SUMMARY: Objectives: To evaluate the effect of application protocol in resin–enamel microshear bond strength (μSBS), in situ degree of conversion, and etching pattern of three universal adhesive systems. Methods and Materials: Sixty-three extracted third molars were sectioned in four parts (buccal, lingual, and proximals) and divided into nine groups, according to the combination of the main factors—Adhesive (Clearfil Universal, Kuraray Noritake Dental Inc, Tokyo, Japan; Futurabond U, VOCO, Cuxhaven, Germany; and Scotchbond Universal Adhesive, 3M ESPE, St Paul, MN, USA)—and enamel treatment/application time (etch-and-rinse mode [ER], self-etch [SE] application for 20 seconds [SE20], and SE application for 40 seconds [SE40]). Specimens were stored in water (37°C/24 h) and tested at 1.0 mm/min (μSBS). The degree of conversion of the adhesives at the resin–enamel interfaces was evaluated using micro-Raman spectroscopy. The enamel-etching pattern was evaluated under a scanning electron microscope. Data were analyzed with two-way analysis of variance and Tukey test (α=0.05). Results: In general, the application of the universal adhesives in the SE40 produced μSBS and degree of conversion that were higher than in the SE20 (p<0.01) and similar to the ER mode. The deepest enamel-etching pattern was obtained in the ER mode, followed by the SE40. Conclusions: The active and prolonged application of universal adhesives in the SE mode may be a viable alternative to increase the degree of conversion, etching pattern, and resin–enamel bond strength.

Objectives: The purpose of this study was to evaluate the effect of the pre-conditioning step using different dentin conditioners on the shear bond strength (SBS) of the nano-filled resin-modified glass ionomer (RMGI) to dentin. Methods: Twenty-four human molars were used in this study. Subsequent to teeth sectioning in the mesio-distal direction and creation of the smear layer, the teeth were divided into six groups with and without the pre-conditioning step. Dentin surfaces were restored with RMGI cylinders and the specimens were stored in distilled water at 37ºC for 24 hours. SBS test were performed using a Universal Testing Machine at a crosshead speed of 0.5 mm/minute. Statistical analysis was performed using One-Way ANOVA followed by Duncan’s Multiple Range Test. RMGI/dentin interface was evaluated using SEM operated at 12 Kv at 2000X magnification. Results: 35% phosphoric acid and EDTA yielded significantly higher SBS (12.0±1.8 and 11.9±4.4 MPa, respectively), compared to all tested groups. In addition, 25% polyacrylic acid (8.6±3.1 MPa) reported significantly higher SBS than the nano-filled RMGI when applied according to manufacturer instructions (5.5±2.2 MPa). When nano-filled RMGI was applied without its nano-primer, or directly over 25% polyacrylic acid conditioned dentin exhibited 100% pre-test failure, and their SBS were expressed as 0.0±0.0 MPa. SEM revealed that the nano-primer was unable to decalcify and hybridize the dentin surface. Conclusions: Based on the results of the current study, the pre-conditioning step effectively improves the SBS of nano-filled RMGI to dentin. The self-adhesiveness of nano-filled RMGI was not proved in this study. (Eur J Dent 2011;5:150-156)

Objectives: The aim of this study was to evaluate the outcome of immediate or delayed bonding of a single-step self-etch adhesive to coronal dentin after the application of different endodontic irrigants.Methods: Thirty five human molars were used. The coronal dentin was irrigated with either 0.9% physiologic saline (NS), 2% Chlorhexidine gluconate (CHX) or 2.5% commercially used sodium hypochlorite (NaOCl). Compositecylinders were bonded with the coronal dentin using the Clearfil S3 bond, which was applied either immediatelyor after one week storage time following the irrigation procedures. Shear bond strength testing was performed at a cross-head speed of 0.5 mm/min, and the resin/dentin interface was evaluated using SEM.Results: Irrigation with NS, CHX, or NaOCL followed by immediate adhesive application resulted in a reduction in the shear bond strength values recorded and this was statistically significant in comparison with the control group (P<.05). However, delaying the adhesive application resulted in a statistically significant (P<.05) improvement in the shear bond strength recorded in specimens irrigated with NS and CHX only.Conclusions: Delaying the bonding procedures for one week appeared to be beneficial in improving the shear bond strength of Clearfil S3 bond with coronal dentin especially when NS and CHX were used as endodontic irrigants. NaOCL proved to be an incompatible irrigating solution when used prior to the application of such adhesive. (Eur J Dent 2009;3:83-89)

This study evaluated ascending order of light attenuation distance (0, 2, 4, 8 mm) and specimen dimensions (2 × 2 × 10, 2 × 2 × 12, 2 × 2 × 15 mm³) differing from requirements of ISO 4049 (2 × 2 × 25 mm³) on the flexural strength of nano-hybrid resin composite. Specimens (N = 160) were prepared accordingly and randomly assigned into groups for the factors studied. Specimens were photo-polymerized from increased distances through 1, 2, 3 and 5 overlapping cycles depending on the specimen length after which they were subjected to three-point bending test (0.5 mm/min). Data were statistically analysed using one-way, two-way ANOVA and Tukey’s HSD post hoc tests (α = 0.05). Two-parameter Weibull modulus, scale (m) and shape (₀) were calculated. Both light attenuation distance (p < 0.001) and specimen dimensions (p < 0.001) significantly affected the results. Regardless of the specimen dimensions, 0.2 mm polymerization distance resulted in significantly higher mean flexural strength compared to 4 and 8 mm. Polymerization distance did not significantly affect the mean flexural strength of specimens prepared according to ISO norms (p > 0.05). Weibull distribution presented the highest shape (m) for 10–8 mm (24.65), 12–4 mm (14.54), 15–2 mm (12.32), 25–2 mm (17.56), length–light distance combinations. Specimen dimensions prepared in accordance with ISO 4049 do not allow for comparison of the effect of light attenuation distance on the flexural strength of resin composite tested.