Long-term bonding efficacy of adhesives containing benzodioxioles as alternative co-initiators

Abstract

This study evaluated the three-year lifespan of the bond to dentin of experimental self-etch adhesives containing benzodioxole derivatives-1,3-benzodioxole (BDO) and piperonyl alcohol (PA)-as co-initiator alternative to amines. Adhesive resins were formulated using Bis-GMA, TEGDMA, HEMA, camphorquinone and different co-initiators: BDO, PA or ethyl 4-dimethylamino benzoate (EDAB-amine). An experimental selfetch primer was used to complete the two-step, self-etch adhesive system. Clearfil SE Bond (CSE) was used as commercial reference. Bond strength to human dentin was assessed by microtensile bond strength (µTBS) test, and failure mode was classified. Morphology of the dentin bonding interface was assessed via scanning electron microscopy (SEM). Irrespective of the dental adhesives evaluated, µTBS was higher after 24 hours compared with that after 1.5 and 3 years (p ≤ 0.001). However, adhesives with BDO and PA as co-initiators showed significantly higher bond strength than the bonding resin with EDAB (p ≤ 0.002), independent of the time evaluated. The commercial adhesive CSE showed similar bond strength compared with the other groups (p ≥ 0.05). Mixed failures were mainly observed after 24 hours, while adhesive failures were more frequently observed after 1.5 and 3 years. No notable differences in homogeneity and continuity along the bonded interfaces were detected among the materials in the SEM analysis. In conclusion, benzodioxole derivatives are feasible alternative coinitiators to tertiary amine in camphorquinone-based self-etching dental adhesive formulations.

Moist vs over‐dried etched dentin: FE‐SEM/TEM and bond strength evaluation of resin‐dentin interfaces produced by universal adhesives

“…Afterward, polishing was performed with 400, 600, 800, and 1200‐grit Silicon Carbide paper (Buehler Inc.) and six, three, one, and one quarter micrometer diamond paste (Arotec, Cotia, SP, Brazil). Specimens were then etched with 50% phosphoric acid for 5 seconds and immersed in 2.5% sodium hypochlorite for 10 minutes . Afterward, they were dehydrated in ascending ethanol series and sputter‐coated with platinum.…”

“…Universal adhesives (UAs) have been recently introduced in the market . The UAs may be also classified as multimode adhesives, to be used in the self‐etch, etch‐and‐rinse mode or selective‐etch mode .…”