Decreases of occlusal vertical dimension induce changes in masticatory muscle fiber composition

Masahiro Seiryu, Takayoshi Daimaruya, Masahiro Iikubo, Kouichi Watanabe, Teruko Takano-Yamamoto

Research output: Contribution to journalArticlepeer-review

5 Citations (Scopus)


Objectives: To evaluate the effects of artificially decreased occlusal vertical dimension on the fiber phenotypes of the masseter muscle in the rat. Materials and methods: The experimental animals were divided into two groups: A decreased occlusal vertical dimension (DOVD) group and a sham-operated control group. Five rats from each group were sacrificed on days 0, 3, 7, and 14 after the operation. The extent of DOVD, the masseter muscle fiber composition, and fiber diameter were analyzed. Results: The average decrease in the vertical dimension was 1.1 ± 0.5. mm. The masseter muscle fiber composition of Type IIA and Type IIB muscle fibers shifted significantly in favor of Type IIA fibers on day 3 in the DOVD group. Toward the end of the observation period, shifting occurred back to the original composition. A significant decrease in the diameter of muscle fibers was seen on day 3 in the DOVD group. Conclusion: In this experiment, when the occlusal vertical dimension was artificially reduced, the masseter muscle atrophied and the muscle fiber type changed temporarily while adapting to the new position of the mandible.

Original languageEnglish
Pages (from-to)123-128
Number of pages6
JournalOrthodontic Waves
Issue number4
Publication statusPublished - 2012 Dec


  • Enzyme histochemistry
  • Masseter muscle
  • Occlusal vertical dimension


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