Photoinitiator type and applicability of exposure reciprocity law in filled and unfilled photoactive resins

J. G. Leprince; M. Hadis; A. C. Shortall; J. L. Ferracane; J. Devaux; G. Leloup; W. M. Palin

doi:10.1016/j.dental.2010.09.011

Photoinitiator type and applicability of exposure reciprocity law in filled and unfilled photoactive resins

J. G. Leprince
, M. Hadis
, A. C. Shortall
, J. L. Ferracane
, J. Devaux
, G. Leloup
, W. M. Palin

School of Dentistry

Research output: Contribution to journal › Article › peer-review

154 Scopus citations

Abstract

Objectives: To test the influence of photoinitiator type and filler particle inclusion on the validity of exposure reciprocity law. Materials and methods: 50/50 wt% Bis-GMA/TEGDMA resins were prepared with equimolar concentrations of camphorquinone/DMAEMA (0.20/0.80 mass%) (CQ) or Lucirin-TPO (0.42 mass%), and were used either unfilled or filled to 75 mass%. Specimens were cured with a halogen Swiss Master Light (EMS, Switzerland) using four different curing protocols: 400 mW/cm² for 45 s as reference protocol (18 J/cm²), 1500 mW/cm² for 12 s (18 J/cm²), 3000 mW/cm² for 6 s (18 J/cm²) and 3 s (9 J/cm ²). Degree of conversion (DC) was measured in real time for 70 s by FT-NIRS and temperature rise using a thermocouple. Depth of cure was determined with a penetrometer technique. Results: With respect to DC and depth of cure, exposure reciprocity law did not hold for any tested material, except for the depth of cure of filled CQ-based materials. At similar radiant exposure, DC was significantly higher (p < 0.05) for all unfilled and filled TPO-based materials compared with CQ-based materials. As exposure time was reduced and irradiance increased, TPO-based materials exhibited higher DC whilst an opposite trend was observed for CQ-based materials (p < 0.05). For similar curing regimes, depth of cure of CQ-based materials remained significantly greater than that of TPO-based materials. Adding fillers generally reduced DC, except at higher irradiance for CQ-based materials where a positive effect was observed (p < 0.05). Significance: The validity of exposure reciprocity law was dependent on several factors, among which photoinitiator type and filler content were important. Lucirin-TPO is a highly reactive and efficient photoinitiator, which may allow the potential for a reduction in curing time of TPO-based photoactive materials in thin sections.

Original language	English (US)
Pages (from-to)	157-164
Number of pages	8
Journal	Dental Materials
Volume	27
Issue number	2
DOIs	https://doi.org/10.1016/j.dental.2010.09.011
State	Published - Feb 2011

Funding

J. Leprince thanks the Funds for Scientific Research (F.R.S.-FNRS) for his research fellow position and J Ferracane's effort was supported in part by NIH/NIDCR grant 5R21DE16758-2 . This investigation was funded by the Engineering and Physical Sciences Research Council (grant number EP/E026257/1 ) and the work presented at the Academy of Dental Materials conference, 2009 (Portland, OR, USA) and winner of the Paffenbarger Award for outstanding student presentation. The authors would like to thank the Academy for their continual support for young investigators.

Funders	Funder number
Author National Institutes of Health National Institutes of Health National Institutes of Health National Institutes of Health The Bev Hartig Huntington's Disease Foundation National Institutes of Health
National Institute of Dental and Craniofacial Research	5R21DE16758-2
Engineering and Physical Sciences Research Council	EP/E026257/1
Fonds De La Recherche Scientifique - FNRS

Keywords

Degree of conversion
Dental resin composite
Depth of cure
Exposure reciprocity law
Photoinitiator
Polymerization kinetics

ASJC Scopus subject areas

General Materials Science
General Dentistry
Mechanics of Materials

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10.1016/j.dental.2010.09.011

