Influence of silanes on the stability of resin-ceramic bond strength.

PURPOSE: To evaluate the in vitro stability of resin-ceramic bond strength provided for silanes with acidic functional monomers. METHODS: Five ceramic blocks were fabricated. The blocks were randomly divided into groups (n=30) and assigned to the following surface treatments: ( C) HF + RelyX Ceramic Primer, ( G1) HF + Porcelain Liner M, ( G2) HF + Clearfil Ceramic Primer, ( G3) Phosphoric acid ( H3PO4) + Clearfil Ceramic Primer, ( G4) H3PO4 + Porcelain Liner M. Two adhesives were used: Single Bond in Group C and Clearfil SE Bond in the other groups, after which, each block received four 1 mm increments of resin composite Filtek Z350. The resin-ceramic blocks were sectioned, obtaining samples of approximately 0.8 mm + à¡© 0.8 mm. The groups were subdivided according to aging mode: I - immediate ( 24 hours storage in artificial saliva) and A - aged ( 3 months in artificial saliva + 5,000 thermal cycles 5°C/55°C). The microtensile test was performed with a 0.5 mm/minute crosshead speed ( n = 15) on a universal testing machine. The fracture patterns were categorized with scanning electron microscopy. The results were analyzed using three-way ANOVA and Tukey's test ( P≤ 0.05). RESULTS: Silanes containing acidic functional monomers did not affect the stability of the resin-ceramic bond strength. The use of HF acid was a necessary condition for stability. The highest values after aging were obtained by silanes with functional molecules without a statistically significant difference. The storage influenced the values of bond strength. The use of acidic functional monomers did not affect the resin-ceramic bond after storage in saliva followed by thermal cycling. CLINICAL SIGNIFICANCE: Silane agents containing acidic functional monomers did not influence the stability of the resin-ceramic bond. The use of hydrofluoric acid is recommended to provide stability of the bonds.

Post-etching cleaning and resin/ceramic bonding: microtensile bond strength and EDX analysis.

PURPOSE: The aim of this study was to evaluate the microtensile bond strength of a resin composite bonded to two heat-pressed ceramics after performing different post-etching cleaning techniques. MATERIALS AND METHODS: Resin composite specimens were bonded to IPS Empress Esthetic (EE) and IPS Empress 2 (E2) heat-pressed ceramic disks after etching with 10% HF, surface cleaning, silanization and application of an unfilled hydrophobic resin. Resin composite specimens were fabricated using 4-mm (height) Tygon tubes of 0.8 mm diameter and bonded according to the post-etching cleaning technique employed (n = 30): no cleaning (NC); air-water spray for 30 s (AWS); 37% phosphoric acid etching for 30 s (PA); ultrasonic bath in distilled water for 5 min (UB); PA + UB (PAUB); application of a self-etching silane/bonding system Clearfil Silane Kit (CSK). The resin composite specimens were subjected to tensile tension at a crosshead speed of 0.5 mm/min. SEM observation and EDX analysis were performed for each group to determine elemental distribution in the samples. RESULTS: Two-way ANOVA with random effect showed statistically differences between subgroups for E2, in which E2NC only showed bond strength significantly lower than E2AWS and E2BU, as indicated by Student's t-test and a contrast method. For EE, subgroups EENC and EECSK groups showed statistically significant differences between each other and among the other post-etching cleaning technique groups (p < 0.05). CONCLUSION: Air-water spray may be used as a post-etching cleaning technique for both ceramics. The presence of residues did not significantly reduce the bond strength of resin composite to IPS Empress 2 ceramic.

Effect of different ceramic surface treatments on resin microtensile bond strength.

PURPOSE: The objective of this study was to evaluate the effect of different surface treatments on the microtensile bond strength (micro-tbs) of composite bonded to hot-pressed ceramic. The null hypothesis tested was that neither of the surface treatments (silanization or fluoric acid etching) would produce greater bond strength of composite resin to the ceramic. MATERIALS AND METHODS: Four 7 x 7 x 5 mm hot-pressed ceramic blocks of IPS Empress 2 were fabricated and polished to 600 grit followed by sandblasting with 50 microm alumina. The ceramic blocks were then divided into four groups and submitted to the following surface treatments: Group 1: 9.5% hydrofluoric (HF) acid for 20 seconds and silane (S) for 3 minutes; Group 2: silane for 3 minutes; Group 3: 9.5% HF acid for 20 seconds; Group 4: no treatment. Scotchbond adhesive was applied to the treated ceramic surfaces and covered with Filtek Z250 composite resin. The composite-ceramic blocks were cut with an Isomet low speed diamond saw machine producing sticks (n = 25), which were loaded to failure under tension in an Instron Universal testing machine. The mean micro-tbs was analyzed with one-way ANOVA and Bonferroni "t" test. RESULTS: All specimens of Group 4 experienced adhesive failure during the cutting of the block and were eliminated. The mean micro-tbs and standard deviations (SD) in megaPascals were: Group 1 = 56.8 (+/-10.4), Group 2 = 44.8 (+/-11.6), Group 3 = 35.1 (+/-7.7). Statistical analysis showed that the bond strength was significantly affected by surface treatment (p < 0.0001). Group 1 (HF + S) had the highest micro-tbs, and Group 2 (S) had higher micro-tbs than Group 3 (HF). The mode of fracture of the specimens was examined using scanning electron microscopy (SEM), and all fractures occurred within the adhesion zone. CONCLUSION: The results show that surface treatment is important for resin adhesion to ceramic and suggestthat silane treatment was the main factor responsible for resin bonding to ceramic.