Light irradiance through novel CAD-CAM block materials and degree of conversion of composite cements.

Autor: Lise DP; KU Leuven (University of Leuven), Department of Oral Health Sciences, BIOMAT & University Hospitals Leuven (UZ Leuven), Dentistry, Leuven, Belgium; UFSC (Federal University of Santa Catarina), Department of Dentistry, Operative Dentistry, Florianópolis, Brazil., Van Ende A; KU Leuven (University of Leuven), Department of Oral Health Sciences, BIOMAT & University Hospitals Leuven (UZ Leuven), Dentistry, Leuven, Belgium., De Munck J; KU Leuven (University of Leuven), Department of Oral Health Sciences, BIOMAT & University Hospitals Leuven (UZ Leuven), Dentistry, Leuven, Belgium., Yoshihara K; Okayama University Hospital, Center for Innovative Clinical Medicine, Okayama, Japan., Nagaoka N; Okayama University Dental School, Advanced Research Center for Oral and Craniofacial Sciences, Okayama, Japan., Cardoso Vieira LC; UFSC (Federal University of Santa Catarina), Department of Dentistry, Operative Dentistry, Florianópolis, Brazil., Van Meerbeek B; KU Leuven (University of Leuven), Department of Oral Health Sciences, BIOMAT & University Hospitals Leuven (UZ Leuven), Dentistry, Leuven, Belgium. Electronic address: bart.vanmeerbeek@kuleuven.be.
Jazyk: angličtina
Zdroj: Dental materials : official publication of the Academy of Dental Materials [Dent Mater] 2018 Feb; Vol. 34 (2), pp. 296-305. Date of Electronic Publication: 2017 Nov 21.
DOI: 10.1016/j.dental.2017.11.008
Abstrakt: Objective: To assess light irradiance (LI) delivered by two light-curing units (LCU's) and to measure the degree of conversion (DC) of three composite cements, when cured through different thicknesses of two novel CAD-CAM block materials.
Methods: 100-μm-thick films of a dual-curable composite cement (G-CEM LinkAce, GC), a light-curable flowable resin-based composite (RBC) (G-ænial Universal Flo, GC) and a micro-hybrid RBC (G-ænial Posterior, GC) were investigated as luting agents. Two 'polymer-ceramic' CAD-CAM blocks (Cerasmart, GC; Enamic, Vita Zahnfabrik) were sectioned in slabs with different thicknesses (1, 3 and 5mm). LI at the bottom of the specimens was measured using a calibrated spectrometer, while being light-cured through the CAD-CAM block slabs for 40s with a low- (±500mW/cm 2 ) or high- (±1,600mW/cm 2 ) irradiance LCU (n=5). After light-curing, micro-Raman spectra of the composite films were acquired to determine DC at 5min, 10min, 1h and 24h. LI data were statistically analyzed by Kruskal-Wallis followed by post-hoc comparisons, while a linear mixed-effect model was applied for the DC analysis. In addition, the CAD-CAM blocks ultrastructure was characterized upon argon-ion slicing using scanning transmission electron microscopy (STEM). Finally, light transmission (LT) through each CAD-CAM block material was assessed using a spectrophotometer.
Results: Curing-light attenuation and DC were significantly influenced by thickness and type of the overlying material. LCU only had a significant effect on DC of the micro-hybrid RBC. DC significantly increased over time for all composite cements. CAD-CAM block structural analysis revealed a relatively small and homogenous filler configuration (mean filler size of 0.2-0.5μm) for Cerasmart, while Enamic contained ceramic grains varying in shape and size (1-10μm), which were interconnected by the polymer-based network. LT was much higher at a wavelength range of 300-800nm for Cerasmart than for Enamic.
Significance: Light-curable composite cements can be cured through a restoration up to 2.7-mm thickness, depending on the kind of CAD-CAM material. A high-irradiance LCU only has a limited effect on the maximum thickness of the polymer-ceramic CAD-CAM material that can be cured through.
(Copyright © 2017 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.)
Databáze: MEDLINE
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