A study of the penetration of extrinsic tracers into exposed cementum in vitro.

Suda, Reiko; Y, Motegi; Kokatsu, Hiroaki; Miyashita, Hajime; Hasegawa, Kohji; Tachikawa, Tetsuhiko; Yoshiki, Shusaku

doi:10.2329/perio.31.849

Cited by 3 publications

(4 citation statements)

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“…An important question is whether cementocytes maintain their connectivity to the surface in order to receive and send signals. Our SEM analyses indicate such connectivity, and previous studies using tracer penetration into extracted human teeth (42) or in vivo intravenous injection of tracers into rats (43) provide added support that cementocytes remain connected, even in the deep cementum close to the cementum-dentin junction. Interestingly, cementocytes located farther from the surface are reported to be less metabolically active, (43) and over time these cells may lose contact, become quiescent, and die.…”

Section: Discussionsupporting

confidence: 78%

Isolation and Functional Analysis of an Immortalized Murine Cementocyte Cell Line, IDG-CM6

Zhao

Nociti

Duan

et al. 2015

Journal of Bone and Mineral Research

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The dental cementum covering the tooth root is similar to bone in several respects, but remains poorly understood in terms of development and differentiation of cementoblasts, as well as the potential function(s) of cementocytes residing in the cellular cementum. It is not known if the cementocyte is a dynamic actor in cementum metabolism, comparable to the osteocyte in the bone. Cementocytes exhibit irregular spacing and lacunar shape, with fewer canalicular connections compared to osteocytes. Immunohistochemistry and quantitative PCR (qPCR) revealed that the in vivo expression profile of cementocytes paralleled that of osteocytes, including expression of dentin matrix protein 1 (Dmp1/DMP1), Sost/sclerostin, E11/gp38/podoplanin, Tnfrsf11b (osteoprotegerin; OPG), and Tnfsf11 (receptor activator of NF-kB ligand; RANKL). We used the Immortomouse+/−; Dmp1-GFP+/− mice to isolate cementocytes as Dmp1-expressing cells followed by immortalization using the interferon (IFN)-γ-inducible promoter driving expression of a thermolabile large T antigen to create the first immortalized line of cementocytes, IDG-CM6. This cell line reproduced the expression profile of cementocytes observed in vivo, including alkaline phosphatase activity and mineralization. IDG-CM6 cells expressed higher levels of Tnfrsf11b, and lower levels of Tnfsf11 compared to IDG-SW3 osteocytes, and under fluid flow shear stress, IDG-CM6 cells significantly increased OPG while decreasing RANKL, leading to a significantly increased OPG/RANKL ratio, which would inhibit osteoclast activation. These studies indicate similarities yet potentially important differences in the function of cementocytes as compared to osteocytes and support cementocytes as mechanically responsive cells.

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Section: Discussionsupporting

confidence: 78%

Isolation and Functional Analysis of an Immortalized Murine Cementocyte Cell Line, IDG-CM6

Zhao

Nociti

Duan

et al. 2015

Journal of Bone and Mineral Research

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“…While this study suggests an uneven circulation within the cementocyte lacuno-canalicular system, it does indicate the existence of a cementum fluid equivalent to canalicular fluid in bone and confirms that cementocytes can remain connected, even in the deep cementum. Fluorochrome labeling of rat cementocyte lacuno-canalicular systems (Kagayama et al 1997) and fluorescein isothiocyanate (FITC) penetration into deep cementocyte lacunae and canaliculi in extracted human teeth (Suda et al 1989) also support these findings.…”

Section: Introductionmentioning

confidence: 76%

The Cementocyte—An Osteocyte Relative?

2016

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Cementum is a mineralized tissue covering the tooth root that functions in tooth attachment and posteruptive adjustment of tooth position. During formation of the apically located cellular cementum, some cementoblasts become embedded in the cementoid matrix and become cementocytes. As apparently terminally differentiated cells embedded in a mineralized extracellular matrix, cementocytes are part of a select group of specialized cells, also including osteocytes, hypertrophic chondrocytes, and odontoblasts. The differentiation and potential function(s) of cementocytes are virtually unknown, and the question may be posed whether the cementocyte is a dynamic actor in cementum in comparable fashion with the osteocyte in the skeleton, responding to changing tooth functions and endocrine signals and actively directing local cementum metabolism. This review summarizes the literature with regard to cementocytes, comparing them to their closest "cousins," the osteocytes, where insights gained from osteocyte studies serve to inform the critical examination of cementocytes. The review identifies important unanswered questions about these cells regarding their origins, differentiation, morphology and lacuno-canalicular system, selective markers, and potential functions.

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“…Cementocytes share many features of osteocytes and may therefore mimic some osteocyte functions in cementum 6 . Cementocytes become embedded in cementum ECM, reside in a lacunocanalicular system, and maintain gap junctions that make possible cell‐cell communication 33–37 . Therefore, a plausible mechanism exists for cementocytes to respond to altered tooth loading.…”

Section: Discussionmentioning

confidence: 99%

“…6 Cementocytes become embedded in cementum ECM, reside in a lacunocanalicular system, and maintain gap junctions that make possible cell-cell communication. [33][34][35][36][37] Therefore, a plausible mechanism exists for cementocytes to respond to altered tooth loading. Cementocytes present an in vivo and in vitro expression profile parallel to osteocytes, including key markers, dentin matrix protein 1 (DMP1), sclerostin (SOST), E11/gp38, tumor necrosis factor receptor superfamily member 11b (TNFRSF11B; osteoprotegerin/OPG), and tumor necrosis factor superfamily member 11 (TNFSF11, RANKL).…”

Section: A Role For Cementocytes In Cementum Biologymentioning

confidence: 99%

Cementocyte alterations associated with experimentally induced cellular cementum apposition in Hyp mice

Santos

Salmon

Chavez

et al. 2021

Journal of Periodontology

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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 supereruption, 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.

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A study of the penetration of extrinsic tracers into exposed cementum in vitro.

Cited by 3 publications

References 0 publications

Isolation and Functional Analysis of an Immortalized Murine Cementocyte Cell Line, IDG-CM6

Isolation and Functional Analysis of an Immortalized Murine Cementocyte Cell Line, IDG-CM6

The Cementocyte—An Osteocyte Relative?

Cementocyte alterations associated with experimentally induced cellular cementum apposition in Hyp mice

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