Photobleaching of camphorquinone during polymerization of dimethacrylate-based resins.

Objective: The aim of this study was to compare the photobleaching rate of CQ in different dental resins.

Methods: The photodecomposition rate of CQ/amine system in bis-GMA/TEGDMA, bis-EMA and UDMA polymerizing monomers was evaluated at different light intensities. The photobleaching of the CQ was studied by monitoring the decrease in light absorption as a function of continuous irradiation time.

Influence of thermal expansion on shrinkage during photopolymerization of dental resins based on bis-GMA/TEGDMA.

Objective: The aim of this study was to assess volume changes that occur during photopolymerization of unfilled dental resins based on bis-GMA-TEGDMA.

Methods: The resins were activated for visible light polymerization by the addition of camphorquinone (CQ) in combination with dimethylamino ethylmethacrylate (DMAEMA) or ethyl-4-dimethyl aminobenzoate (EDMAB). A fibre-optic sensing method based on a Fizeau-type interferometric scheme was employed for monitoring contraction during photopolymerization.

Photopolymerization of N,N-dimethylaminobenzyl alcohol as amine co-initiator for light-cured dental resins.

Objective: The present study was carried out in order to assess the suitability of N,N-dimethylaminobenzyl alcohol (DMOH) as co-initiator of camphorquinone (CQ) and 1-phenyl-1,2-propanedione (PPD) in light-cured dental resins.

Methods: DMOH was synthesized and used as co-initiator for the photopolymerization of a model resin based on {2,2-bis[4-(2-hydroxy-3-methacryloxyprop-1-oxy)phenyl]propane} (Bis-GMA)/triethylene glycol dimethacrylate (TEGDMA). Experimental formulations containing CQ or PPD in combination with DMOH at different concentrations were studied.

Effect of different photoinitiator systems on conversion profiles of a model unfilled light-cured resin.

Objective: The aim of this study was to compare the efficiency of different camphorquinone (CQ)/amine photo-initiating systems for the photopolymerization of a model dental resin based in Bis-GMA/TEGDMA.

Methods: The monomer conversion versus exposure time was measured in resins containing different types and concentrations of photoinitiators and subjected to different irradiation procedures. The conversion profiles during photopolymerization were investigated using near-infrared spectroscopy (NIR).

Properties of acrylic bone cements formulated with Bis-GMA.

Experimental cement formulations were prepared by replacing part of the methylmethacrylate (MMA) liquid phase of a conventional surgical cement with an equivalent weight of 2,2-bis [4(2-hydroxy-3-methacryloxypropoxy) phenyl] propane (Bis-GMA), which is the reaction product of diglycidyl ether of bisphenol A and methacrylic acid. It was found that up to 50 wt % of the MMA could be replaced by Bis-GMA without reductions in flow characteristics of the precured polymers. Cements containing 20, 30, 40, and 50 wt % of Bis-GMA in the liquid component were prepared.

Influence of pressurization on flexural strength distributions of PMMA-based bone cements.

Flexural strength distributions of standard viscosity and low viscosity bone cements based on Polymethylmethacrylate were obtained by testing the materials in four-point bending according to the ISO 5833 protocol. The cement dough was poured into a mold and was allowed to cure at atmospheric pressure. An additional set of specimens of the standard viscosity cement was prepared under pressure while the cement dough was polymerizing in the mold.

Theoretical prediction and experimental determination of the effect of mold characteristics on temperature and monomer conversion fraction profiles during polymerization of a PMMA-based bone cement.

The present work is concerned with applications of a kinetic model for free-radical polymerization of a polymethylmethacrylate-based bone cement. Autocatalytic behavior at the first part of the reaction as well as a diffusion control phenomenon near vitrification are described by the model. Comparison of theoretical computations with experimental measurements for the temperature evolution during batch casting demonstrated the capacity of the proposed model to represent the kinetic behavior of the polymerization reaction.

Flexural strength distribution of a PMMA-based bone cement.

Polymethylmethacrylate bone cement containing either no added antibiotic or 0.5 g of Gentamicin was prepared and stored either in air at room temperature or in a 37 degree C water bath for 48 h. An additive-free cement stored in air at room temperature was also tested for purposes of comparison.