Cite this

@article{bf80ff4bb6a246a993b12602717de620,

title = "Photoinitiator type and applicability of exposure reciprocity law in filled and unfilled photoactive resins",

abstract = "Objectives: To test the influence of photoinitiator type and filler particle inclusion on the validity of exposure reciprocity law. Materials and methods: 50/50 wt\% Bis-GMA/TEGDMA resins were prepared with equimolar concentrations of camphorquinone/DMAEMA (0.20/0.80 mass\%) (CQ) or Lucirin-TPO (0.42 mass\%), and were used either unfilled or filled to 75 mass\%. Specimens were cured with a halogen Swiss Master Light (EMS, Switzerland) using four different curing protocols: 400 mW/cm2 for 45 s as reference protocol (18 J/cm2), 1500 mW/cm2 for 12 s (18 J/cm2), 3000 mW/cm2 for 6 s (18 J/cm2) and 3 s (9 J/cm 2). Degree of conversion (DC) was measured in real time for 70 s by FT-NIRS and temperature rise using a thermocouple. Depth of cure was determined with a penetrometer technique. Results: With respect to DC and depth of cure, exposure reciprocity law did not hold for any tested material, except for the depth of cure of filled CQ-based materials. At similar radiant exposure, DC was significantly higher (p < 0.05) for all unfilled and filled TPO-based materials compared with CQ-based materials. As exposure time was reduced and irradiance increased, TPO-based materials exhibited higher DC whilst an opposite trend was observed for CQ-based materials (p < 0.05). For similar curing regimes, depth of cure of CQ-based materials remained significantly greater than that of TPO-based materials. Adding fillers generally reduced DC, except at higher irradiance for CQ-based materials where a positive effect was observed (p < 0.05). Significance: The validity of exposure reciprocity law was dependent on several factors, among which photoinitiator type and filler content were important. Lucirin-TPO is a highly reactive and efficient photoinitiator, which may allow the potential for a reduction in curing time of TPO-based photoactive materials in thin sections.",

keywords = "Degree of conversion, Dental resin composite, Depth of cure, Exposure reciprocity law, Photoinitiator, Polymerization kinetics",

author = "Leprince, \{J. G.\} and M. Hadis and Shortall, \{A. C.\} and Ferracane, \{J. L.\} and J. Devaux and G. Leloup and Palin, \{W. M.\}",

note = "Funding Information: J. Leprince thanks the Funds for Scientific Research (F.R.S.-FNRS) for his research fellow position and J Ferracane's effort was supported in part by NIH/NIDCR grant 5R21DE16758-2 . Funding Information: This investigation was funded by the Engineering and Physical Sciences Research Council (grant number EP/E026257/1 ) and the work presented at the Academy of Dental Materials conference, 2009 (Portland, OR, USA) and winner of the Paffenbarger Award for outstanding student presentation. The authors would like to thank the Academy for their continual support for young investigators. ",

year = "2011",

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doi = "10.1016/j.dental.2010.09.011",

language = "English (US)",

volume = "27",

pages = "157--164",

journal = "Dental Materials",

issn = "0109-5641",

publisher = "Elsevier Inc.",

number = "2",

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TY - JOUR

T1 - Photoinitiator type and applicability of exposure reciprocity law in filled and unfilled photoactive resins

AU - Leprince, J. G.

AU - Hadis, M.

AU - Shortall, A. C.

AU - Ferracane, J. L.

AU - Devaux, J.

AU - Leloup, G.

AU - Palin, W. M.

N1 - Funding Information: J. Leprince thanks the Funds for Scientific Research (F.R.S.-FNRS) for his research fellow position and J Ferracane's effort was supported in part by NIH/NIDCR grant 5R21DE16758-2 . Funding Information: This investigation was funded by the Engineering and Physical Sciences Research Council (grant number EP/E026257/1 ) and the work presented at the Academy of Dental Materials conference, 2009 (Portland, OR, USA) and winner of the Paffenbarger Award for outstanding student presentation. The authors would like to thank the Academy for their continual support for young investigators.

