Nanoleakage, ultramorphological characteristics, and microtensile bond strengths of a new low-shrinkage composite to dentin after artificial aging.
OBJECTIVE
To study the microtensile bond strengths and nanoleakage of low-shrinkage composite to dentin. The null hypotheses tested were (1) aging does not affect the bonding of low-shrinkage composite; (2) there is no difference in microtensile bond strengths and nanoleakage using different bonding strategies.


METHODS
32 extracted molars were assigned to one of four groups: LS System Adhesive (LS, 3M ESPE); dentin etched for 15s with phosphoric acid+LS System Adhesive (LSpa); Adper Single Bond Plus (SB, 3M ESPE); SB+LS Bond (SBLS). Occlusal dentin was exposed and restored with Filtek LS (3M ESPE). The samples were tested after 24h or after 20,000 thermocycles and 6 months of aging. Teeth were sectioned with a cross-section of 0.8+/-0.2mm(2) and fractured at a crosshead speed of 1mm/min. The data were submitted to ANOVA/Duncan's post hoc test, at p<0.05. Five slabs from each group were selected and immersed in 50wt% ammoniacal silver nitrate. Then, specimens were processed for SEM, the silver penetration was measured and data analyzed with Kruskal-Wallis at p<0.05.


RESULTS
No statistically significant difference was found among the experimental groups for the factor dentin treatment (p=0.165) and aging (p=0.091). All experimental groups exhibit some degree of nanoleakage. There was no adhesion of Filtek LS applied directly over dentin surfaces treated with SB.


CONCLUSIONS
The new low-shrinkage resin composite showed compatibility only with its dedicated adhesive. Pre-etching did not improve the bond strengths to low-shrinkage resin composite. Some degree of nanoleakage was evident in all groups.
Duarte
Sillas
S
Department of Comprehensive Care, Case Western Reserve University, School of Dental Medicine, 10900 Euclid Avenue, Cleveland, OH 44106-4905, USA. sillas.duarte@case.edu
Phark
Jin-Ho
JH
Varjão
Fabiana Mansur
FM
Sadan
Avishai
A
D000134:Acid Etching, Dental / Q000379:methods; D017438:Bisphenol A-Glycidyl Methacrylate; D003188:Composite Resins / Q000737:chemistry*; D001840:Dental Bonding; D003763:Dental Leakage / Q000517:prevention & control*; D003799:Dental Stress Analysis; D003804:Dentin; D017220:Dentin-Bonding Agents / Q000737:chemistry*; D004356:Drug Storage; D006801:Humans; D008422:Materials Testing; D008689:Methacrylates / Q000737:chemistry; D008855:Microscopy, Electron, Scanning; D008964:Molar, Third; D053761:Nanocomposites / Q000737:chemistry; D019279:Resin Cements / Q000737:chemistry; D062047:Silorane Resins; D013718:Tensile Strength
D003188:Composite Resins; D017220:Dentin-Bonding Agents; D008689:Methacrylates; D019279:Resin Cements; D062047:Silorane Resins; C511238:Single Bond Plus; D017438:Bisphenol A-Glycidyl Methacrylate