Effect of diode laser irradiation (780-980 nm) on resin-dentin microtensile bond strength: a systematic review of in vitro studies.

BACKGROUND: The intricate structural makeup of dentin and the hybrid layer's vulnerability to deterioration make it difficult to achieve long-lasting resin-dentin bonding. One technique for dentin biomodification that may enhance adhesive performance is diode laser irradiation. OBJECTIVE: This systematic review aimed to evaluate the effect of diode laser irradiation (780-980 nm) on the microtensile bond strength (µTBS) of resin-dentin interfaces across in vitro studies. METHODS: Following PRISMA 2020 guidelines and an OSF-registered protocol (OSF Registration ID: QJ6S8), an electronic search was conducted in PubMed, Scopus and Web of science for studies published between 2015 and 2025. In vitro studies using diode lasers (780-980 nm) on human dentin with µTBS outcomes were included. Risk of bias was assessed using the Quality Assessment Tool for in vitro studies tool. RESULTS: Five in vitro studies met the inclusion criteria. Three studies reported statistically significant improvements in µTBS following diode laser pretreatment (range: approximately 30%-100% increase over controls), attributed to laser-induced collagen modification, reduced dentinal permeability, and enhanced resin infiltration. Two studies reported no statistically significant benefit, with suboptimal irradiation parameters identified as the likely contributing factor. Heterogeneity in irradiation protocols precluded meta-analysis. CONCLUSION: Diode laser irradiation at optimised parameters (940-970 nm, ≥1 W continuous mode) demonstrates a tendency to improve resin-dentin µTBS in vitro. However, the limited number of eligible studies, parameter heterogeneity, and absence of long-term clinical evidence preclude definitive clinical recommendations. Standardised protocols and controlled clinical trials are warranted. SYSTEMATIC REVIEW REGISTRATION: https://doi.org/10.17605/OSF.IO/QJ6S8, QJ6S8.