THE PERIODONTIUM MORPHOLOGICAL CHANGESUNDER THE REDUCED CHEWING LOAD INFLUENCE

The studying the influence of masticatory load on the structure and function of the periodontium is an important area of ​​research in dentistry. Disruption of occlusal relationships, the absence of teeth, or prolonged use of a soft diet led to hypofunction of the masticatory apparatus, which provokes atrophic and dystrophic processes in periodontal tissues. Masticatory load is a key factor maintaining periodontal homeostasis. The aim of this study was to establish patterns of structural and functional reorganization of the periodontium during experimental masticatory hypofunction. The temporal and qualitative characteristics of morpho-functional changes in the periodontium were studied during experimental modeling of masticatory hypofunction. Sixty mature outbred white rats (6 months old, weighing 250-300 g) were used in the study. The animals were divided into 2 groups. The main group (n=45) with experimentally modeled masticatory hypofunction, and the control group (n=15) consisted of intact animals. Masticatory hypofunction was simulated by feeding the animals soft food dispersed to a puree state. The experiment lasted 12 weeks. The results were evaluated using a micro-computerized X-ray method, histological, immunohistochemical, molecular biological, and biomechanical analyses. After 12 weeks of hypofunction, the bone volume to total bone tissue ratio decreased by 29% (<0.001), indicating pronounced bone resorption. The trabecular thickness decreased by 33%, and the number of trabeculae decreased by 34% (<0.001), which generally confirms a disruption of bone tissue microarchitecture. Histological studies showed that by week 12 of the experiment, the periodontal ligament thickness decreased by 38.7%, the osteocyte count decreased by 42.3%, and the osteoclast count increased by 2.1 times. Molecular biological changes relative to the control included a 0.6-fold decrease in the synthesis of the alpha chain of type I collagen and a 0.5-fold decrease in alkaline phosphatase activity, as well as a 1.8-fold increase in the activity of tartrate-resistant acid phosphatase (all changes are significant (p<0.001). The results of the experimental study explain the accelerated tooth loss in patients with unilateral chewing.

1. Tsimbalistov AV, Mikhaylova ES. Molekulyarnye mekhanizmy remodelirovaniya kostnoy tkani pri zhevatel'noy gipofunktsii. Parodontologiya. 2021;26(3):45-51. https://doi.org/10.33925/1683-3759-2021-26-3-45-51. In Russian

2. Kuroshima S, Sasaki M. Recent advances in understanding periodontal mechanobiology under masticatory loading. Journal of Dental Research. 2023;102(5):489-499. https://doi.org/10.1177/00220345221149901

3. Sych VF, Bezzubenkova OE. Morfofunktsional’nye osobennosti dvigatel’nykh nervnykh okonchaniy poverkhnostnoy zhevatel’noy myshtsy belykh krys posle prodolzhitel’noy gipodinamii. Morfologicheskie vedomosti. 2005;(1-2):55-58. In Russian

4. Bezzubenkova OE, Kurnosova IA. Konsistentsiya pishchi kak fizicheskiy faktor regulyatsii morfogeneza muskulatury chelyustnogo apparata krysy. Morfologicheskie vedomosti. 2010;(4):15-24. In Russian

5. Drozhdina EP, Sych VF, Khayrullin RM, Slesarev SM. O vliyanii dlitel’nogo potrebleniya dispergirovannoy pishchi na morfogenez myshechnoy obolochki obodochnoy kishki belykh krys. Morfologicheskie vedomosti. 2006;(1-2):21-23. In Russian

6. Kuznetsova TI, Khayrullin RM, Sych VF, Tsyganova NA. Vliyanie melkoizmel’chennogo vivarnogo korma na strukturno-funkcional’noe sostoyanie gepatotsitov pecheni u krys. Voprosy pitaniya. 2010;79(4):9-14. In Russian

7. Ahn BD, Kim YI. Effects of masticatory hypofunction on periodontal tissue remodeling: A longitudinal micro-CT study. Archives of Oral Biology. 2023;145:105590. https://doi.org/10.1016/j.archoralbio.2022.105590

8. Kiliaridis S. Masticatory function and its influence on craniofacial growth. European Journal of Orthodontics. 2003;25(4):371-376. https://doi.org/10.1093/ejo/25.4.371

9. Melsen B, Dalstra M. Mechanical stimulation and bone remodeling. Orthodontics & Craniofacial Research. 2017;20(1):43-48. https://doi.org/10.1111/ocr.12172

10. Mori H, Hiraiwa T, Kawakami M et al. Three-dimensional analysis of alveolar bone loss in occlusal hypofunction models. Archives of Oral Biology. 2017;82:41-47. https://doi.org/10.1016/j.archoralbio.2017.05.019

11. Katsaros C, Bergé S, van't Hof M. Alveolar bone loss and tooth mobility in unilateral chewing. European Journal of Orthodontics. 2006;28(3):262-266. https://doi.org/10.1093/ejo/cji114

12. Huang H, Williams RC, Kyrkanides S. Accelerated orthodontic tooth movement: Molecular mechanisms. American Journal of Orthodontics and Dentofacial Orthopedics. 2015;148(4):620-629. https://doi.org/10.1016/j.ajodo.2015.04.034

13. Moxham BJ, Berkovitz BKB. The effects of mechanical forces on periodontal ligament metabolism - a review. Journal of Periodontal Research. 1984;19(1):1-15. https://doi.org/10.1111/j.1600-0765.1984.tb01190.x

14. Ebersole JL, Kirakodu SS, Novak MJ et al. Gingival tissue inflammation promotes systemic inflammation in experimental periodontitis [Electronic resource]. Journal of Periodontal Research. 2023; URL: https://doi.org/10.1111/jre.13128

15. Kwon T, Lamster IB, Levin L. Current concepts in the management of periodontitis. International Dental Journal. 2021;71(6):462-476. https://doi.org/10.1111/idj.12630

16. Melsen B. Contemporary views on alveolar bone remodeling in hypofunction. Orthodontics & Craniofacial Research. 2017;20(1):43-48. https://doi.org/10.1111/ocr.12172

17. Van der Weijden GA, van der Velden U. Periodontal risks of masticatory hypofunction. Journal of Clinical Periodontology. 2009;36(4):295-302. https://doi.org/10.1111/j.1600-051X.2009.01379.x