Cementocytes: Analysis Under Experimentally-Induced Dental Cementum Apposition

Objectives: This study aimed at investigating cementocyte’s morphological and ultrastructural changes under dental cementum (DC) continuous apposition.
Methods: DC apposition was experimentally induced (EIA) in mice to access a potential role of cementocytes in periodontal homeostasis. Mandibular 1st molars were randomly induced to erupt for 6 and 21 days after extracting their opposing maxillary molars, whereas contralateral teeth were used as controls. Transmission and scanning electron microscopy (TEM and SEM, respectively) and confocal microscopic analyses were performed. Quantitative data was submitted to two-way ANOVA (α=5%) followed by the Tukey’s test (α=5%).
Results: Data analysis showed an increased area of DC for the EIA group compared to control at 21 days (p<0.05), and therefore, confirmed DC apposition. Intriguingly, as cementocyte’s number was not affected by DC apposition, at 21 days a lower cell density was found in the area where DC apposition was induced (p<0.05). Cementocyte volume was significantly increased when DC apposition was induced for 21 days (p<0.05). TEM analysis showed that, for the EIA group, cementocytes presented larger body and nuclei sizes, more peripherally condensed chromatin and euchromatin spread in the nuclei than the controls. Furthermore, SEM analysis revealed two patterns at the cellular cementum were either lacunae with cell remnants or empty lacunae, with the present cementocytes occupying lacunae irregularly shaped and unevenly distributed into the matrix. Moreover, Sharpey's and matrix fiber bundles were well organized with no evidence of organizational changes between the experimental groups.
Conclusions: Together, these findings provide new insights on DC biology and reveal cementocytes as potential targets for tissue engineering applications.