IADR Abstract Archives
Nd:YAG Laser Irradiation Favors Medium-Term Bond-Strength to Simulated Hypersensitive Dentin
Objectives: Non- or minimally invasive desensitizing strategies are usually applied before restorations are indicated for treating hypersensitive dentin; hence they may influence, perhaps lengthwise, behavior of the established adhesive interface. Immediate and medium-term bond strength (BS) of an adhesive plus a composite to simulated hypersensitive dentin, compared to normal dentin, in function of previous treatment with Nd:YAG laser, was evaluated.
Methods: Superficial occlusal dentin of third-molars (n=28) was submitted to a 600-grit SiC paper (1min) and to a challenge with citric acid (6%, 1min; H:simulated hypersensitive dentin/n=14), or not (N:normal dentin/n=14). Then, it was irradiated with Nd:YAG laser (L: laser; 1.0W/10Hz/100mJ/4 irradiations of 50-60s; HL/n=7, NL/n=7), or was not (C:control, HC/n=7, NC/n=7). Clearfil-SE-Bond was applied and composite buildups were constructed (Filtek Z350). After 24h (distilled water/37oC), specimens were sectioned in beams, which were tested (µTBS; 0.5mm/min) immediately (I) or after 6-months aging (6m). An extra tooth for each group was treated exactly as the others, but rhodamine-B was previously added (0.02mg/mL) to Clearfil-SE-Bond to allow a qualitative evaluation of the adhesive interface by Confocal Microscopy. BS data were analyzed by three-way ANOVA and Tukey test (α=0.05).
Results: Mean BS values (MPa±sd; I/6m) were: NL(33.86±10.36Aa†/25.87±8.04Aa‡), NC(27.84±5.01Aa†/19.88±5.03Aa‡), HL(60.28±9.66Ab†/52.85±8.83Ab‡), HC(37.09±9.27Bb†/37.09±9.27Bb‡). All factors under study significantly influenced results (p<0.001 for substrate and irradiation, and p=0.002 for aging) and there was an interaction between substrate and irradiation (p<0.001). Laser irradiation favored, either immediately or after 6 months, BS only to hypersensitive dentin. BS to this substrate was shown to be always higher than that to the normal substrate, and immediate BS, to any of the substrates, always higher than that after aging for 6 months.
Conclusions: Previous treatment of hypersensitive dentin with Nd:YAG laser irradiation may favor, even in the course of time, the establishment of adhesive interfaces in this substrate.
Methods: Superficial occlusal dentin of third-molars (n=28) was submitted to a 600-grit SiC paper (1min) and to a challenge with citric acid (6%, 1min; H:simulated hypersensitive dentin/n=14), or not (N:normal dentin/n=14). Then, it was irradiated with Nd:YAG laser (L: laser; 1.0W/10Hz/100mJ/4 irradiations of 50-60s; HL/n=7, NL/n=7), or was not (C:control, HC/n=7, NC/n=7). Clearfil-SE-Bond was applied and composite buildups were constructed (Filtek Z350). After 24h (distilled water/37oC), specimens were sectioned in beams, which were tested (µTBS; 0.5mm/min) immediately (I) or after 6-months aging (6m). An extra tooth for each group was treated exactly as the others, but rhodamine-B was previously added (0.02mg/mL) to Clearfil-SE-Bond to allow a qualitative evaluation of the adhesive interface by Confocal Microscopy. BS data were analyzed by three-way ANOVA and Tukey test (α=0.05).
Results: Mean BS values (MPa±sd; I/6m) were: NL(33.86±10.36Aa†/25.87±8.04Aa‡), NC(27.84±5.01Aa†/19.88±5.03Aa‡), HL(60.28±9.66Ab†/52.85±8.83Ab‡), HC(37.09±9.27Bb†/37.09±9.27Bb‡). All factors under study significantly influenced results (p<0.001 for substrate and irradiation, and p=0.002 for aging) and there was an interaction between substrate and irradiation (p<0.001). Laser irradiation favored, either immediately or after 6 months, BS only to hypersensitive dentin. BS to this substrate was shown to be always higher than that to the normal substrate, and immediate BS, to any of the substrates, always higher than that after aging for 6 months.
Conclusions: Previous treatment of hypersensitive dentin with Nd:YAG laser irradiation may favor, even in the course of time, the establishment of adhesive interfaces in this substrate.