Akiko Enomoto1, Junichi Watahiki2, Tomoki Nampo1, Tarou Irie3, Yuuta Ichikawa4, Tetsuhiko Tachikawa5, Koutaro Maki6. 1. Postgraduate researcher, Department of Orthodontics, School of Dentistry, Showa University, Tokyo, Japan. 2. Lecturer, Department of Orthodontics, School of Dentistry, Showa University, Tokyo, Japan. Electronic address: junwata2000@ybb.ne.jp. 3. Lecturer, Dapartment of Oral Pathology, School of Dentistry, Showa University, Tokyo, Japan. 4. Assistant lecturer, Department of Orthodontics, School of Dentistry, Showa University, Tokyo, Japan. 5. Professor, Department of Oral Pathology, School of Dentistry, Showa University, Tokyo, Japan. 6. Professor, Department of Orthodontics, School of Dentistry, Showa University, Tokyo, Japan.
Abstract
INTRODUCTION: Mandibular growth is believed to be strongly related to mastication. Furthermore, mandibular condylar cartilage is known to be derived from neural crest cells. We examined whether the degree of chewing affects condylar cartilage growth of the mandible. METHODS: Mice were fed diets with varying hardness. Genes specific to neural crest-derived cells were measured by real-time polymerase chain reaction to compare the expression changes between the mandibular and tibia cartilages. The mandibular condylar cartilage was then evaluated histologically, and proliferation was evaluated using proliferating cell nuclear antigen. Immunostaining was conducted for osteopontin, type X collagen, and Musashi1, and real-time polymerase chain reaction was used to assess the expression levels of osteopontin and type X collagen. RESULTS: Markers including P75, Wnt-1, Musashi1, and Nestin were upregulated in the mandibular condylar cartilage as compared with the tibial cartilage. Histologic assessment of the mandibular cartilage showed that the hypertrophic chondrocyte zone was statistically significantly thicker in mice fed a hard diet. Chondrocyte proliferation and Musashi1 expression were lower in mice fed a hard diet. After 4 weeks, numerous osteopontin and type X collagen-positive cells were observed in mice fed a mixed diet. CONCLUSIONS: Mastication affects the balance between differentiation and proliferation in the mandibular condylar cartilage. This phenomenon might be attributed to the presence of neural crest-derived cells.
INTRODUCTION: Mandibular growth is believed to be strongly related to mastication. Furthermore, mandibular condylar cartilage is known to be derived from neural crest cells. We examined whether the degree of chewing affects condylar cartilage growth of the mandible. METHODS:Mice were fed diets with varying hardness. Genes specific to neural crest-derived cells were measured by real-time polymerase chain reaction to compare the expression changes between the mandibular and tibia cartilages. The mandibular condylar cartilage was then evaluated histologically, and proliferation was evaluated using proliferating cell nuclear antigen. Immunostaining was conducted for osteopontin, type X collagen, and Musashi1, and real-time polymerase chain reaction was used to assess the expression levels of osteopontin and type X collagen. RESULTS: Markers including P75, Wnt-1, Musashi1, and Nestin were upregulated in the mandibular condylar cartilage as compared with the tibial cartilage. Histologic assessment of the mandibular cartilage showed that the hypertrophic chondrocyte zone was statistically significantly thicker in mice fed a hard diet. Chondrocyte proliferation and Musashi1 expression were lower in mice fed a hard diet. After 4 weeks, numerous osteopontin and type X collagen-positive cells were observed in mice fed a mixed diet. CONCLUSIONS: Mastication affects the balance between differentiation and proliferation in the mandibular condylar cartilage. This phenomenon might be attributed to the presence of neural crest-derived cells.
Authors: Patricia Valerio; Filipi Perfeito; Livia P Moura; Deborah N Ribeiro; Simone O A Fernandes; Almir S Martins; Maria F Leite Journal: Ann Stomatol (Roma) Date: 2018-03-08