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Curing kinetics and pot life are two vital characteristics for the application of poly(furfuryl alcohol) (PFA) resin because of the complexities both in the resin composition and curing mechanisms involved. However, few reports have provided a complete picture of PFA curing behavior. In this research, the effect of the addition of catalysts on the pot life and curing behavior of a PFA resin were evaluated. A homologous series of dicarboxylic acids [i.e., oxalic acid (OX), succinic acid (SU), and adipic acid (SA)] were used as the catalysts. Rheometric and nonisothermal differential scanning calorimetry (DSC) measurements and headspace gas chromatography/mass spectrometry analysis were carried out at 0, 6, and 24 h after the addition of the catalyst. The relaxation exponent (n), gel stiffness (S), and gel strength (A F ) of the prepared compositions were calculated with the Winter and Chambon and Gabriele rheological models. Furthermore, the curing kinetics were evaluated by the fitting of nonisothermal, multiple-heating-rate models. The DSC measurements showed a higher curing degree for samples containing OX catalyst compared to their counterparts containing either SU or AD. The rheometric findings supported an increased stiffness, gel strength, and curing development of the resin in the presence of OX compared to samples containing SU or AD.

The purpose of this study was to synthesize nano-sized β-tricalcium phosphate (nano-TCP) particles and determine its concentration-dependent properties on incipient enamel caries lesions. Nano-TCP was synthesized as a wet chemical through a method using low concentration of precursors and low addition rate of calcium nitrate tetrahydrate as a second phase. Morphology and phase composition of the particles were analyzed by SEM, XRD, and EDXA techniques. Incipient enamel lesions were created in human premolars with an acidic buffer. The teeth were then incubated in aqueous dispersions of nano-TCP as remineralization solutions. Sodium fluoride solution and deionized water were used as positive and negative control groups, respectively. The quality and thickness of the remineralized layer on enamel were investigated using SEM. The data were statistically analyzed by analysis of variance (ANOVA) and post hoc Tukey's test. The synthesized nano-TCP mostly consisted of porous platelet-like crystals of 50-100 nm thickness and pore diameters of 100-300 nm. SEM observation showed that a homogenous layer was formed on the surface of the enamels remineralized in nano-TCP solutions. The thickness of the mineralized layer was dependent on the incubation time and nano-TCP concentration.

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