Background: This experimental study aimed to assess the effect of irradiation of red light-emitting diode (LED) and Diode low-level laser (LLL) 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 4 J/cm² diode low level laser and red LED irradiation in osteogenic medium. The control group did not receive any irradiation. Cell viability/proliferation of SCAPs was assessed by the methyl thiazolyl tetrazolium (MTT) assay on days 1 and 2 (n = 9). Osteogenic differentiation was evaluated by alizarin red staining (ARS) (n = 3), and expression of osteogenic genes by real-time polymerase chain reaction (RT-PCR) (n = 12) on days 1 and 2. SPSS version 18 was used for data evaluation. The Kruskal-Wallis and Mann-Whitney tests were used to compare the groups at each time point. Results: The MTT assay showed no significant difference in cell viability/proliferation of SCAPs in the low level laser, red LED, and control groups at 24 or 48 h (P < 0.001). The ARS assessment showed that low level laser and red LED irradiation enhanced osteogenic differentiation of SCAPs. low level laser and red LED irradiation both induced over-expression of osteogenic/dentinogenic genes including alkaline phosphatase (ALP), dentin sialophosphoprotein (DSPP), dentin matrix protein 1 (DMP-1), and bone sialoprotein (BSP) in SCAPs. Up-regulation of genes was significantly greater in low level laser irradiation group than red LED group (P < 0.001). Conclusion: Diode low level laser irradiation with 4 J/cm² energy density and red LED irradiation enhanced osteogenic differentiation of SCAPs without adversely affecting cell viability.

Background: Prediction of skeletal growth is necessary for growth modification and surgical orthodontic treatments and is usually done by assessing skeletal maturity indicators in hand-wrist radiographs. The use of growth stages of cervical vertebrae in lateral cephalograms has been suggested to avoid overexposure. Objectives: This study seeks to assess the degree of agreement between hand-wrist and cervical vertebrae maturation stages for skeletal age determination and prediction of the peak growth spurt (PGS). Patients and Methods: This cross-sectional study was conducted with 67 boys and 66 girls between 8 and 18 years of age, divided into 11 age groups; 266 hand-wrist radiographs and lateral cephalograms were obtained and analyzed. Hand-wrist maturation stages were evaluated according to the Grave and Brown, Bjork system (stages 1 - 9). The cervical vertebral maturation stage (CVMS) was determined on lateral cephalograms based on a system described by Baccetti et al. (CVMS 1-5). To apply the Cohen’s kappa index, the stages of growth were reduced to 5 intervals (A - E) to relate the 5 CVMS to the 9 stages of Bjork hand-wrist analysis. Results: In all age groups, the skeletal maturity stages of the hand and wrist bones and the cervical vertebrae of the girls were ahead of the boys. Cohen’s kappa test revealed a low level of agreement between the two methods [Kappa (95% CI) = 0.312 (0.290 - 0.377)]; concordance was slightly higher in males (K = 0.33 for males versus 0.27 for females). Evaluation of concordance coefficients between the stages determined by the two methods indicated the highest concordance in 8- and 9-year-olds and the lowest in 12- and 14-year-olds. The level of agreement between the two methods was only acceptable in 8- and 9-year-olds of both genders and 10-year-old boys. The level of agreement between the two methods in other age groups was not acceptable. Conclusion: The level of agreement between the two methods was low; thus, they cannot be used alternatively to estimate patients’ skeletal age or to predict the PGS. This may be due to the effect of different maturation levels (influenced by the environment, ethnicity, and gender) on the agreement between methods for skeletal age determination. Keywords: Growth; Hand; Wrist; Cervical Vertebrae; Skeletal Age

Background: This study aimed to assess the root canal morphology of primary molars using cone-beam computed tomography (CBCT). Methods: This cross-sectional study evaluated 60 maxillary and mandibular primary first and second molars on CBCT scans of patients retrieved from the archives of Hamadan School of Dentistry between 2018-2020. The teeth were evaluated regarding the number of roots and canals, canal type according to the Vertucci’s classification, and root surface concavities. Data were analyzed descriptively and by independent t-test. Results: The most frequent number of canals and roots in the maxillary right and left first molars was 3 canals (60%) and 3 roots (80%). These values were 4 canals (80%) and 5 canals (50%) with 3 roots in the maxillary right and left second molars, respectively, 4 canals (100%) and 2 roots (50%), and 3 canals (60%) and 2 roots (50%) in mandibular right and left first molars, respectively, and 4 canals (92.3%) and 3 roots (61.5%) in mandibular right and left second molars. Vertucci’s type IV was the most common canal type in mesial and distal canals, type I was the most common in mesiobuccal, mesiolingual, distobuccal, and distolingual, and types I and II were the most common in the palatal canal. The maximum and minimum concavities were noted in the buccal (26.7%) and mesial (8.3%) surfaces, respectively. Conclusions: A wide variation exists in the number of roots and canals of maxillary and mandibular primary molars, which calls for further attention in treatment of such teeth.

Background Zinc oxide nanoparticles (ZnONPs) have shown potential in regenerative medicine, particularly when combined with light-emitting diode (LED) radiation. This study aimed to explore the effects of ZnONPs combined with LED radiation on human stem cells derived from the apical papilla (HSCAPs), focusing on primary outcomes of cell viability, odontoblast-like differentiation, and mineralization. Methods This in vitro experimental study utilized ZnONPs synthesized via a green method using pomegranate peel extract. HSCAPs were divided into four groups: control, ZnONPs-only, LED-only, and ZnONPs + LED (experimental group). Cell viability, a primary outcome, was assessed using the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay at 24 h. Odontogenic and osteogenic differentiation, evaluated through dentin sialophosphoprotein (DSPP), bone sialoprotein (BSP), alkaline phosphatase (ALP), and dentin matrix acidic phosphoprotein 1 (DMP1) gene expression using qRT-PCR, were assessed on day 7. Mineralization, determined through Alizarin Red S staining, was measured on day 14. The doses used were 1 μg/mL ZnONPs and 620–640 nm range, 85% total emission LED radiation at 5 mW/cm² for 30 s, the energy density would be 6 Joules/cm². Statistical analyses were performed using Kruskal–Wallis and dunn’s post hoc tests. (P < 0.05). Results Cell viability was highest at 1 μg/mL ZnONPs, comparable to control (p > 0.05), and decreased at higher concentrations (p < 0.05). Odontogenic and osteogenic gene expression, including DSPP, ALP, BSP and DMP1was significantly upregulated (p < 0.05) in the ZnONPs + LED group compared to all other groups. Alizarin Red S staining revealed the densest mineralization in the ZnONPs + LED group, followed by LED-only and ZnONPs-only groups. Conclusion The synergistic application of ZnONPs and LED irradiation significantly enhanced odontogenic and osteogenic differentiation and mineralization of HSCAPs, suggesting their potential utility in endodontic regenerative therapies.