Elis J Lira Dos Santos1,2, Cristiane R Salmon1,3, Michael B Chavez2, Amanda B de Almeida1, Michelle H Tan2, Emily Y Chu4, Enilson A Sallum1, Marcio Z Casati1, Karina G S Ruiz1, Kamila R Kantovitz5, Brian L Foster2, Francisco H Nociti Júnior1,6. 1. Department of Prosthodontics and Periodontics, Division of Periodontics, Piracicaba Dental School, State University of Campinas, São Paulo, Brazil. 2. Division of Biosciences, College of Dentistry, The Ohio State University, Columbus, OH. 3. Faculty of Dentistry, N. Sra. do Patrocínio University Center, Itu, São Paulo, Brazil. 4. National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS), National Institutes of Health (NIH), Bethesda, MD. 5. Department of Dental Materials, São Leopoldo Mandic Research Center, Campinas, São Paulo, Brazil. 6. São Leopoldo Mandic Research Center, Campinas, São Paulo, Brazil.
Abstract
BACKGROUND: Cellular cementum, a mineralized tissue covering apical tooth roots, grows by apposition to maintain the tooth in its occlusal position. We hypothesized that resident cementocytes would show morphological changes in response to cementum apposition, possibly implicating a role in cementum biology. METHODS: Mandibular first molars were induced to super-erupt (EIA) by extraction of maxillary molars, promoting rapid new cementum formation. Tissue and cell responses were analyzed at 6 and/or 21 days post-procedure (dpp). RESULTS: High-resolution micro-computed tomography (micro-CT) and confocal laser scanning microscopy showed increased cellular cementum by 21 dpp. Transmission electron microscopy (TEM) revealed that cementocytes under EIA were 50% larger than control cells, supported by larger pore sizes detected by micro-CT. Cementocytes under EIA displayed ultrastructural changes consistent with increased activity, including increased cytoplasm and nuclear size. We applied EIA to Hyp mutant mice, where cementocytes have perilacunar hypomineralization defects, to test cell and tissue responses in an altered mechanoresponsive milieu. Hyp and WT molars displayed similar super-eruption, with Hyp molars exhibiting 28% increased cellular cementum area versus 22% in WT mice at 21 dpp. Compared to control, Hyp cementocytes featured well-defined, disperse euchromatin and a thick layer of peripherally condensed heterochromatin in nuclei, indicating cellular activity. Immunohistochemistry (IHC) for cementum markers revealed intense dentin matrix protein-1 expression and abnormal osteopontin deposition in Hyp mice. Both WT and Hyp cementocytes expressed gap junction protein, connexin 43. CONCLUSION: This study provides new insights into the EIA model and cementocyte activity in association with new cementum formation.
BACKGROUND: Cellular cementum, a mineralized tissue covering apical tooth roots, grows by apposition to maintain the tooth in its occlusal position. We hypothesized that resident cementocytes would show morphological changes in response to cementum apposition, possibly implicating a role in cementum biology. METHODS: Mandibular first molars were induced to super-erupt (EIA) by extraction of maxillary molars, promoting rapid new cementum formation. Tissue and cell responses were analyzed at 6 and/or 21 days post-procedure (dpp). RESULTS: High-resolution micro-computed tomography (micro-CT) and confocal laser scanning microscopy showed increased cellular cementum by 21 dpp. Transmission electron microscopy (TEM) revealed that cementocytes under EIA were 50% larger than control cells, supported by larger pore sizes detected by micro-CT. Cementocytes under EIA displayed ultrastructural changes consistent with increased activity, including increased cytoplasm and nuclear size. We applied EIA to Hyp mutant mice, where cementocytes have perilacunar hypomineralization defects, to test cell and tissue responses in an altered mechanoresponsive milieu. Hyp and WT molars displayed similar super-eruption, with Hyp molars exhibiting 28% increased cellular cementum area versus 22% in WT mice at 21 dpp. Compared to control, Hyp cementocytes featured well-defined, disperse euchromatin and a thick layer of peripherally condensed heterochromatin in nuclei, indicating cellular activity. Immunohistochemistry (IHC) for cementum markers revealed intense dentin matrix protein-1 expression and abnormal osteopontin deposition in Hyp mice. Both WT and Hyp cementocytes expressed gap junction protein, connexin 43. CONCLUSION: This study provides new insights into the EIA model and cementocyte activity in association with new cementum formation.
Authors: Danielle Tokarz; Janaina S Martins; Elizabeth T Petit; Charles P Lin; Marie B Demay; Eva S Liu Journal: J Bone Miner Res Date: 2017-11-17 Impact factor: 6.741
Authors: M Ao; M B Chavez; E Y Chu; K C Hemstreet; Y Yin; M C Yadav; J L Millán; L W Fisher; H A Goldberg; M J Somerman; B L Foster Journal: Bone Date: 2017-09-01 Impact factor: 4.398
Authors: V Thumbigere-Math; A Alqadi; N I Chalmers; M B Chavez; E Y Chu; M T Collins; C R Ferreira; K FitzGerald; R I Gafni; W A Gahl; K S Hsu; M S Ramnitz; M J Somerman; S G Ziegler; B L Foster Journal: J Dent Res Date: 2017-12-15 Impact factor: 6.116
Authors: Elis J Lira Dos Santos; Amanda B de Almeida; Michael B Chavez; Cristiane R Salmon; Luciana S Mofatto; Mariana Barbosa Camara-Souza; Michelle H Tan; Tamara N Kolli; Fatma F Mohamed; Emily Y Chu; Pedro Duarte Novaes; Eduardo C A Santos; Kamila R Kantovitz; Brian L Foster; Francisco H Nociti Journal: Bone Date: 2021-08-05 Impact factor: 4.626