The Influence of 980 and 940 nm Diode Laser-Activated Hydrogen Peroxide Bleaching on Microleakage in Class V Resin Composite Restorations.

OBJECTIVE

To evaluate the effect of hydrogen peroxide bleaching, activated by 980 and 940 nm diode lasers, on the interfacial micropermeability of Class V resin composite restorations.

METHODOLOGY

60 extracted, mandibular premolars with a single root were selected and subjected to bleaching using Opalescence Boost, a 40% hydrogen peroxide gel. An even application of bleaching gel, measuring 1 mm in thickness, was administered to the buccal aspect of the tooth surface of each specimen and allowed to remain undisturbed for 20 min, after which it was removed via suction. Specimens were then randomly allocated into three distinct experimental cohorts (n = 20 per cohort): Group I (control) underwent conventional bleaching with 40% hydrogen peroxide; Group II received bleaching activated by a 980 nm diode laser; Group III by a 940 nm diode laser. Ten days postbleaching, standardized Class V cavities were precisely prepared on the buccal surfaces of the teeth using a high-speed handpiece equipped with a diamond fissure bur under continuous water cooling, incorporating a 45° enamel margin bevel. All prepared cavities were subsequently restored using a resin composite material. Quantitative assessment of microleakage at the occlusal and gingival interfaces was conducted through stereomicroscopic examination and scored using the criteria established by Khoroushi et al.

RESULTS

Groups II and III demonstrated comparatively lower interfacial microleakage occurring along the occlusal and gingival restorative margins relative to Group I. Although Group III exhibited minimal microleakage among all groups, comparative analysis indicated no appreciable difference between Group II and Group III based on the observed data.

CONCLUSION

Within the scope and boundaries of the present study, it may be inferred that tooth bleaching employing 40% hydrogen peroxide resulted in the greatest microleakage along the occlusal and gingival interfaces, whereas diode laser-activated bleaching at 940 and 980 nm yielded significantly lower microleakage. Comparative analysis indicated no appreciable difference between Groups II and III.