Determination of the optimal photoinitiator concentration in dental composites based on essential material properties

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40 Citations (Scopus)

Abstract

Objectives: The aim of this study was to determine the concentrations of the photosensitizer (camphoroquinone, CQ) and coinitiator (ethyl-4-dimethylaminobenzoate, EDMAB) that resulted in maximum conversion but generated minimum contraction stress in experimental composites. Methods: Experimental composites were prepared with an identical resin formulation [TEGDMA:UDMA:bis-GMA of 30.25:33.65:33.65]. Five groups of resin were prepared at varied CQ concentrations (0.1, 0.2, 0.4, 0.8 and 1.6 wt% of the resin). Five subgroups of resin were prepared at each level of CQ concentration, by adding EDMAB at 0.05, 0.1, 0.2, 0.4 and 0.8 wt% of the resin, resulting in 25 experimental resins. Finally, strontium glass (∼3 μm) and silica (0.04 μm) were added at 71.5 and 12.6 wt% of the composite, respectively. Samples (n = 3) were then evaluated for Knoop hardness (KHN), degree of conversion (DC), depth of cure (DoC) and contraction stress (CS). Results: There was an optimal CQ and EDMAB concentration that resulted in maximum DC and KHN, beyond which increased concentration resulted in a decline in those properties. KHN testing identified two regions of maxima with best overlaps occurring at CQ:EDMAB ratio of 1.44:0.42 and 1.05:1.65 mol%. DC evaluation showed one region of maximum, the best overlap occurring at CQ:EDMAB ratio of 2.40:0.83 mol%. DoC was 4 mm. Overall, maximum CS was attained before the system reached the maximum possible conversion and hardness. Significance: (1) Selection of optimal photoinitiator/amine concentration is critical to materials' formulation, for excessive amounts can compromise materials' properties. (2) There was no sufficient evidence to suggest that contraction stress can be reduced by lowering CQ/EDMAB concentration without compromising DC and KHN.

Original languageEnglish (US)
Pages (from-to)994-1000
Number of pages7
JournalDental Materials
Volume25
Issue number8
DOIs
StatePublished - Aug 2009

Fingerprint

Dental composites
Materials properties
Tooth
Hardness
Resins
Composite materials
Hardness testing
Bisphenol A-Glycidyl Methacrylate
Photosensitizers
Strontium
Photosensitizing Agents
camphoroquinone
Amines
Silicon Dioxide
Glass
ethyl 4-dimethylaminobenzoate
Silica

Keywords

  • Coinitiator
  • Contraction stress
  • Degree of conversion
  • Depth of cure
  • Knoop hardness
  • Photosensitizer

ASJC Scopus subject areas

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

Cite this

@article{be12e3e45bf94de3bb9b239be52bae20,
title = "Determination of the optimal photoinitiator concentration in dental composites based on essential material properties",
abstract = "Objectives: The aim of this study was to determine the concentrations of the photosensitizer (camphoroquinone, CQ) and coinitiator (ethyl-4-dimethylaminobenzoate, EDMAB) that resulted in maximum conversion but generated minimum contraction stress in experimental composites. Methods: Experimental composites were prepared with an identical resin formulation [TEGDMA:UDMA:bis-GMA of 30.25:33.65:33.65]. Five groups of resin were prepared at varied CQ concentrations (0.1, 0.2, 0.4, 0.8 and 1.6 wt{\%} of the resin). Five subgroups of resin were prepared at each level of CQ concentration, by adding EDMAB at 0.05, 0.1, 0.2, 0.4 and 0.8 wt{\%} of the resin, resulting in 25 experimental resins. Finally, strontium glass (∼3 μm) and silica (0.04 μm) were added at 71.5 and 12.6 wt{\%} of the composite, respectively. Samples (n = 3) were then evaluated for Knoop hardness (KHN), degree of conversion (DC), depth of cure (DoC) and contraction stress (CS). Results: There was an optimal CQ and EDMAB concentration that resulted in maximum DC and KHN, beyond which increased concentration resulted in a decline in those properties. KHN testing identified two regions of maxima with best overlaps occurring at CQ:EDMAB ratio of 1.44:0.42 and 1.05:1.65 mol{\%}. DC evaluation showed one region of maximum, the best overlap occurring at CQ:EDMAB ratio of 2.40:0.83 mol{\%}. DoC was 4 mm. Overall, maximum CS was attained before the system reached the maximum possible conversion and hardness. Significance: (1) Selection of optimal photoinitiator/amine concentration is critical to materials' formulation, for excessive amounts can compromise materials' properties. (2) There was no sufficient evidence to suggest that contraction stress can be reduced by lowering CQ/EDMAB concentration without compromising DC and KHN.",
keywords = "Coinitiator, Contraction stress, Degree of conversion, Depth of cure, Knoop hardness, Photosensitizer",
author = "L. Musanje and Jack Ferracane and Ronald Sakaguchi",
year = "2009",
month = "8",
doi = "10.1016/j.dental.2009.02.010",
language = "English (US)",
volume = "25",
pages = "994--1000",
journal = "Dental Materials",
issn = "0109-5641",
publisher = "Elsevier Science",
number = "8",

}

TY - JOUR

T1 - Determination of the optimal photoinitiator concentration in dental composites based on essential material properties

AU - Musanje, L.

