This study evaluated the internal morphology of lower incisors using computerized microtomography (micro-CT) images. Eighty-nine lower incisors were scanned by micro-CT and reconstructed with NRecon software. 2D parameters (perimeter, root length, circularity and canal diameter) and 3D parameters (volume, surface area and structure model index) were evaluated with CTAn and CTVol software. The results are presented descriptively. It was found that 89.9% of the canals had a single main root canal (type I), followed by type II (6.7%) and III (3.4%), while 5.6% of the specimens presented lateral canals and 1.1% had an apical delta. Mean volume and surface area were 31.80mm³ and 90.58mm², respectively. The most prevalent shape of the root canal at CEJ level was circular (41.6%) and 1mm from the apex, 73% of the samples were classified as oval. Lower incisors with internal anatomical variations may offer a high degree of technical complexity and may result in treatment failure.

An endodontic material must be minimally harmful to stem cells since they are essential, thanks to their capacity for cell proliferation, self-renewal, and differentiation. For this reason, in this in vitro study, the cell viability and the expression of genes involved in cell plasticity and differentiation were investigated in stem cells recovered from human dental pulp (hDPSCs) that were in contact with four endodontic materials (Endofill, MTA, Pulp Canal Sealer, and Sealer 26). The viability of HDPSCs was assessed by MTT and trypan blue exclusion assays. PCR evaluated cellular plasticity by determining the CD34, CD45, Nestin, CD105, Nanog, and OCT4 expressions. The effect on cell differentiation was determined by RT-PCR expression of the RUNX2, ALP, OC/BGLAP, and DMP1 genes. The data were analyzed using ANOVA with Bonferroni correction (p <0.05). Pulp Canal Sealer and Endofill decreased cell viability after 48 hours (p <0.001). MTA and Sealer 26 did not disrupt cell viability (p> 0.05). When cultivated in the presence of MTA and Sealer 26, hDPSCs expressed Nestin, CD105, NANOG, and OCT-4 and did not express CD34 and CD45. MTA and Sealer 26 interfered with DMP1, OC/BGLAP and RUNX2 expressions (p <0.05) but did not change ALP gene expression (p> 0.05). MTA and Sealer 26 showed biological compatibility in the presence of hDPSCs.

Dens in dente is a developmental anomaly characterized by dental tissues invagination that varies from a slight increase of the cingulum´s fossa to a deep groove that can extend up to the dental apex. Objectives The aim of this study was to report a dens in dente endodontic retreatment case with the presence of fistula and periapical lesion. Case report: Non-surgical retreatment was performed from the removal of the filling endodontic material, use of Calcium Hydroxide as intracanal medication changed every two months for a one year and a half period, and later, apical closure with MTA and endodontic filling of the remaining thirds with thermoplastic gutta-percha. Results: Postoperative follow-ups were performed for a 4 years period where a reduction of the periapical lesion diameter and disappearance of the fistula were observed. Conclusion: These results demonstrate that the present non-surgical dens in dente endodontic retreatment protocol could be considered a viable option for success.

Objective: In this study, the effects of the low intensity laser were evaluated in the proliferation of human dental pulp stem cells (DPSCs). Design: These cells were irradiated every 12 hours for 72 hours or at 0 and 48 hours only, with a Red-InGaAlP laser (660nm, 30mW and 0.5 or 1J/cm 2) for 16 or 33 seconds and their proliferation was assessed by the MTT assay. In addition, the Trypan Blue assay was used to analyze the viability of DPSCs in the best parameter recorded by MTT. Results: It was observed that the lowest dose of the laser (0.5J/cm 2) in applications at 0 and 48 hours obtained the higher proliferation rates then all the other groups. Finally, through the Trypan Blue assay, we observed that the viability of the stem cells was not affected by the low intensity laser (0.5J/cm 2). Conclusions: Our data corroborate with other data from the literature and therefore suggest that the low intensity laser can be used in order to improve cell proliferation. However, further studies should be carried out in order to evaluate if these parameters can be used in other cell lines.