Histological evaluation of pulpal healing following direct pulp capping with polytetrafluoroethylene or melatonin, with or without adjunctive low-level laser therapy in Wistar rat molars

This study evaluated pulpal healing following direct pulp capping with polytetrafluoroethylene (PTFE) or melatonin (MEL), with or without adjunctive low-level laser therapy (LLLT), in Wistar rat molars. Fifty-two maxillary first molars from 26 male Wistar rats were included. Forty-eight molars with standardized pulp exposures were randomly allocated to four groups ( n = 12): Group I, PTFE; Group II, MEL; Group III, PTFE + LLLT; and Group IV, MEL + LLLT; four unexposed molars served as negative controls. LLLT (650 nm, 100 mW; fluence 11.9 J/cm 2 ) was applied after placement of the capping material. Irradiation was performed on alternate days, with animals receiving either three sessions (1-week group) or six sessions (2- and 4-week groups). Histological evaluation was performed after 1, 2, and 4 weeks, assessing inflammation, necrosis, vascularity, fibrosis, odontoblast-like layer organization, dentin bridge formation, and dentin bridge thickness. LLLT-treated groups showed reduced inflammation, improved odontoblast-like layer organization, enhanced vascularity, and greater dentin bridge thickness compared with non-irradiated groups. The MEL + LLLT group demonstrated the most favorable overall histological profile. Adjunctive LLLT was associated with improved pulpal healing outcomes, while melatonin showed supportive effects on the pulpal microenvironment. Their combined application produced the most favorable histological outcomes and warrants further investigation in vital pulp therapy.