Only air abrasion associated with a self-etching system provided repair bond strength comparable to composite UTS.

The decrease in shear bond strength values is time dependent. A delay in bonding procedures for composite resin restoration is recommended. According to the results, a satisfactory time to perform the restoration of composite resin for both enamel and dentin is 2 weeks after bleaching.

No abstract

SUMMARYThis study evaluated the influence of different thermal (TC) and mechanical (MC) cycling protocols on microtensile bond strength (µTBS) to cervical dentin margins of Class II restorations using two total-etch (TE) adhesives and one selfetching (SE) primer. Class II slot cavities were prepared on the mesial surfaces of 168 bovine incisors and were divided into three groups according to the bonding system used: Single Bond, OptiBond Solo Plus and Clearfil SE Bond. All cavities were restored with Filtek Z250 composite. Following restorative procedures, the restored teeth were allocated to seven subgroups (n=8) according to the thermal/mechanical protocol performed: G1-control (no cycling), G2-100,000 MC, G3-200,000 MC, G4-500,000 MC, G5-100,000 MC+1,000 TC, G6-200,000 MC+1,000 TC, G7-500,000 MC+1,000 TC. TC was performed using 5 ± 2°C and 55 ± 2°C baths, with a dwell time of 60 seconds in each bath. MC was achieved with an axial force of 80 N at 2 cycles/second. The restorations were sectioned perpendicular to the cervical bonded interface into two 0.8-1-mm thick slabs. The slabs were trimmed at the interface to obtain a cross-sectional surface area of 0.

The aim of this study was to evaluate the microleakage of class II resin composite restorations polymerized with light-emitting diodes (LEDs) with different numbers of blue diodes. One hundred sixty-eight class II cavities were prepared in bovine teeth. A one-bottle adhesive system (Single Bond/3M ESPE) was applied. The microhybrid or packable resin composites were inserted in three horizontal increments and cured for 40 seconds each, according to the following groups (n=21): G1- Z250 + LED light curing unit with 19 LEDs (3M ESPE); G2- Surefil + LED light curing unit with 19 LEDs; G3- Z250 + LED light curing unit with 7 LEDs (DMC); G4-Surefil + LED light curing unit with 7 LEDs; G5- Z250 + LED light curing unit with 6 LEDs (MM Optics); G6- Surefil + LED light curing unit with 6 LEDs; G7- Z250 + conventional halogen light curing unit (Demetron-Kerr); G8-Surefil + conventional halogen light curing unit. After thermocycling, the specimens were immersed in 2% methylene blue solution and then evaluated for microleakage. The Kruskal-Wallis and non-parametric Multiple Comparison tests (p<0.05) showed statistically significant differences among groups median: G1: 1(d); G2: 4(a); G3: 1(cd); G4: 4(a); G5: 2(bc); G6: 4(a); G7: 1(cd); G8: 4(ab). The blue light-emitting diode units (LEDs) demonstrated similar results to the conventional halogen lamp unit and the microleakage of the packable resin composite was significantly more severe than that of the microhybrid resin composite.