PY - 2011/2

Y1 - 2011/2

N2 - Objectives: To test the influence of photoinitiator type and filler particle inclusion on the validity of exposure reciprocity law. Materials and methods: 50/50 wt% Bis-GMA/TEGDMA resins were prepared with equimolar concentrations of camphorquinone/DMAEMA (0.20/0.80 mass%) (CQ) or Lucirin-TPO (0.42 mass%), and were used either unfilled or filled to 75 mass%. Specimens were cured with a halogen Swiss Master Light (EMS, Switzerland) using four different curing protocols: 400 mW/cm2 for 45 s as reference protocol (18 J/cm2), 1500 mW/cm2 for 12 s (18 J/cm2), 3000 mW/cm2 for 6 s (18 J/cm2) and 3 s (9 J/cm 2). Degree of conversion (DC) was measured in real time for 70 s by FT-NIRS and temperature rise using a thermocouple. Depth of cure was determined with a penetrometer technique. Results: With respect to DC and depth of cure, exposure reciprocity law did not hold for any tested material, except for the depth of cure of filled CQ-based materials. At similar radiant exposure, DC was significantly higher (p < 0.05) for all unfilled and filled TPO-based materials compared with CQ-based materials. As exposure time was reduced and irradiance increased, TPO-based materials exhibited higher DC whilst an opposite trend was observed for CQ-based materials (p < 0.05). For similar curing regimes, depth of cure of CQ-based materials remained significantly greater than that of TPO-based materials. Adding fillers generally reduced DC, except at higher irradiance for CQ-based materials where a positive effect was observed (p < 0.05). Significance: The validity of exposure reciprocity law was dependent on several factors, among which photoinitiator type and filler content were important. Lucirin-TPO is a highly reactive and efficient photoinitiator, which may allow the potential for a reduction in curing time of TPO-based photoactive materials in thin sections.

AB - Objectives: To test the influence of photoinitiator type and filler particle inclusion on the validity of exposure reciprocity law. Materials and methods: 50/50 wt% Bis-GMA/TEGDMA resins were prepared with equimolar concentrations of camphorquinone/DMAEMA (0.20/0.80 mass%) (CQ) or Lucirin-TPO (0.42 mass%), and were used either unfilled or filled to 75 mass%. Specimens were cured with a halogen Swiss Master Light (EMS, Switzerland) using four different curing protocols: 400 mW/cm2 for 45 s as reference protocol (18 J/cm2), 1500 mW/cm2 for 12 s (18 J/cm2), 3000 mW/cm2 for 6 s (18 J/cm2) and 3 s (9 J/cm 2). Degree of conversion (DC) was measured in real time for 70 s by FT-NIRS and temperature rise using a thermocouple. Depth of cure was determined with a penetrometer technique. Results: With respect to DC and depth of cure, exposure reciprocity law did not hold for any tested material, except for the depth of cure of filled CQ-based materials. At similar radiant exposure, DC was significantly higher (p < 0.05) for all unfilled and filled TPO-based materials compared with CQ-based materials. As exposure time was reduced and irradiance increased, TPO-based materials exhibited higher DC whilst an opposite trend was observed for CQ-based materials (p < 0.05). For similar curing regimes, depth of cure of CQ-based materials remained significantly greater than that of TPO-based materials. Adding fillers generally reduced DC, except at higher irradiance for CQ-based materials where a positive effect was observed (p < 0.05). Significance: The validity of exposure reciprocity law was dependent on several factors, among which photoinitiator type and filler content were important. Lucirin-TPO is a highly reactive and efficient photoinitiator, which may allow the potential for a reduction in curing time of TPO-based photoactive materials in thin sections.

KW - Degree of conversion

KW - Dental resin composite

KW - Depth of cure

KW - Exposure reciprocity law

KW - Photoinitiator

KW - Polymerization kinetics

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UR - https://www.scopus.com/pages/publications/78651255366#tab=citedBy

U2 - 10.1016/j.dental.2010.09.011

DO - 10.1016/j.dental.2010.09.011

M3 - Article

C2 - 21067803

AN - SCOPUS:78651255366

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Photoinitiator type and applicability of exposure reciprocity law in filled and unfilled photoactive resins

Abstract

Funding

Keywords

ASJC Scopus subject areas

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