Influence of laser-activated irrigation protocols on smear layer removal and fiber post bond strength

OBJECTIVES: To evaluate whether laser-activated irrigation applied during root canal preparation and/or post space preparation influences smear layer removal and fiber post push-out bond strength. METHODS: One hundred fourteen single-rooted teeth were allocated to syringe needle irrigation (SNI) or activation protocols including passive ultrasonic irrigation (PUI), photon-induced photoacoustic streaming, micro-short pulse, and shockwave-enhanced emission photoacoustic streaming (SWEEPS) during root canal preparation. In selected groups, activation was additionally performed during post space preparation. Smear layer removal was assessed using scanning electron microscopy, and fiber post push-out bond strength was measured. RESULTS: All laser activation protocols significantly improved smear layer removal compared with SNI (p < 0.05), with SWEEPS demonstrating the most consistent cleanliness, particularly in the apical third. Laser activation during root canal preparation significantly increased push-out bond strength relative to SNI (p < 0.05). SWEEPS achieved the highest bond strength values overall and showed no significant difference between single-stage and dual-stage activation (p > 0.05). PUI demonstrated improved bonding only when activation was performed during both root canal and post space preparation. CONCLUSION: Laser-activated irrigation enhances dentin surface cleanliness and fiber post retention. SWEEPS applied during root canal preparation alone may provide sufficient substrate optimization for subsequent bonding. CLINICAL RELEVANCE: Optimizing laser activation timing may simplify clinical protocols while maintaining improved post retention.