The effect of polymerization conditions on the amounts of unreacted monomer and bisphenol A in dental composite resins

Abstract

The aim of this study was to analyze the unreacted monomers of four commonly used composite resins, which were released after curing with different polymerization conditions. Four composite resins, consisting of two hybrid types and two flowable types from two manufacturers, were photopolymerized using different curing times and curing distances. After polymerization, samples were extracted for analysis at different time points up to 24 h. Released monomers were analyzed by reversed-phase liquid chromatography at UV 210 nm. Longer curing times and shorter curing distances resulted in higher polymerization rates and decreased release of TEGDMA and UDMA, but changes in curing time and distance had no significant effect on Bis-GMA. Release of BPA increased with increase in curing time or decrease in curing distance, in contrast to the results of TEGDMA and UDMA. Polymerization conditions need to be differently applied according to both monomer and resin types.

Bacteria‐Resistant Single Chain Cyclized/Knotted Polymer Coatings

“…While the mechanical properties of the films were improved by the incorporation of a soft component, their antimicrobial property was affected to a certain degree . Most importantly, the unreacted monomers in the film coating could pose serious safety risks when the films contact tissues or cells, in addition to the difficulty in the formation of homogenous coatings directly from monomers …”

Influence of curing protocols on water sorption and solubility of a self-adhesive resin-cement

“…It should be noted that a 10-min delay was proven to be harmful in another study 12 and it is a time too long for a clinical procedure. The expansion promoted by the solvent inside the resin matrix, separating the polymer chains, promotes plastification of the material and diffusion of the unreacted monomer, called elution 16,18 . This elution of unreacted monomers during the immersion in water period, results in mass loss and is calculated as solubility.…”

“…Inadequate polymerization, in addition to reducing the mechanical properties 10,13 , may have biological consequences 14,15 related to the unreacted free monomers. 16 Water sorption and hydrogen bonds with the polar groups of polymers produce separation of the molecules and reduction of hydrogen bonds between them 17 . The expansion resulting from water sorption favours the release of the monomers not linked into chains, reduction of mechanical properties 18 and the cement plasticisation can generate unsupported areas, causing fracture to indirect restorations 19 .…”

Bacteria‐Resistant Single Chain Cyclized/Knotted Polymer Coatings

“…[9,10] However, the resulting films possess ah ard glassy surface,s how poor mechanical properties, [10,11] are subject to biofilm formation, [12] and the rough surface may also cause damage to tissues. [15] Theo bjective of this work is to design and synthesize antimicrobial SCKPs and explore whether the single chain cyclized/knotted architecture would impart SCKPs with enhanced resistance to bacteria, thus circumventing the limitations associated with conventional polymer coatings prepared from the direct free radical polymerization of vinyl monomers.T od emonstrate the generalizability of our strategy,f our representative MVMs,i ncluding tricyclo[5.2.1.0 2,6 ]decanedimethanol diacrylate (TDDA), tetra(ethylene glycol) diacrylate (TEGDA), neopentyl glycol diacrylate (NPGDA), and bisphenol Fe thoxylate (2 EO/ phenol) diacrylate (BPGDA), with entirely different types of spacer between the two vinyl groups were selected. [14] Most importantly,the unreacted monomers in the film coating could pose serious safety risks when the films contact tissues or cells,i n addition to the difficulty in the formation of homogenous coatings directly from monomers.…”

“…[14] Most importantly,the unreacted monomers in the film coating could pose serious safety risks when the films contact tissues or cells,i n addition to the difficulty in the formation of homogenous coatings directly from monomers. [15] Theo bjective of this work is to design and synthesize antimicrobial SCKPs and explore whether the single chain cyclized/knotted architecture would impart SCKPs with enhanced resistance to bacteria, thus circumventing the limitations associated with conventional polymer coatings prepared from the direct free radical polymerization of vinyl monomers.T od emonstrate the generalizability of our strategy,f our representative MVMs,i ncluding tricyclo[5.2.1.0 2,6 ]decanedimethanol diacrylate (TDDA), tetra(ethylene glycol) diacrylate (TEGDA), neopentyl glycol diacrylate (NPGDA), and bisphenol Fe thoxylate (2 EO/ phenol) diacrylate (BPGDA), with entirely different types of spacer between the two vinyl groups were selected. Reversible addition fragmentation chain transfer (RAFT) homopolymerization was utilized to synthesize SCKPs,which were then coated onto the glass substrates and crosslinked by UV to generate the SCKP films (Scheme 1).…”