This study aimed to determine the effect of photobiomodulation therapy induced by semiconductor laser irradiation on human dental pulp stem cell (hDPSC) proliferation and their differentiation into odontoblast-like cells (OLCs). The effects of various semiconductor laser irradiation conditions on hDPSCs were examined. Three groups were evaluated: a single laser irradiation at 6 h post-seeding, multiple laser irradiations up to four times every 4 days after the first dose, and a control with no laser irradiation. The cells were irradiated at 10, 30, and 150 mW using a semiconductor laser. The effect of laser irradiation on hDPSC differentiation into OLCs was also determined. Four groups were evaluated, including co-culture using basic medium and dentin discs, simple culture using OLC differentiation-inducing medium, co-culture using OLC differentiation-inducing medium and dentin discs, and control culture with basic medium. The expression of the nestin, ALP, DSPP, and DMP-1 genes was measured using real-time PCR. The multiple irradiation group irradiated at 30 mW exhibited significantly more cell proliferation than the control. The expression of nestin associated with differentiation into OLCs during each culture period tended to be lower, whereas DSPP and ALP expression was higher compared with that of the control. Multiple laser irradiations at a low power of 30 mW induced significant hDPSC proliferation and might induce differentiation into OLCs.

Background/Objectives: Dental fear and anxiety can arise from dental procedures, sensory stimuli, environmental factors, and interpersonal factors. This study investigated dental treatment-related fear and differences between professionals’ estimates for patients in general and patients’ self-reports. Methods: This single-center, cross-sectional study included 219 participants: 53 dentists, 65 dental hygienists, and 101 patients. Fear intensity was assessed using a 0–100 visual analog scale. Dental professionals estimated fear in patients in general, whereas patients rated their own fear; assessments were unpaired. Ratings for 13 dental procedures were compared across the three groups. Fear ratings for six dental-related factors were also compared within patients. Results: Before Holm adjustment, 6 of the 13 procedures showed significant between-group differences; 3 remained significant after adjustment: injection in the hand, intraoral injection, and scaling. The largest effect size was observed for injection in the hand, with median fear scores of 69, 74, and 21 for dentists, dental hygienists, and patients, respectively (p < 0.001, ε² = 0.254). Within patient ratings, fear ratings differed significantly across the six factors (p < 0.001, Kendall’s W = 0.25). Fear ratings for dental treatment and dental sounds were higher than those for the dentist, dental odors, the dental clinic, and sitting in the dental chair, with no significant difference between treatment and sounds. Conclusions: Group-level differences between professionals’ estimates and patients’ self-reports were procedure-specific and cannot establish individual-level estimation accuracy. Direct assessment of patients’ fear of specific procedures and sensory stimuli may improve understanding of dental treatment-related fear.