Spatio-temporal analysis of shrinkage vectors during photo-polymerization of composite

Hyun Jeong Kweon, Jack Ferracane, Kyongok Kang, Jan Dhont, In Bog Lee

Research output: Contribution to journalArticle

13 Citations (Scopus)

Abstract

Objectives The purpose of this study was to validate a new method to investigate the polymerization shrinkage vectors of composite during light curing and to evaluate the overall utility and significance of the technique. Methods An optical instrument was developed to measure the location and direction of the polymerization shrinkage strain vectors of dental composite during light curing using a particle tracking method with computer vision. The measurement system consisted of a CCD color camera, a lens and a filter, and software for multi-particle tracking. A universal hybrid composite (Z250, 3M ESPE, St. Paul MN, USA) was molded into thin disk-shaped specimens (un-bonded and bonded) or filled into a cavity within a tooth slab (bonded). The composite surface was coated with fluorescent particles prior to light curing. The images of the fluorescent particles were stored at 2 frames/s for 10 min, and the movements of the particles on the composite surface were tracked with computer vision during curing. The polymerization shrinkage strain vectors as a function of time and location were analyzed. The volume shrinkage of the composite was also measured for comparison. Results The linear and volume shrinkage of the composite at 10 min were 0.75 (0.12)% and 2.26 (0.18)%, respectively. The polymerization shrinkage vectors were directed toward the center of the specimen and were isotropic in all directions when the composite was allowed to shrinkage freely without bonding. In contrast, the shrinkage vectors were directed toward the bonding surface and were anisotropic when the composite was bonded to a fixed wall. The regional displacement vectors of composite in a tooth cavity were dependent on the location, depth and time. Significance The new instrument was able to measure the regional linear shrinkage strain vectors over an entire surface of a composite specimen as a function of time and location. Therefore, this instrument can be used to characterize the shrinkage behaviors for a wide range of commercial and experimental visible-light-cure materials in relation to the composition, boundary condition and cavity geometry.

Original languageEnglish (US)
Pages (from-to)1236-1243
Number of pages8
JournalDental Materials
Volume29
Issue number12
DOIs
StatePublished - Dec 2013

Fingerprint

Spatio-Temporal Analysis
Photopolymerization
Polymerization
Light
Tooth
Composite materials
Curing
Lenses
Software
Color
Computer vision
Dental composites
Optical instruments
Charge coupled devices
Cameras
Direction compound
Boundary conditions

Keywords

  • Composite
  • Computer vision
  • Particle tracking
  • Polymerization shrinkage vector

ASJC Scopus subject areas

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

Cite this

Spatio-temporal analysis of shrinkage vectors during photo-polymerization of composite. / Kweon, Hyun Jeong; Ferracane, Jack; Kang, Kyongok; Dhont, Jan; Lee, In Bog.

In: Dental Materials, Vol. 29, No. 12, 12.2013, p. 1236-1243.

Research output: Contribution to journalArticle

Kweon, Hyun Jeong ; Ferracane, Jack ; Kang, Kyongok ; Dhont, Jan ; Lee, In Bog. / Spatio-temporal analysis of shrinkage vectors during photo-polymerization of composite. In: Dental Materials. 2013 ; Vol. 29, No. 12. pp. 1236-1243.
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abstract = "Objectives The purpose of this study was to validate a new method to investigate the polymerization shrinkage vectors of composite during light curing and to evaluate the overall utility and significance of the technique. Methods An optical instrument was developed to measure the location and direction of the polymerization shrinkage strain vectors of dental composite during light curing using a particle tracking method with computer vision. The measurement system consisted of a CCD color camera, a lens and a filter, and software for multi-particle tracking. A universal hybrid composite (Z250, 3M ESPE, St. Paul MN, USA) was molded into thin disk-shaped specimens (un-bonded and bonded) or filled into a cavity within a tooth slab (bonded). The composite surface was coated with fluorescent particles prior to light curing. The images of the fluorescent particles were stored at 2 frames/s for 10 min, and the movements of the particles on the composite surface were tracked with computer vision during curing. The polymerization shrinkage strain vectors as a function of time and location were analyzed. The volume shrinkage of the composite was also measured for comparison. Results The linear and volume shrinkage of the composite at 10 min were 0.75 (0.12){\%} and 2.26 (0.18){\%}, respectively. The polymerization shrinkage vectors were directed toward the center of the specimen and were isotropic in all directions when the composite was allowed to shrinkage freely without bonding. In contrast, the shrinkage vectors were directed toward the bonding surface and were anisotropic when the composite was bonded to a fixed wall. The regional displacement vectors of composite in a tooth cavity were dependent on the location, depth and time. Significance The new instrument was able to measure the regional linear shrinkage strain vectors over an entire surface of a composite specimen as a function of time and location. Therefore, this instrument can be used to characterize the shrinkage behaviors for a wide range of commercial and experimental visible-light-cure materials in relation to the composition, boundary condition and cavity geometry.",
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AB - Objectives The purpose of this study was to validate a new method to investigate the polymerization shrinkage vectors of composite during light curing and to evaluate the overall utility and significance of the technique. Methods An optical instrument was developed to measure the location and direction of the polymerization shrinkage strain vectors of dental composite during light curing using a particle tracking method with computer vision. The measurement system consisted of a CCD color camera, a lens and a filter, and software for multi-particle tracking. A universal hybrid composite (Z250, 3M ESPE, St. Paul MN, USA) was molded into thin disk-shaped specimens (un-bonded and bonded) or filled into a cavity within a tooth slab (bonded). The composite surface was coated with fluorescent particles prior to light curing. The images of the fluorescent particles were stored at 2 frames/s for 10 min, and the movements of the particles on the composite surface were tracked with computer vision during curing. The polymerization shrinkage strain vectors as a function of time and location were analyzed. The volume shrinkage of the composite was also measured for comparison. Results The linear and volume shrinkage of the composite at 10 min were 0.75 (0.12)% and 2.26 (0.18)%, respectively. The polymerization shrinkage vectors were directed toward the center of the specimen and were isotropic in all directions when the composite was allowed to shrinkage freely without bonding. In contrast, the shrinkage vectors were directed toward the bonding surface and were anisotropic when the composite was bonded to a fixed wall. The regional displacement vectors of composite in a tooth cavity were dependent on the location, depth and time. Significance The new instrument was able to measure the regional linear shrinkage strain vectors over an entire surface of a composite specimen as a function of time and location. Therefore, this instrument can be used to characterize the shrinkage behaviors for a wide range of commercial and experimental visible-light-cure materials in relation to the composition, boundary condition and cavity geometry.

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