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Background: Knowing the shape of the root and the root canal system is essential for the success of the surgical and non-surgical treatment of the root canal, however; it is difficult to judge root and root canal anatomy from two-dimensional radiographs . The aim of this study is to investigate correlation between root morphology of the mandibular second molars in panoramic view and the root type of these teeth based on Cone Beam Computed Tomography (CBCT) images. Methods: In this study, 1231 CBCT scans of the second mandible molars were selected from archives of a private radiology clinic from October 2018 to March 2021, and panoramic images reconstructed from CBCT images. The root morphology of the second mandible molar was classified on panoramic image in type 1,2,3,4,5. Root pattern in cross-section of CBCT image was classified into three types of single, double and c-shape.Correlation between root morphology in panoramic image and CBCT was analyzed with Chi-Square test and significance level was 0.05. Results: 62.7% of the second mandibular molars were type1, 97.3% of them had double pattern in cross-section of CBCT.28.6% of the samples were type2, which showed 92.6% double pattern. 3.9% of them were type3, 47.9% had c-shape pattern.0.9% of them were type4, 45.5% of them showed single pattern.3.8% of teeth were type5, 76.6% had single pattern. The prevalence of c-shape canals was higher in women and most c-shape canals showed C3 pattern. Conclusion: There was a strong correlation between the root morphology in panoramic image and root canal pattern in the axial section of the CBCT images. According to this study, if the second mandibular molar has a type3 morphology in the panoramic image, it may have a c-shape canal with a high probability.

Background This study aimed to assess the effect of irradiation of light-emitting diode (LED) and low-level diode laser on osteogenic/odontogenic differentiation of stem cells from the apical papilla (SCAPs). Materials and Methods SCAPs were isolated from the human tooth root. The experimental groups were subjected to 2–4 J/cm2 diode laser and LED irradiation in osteogenic medium. The control group did not receive any irradiation. Cell proliferation was assessed by the methyl thiazolyl tetrazolium (MTT) assay. Osteogenic differentiation was evaluated by alizarin red staining (ARS), and expression of osteogenic genes by real-time polymerase chain reaction (RT-PCR). Results The MTT assay showed no significant difference in cell viability/proliferation of SCAPs in the laser, LED, and control groups at 24 or 48 hours (P 2 energy density and LED can cause osteogenic differentiation and proliferation of SCAPs. Further studies are required to assess the mechanism of effect of diode laser and LED.

Background: This study assessed the effect of Biodentine coated with Emdogain (Biodentine/Emdogain) on proliferation and differentiation of stem cells from the apical papilla (SCAP). Methods and Results: In this in vitro, experimental study, SCAP were isolated from two immature impacted third molars and cultured. After ensuring the stemness of the cells by assessing their cell surface markers, they were exposed to Biodentine, Emdogain, and Biodentine/Emdogain for 24 and 72 hours. The control cells did not receive any intervention. Cell viability was evaluated by the methyl thiazolyl tetrazolium (MTT) assay. Expression of odontogenic differentiation genes was analyzed by the quantitative reverse transcription polymerase chain reaction (qRT-PCR). Alkaline phosphatase (ALP) activity was quantified by the respective kit. Data were analyzed by one-way ANOVA, t-test, and Mann-Whitney test (α=0.05). Cell viability did not change after 24 hours of exposure to biomaterials. At 72 hours, the viability of the cells exposed to Biodentine and Biodentine/Emdogain decreased compared with the control group. The expression of dentin sialophosphoprotein (DSPP), dentin matrix protein 1 (DMP1), and bone sialoprotein (BSP) genes, and ALP activity significantly increased in all three experimental groups, compared with the control group at both 24 and 72 hours; this increase was significantly greater in Biodentine/Emdogain group. The number of mineralized nodules significantly increased in all groups after 72 hours with a greater rate in Biodentine/Emdogain group.Conclusions: All biomaterials increased the differentiation of SCAP, expression of odontogenic genes, and ALP activity, but Biodentine/Emdogain was significantly more effective for this purpose.

Objective: This study sought to assess the effect of cryogenic treatment on cyclic fatigue of Neoniti and Reciproc nickel-titanium (NiTi) rotary files. This in vitro, experimental study was performed on 48 Neoniti and Reciproc NiTi rotary files (#25, 6% taper) in two subgroups with and without cryogenic treatment. The files in cryogenic subgroups were stored in liquid nitrogen chamber at -196°C for 24 h. Next, they were placed at room temperature (25°C) to gradually warm up. Stainless steel (SS) blocks were used to standardize the degree of rotation of the files. The SS blocks simulated a root canal with the negative pattern of gutta-percha with 0.08 taper, #25 tip size, and 45° canal curvature. Each endodontic file was rotated in this canal until fracture. The time until fracture was recorded by a digital chronometer. Time to fracture was used to calculate the number of rotations before file fracture as the cyclic fatigue scale. Results: The mean cyclic fatigue resistance of both Neoniti and Reciproc rotary files in cryogenic subgroups was significantly higher than that in non-cryogenic control subgroups (P