Differential lncRNA/mRNA Expression Profiling and Functional Network Analyses in Bmp2 Deletion of Mouse Dental Papilla Cells

Bmp2 is essential for dentin development and formation. Bmp2 conditional knock-out (KO) mice display a similar tooth phenotype of dentinogenesis imperfecta (DGI). To elucidate a foundation for subsequent functional studies of cross talk between mRNAs and lncRNAs in Bmp2-mediated dentinogenesis, we investigated the profiling of lncRNAs and mRNAs using immortalized mouse dental Bmp2 flox/flox (iBmp2fx/fx) and Bmp2 knock-out (iBmp2ko/ko) papilla cells. RNA sequencing was implemented to study the expression of the lncRNAs and mRNAs. Quantitative real-time PCR (RT-qPCR) was used to validate expressions of lncRNAs and mRNAs. The Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) databases were used to predict functions of differentially expressed genes (DEGs). Protein–protein interaction (PPI) and lncRNA–mRNA co-expression network were analyzed by using bioinformatics methods. As a result, a total of 22 differentially expressed lncRNAs (16 downregulated vs 6 upregulated) and 227 differentially expressed mRNAs (133 downregulated vs. 94 upregulated) were identified in the iBmp2ko/ko cells compared with those of the iBmp2fx/fx cells. RT-qPCR results showed significantly differential expressions of several lncRNAs and mRNAs which were consistent with the RNA-seq data. GO and KEGG analyses showed differentially expressed genes were closely related to cell differentiation, transcriptional regulation, and developmentally relevant signaling pathways. Moreover, network-based bioinformatics analysis depicted the co-expression network between lncRNAs and mRNAs regulated by Bmp2 in mouse dental papilla cells and symmetrically analyzed the effect of Bmp2 during dentinogenesis via coding and non-coding RNA signaling.

The effect of horizontal and vertical dimensions of the interproximal space on the existence of interdental papillae – A clinical study

The aim of the present study was to determine the existence of inter dental papilla according to the vertical dimension, horizontal dimension and the combined effects of the vertical and horizontal dimensions of the interproximal space on the existence of interdental papilla.182 interdental sites of 42 periodontitis patients undergoing open flap debridement were included in the study. The existence of interdental papilla was determined based on the Papilla Presence Index (PPI). The vertical dimension (VD) was measured from the alveolar crest to the contact point using UNC-15 probe. Horizontal dimension (HD) was measured from the mesial surface of the distal tooth and the distal surface of the mesial tooth at the level of the alveolar crest using castroviejocaliper. Statistical analysis was done by using independent ‘t’ test, Pearson’s Chi-square test and Trend Chi-square test. The existence of papilla was significantly higher in VD ≤ 5mm (91.5%) compared to VD > 5mm (9.8%) [p< 0.0001]. The existence of papilla was significantly higher in HD < 2mm (97%) compared to HD ≥ 2mm (1.2%) [p< 0.0001]. The contribution of both vertical dimension and horizontal dimension to the existence of papilla was about 61.6% and thus the existence of papilla may be influenced by various other factors (about 38.4%) which were not included in this study.The vertical and horizontal dimensions of the interproximal space gains significance in determining the existence of papilla and further research is needed to analyze the other factors influencing the papilla.

Dental Management of Congenital Granular Cell Lesion and Neonatal Teeth: A Case Report

Congenital granular cell lesion (CGCL) is a rare benign oral cavity tumor in infants. Neonatal teeth are also rare dental anomalies that appear during the first month of life. This report describes a case of eruption of neonatal teeth after surgical excision of CGCL. Surprisingly, residual neonatal teeth erupted after extraction of the neonatal teeth. If neonatal teeth are mobile, they should be carefully extracted with curettage of the underlying tissues of the dental papilla; failure to curette the socket might result in eruption of odontogenic remnants. If neonatal teeth were exfoliated, parents should be informed of the need for regular checkups with a dentist due to possibility of development of residual neonatal teeth.

