Shear bond strength of different types of adhesive systems to dentin and enamel of deciduous teeth in vitro.

OBJECTIVES: The present study aimed to evaluate the suitability of self-etch adhesives for restoration of deciduous teeth compared with etch and rinse approaches. MATERIALS AND METHODS: One hundred twenty primary teeth were divided into five groups, each being assigned to an adhesive system. Self-etch adhesives XenoV (XV) and Clearfil S(3) Bond (CB), Prime&Bond NT with (PBE)/without preliminary etching (PBN), and Optibond FL (OBFL) as an etch and rinse system were included. Enamel and dentin specimens were prepared (n = 36/group), adhesives applied, and compomer cylinders polymerized. After 24-h storage in 37 °C distilled water and thermo-cycling (1440 cycles, 5/55 °C, 27 s), shear bond tests and fracture mode classification based on SEM investigation were performed. Statistical analysis involved ANOVA and Scheffé procedure with Bonferroni-Holm correction (p ≤ 0.005). RESULTS: High shear bond strengths to primary enamel were determined for PBE (mean [M] = 22.48 ± 7.7 MPa) > OBFL (M = 19.06 ± 5.62 MPa) > CB (M = 17.6 ± 6.55 MPa), and XV (M = 16.85 ± 5.38 MPa) and PBN (M = 8.26 ± 4.46 MPa) formed significantly less reliable enamel-resin interfaces (p ≤ 0.005). PBE generated the highest bond strength on primary dentin (M = 21.97 ± 8.02 MPa); significantly lower values were measured for XV (M = 13.44 ± 5.43 MPa) and OBFL (M = 12.92 ± 4.31 MPa) (p ≤ 0.005). CONCLUSIONS: Adhesives requiring preliminary etching ensure optimal bond strength to primary enamel. If separate etching is to be avoided, selected self-etch adhesives obtain acceptable shear bond values on primary enamel and dentin. CLINICAL RELEVANCE: The treatment of pediatric patients presents a great challenge in dental practice, and optimization of treatment processes is important.

Effect of safflower oil on the protective properties of the in situ formed salivary pellicle.

AIM: The prevalence of dental erosion is still increasing. A possible preventive approach might be rinsing with edible oils to improve the protective properties of the pellicle layer. This was tested in the present in situ study using safflower oil. METHODS: Pellicle formation was carried out in situ on bovine enamel slabs fixed buccally to individual upper jaw splints (6 subjects). After 1 min of pellicle formation subjects rinsed with safflower oil for 10 min, subsequently the samples were exposed in the oral cavity for another 19 min. Enamel slabs without oral exposure and slabs exposed to the oral cavity for 30 min without any rinse served as controls. After pellicle formation in situ, slabs were incubated in HCl (pH 2; 2.3; 3) for 120 s, and kinetics of calcium and phosphate release were measured photometrically (arsenazo III, malachite green). Furthermore, the ultrastructure of the pellicles was evaluated by transmission electron microscopy (TEM). RESULTS: Pellicle alone reduced erosive calcium and phosphate release significantly at all pH values. Pellicle modification by safflower oil resulted in an enhanced calcium loss at all pH values and caused an enhanced phosphate loss at pH 2.3. TEM indicated scattered accumulation of lipid micelles and irregular vesicle-like structures attached to the oil-treated pellicle layer. Acid etching affected the ultrastructure of the pellicle irrespective of oil rinsing. CONCLUSION: The protective properties of the pellicle layer against extensive erosive attacks are limited and mainly determined by pH. The protective effects are modified and reduced by rinses with safflower oil.