Expression features of DNA methylcytosine dioxygenase ten-eleven translocation 1 in human dental pulp cells.

INTRODUCTION: Human dental pulp cells (hDPCs) can specifically generate reparative dentin under external stimuli, and numerous mechanisms are involved in their odontogenic differentiation process. Ten-eleven translocation 1 (TET1) is a recently discovered DNA dioxygenase that plays important roles in promoting DNA demethylation and transcriptional regulation. Although several studies regarding its effect on cell differentiation and proliferation have been conducted, the expression and function of TET1 have not yet been characterized in hDPCs. The purpose of this study was to explore the expression features of TET1 in hDPCs. METHODS: Cellular TET1 localization in hDPCs was determined by immunofluorescence. The expression pattern of TET1 and its potential changes during odontogenic induction were confirmed using real-time quantitative polymerase chain reaction and Western blot analyses. RESULTS: TET1 existed in both the cytoplasm and the nucleus of the hDPCs. During serial cell passaging, TET1 expression significantly increased until the 6th passage and then decreased from the 7th-9th passages (P < .05, n = 3). TET1 gene and protein expression increased during the odontogenic differentiation of the hDPCs in a time-dependent manner (P < .05, n = 3). CONCLUSIONS: TET1 messenger RNA and protein were both present in the hDPCs. TET1 expression increased during early spontaneous differentiation and odontogenic induction.

Evaluation of root-end preparation with a new ultrasonic tip.

INTRODUCTION: This study was conducted to evaluate the effect of a new ultrasonic tip (Jetip) for root-end preparation. METHODS: A total of 80 single-rooted teeth were endodontically treated, and the apical 3 mm of the root apex was resected. Teeth were randomly distributed into 2 experimental groups according to the ultrasonic tips used to prepare the root-end cavity. Epoxy resin replicas of root-end surfaces after root-end resection were obtained. A root-end cavity was then prepared with an ultrasonic tip, either Jetip or AS3D. Replicas of the apices were fabricated after the retropreparations, and they were processed for analysis by scanning electron microscopy (SEM) to evaluate the presence of microcracks and the quality of the root-end preparation. The morphologic characteristics of the ultrasonic tip were also assessed by SEM. The time required for root-end preparation was recorded. RESULTS: There were no statistically significant differences between the Jetip and AS3D groups in the mean time for the root-end preparation, the incidence of microcracks, or the quality of the root-end preparation (P > .05). SEM analysis showed that Jetip exhibited smoothed microprojections after the root preparations, whereas the loss of diamond particles was observed in AS3D. CONCLUSIONS: Both Jetip and AS3D provided rapid and regular root-end preparations. The cutting efficiencies of both Jetip and AS3D decreased with the number of times the tips were used. The Jetip showed smooth microprojections after root-end preparation, whereas the AS3D tip exhibited the loss of diamond particles.