Adverse surface interactions between one-bottle light-cured adhesives and chemical-cured composites.
OBJECTIVE
This study examined the effect of one-bottle adhesives with different acidities on bonding to chemical-cured and light-cured resin composites.


METHODS
Twenty-four non-carious human third molars were divided into eight groups. A flat dentin surface was created for each tooth. Acid-conditioned dentin surfaces were bonded with Prime&Bond NT (Dentsply), OptiBond SOLO (Kerr), Single Bond (3M) or One-Step (Bisco). Each adhesive group was covered with composite buildups, using either a light-cured (Z100, 3M) or a chemical-cured composite (BisFil 2, Bisco). Specimens were vertically sectioned into 0.9x0.9 mm beams. Microtensile bond strengths were recorded and failure modes were classified using a stereoscopical microscope. Four representative beams from each group were further prepared for SEM examination.


RESULTS
Two-way ANOVA showed that the effect of adhesive types, composite curing modes and their interaction were statistically significant (P<0.001). Multiple comparison tests revealed no statistically significant difference in the bond strength of the four adhesives with the light-cured composite (P>0.05). However, they were significantly lower when used with the chemical-cured composite (P<0.01). A positive correlation was observed between the acidity of adhesives and the bond strengths of the chemical-cured composite. Failure occurred predominantly along the composite-adhesive interface, with microporosities on the adhesive surface and voids within the chemical-cured composite.


CONCLUSIONS
Air incorporated during mixing of chemical-cured composites only contributed partially to the decreased bond strength observed in simplified-step adhesives. Ultrastructural observations suggested the presence of a surface interaction between the uncured, acidic resin monomers from the oxygen inhibition layer of the adhesive and the initiator components in the chemical-cured composite.
Sanares
A M
AM
Faculty of Dentistry, The University of Hong Kong, 34 Hospital Road, SAR, Hong Kong, China.
Itthagarun
A
A
King
N M
NM
Tay
F R
FR
Pashley
D H
DH
D000180:Acrylic Resins / Q000737:chemistry; D000269:Adhesives / Q000737:chemistry; D000704:Analysis of Variance; D017438:Bisphenol A-Glycidyl Methacrylate / Q000737:chemistry; D001843:Bone Cements; D003188:Composite Resins / Q000737:chemistry*; D001840:Dental Bonding; D019232:Dental Restoration Failure; D003793:Dental Restoration, Permanent / Q000379:methods; D017220:Dentin-Bonding Agents / Q000737:chemistry*; D004347:Drug Interactions; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008027:Light; D008422:Materials Testing; D008689:Methacrylates / Q000737:chemistry; D008855:Microscopy, Electron, Scanning; D008964:Molar, Third; D011108:Polymers / Q000737:chemistry; D011109:Polymethacrylic Acids / Q000737:chemistry; D019904:Polymethyl Methacrylate; D016062:Porosity; D011897:Random Allocation; D012822:Silicon Dioxide / Q000737:chemistry; D018709:Statistics, Nonparametric; D013499:Surface Properties; D013674:Technology, Dental; D013718:Tensile Strength; D015040:Zirconium / Q000737:chemistry
D000180:Acrylic Resins; D000269:Adhesives; C103506:Bis-GMA, BPDM, HEMA dental-bonding resin; D001843:Bone Cements; D003188:Composite Resins; D017220:Dentin-Bonding Agents; D008689:Methacrylates; C428805:OptiBond SOLO; D011108:Polymers; D011109:Polymethacrylic Acids; C425843:Prime and Bond NT; C083568:Z100 composite resin; C078905:Bisfil; D017438:Bisphenol A-Glycidyl Methacrylate; C035124:CMW cement; D012822:Silicon Dioxide; D019904:Polymethyl Methacrylate; D015040:Zirconium