Can a New HEMA-free Two-step Self-etch Adhesive Improve Dentin Bonding Durability and Marginal Adaptation?

J Adhes Dent. 2021 Dec 3;23(6):505-512. doi: 10.3290/j.jad.b2288233.

Abstract

Purpose: A new two-step self-etch adhesive (2-SEA) free of hydrophilic monomers was evaluated. Its microtensile bond strength (µTBS) to dentin under various aging conditions, interfacial gap formation, water sorption/solubility, and formation of an acid-base resistant zone (ABRZ) were evaluated and compared with a gold-standard 2-SEA.

Materials and methods: The new 2-SEA G2-Bond Universal (G2; GC) was compared to Clearfil SE Bond 2 (CSE2, Kuraray Noritake). Their µTBS to sound coronal dentin was tested after 1 week, 10,000 thermal cycles (TC), 20,000 TC, 6 months and 1 year. Failure mode was determined using scanning electron microscopy (SEM). Gap formation at the interface of 2-mm deep tapered cavities with an enamel border was observed using swept-source optical coherence tomography after 1 day, 1 week, 10,000 TC, and 20,000 TC. In addition, water sorption and solubility of the bonding agents was measured, and ABRZ formation was evaluated using SEM.

Results: There was no significant difference in µTBS between G2 and CSE2 (p > 0.05), and the aging conditions had no significant effect on µTBS (p > 0.05). In all groups, cohesive failures prevailed (55%-95%). Interfacial gap formation was initially similar for both adhesives (p > 0.05), but G2 exhibited a significantly lower gap formation than CSE2 after TC (p < 0.05). The water sorption of G2 was significantly lower compared to CSE2 (p < 0.05), and their solubility was statistically similar (p > 0.05). ABRZ of similar thickness was observed with both adhesives.

Conclusion: The new 2-SEA exhibited stable dentin bonding and increased hydrophobicity resulting from the absence of hydrophilic monomers.

Keywords: HEMA; acid-base resistant zone; adhesion; aging; gap formation; hydrophilicity; microtensile bond strength; optical coherence tomography.

MeSH terms

  • Dental Bonding*
  • Dental Cements
  • Dentin
  • Dentin-Bonding Agents*
  • Materials Testing
  • Resin Cements
  • Tensile Strength

Substances

  • Dental Cements
  • Dentin-Bonding Agents
  • Resin Cements