Human dental pulp stem cells (DPSCs) are oral mesenchymal stem cells with potential to differentiate into various cell types. Recent studies of DPSCs have focused on microRNAs (miRNAs), a class of small noncoding RNAs that play crucial roles in regulating DPSC phenotypes. In the current study, the expression of miR-140-5p was significantly decreased during lipopolysaccharide (LPS)-mediated differentiation of DPSCs in vitro. Overexpression of miR-140-5p enhanced proliferation of DPSCs and inhibited DPSC differentiation, whereas suppression of miR-140-5p produced the opposite effect. Moreover, the expression of toll-like receptor 4 (TLR-4), a critical regulator of DPSCs, was negatively correlated with the levels of miR-140-5p. A luciferase reporter analysis confirmed that miR-140-5p could regulate TLR-4 by directly binding to the 3'-untranslated region (3'-UTR) of the TLR4 mRNA. Additionally, we suppressed TLR-4 expression by treating cells with a TLR-4 inhibitor, CLI-095, and demonstrated that the effect of the miR-140-5p inhibitor on DPSC proliferation and differentiation could be partially reversed by blocking TLR-4. Taken together, our data suggest that miR-140-5p is a novel miRNA that regulates DPSC proliferation and differentiation.

The aim of this study was to explore the root morphology and root canal configuration of first premolars among Shandong Chinese residents using cone-beam computed tomography (CBCT). Randomly selected CBCT images were collected from 648 patients (44% women, 56% men). In total, 1268 maxillary and 1296 mandibular first premolars were analyzed. The number of roots and the canal configuration were recorded and identified based on Vertucci's classification. The majority of the maxillary first premolars had 1 root (67.4%), followed by 2 roots (32%). A 2-canal configuration (89%) was the most prevalent observation. For mandibular first premolars, 98.8% had 1 root and 81% presented the type I configuration. There were no statistical differences in the number of roots or morphology in terms of the left/right side or sex (P > .05). Among Chinese residents, the majority of maxillary first premolars had 1 root and 2 canals, whereas the most common anatomical configuration for mandibular first premolars was 1 root with 1 canal.

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