Effect of combining photoinitiators on cure efficiency of dental resin-based composites

Authors

  • Lucas Lara Universidade Estadual de Campinas – UNICAMP, Faculdade de Odontologia de Piracicaba, Departamento de Odontologia Restauradora, Piracicaba
  • Mateus Garcia Rocha Universidade Federal do Rio de Janeiro, Instituto de Macromoléculas Professora Eloisa Mano, Rio de Janeiro http://orcid.org/0000-0001-5658-5640
  • Livia Rodrigues de Menezes Universidade Federal do Rio de Janeiro, Instituto de Macromoléculas Professora Eloisa Mano, Rio de Janeiro http://orcid.org/0000-0003-1172-1199
  • Américo Bortolazzo Correr Universidade Estadual de Campinas – UNICAMP, Faculdade de Odontologia de Piracicaba, Departamento de Odontologia Restauradora, Piracicaba
  • Mario Alexandre Coelho Sinhoreti Universidade Estadual de Campinas – UNICAMP, Faculdade de Odontologia de Piracicaba, Departamento de Odontologia Restauradora, Piracicaba
  • Dayane Oliveira University of Florida, Division of Operative Dentistry, Department of Restorative Dental Sciences, Gainesville http://orcid.org/0000-0003-1420-5720

DOI:

https://doi.org/10.1590/1678-7757-2020-0467%20

Keywords:

Dental photoinitiators, Polymerization, Raman spectroscopy, Spectrophotometry

Abstract

Camphorquinone is the most conventionally used photoinitiator in Dentistry. Although different alternative photoinitiators have been proposed, no photoinitiator was capable of completely substituting camphorquinone. The combination of photoinitiators has been considered the best alternative. Objectives: To evaluate the effect of combining Norrish type I and II photoinitiators on the cure efficiency of dental resin-based composites. Methodology: Experimental composites were produced containing different photoinitiator systems: Norrish type I-only, mono-alkyl phosphine oxide (TPO); Norrish type II-only, camphorquinone (CQ); or its combination, CQ and TPO, in a 1: 1 molar ratio. UV-vis absorption spectrophotometry was performed to assess the consumption of each photoinitiator after curing (n=3). A multi-wave LED (Bluephase® G2, Ivoclar Vivadent) was pre-characterized and used with a radiant exposure of 24 J/cm2. The degree of conversion was evaluated by Raman spectrometry, and the elution of the monomers by nuclear magnetic resonance analysis (n=3). Data were analyzed using ANOVA and Tukey's test (α=0.05; β=0.2). Results: The combination of CQ and TPO increased the consumption of the photoinitiator system compared to CQ-only (p=0.001), but presented similar consumption compared to TPO-only (p=0.52). There was no significant difference in the degree of conversion between the composites regardless of the photoinitiator system (p=0.81). However, the elution of the monomers was reduced when both photoinitiators were combined. TPO-based material presented the highest elution of monomers. Conclusions: The combination of the photoinitiator systems seems to be beneficial for the cure efficiency of dental resin-based composites.

Downloads

Download data is not yet available.

Downloads

Published

2021-08-13

Issue

Section

Original Articles