Microtensile bond strength of two single-step adhesive systems to bur-prepared dentin.
OBJECTIVE
To compare the microtensile bond strength (MTBS) of two single-step adhesive systems to two types of bur-prepared dentin.


METHODS
Using either of two adhesives, the experimental MZ-2000 (MZ) and the commercial One-Up Bond F (OUB), resin composite was bonded to flat buccal and root dentin surfaces of eight extracted human premolars. These surfaces were produced by grinding with either regular-grit or superfine-grit diamond burs in a high-speed handpiece. After storage overnight in 37 degrees C water, the bonded specimens were sectioned into ten slices approximately 0.7 mm thick, perpendicular to the bonded surface. They were then subjected to microtensile testing. The surfaces of the fractured specimens were observed both visually and microscopically to determine the failure mode. In addition, to observe the effect of conditioning, the two types of bur-ground dentin surfaces were conditioned with the adhesives, rinsed with acetone, and observed under SEM.


RESULTS
When MZ was bonded to dentin prepared with a regular-grit diamond bur, MTBS was the lowest and failures occurred adhesively at the interface, whereas other groups revealed primarily mixed failures. MZ-conditioned dentin surfaces ground with a regular-grit diamond bur were covered with a residual smear layer. However, the smear layers on the surface of MZ-conditioned dentin ground with a superfine-grit diamond bur and on OUB-conditioned dentin prepared either with a regular-grit or superfine-grit diamond bur were mostly or partially dissolved.


CONCLUSIONS
Some of the single-step adhesive systems may produce low bond strengths to smear layers created by regular-grit diamond burs.
Inoue
H
H
Department of Oral Health Science, Hokkaido University Graduate School of Dental Medicine, Sapporo, Japan. hiroppy@den.hokudai.ac.jp
Inoue
S
S
Uno
S
S
Takahashi
A
A
Koase
K
K
Sano
H
H
D000096:Acetone / Q000737:chemistry; D000268:Adhesiveness; D000269:Adhesives / Q000737:chemistry; D001641:Bicuspid; D003188:Composite Resins / Q000737:chemistry; D001840:Dental Bonding; D003737:Dental Cavity Preparation / Q000295:instrumentation; D003754:Dental High-Speed Equipment; D003804:Dentin / Q000648:ultrastructure*; D017220:Dentin-Bonding Agents / Q000737:chemistry*; D005459:Fluorides / Q000737:chemistry; D005898:Glass / Q000737:chemistry; D006801:Humans; D008689:Methacrylates / Q000737:chemistry; D008855:Microscopy, Electron, Scanning; D011140:Polyurethanes / Q000737:chemistry; D012824:Silicic Acid / Q000737:chemistry; D016369:Smear Layer; D012995:Solubility; D012997:Solvents / Q000737:chemistry; D013499:Surface Properties; D013696:Temperature; D013718:Tensile Strength; D014050:Toluene / Q000031:analogs & derivatives* / Q000737:chemistry; D014092:Tooth Root / Q000648:ultrastructure; D014867:Water
D000269:Adhesives; D003188:Composite Resins; D017220:Dentin-Bonding Agents; D008689:Methacrylates; D011140:Polyurethanes; D012997:Solvents; D014867:Water; C029824:urethane dimethacrylate luting resin; D012824:Silicic Acid; D000096:Acetone; D014050:Toluene; C035291:hexafluorosilicic acid; C005044:hydroxyethyl methacrylate; C034139:4-methacryloxyethyltrimellitic acid anhydride; C065428:4-toluenesulfinic acid; D005459:Fluorides