André L Faria-E-Silva1, Carmem S Pfeifer2. 1. Department of Dentistry, Federal University of Sergipe, Rua Claudio Batista s/n, 49060-100, Aracaju, SE, Brazil. Electronic address: fariaesilva.andre@gmail.com. 2. Department of Restorative Dentistry, Division of Biomaterials and Biomechanics, Oregon Health & Science University, 2730 SW Moody Ave, 97201, Portland, OR, USA. Electronic address: pfeiferc@ohsu.edu.
Abstract
OBJECTIVE: This study evaluated the properties of experimental dual-cured cements containing thiourethane (TU) and low concentrations of p-Tolyldiethanolamnie (DHEPT) and benzoyl peroxide (BPO) as chemical initiators. METHODS: BisGMA/TEGDMA-based dual-cured cement was formulated with 1.0 wt% DHEPT and 0.75 wt% BPO as initiators and used as control. The concentration of BPO was adjusted to 0.1 wt% in catalyst paste of experimental cements, and two base pastes containing TU and 0.5 wt% or 0.25 wt% of DHEPT were formulated. The rheological behavior and kinetics of polymerization of cements were assessed in the absence of light activation. The kinetics of polymerization was also evaluated for cements light-activated immediately or 5 min after the start of mixing. Polymerization stress, flexural strength and elastic modulus (n = 5) were also evaluated under these conditions. RESULTS: Cements with TU presented lower viscosity than the control, improved working time (0.25% DHEPT > 0.5% DHEPT) and higher conversion in the absence of light-activation. Delaying the light-activation reduced the maximum rate of polymerization (Rpmax) but did not affect the conversion or stress. The addition of TU increased the Rpmax and conversion, and reduced the stress when compared to the control, without affecting the flexural strength. Except for the control with delayed light-activation (highest values), the other experimental conditions yielded similar modulus. SIGNIFICANCE: Adding TU and using a low concentration of DHEPT/BPO resulted in dual-cured cements with longer working time, reduced polymerization stress and increased conversion even in the absence of light, with no significant effect on the mechanical properties.
OBJECTIVE: This study evaluated the properties of experimental dual-cured cements containing thiourethane (TU) and low concentrations of p-Tolyldiethanolamnie (DHEPT) and benzoyl peroxide (BPO) as chemical initiators. METHODS:BisGMA/TEGDMA-based dual-cured cement was formulated with 1.0 wt% DHEPT and 0.75 wt% BPO as initiators and used as control. The concentration of BPO was adjusted to 0.1 wt% in catalyst paste of experimental cements, and two base pastes containing TU and 0.5 wt% or 0.25 wt% of DHEPT were formulated. The rheological behavior and kinetics of polymerization of cements were assessed in the absence of light activation. The kinetics of polymerization was also evaluated for cements light-activated immediately or 5 min after the start of mixing. Polymerization stress, flexural strength and elastic modulus (n = 5) were also evaluated under these conditions. RESULTS: Cements with TU presented lower viscosity than the control, improved working time (0.25% DHEPT > 0.5% DHEPT) and higher conversion in the absence of light-activation. Delaying the light-activation reduced the maximum rate of polymerization (Rpmax) but did not affect the conversion or stress. The addition of TU increased the Rpmax and conversion, and reduced the stress when compared to the control, without affecting the flexural strength. Except for the control with delayed light-activation (highest values), the other experimental conditions yielded similar modulus. SIGNIFICANCE: Adding TU and using a low concentration of DHEPT/BPO resulted in dual-cured cements with longer working time, reduced polymerization stress and increased conversion even in the absence of light, with no significant effect on the mechanical properties.
Authors: Paulo Henrique Perlatti D'Alpino; Marília Santos Silva; Marcus Vinícius Gonçalves Vismara; Vinicius Di Hipólito; Alejandra Hortencia Miranda González; Carlos Frederico de Oliveira Graeff Journal: J Mech Behav Biomed Mater Date: 2015-02-26
Authors: Aloísio O Spazzin; Ataís Bacchi; Rodrigo Alessandretti; Mateus B Santos; Gabriela R Basso; Jason Griggs; Rafael R Moraes Journal: Dent Mater Date: 2017-02-04 Impact factor: 5.304
Authors: André Luis Faria-e-Silva; Aline Carvalho Peixoto; Marcela Gonçalves Borges; Murilo de Sousa Menezes; Rafael Ratto de Moraes Journal: Braz Oral Res Date: 2014