title: Real-time dimensional change in light-cured composites at various depths using laser speckle contrast analysis.
abstract: Laser speckle contrast analysis is an interferometric technique that is used to measure the displacement of the rough surface of a specimen. The purpose of this study was to present a laser speckle correlation method for monitoring real-time dimensional changes of light-cured composites. Uncured composite was condensed into a glass tube and irradiated for 30 s with 600 or 200 mW cm(-2). The speckle patterns obtained from lateral and bottom composite surfaces were monitored using a speckle analyser. The speckle field is recorded in a digital frame and stored by image processing system as the carrier of information on the displacement of the tested surface. The calculated values were obtained for each pair of adjacent patterns and the changes in speckle contrast as a function time were obtained from five repeated measurements. The overall magnitude of the speckle contrasts decreased soon after the initial light exposure and gradually increased thereafter. The speckle contrasts obtained from the bottom surface were smaller than those obtained from the lateral surface. This tendency was more pronounced when the specimen was irradiated with lower power density. It can be concluded that monitoring differential shrinkage at various levels of depth can be achieved with this new technique.
authors.affiliation: Department of Operative Dentistry, Nihon University Graduate School of Dentistry, 1-8-13, Kanda-Surugadai, Chiyoda-ku, Tokyo 101-8310, Japan.
authors.forename: Tomomi
authors.initials: T
authors.lastname: Sato
authors.forename: Masashi
authors.initials: M
authors.lastname: Miyazaki
authors.forename: Akitomo
authors.initials: A
authors.lastname: Rikuta
mesh_terms: D017438:Bisphenol A-Glycidyl Methacrylate / Q000737:chemistry / Q000528:radiation effects; D003188:Composite Resins / Q000737:chemistry* / Q000528:radiation effects; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007368:Interferometry / Q000295:instrumentation / Q000379:methods; D007834:Lasers; D008027:Light; D008422:Materials Testing; D011108:Polymers / Q000737:chemistry / Q000528:radiation effects; D013499:Surface Properties; D013997:Time Factors
chemical_list: C470433:Beautifil composite resin; D003188:Composite Resins; C444701:Filtek Z250; C083468:Lite-fil CR; D011108:Polymers; C086113:palfique estelite; D017438:Bisphenol A-Glycidyl Methacrylate