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

Author(s)

Ramos Salles de Oliveira, Dayane Carvalho ; Rocha, Mateus Garcia ; Correa, No Carlos ; Correr, Americo Bortolazzo ; Ferracane, Jack L. ; Coelho Sinhoreti, Mario Alexandre

• Document type: Journal article
• Source: Dental Materials; v. 32, n. 10, p. 1209-1217, OCT 2016.
• Web of Science Citations: 7

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 x 5 mm x 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 (alpha = 0.05; beta = 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. (C) 2016 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved. (AU)

• FAPESP's process: 16/06019-3 - PHYSICOCHEMICAL PROPERTIES AND WEAR RESISTANCE OF COMMERCIAL AND EXPERIMENTAL BULKFILL DENTAL COMPOSITES BASED ON ELASTOMERIC MONOMER
• Grantee: Mateus Garcia Rocha
• Support Opportunities: Scholarships in Brazil - Doctorate
• FAPESP's process: 13/04241-2 - The influence of the photoinitiator system and reducing agents on physical properties of experimental resins photoactivated by LEDs
• Grantee: Dayane Carvalho Ramos Salles de Oliveira
• Support Opportunities: Scholarships in Brazil - Doctorate