Five second photoactivation? A microhardness and marginal adaptation in vitro study in composite resin restorations

Shimokawa, Carlos Alberto Kenji; Carneiro, Paula Mendes Acatauassú; Lobo, Tamile Rocha da Silva; Arana-Chavez, Victor E.; Youssef, Michel Nicolau; Turbino, Miriam Lacalle

doi:10.1111/idj.12227

Cited by 10 publications

(7 citation statements)

References 38 publications

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“…However, the soft-start technique does not have a rigid mathematical standardization for the contraction stress function optimization and, because of this, the results obtained from this technique are not as significant as those presented in this study. On this basis, the exponential photoactivation method can improve the marginal adaptation of composite restorations 16 .…”

Section: Discussionmentioning

confidence: 99%

“…However, there is no consensus about the time and irradiance parameters in the soft-start techniques. Therefore, in the literature, it is possible to find soft-start protocols with different values of irradiance and activation time, both for the initial phase of low irradiance and for the final phase of high irradiance 16 . In addition, this type of study is limited to the functions of conventional light curing devices, which do not allow continuous variation of the irradiance during the activation.…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2018

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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.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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

et al. 2018

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“…The moment of the restriction mobility of free radicals is named the gel point (Dall'Magro et al, 2007;Rueggeberg et al, 2017). In the third event, i.e., vitrification, the reaction ends with an extremely high viscosity level and ultimate properties of the resin-matrix composites (Andrzejewska, 2001;Shimokawa et al, 2016). At the molecular level, viscosity has a complex performance that determines the atomic diffusion during polymerization, which directly affects the degree of conversion of monomers in the organic matrix (Fugolin et al, 2020a).…”

Section: Relationship Between Polymerization Inorganic Load and Organ...mentioning

confidence: 99%

“…O momento de perda dessa capacidade é designado de ponto de gelificação ou ponto de gel (Dall'Magro et al, 2007;Rueggeberg et al, 2017). A terceira etapa, chamada de vitrificação, é caracterizada pela limitação na taxa de propagação, terminando a reação com um nível de extrema viscosidade e obtenção das propriedades esperadas do material (Andrzejewska, 2001;Shimokawa et al, 2016). A viscosidade das resinas compostas tem uma ação fundamental na cinética da polimerização, absorção de água, solubilidade, tensões de polimerização, propriedades mecânicas e et al, 2020; Uctasli et al, 2005).…”

Section: Relação Entre a Polimerização Carga Inorgânica E Matriz Orgâ...unclassified

Relationship between the inorganic content and the polymerization of the organic matrix of resin composites for dentistry: a narrative review

Fidalgo-Pereira¹,

Carpio²,

Carvalho³

et al. 2022

RevSALUS

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Introduction: In recent years, resin-matrix composite materials have revealed a fast technological improvement for dental applications. However, there are still some drawbacks related to the chemical composition, polymerization, and mechanical properties of resin-matrix composites with consequences in long-term clinical success. Objective: This study aimed to perform a narrative review regarding the effects of inorganic fillers on the organic matrix polymerization of resin-matrix composites. Materials and Methods: A search was performed in PubMed using relevant related key terms related to the chemical composition, properties and polymerization of resin matrix composites. Relevant studies published between 2001 and 2021 were selected. Results: The studies included in the present research provided relevant information on the chemical composition and properties of resin composites and polymerization factors, including the time, wavelength mode, and equipment. Studies have reported that silica and silicate nano-scale particles improve light transmission through resin-matrix composites and the degree of conversion of monomers in the organic matrix. Micrometric particles with a high refractive index can decrease the degree of conversion of monomers in the organic matrix. Conclusion: The polymerization of resin matrix composites is affected by light scattering due to the type of inorganic particles and the differences in refractive indexes of inorganic and organic contents.

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“…Tauböck et al 5 verificaram que os valores de dureza não foram afetados quando se utilizou a técnica de polimerização de pulso tardio, comparando quatro tipos de resinas compostas. Corroborando com esse achado, Shimokawa et al 9 não detectaram alteração na dureza das restaurações ao utilizar diferentes protocolos de fotoativação para resinas compostas (luz contínua -20 segundos, tecnologia PLS -5 segundos e pulso tardio -20 segundos a 6 mm distância + 10 segundos próximo superfície). Já os resultados apresentados nos desfechos aqui alcançados demonstraram a influência do fator isolado da técnica (p < 0,01) na variável dependente estudada (Tabela 2).…”

Section: Discussionunclassified

O método de fotopolimerização é capaz de influenciar nos valores de microdureza das resinas compostas? Um estudo in vitro

FERNANDES¹,

Belém

Paschoal

et al. 2022

Rev. odontol. UNESP

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Resumo Introdução a inovação dos métodos de fotopolimerização foi proposta na tentativa de diminuir o estresse de contração de polimerização das resinas compostas e proporcionar maior conforto ao paciente, reduzindo o tempo de atendimento odontológico. Objetivo avaliar a microdureza de duas resinas compostas nanoparticuladas submetidas a diferentes técnicas de polimerização. Material e método quarenta espécimes foram divididos em quatro grupos (n=10) da seguinte forma: Filtek Z350 XT® + técnica imediata (GI); Filtek One Bulkfill® + técnica imediata (GII); Filtek Z350 XT® + técnica de pulso tardio (GIII); Filtek One Bulkfill® + técnica de pulso tardio (GIV). Após o armazenamento em água destilada à temperatura ambiente, os corpos de prova foram direcionados para a medição de microdureza. Utilizou-se teste T para comparação de técnicas e teste Two-Way ANOVA para calcular os efeitos das resinas compostas, técnicas de polimerização e interações referentes à variável dependente (p ≤0,05). Resultado a resina Filtek Z350 XT® apresentou maior dureza na técnica imediata (GI - 312,45 ± 64,37) e pulso tardio (GIII - 244,50 ± 75,63) comparado à resina Filtek One Bulkfill®, em ambas as técnicas. Observaram-se maiores valores de dureza referentes à técnica imediata, com diferença estatística significativa em relação à resina testada (p = 0,04 - Filtek Z350 XT®; p = 0,03 - Filtek One Bulkfill®). Ambos os fatores isolados (resina e técnicas) apresentaram efeito nos valores de microdureza (p = 0,02 e p < 0,01, respectivamente). Conclusão a técnica convencional demonstrou atingir maiores valores de dureza quando comparada à técnica de polimerização alternativa.

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Five second photoactivation? A microhardness and marginal adaptation in vitro study in composite resin restorations

Abstract: The PLS - 5 second and soft-start protocols did not alter the hardness of the restorations. Moreover, the PLS - 5 second protocol did not alter the marginal adaptation, whereas the soft-start protocol improved marginal adaptation.

Cited by 10 publications

References 38 publications

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

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

Relationship between the inorganic content and the polymerization of the organic matrix of resin composites for dentistry: a narrative review

O método de fotopolimerização é capaz de influenciar nos valores de microdureza das resinas compostas? Um estudo in vitro

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