C-Jun N-terminal kinase (JNK) pathway activation is essential for dental papilla cells polarization

During tooth development, dental papilla cells differentiate into odontoblasts with polarized morphology and cell function. Our previous study indicated that the C-Jun N-terminal kinase (JNK) pathway regulates human dental papilla cell adhesion, migration, and formation of focal adhesion complexes. The aim of this study was to further examine the role of the JNK pathway in dental papilla cell polarity formation. Histological staining, qPCR, and Western Blot suggested the activation of JNK signaling in polarized mouse dental papilla tissue. After performing an in vitro tooth germ organ culture and cell culture, we found that JNK inhibitor SP600125 postponed tooth germ development and reduced the polarization, migration and differentiation of mouse dental papilla cells (mDPCs). Next, we screened up-regulated polarity-related genes during dental papilla development and mDPCs or A11 differentiation. We found that Prickle3, Golga2, Golga5, and RhoA were all up-regulated, which is consistent with JNK signaling activation. Further, constitutively active RhoA mutant (RhoA Q63L) partly rescued the inhibition of SP600125 on cell differentiation and polarity formation of mDPCs. To sum up, this study suggests that JNK signaling has a positive role in the formation of dental papilla cell polarization.

Dens Invaginatus: A Report of Two Cases

Dens invaginatus (DI) is an anomaly of developmental origin arising due to disturbances during the morphodifferentiation stage, resulting from infolding of enamel organ toward the dental papilla. Different presentations of the invagination, altered canal morphology, and presence of constrictions and dilatations sometimes make its management really challenging. With the advent of modern diagnostic and treatment aids, their easy availability and routine use, it is now possible to have detailed view of the invagination, thus making the management easy and the outcome predictable. This article presents two different presentations of DI and their management.

RORα Regulates Odontoblastic Differentiation and Mediates the Pro-Odontogenic Effect of Melatonin on Dental Papilla Cells

Dental papilla cells (DPCs), precursors of odontoblasts, are considered promising seed cells for tissue engineering. Emerging evidence suggests that melatonin promotes odontoblastic differentiation of DPCs and affects tooth development, although the precise mechanisms remain unknown. Retinoid acid receptor-related orphan receptor α (RORα) is a nuclear receptor for melatonin that plays a critical role in cell differentiation and embryonic development. This study aimed to explore the role of RORα in odontoblastic differentiation and determine whether melatonin exerts its pro-odontogenic effect via RORα. Herein, we observed that RORα was expressed in DPCs and was significantly increased during odontoblastic differentiation in vitro and in vivo. The overexpression of RORα upregulated the expression of odontogenic markers, alkaline phosphatase (ALP) activity and mineralized nodules formation (p < 0.05). In contrast, odontoblastic differentiation of DPCs was suppressed by RORα knockdown. Moreover, we found that melatonin elevated the expression of odontogenic markers, which was accompanied by the upregulation of RORα (p < 0.001). Utilising small interfering RNA, we further demonstrated that RORα inhibition attenuated melatonin-induced odontogenic gene expression, ALP activity and matrix mineralisation (p < 0.01). Collectively, these results provide the first evidence that RORα can promote odontoblastic differentiation of DPCs and mediate the pro-odontogenic effect of melatonin.

Expression of the of STRO-1 and HSP-25 markers during odontogenesis

ABSTRACT Objective: Therefore, the purpose of the currently study was to analyze the expression of the STRO-1 stem cell marker and the marker related to Hsp25 differentiation and dental development during odontogenesis in rats. Methods: Eighteen-day Wistar rat embryos and 7-day-old animals were analyzed morphologically via Hematoxylin and Eosin (HE) staining and via immunohistochemical marking for Stro-1 and Hsp25 in 5uM serial sections. Results: In the HE morphological analysis in 18-day embryos, the stage of tooth development was in the cap phase, while in the 7-day old animals it was in the bell phase. Conclusion: The expression of STRO-1 in the embryos was not found in the region of the dental papilla or enamel organ, however, in the 7-day-old animals, STRO-1-positive cells were found in the region of the dental follicle and dental papilla. As for the Hsp25, this exhibited weak marking in the cap phase while in the bell phase, there was a reaction, mainly in the odontoblasts. The expressions in the site of these markers vary according to the stage of tooth development.