Influence of different tests used to measure the bond strength to dentin of two adhesive systems.
OBJECTIVE
To investigate the behavior of two bonding systems: self-etching primer Clearfil Liner Bond 2V (CLB) and total-etch Single Bond (SB) when submitted to two bond strength tests: shear bond strength (SBS) and microtensile (MTBS).


METHODS
Flat dentin surfaces were obtained at the facial surface of extracted bovine incisors. muTBS started with adhesive application and incremental resin composite insertion. Samples were then sliced into 1 mm slabs parallel to the long axis of the tooth. Half of the specimens from each group were trimmed in order to obtain dumbbell-shaped (D) specimens with a cross-sectional area of 1 mm2, and in the other half of the group, the slabs were cut into beams (B) with a cross section of 1 mm2 area. Specimens were individually fractured on a microtensile apparatus. For SBS, crown segments were embedded in polyester resin and a flat dentin surface was exposed for bonding. After adhesive and restorative procedures were accomplished, the specimens were kept in water for 24 hours prior to bond testing. The tests were performed in a universal testing machine. MPa values were analyzed by Tukey's test (P < 0.05), two-way ANOVA (muTBS) and Student's t-test (SBS).


RESULTS
Mean values (SD) on muTBS were: SB/B: 42.6 (15.1), SB/D: 35.4 (6.8), CLB/B: 14.3 (10.3) and CLB/D: 27.0 (7.9). SBS values (SD) were: SB: 17.3 (5.6) and CLB 15.9 (7.2). Beam specimens bonded with CLB presented the lowest results. SBS did not show statistical differences between groups. The results showed that the shear bond test seemed to lack the sensitivity that is required to detect subtle differences between bonding agents or procedures.
Cavalcante
Larissa Maria Assad
LM
Department of Restorative Dentistry, School of Dentistry at Piracicaba, University of Campinas, São Paulo, Brazil.
Erhardt
Maria Carolina Guilherme
MC
Bedran-de-Castro
Ana Karina Barbieri
AK
Pimenta
Luiz André Freire
LA
Ambrosano
Glaucia Maria Bovi
GM
D000818:Animals; D017438:Bisphenol A-Glycidyl Methacrylate / Q000737:chemistry; D017554:Carbon Compounds, Inorganic / Q000737:chemistry; D002417:Cattle; D003188:Composite Resins / Q000737:chemistry; D001840:Dental Bonding; D003764:Dental Materials / Q000737:chemistry*; D003775:Dental Polishing; D003799:Dental Stress Analysis / Q000295:instrumentation; D003804:Dentin / Q000648:ultrastructure*; D017220:Dentin-Bonding Agents / Q000737:chemistry*; D008422:Materials Testing / Q000379:methods; D008689:Methacrylates / Q000737:chemistry; D011897:Random Allocation; D033081:Shear Strength; D017655:Silicon Compounds / Q000737:chemistry; D013314:Stress, Mechanical; D013499:Surface Properties; D013718:Tensile Strength; D013997:Time Factors; D014867:Water / Q000737:chemistry
D017554:Carbon Compounds, Inorganic; C112274:Clearfil Liner Bond 2; D003188:Composite Resins; D003764:Dental Materials; D017220:Dentin-Bonding Agents; D008689:Methacrylates; D017655:Silicon Compounds; C115612:single bond; D014867:Water; D017438:Bisphenol A-Glycidyl Methacrylate; C022088:silicon carbide