Effects of low power red laser on induced-dental caries in rats.

OBJECTIVE: The purpose of this study was to investigate the effects of low power red laser associated with acidulated phosphate fluoride on the development of induced-dental caries in rats. DESIGN: Dental caries were induced in molars of 40 rats divided into five groups: control group (CG), the teeth were not submitted to any treatment; laser group (LG), teeth were irradiated with a low power red laser (LPRL), power of 30 mW and dose of 5 J/cm(2); fluoride group (FG), teeth were treated with topical acidulated phosphate fluoride (APF) 1.23% applied for 4 min; laser+fluoride group (LFG), teeth were irradiated with LPRL followed by APF; fluoride+laser group (FLG), teeth were treated with APF followed by LPRL. The animals were killed after 48 days, and the first and second molars were extracted to analyze the caries lesion area, microhardness, and calcium and phosphorus ratio. RESULTS: There were no statistical differences among FG, LFG, and FLG regarding to caries area and microhardness, although the caries area were smaller in LFG. Ca/P ratio did not show significant differences among all groups. CONCLUSIONS: Although LPRL before APF application appeared to diminish the caries progression, LPRL did not present any additional benefit compared with acidulated phosphate fluoride on the prevention of induced-dental caries in rats.

Influence of aging treatments on microtensile bond strength of adhesive systems to primary dentin.

PURPOSE: The purpose of this study was to evaluate the in vitro influence of aging treatments on the microtensile bond strength of 2-step total-etch and self-etch adhesive systems to primary dentin. METHODS: Class I cavities (4 mm x 4 mm x 2 mm) were prepared in 80 extracted human primary molars divided into 8 groups (N=5) per adhesive system: (1) Single Bond (SI); and (2) Clearfil SE Bond (SE). Restored teeth were exposed to individual and combined aging treatments: (1) thermal (2,000 x at 5-55 degrees C; T); (2) mechanical load (100,000 x 80 N; M); (3) pH (mineralizing/demineralizing solutions; pH); and (4) control (24-hour water storage; C). Beam-shaped microtensile specimens were prepared (0.8 mm2 cross-sectional area) and loaded at a crosshead speed of 1.0 mm/minute in a universal testing machine. Fracture modes were examined by scanning electron microscope. RESULTS: Means (MPa) and standard deviations (+/-) were: (1) SI-T=24.17 (+/-1.99); (2) SI-M=25.64 (+/-9.75); (3) Si-pH=23.43 (+/-4.19); (4) SI-C=33.81 (+/-2.45); (5) SI-TM=18.60 (+/-3.57); (6) SI-TpH=23.90 (+/-4.28); (7) SI-MpH=20.96 (+/-4.06); (8) SI-TMpH=20.94 (+/-3.15); (9) SE-T=24.08 (+/-4.52); (10) SE-M=18.30 (+/-14.12); (11) SE-pH=19.22 (+/-8.93); (12) SE-C=37.80 (+/-7.28); (13) SE-TM=22.89 (+/-11.74); (14) SE-TpH=27.87 (+/-12.77); (15) SE-MpH=18.87 (+/-10.95); and (16) SE-TMpH=22.55 (+/-3.05). Both adhesive systems presented similar dentin bond strength (P>.05) which were significantly reduced when combined aging treatments were applied or when pH cycling (pH) was done. CONCLUSION(S): Combined aging treatments and also pH cycling alone influenced negatively adhesive bond strengths.

Effect of cut-off points on performance of laser fluorescence for detecting occlusal caries.

This in vitro study aimed to evaluate the influence of cut-off points on the performance of laser fluorescence (LF) in detecting occlusal caries in permanent and primary teeth. The use of different cut-off points influenced the performance of LF device in detection of occlusal caries in both kind of teeth, but the performance in permanent teeth suffered more influence from variation of cut-off points scales than in primary group.