Effect of the Bis-Dimethylamino Benzydrol Coinitiator on the Mechanical and Biological Properties of a Composite.

Bruna Fortes Bittencourt,John Alexis Dominguez,Leticia Antonelo Campos,João Carlos Gomes,Elizabete Brasil Dos Santos,Luís Antonio Pinheiro,Osnara Maria Mongruel Gomes,Paulo Vitor Farago

doi:10.1590/0103-6440201701585

Bruna Fortes Bittencourt, John Alexis Dominguez + Show 6 more

Open Access

https://doi.org/10.1590/0103-6440201701585

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Abstract

To examine the effect of the alternative coinitiator 4,4'bis dimethylamino benzydrol (BZN) in degree of conversion (DC), mechanical and biological properties of experimental composites. The coinitiator BZN was used in three concentrations (0.2, 0.5 and 1.2%), and the coinitiator DMAEMA was used as control at the same concentrations as above. The molar concentration of camphorquinone (CQ) and coinitiators was kept constant (1:1). The composites were manipulated and submitted to microhardness test (VHN), flexural and compressive strength (in MPa), elastic modulus (GPa), DC (FT-IR) and in vitro cytotoxicity (against 3T3 fibroblastic cells) of the experimental resins. Data were subjected to two-way ANOVA and Tukey post-test (α=0.05). The experimental composite resin with BZN showed higher DC values compared to control DMAEMA groups. For the mechanical properties, microhardness values were higher in BZN groups; flexural strength and elastic modulus were similar between all the groups. Compressive strength for groups BZN0.5 and DMAEMA0.5 were not statistically different, being the lowest values attributed to group BZN0.2. The experimental resins with BZN and DMAEMA were considered nontoxic against 3T3 fibroblasts. The inclusion of the coinitiator BZN in experimental composites was considered nontoxic against 3T3 fibroblast cells, without compromising DC and mechanical properties.

Highlights

The light curing systems most commonly employed in the composites are the camphorquinone/amine system
Several studies regarding alternative coinitiators and photoinitiator systems has been conducted in an attempt to ensure appropriate physical and mechanical properties of composite resins, concomitantly to a significant improvement in the biocompatibility of these materials [14,15,16]
These values obtained from the experimental composites with the alternative coinitiator BZN were higher than that with the control DMAEMA

Summary

Introduction

The light curing systems most commonly employed in the composites are the camphorquinone/amine system. Tertiary amines (aliphatic or aromatic) do not absorb light, but interact with the activated camphorquinone to produce reactive species [1]. This photoinitiator system has some disadvantages, such as the tendency to promote yellowing to resin materials [2,3], low compatibility with oral tissues [4] and even mutagenic characteristics [5]. It is well understood that factors such as type of photoinitiator [2], photoinitiator/coinitiator ratio [3,6,7], type and concentration of coinitiator [8] may influence the properties of the resin materials These molecules must show high reactivity and high degree of monomer conversion, since no reactive monomers may diffuse out of the polymer matrix to the oral cavity [8]

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