AU - Ferracane, Jack

AU - Sakaguchi, Ronald

PY - 2009/8

Y1 - 2009/8

N2 - Objectives: The aim of this study was to determine the concentrations of the photosensitizer (camphoroquinone, CQ) and coinitiator (ethyl-4-dimethylaminobenzoate, EDMAB) that resulted in maximum conversion but generated minimum contraction stress in experimental composites. Methods: Experimental composites were prepared with an identical resin formulation [TEGDMA:UDMA:bis-GMA of 30.25:33.65:33.65]. Five groups of resin were prepared at varied CQ concentrations (0.1, 0.2, 0.4, 0.8 and 1.6 wt% of the resin). Five subgroups of resin were prepared at each level of CQ concentration, by adding EDMAB at 0.05, 0.1, 0.2, 0.4 and 0.8 wt% of the resin, resulting in 25 experimental resins. Finally, strontium glass (∼3 μm) and silica (0.04 μm) were added at 71.5 and 12.6 wt% of the composite, respectively. Samples (n = 3) were then evaluated for Knoop hardness (KHN), degree of conversion (DC), depth of cure (DoC) and contraction stress (CS). Results: There was an optimal CQ and EDMAB concentration that resulted in maximum DC and KHN, beyond which increased concentration resulted in a decline in those properties. KHN testing identified two regions of maxima with best overlaps occurring at CQ:EDMAB ratio of 1.44:0.42 and 1.05:1.65 mol%. DC evaluation showed one region of maximum, the best overlap occurring at CQ:EDMAB ratio of 2.40:0.83 mol%. DoC was 4 mm. Overall, maximum CS was attained before the system reached the maximum possible conversion and hardness. Significance: (1) Selection of optimal photoinitiator/amine concentration is critical to materials' formulation, for excessive amounts can compromise materials' properties. (2) There was no sufficient evidence to suggest that contraction stress can be reduced by lowering CQ/EDMAB concentration without compromising DC and KHN.

AB - Objectives: The aim of this study was to determine the concentrations of the photosensitizer (camphoroquinone, CQ) and coinitiator (ethyl-4-dimethylaminobenzoate, EDMAB) that resulted in maximum conversion but generated minimum contraction stress in experimental composites. Methods: Experimental composites were prepared with an identical resin formulation [TEGDMA:UDMA:bis-GMA of 30.25:33.65:33.65]. Five groups of resin were prepared at varied CQ concentrations (0.1, 0.2, 0.4, 0.8 and 1.6 wt% of the resin). Five subgroups of resin were prepared at each level of CQ concentration, by adding EDMAB at 0.05, 0.1, 0.2, 0.4 and 0.8 wt% of the resin, resulting in 25 experimental resins. Finally, strontium glass (∼3 μm) and silica (0.04 μm) were added at 71.5 and 12.6 wt% of the composite, respectively. Samples (n = 3) were then evaluated for Knoop hardness (KHN), degree of conversion (DC), depth of cure (DoC) and contraction stress (CS). Results: There was an optimal CQ and EDMAB concentration that resulted in maximum DC and KHN, beyond which increased concentration resulted in a decline in those properties. KHN testing identified two regions of maxima with best overlaps occurring at CQ:EDMAB ratio of 1.44:0.42 and 1.05:1.65 mol%. DC evaluation showed one region of maximum, the best overlap occurring at CQ:EDMAB ratio of 2.40:0.83 mol%. DoC was 4 mm. Overall, maximum CS was attained before the system reached the maximum possible conversion and hardness. Significance: (1) Selection of optimal photoinitiator/amine concentration is critical to materials' formulation, for excessive amounts can compromise materials' properties. (2) There was no sufficient evidence to suggest that contraction stress can be reduced by lowering CQ/EDMAB concentration without compromising DC and KHN.

KW - Coinitiator

KW - Contraction stress

KW - Degree of conversion

KW - Depth of cure

KW - Knoop hardness

KW - Photosensitizer

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