Comparison between regional micropush-out and microtensile bond strength of resin composite to dentin

Acta Odontol Scand. 2008 Apr;66(2):73-81. doi: 10.1080/00016350801958266.

Abstract

Objective: In this study we compared the micropush-out (micro-PO) and microtensile (micro-TBS) test methods for resin composites on different levels and surfaces of dentin.

Material and methods: Thirty-four sound human molars were divided into two groups in accordance with the dentin surface used (occlusal (O) or mesio-distal (M)), then subdivided into a further two groups in accordance with the test method (micro-PO (P) or micro-TBS (T)). In groups OP and OT, teeth were ground occlusally perpendicular to their axis, and in groups MP and MT, mesio-distally parallel to their axis to expose dentin. Dentin disks were prepared from different regions of the teeth either in an occluso-cervical (group OP) (n=5) or mesio-distal direction (group MP) (n=5) (S, superficial; M, middle; D, deep). One-hundred-and-twenty standardized occlusal cavities were prepared in these dentin disks using a conical-shaped diamond rotary cutting instrument. The adhesive (Adper Scotchbond Multi-Purpose Dental Adhesive) and a composite material (Filtek Z250 Universal Restorative) were applied and polymerized with a LED light curing unit (Elipar FreeLight 2). The disks (n=20/per group) were tested in a universal testing machine and pushed out with a cross-head speed of 1.0 mm/min. In groups OT (n=12) and MT (n=12), the teeth were ground to expose superficial, middle, and deep dentin. Build-ups of resin composite were constructed with the same materials. The specimens were serially sectioned and trimmed to hour-glass shapes, then tested with the micro-TBS tester at a rate of 1 mm/min. Failure modes were examined using a stereomicroscope and scanning electron microscope.

Results: ANOVA revealed significant differences among the groups (p<0.001). With the push-out test, no premature failure occurred, the variability of the data distribution was acceptable, and regional differences in bond strength among dentin levels could be assessed.

Conclusions: The micro-PO test method could be an alternative to the micro-TBS technique.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Analysis of Variance
  • Composite Resins*
  • Dental Bonding*
  • Dental Restoration Failure
  • Dental Restoration, Permanent / methods*
  • Dental Stress Analysis / methods
  • Dentin
  • Dentin-Bonding Agents*
  • Hardness
  • Humans
  • Materials Testing / methods
  • Middle Aged
  • Molar
  • Resin Cements*
  • Tensile Strength

Substances

  • Composite Resins
  • Dentin-Bonding Agents
  • Filtek Z250
  • Resin Cements
  • Scotchbond Multi-Purpose