The effect of combining photoinitiator systems on the color and curing profile of resin-based composites

Dayane Carvalho Ramos Salles de Oliveira, Mateus Garcia Rocha, Ivo Carlos Correa, Américo Bortolazzo Correr, Jack Ferracane, Mario Alexandre Coelho Sinhoreti

Research output: Contribution to journalArticle

15 Scopus citations

Abstract

Objective: To evaluate the effect of combining camphorquinone (CQ) and diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide (TPO) on the color and curing profile of resin-based composites. Methods: Experimental composites were produced with different CQ and TPO molar concentrations: CQ-only, 3CQ:1TPO, 1CQ:1TPO, 1CQ:3TPO, and TPO-only. Polywave LED was characterized using a beam profiler. Block-shaped samples (5. mm. ×. 5. mm. ×. 3. mm depth) were cured in a custom-designed mold with a polywave LED positioned to compare the regions exposed to the 420-495. nm and 380-420. nm LED emittances. To map the cure profile, degree of conversion (DC) of longitudinal cross-sections from each block were evaluated by FT-NIR. Color, light-transmittance and light-absorption during curing were evaluated on specimens 1-3. mm thick. Data were analyzed using ANOVA/Tukey's test (α=0.05; . β=0.2). Results: Though the polywave LED beam profile was non-uniform, up to a depth of 2. mm no differences in DC were found among the composites containing CQ with TPO added up to 50%, regardless of the position under the curing tip. Composites with higher TPO concentration showed a decrease in DC beginning with a depth of 1. mm, while composites with higher or similar CQ concentrations did not show decreased DC until a depth of 3. mm. Higher TPO concentration reduced initial yellowness and color change after curing; and lower CQ concentration decreased light-absorption at greater depths. Significance: The combination of CQ with TPO added up to 50% reduced the yellowness and color change of composites after curing without affecting cure efficiency up to a depth of 2. mm.

Original languageEnglish (US)
JournalDental Materials
DOIs
StateAccepted/In press - Dec 12 2015

Keywords

  • Color
  • Cure profile
  • Degree of conversion
  • Light transmittance
  • Photoinitiator

ASJC Scopus subject areas

  • Materials Science(all)
  • Dentistry(all)
  • Mechanics of Materials

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