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

ÇEKİÇ NAGAŞ I., ERGÜN G., Nagas E., Tezvergil A., Vallittu P. K. , Lassila L. V. J.

ACTA ODONTOLOGICA SCANDINAVICA, vol.66, no.2, pp.73-81, 2008 (SCI-Expanded) identifier identifier identifier

  • Publication Type: Article / Article
  • Volume: 66 Issue: 2
  • Publication Date: 2008
  • Doi Number: 10.1080/00016350801958266
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Page Numbers: pp.73-81
  • Keywords: dentin depth, micropush-out, microtensile, resin composite, surface, FIBER-REINFORCED COMPOSITE, IN-VITRO, SURFACE, SUBSTRATE, ADHESION, WALLS, POSTS, SEM
  • Gazi University Affiliated: Yes


In this study we compared the micropush-out (mu-PO) and microtensile (mu-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 (mu-PO (P) or mu-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 mesiodistal 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 mu-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 mu-PO test method could be an alternative to the mu-TBS technique.