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(Reference retrieved automatically from SciELO through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

Minimization of polymerization shrinkage effects on composite resins by the control of irradiance during the photoactivation process

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Guimaraes, Gabriel Felipe [1] ; Marcelino, Edilmar [2] ; Cesarino, Ivana [1] ; Vicente, Fabio Bossoi [3] ; Grandini, Carlos Roberto [3, 4] ; Simoes, Rafael Plana [1]
Total Authors: 6
[1] Univ Estadual Paulista, Fac Ciencias Agron, Dept Bioproc & Biotecnol, Botucatu, SP - Brazil
[2] Univ Estadual Paulista, Inst Biociencias, Botucatu, SP - Brazil
[3] Univ Estadual Paulista, Fac Ciencias, Lab Relaxacoes Anelast & Biomat, Bauru, SP - Brazil
[4] Inst Biomat Tribocorrosao & Nanomed Ramo Brasilei, Bauru, SP - Brazil
Total Affiliations: 4
Document type: Journal article
Source: Journal of Applied Oral Science; v. 26, p. -, 2018.
Web of Science Citations: 1

Abstract High levels of shrinkage stress caused by volumetric variations during the activation process are one of the main problems in the practical application of composite resins. Objective The aim of this study is to reduce the shrinkage stress and minimize the effects caused by composite resin volumetric variation due to the photopolymerization. In this way, this work proposes a systematic study to determine the optimal dimming function to be applied to light curing processes. Material and Methods The study was performed by applying mathematical techniques to the optimization of nonlinear objective functions. The effectiveness of the dimming function was evaluated by monitoring the polymerization shrinkage stress during the curing process of five brands/models of composites. This monitoring was performed on a universal testing machine using two steel bases coupled in the arms of the machine where the resin was inserted and polymerized. The quality of the composites cured by the proposed method was analyzed and compared with the conventional photoactivation method by experiments to determine their degree of conversion (DC). Absorbance measurements were performed using Fourier-transform infrared spectroscopy (FT-IR). A T-test was performed on DC results to compare the photoactivation techniques. We also used scanning electron microscopy (SEM) to analyze in-vitro the adhesion interface of the resin in human teeth. Results Our results showed that the use of the optimal dimming function, named as exponential, resulted in the significant reduction of the shrinkage stress (~36.88% ±6.56 when compared with the conventional method) without affecting the DC (t=0.86, p-value=0.44). The SEM analyses show that the proposed process can minimize or even eliminate adhesion failures between the tooth and the resin in dental restorations. Conclusion The results from this study can promote the improvement of the composite resin light curing process by the minimization of polymerization shrinkage effects, given an operational standardization of the photoactivation process. (AU)

FAPESP's process: 15/02136-2 - Development of advanced materials based on graphene and metal nanoparticles for analysis of antibiotic in wastewater
Grantee:Ivana Cesarino
Support type: Regular Research Grants