Julián Balanta-Melo1,2,3, María Angélica Torres-Quintana4, Maximilian Bemmann3, Carolina Vega1, Constanza González5, Kornelius Kupczik3,6, Viviana Toro-Ibacache1,6,7, Sonja Buvinic1,8. 1. Institute for Research in Dental Sciences, Faculty of Dentistry, Universidad de Chile, Santiago, Chile. 2. School of Dentistry, Universidad del Valle, Cali, Colombia. 3. Max Planck Weizmann Center for Integrative Archaeology and Anthropology, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany. 4. Department of Pathology and Oral Medicine, Faculty of Dentistry, Universidad de Chile, Santiago, Chile. 5. Biomedical Neuroscience Institute, Santiago, Chile. 6. Center for Quantitative Analysis in Dental Anthropology, Faculty of Dentistry, Universidad de Chile, Santiago, Chile. 7. Department of Human Evolution, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany. 8. Center for Exercise, Metabolism and Cancer Studies CEMC2016, Faculty of Medicine, Universidad de Chile, Santiago, Chile.
Abstract
BACKGROUND: Masseter muscle function influences mandibular bone homeostasis. As previously reported, bone resorption markers increased in the mouse mandibular condyle two days after masseter paralysis induced with botulinum toxin type A (BoNTA), followed by local bone loss. OBJECTIVE: This study aimed to evaluate the bone quality of both the mandibular condyle and alveolar process in the mandible of adult mice during the early stage of a BoNTA-induced masseter muscle atrophy, using a combined 3D histomorphometrics and shape analysis approach. METHODS: Adult BALB/c mice were divided into an untreated control group and an experimental group; the latter received one single BoNTA injection in the right masseter (BoNTA-right) and saline in the left masseter (Saline-left). 3D bone microstructural changes in the mandibular condyle and alveolar process were determined with high-resolution microtomography. Additionally, landmark-based geometric morphometrics was implemented to assess external shape changes. RESULTS: After 2 weeks, masseter mass was significantly reduced (P-value <0.001). When compared to Saline-left and untreated condyles, BoNTA-right condyles showed significant bone loss (P-value <0.001) and shape changes. No significant bone loss was observed in the alveolar processes of any of the groups (P-value >0.05). CONCLUSION: Condyle bone quality deteriorates at an early stage of BoNTA-induced masseter muscle atrophy, and before the alveolar process is affected. Since the observed bone microstructural changes resemble those in human temporomandibular joint degenerative disorders, the clinical safety of BoNTA intervention in the masticatory apparatus remains to be clarified.
BACKGROUND: Masseter muscle function influences mandibular bone homeostasis. As previously reported, bone resorption markers increased in the mouse mandibular condyle two days after masseter paralysis induced with botulinum toxin type A (BoNTA), followed by local bone loss. OBJECTIVE: This study aimed to evaluate the bone quality of both the mandibular condyle and alveolar process in the mandible of adult mice during the early stage of a BoNTA-induced masseter muscle atrophy, using a combined 3D histomorphometrics and shape analysis approach. METHODS: Adult BALB/c mice were divided into an untreated control group and an experimental group; the latter received one single BoNTA injection in the right masseter (BoNTA-right) and saline in the left masseter (Saline-left). 3D bone microstructural changes in the mandibular condyle and alveolar process were determined with high-resolution microtomography. Additionally, landmark-based geometric morphometrics was implemented to assess external shape changes. RESULTS: After 2 weeks, masseter mass was significantly reduced (P-value <0.001). When compared to Saline-left and untreated condyles, BoNTA-right condyles showed significant bone loss (P-value <0.001) and shape changes. No significant bone loss was observed in the alveolar processes of any of the groups (P-value >0.05). CONCLUSION: Condyle bone quality deteriorates at an early stage of BoNTA-induced masseter muscle atrophy, and before the alveolar process is affected. Since the observed bone microstructural changes resemble those in humantemporomandibular joint degenerative disorders, the clinical safety of BoNTA intervention in the masticatory apparatus remains to be clarified.
Authors: Philipp D Lösel; Thomas van de Kamp; Alejandra Jayme; Alexey Ershov; Tomáš Faragó; Olaf Pichler; Nicholas Tan Jerome; Narendar Aadepu; Sabine Bremer; Suren A Chilingaryan; Michael Heethoff; Andreas Kopmann; Janes Odar; Sebastian Schmelzle; Marcus Zuber; Joachim Wittbrodt; Tilo Baumbach; Vincent Heuveline Journal: Nat Commun Date: 2020-11-04 Impact factor: 14.919