibular joint
- temporomandibular joint disorder
- occlusal splint
- degenerative joint disease
- TMJ degeneration models
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