Effects of water content and initiator composition on photopolymerization of a model BisGMA/HEMA resin

Guo, Xinglin; Wang, Yong; Spencer, Paulette; Ye, Qiang; Yao, Xiaomei

doi:10.1016/j.dental.2007.10.003

Cited by 99 publications

(107 citation statements)

References 25 publications

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“…3) are typical for photoinitiated polymerization (Guo et al 2008;Ye et al 2009;Liu and Wang 2013). The close resemblance in plateau DC regardless of 4E's presence (Fig.…”

Section: Discussionmentioning

confidence: 96%

Light-Cured Self-Etch Adhesives Undergo Hydroxyapatite-Triggered Self-Cure

et al. 2015

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Light cure is a popular mode of curing for dental adhesives. However, it suffers from inadequate light delivery when the restoration site is less accessible, in which case a self-cure mechanism is desirable to salvage any compromised polymerization. We previously reported a novel self-cure system mediated by ethyl 4-(dimethylamino)-benzoate (4E) and hydroxyapatite (HAp). The present work aims to investigate if such self-cure phenomenon takes place in adhesives that underwent prior inadequate light cure and to elucidate if HAp released from the dental etching process is sufficient to trigger it. Model self-etch adhesives were formulated with various components, including bis[2-methacryloyloxy)ethyl]-phosphate (2MP) as acidic monomer and trimethylbenzoyl-diphenylphosphine oxide (TPO) as photoinitiator. In vitro evolution of degree of conversion (DC) of HAp-incorporated adhesives was monitored by infrared spectroscopy during light irradiation and dark storage. Selected adhesives were allowed to etch and extract HAp from enamel, light-cured in situ, and stored in the dark, after which Raman line mapping was used to obtain spatially resolved DC across the enamel-resin interface. Results showed that TPO+4E adhesives reached DC similar to TPO-only counterparts upon completion of light irradiation but underwent another round of initiation that boosted DC to ~100% regardless of HAp level or prior light exposure. When applied to enamel, TPOonly adhesives had ~80% DC in resin, which gradually descended to ~50% in enamel, whereas TPO+4E adhesives consistently scored ~80% DC across the enamel-resin interface. These observations suggest that polymerization of adhesives that underwent insufficient light cure is salvaged by the novel self-cure mechanism, and such salvaging effect can be triggered by HAp released from dental substrate during the etching process.

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“…3) are typical for photoinitiated polymerization (Guo et al 2008;Ye et al 2009;Liu and Wang 2013). The close resemblance in plateau DC regardless of 4E's presence (Fig.…”

Section: Discussionmentioning

confidence: 96%

Light-Cured Self-Etch Adhesives Undergo Hydroxyapatite-Triggered Self-Cure

et al. 2015

View full text Add to dashboard Cite

show abstract

“…Some studies have shown that in the presence of water, Bis-GMA/HEMA undergoes microphase separation, the hydrophilic tertiary amine and hydrophobic camphoroquinone tend to exist in the hydrophilic HEMA phase and hydrophobic Bis-GMA phase, respectively. 23,24 This decreases the chance of their coming into contact; therefore, fewer radicals will be generated and a lower degree of conversion could be found in the Ketac N100 matrix than in Vitremer matrix. Moreover, Vitremer shows a third polymerization setting reaction that ensures that any HEMA not polymerized by irradiation will set.…”

Section: Discussionmentioning

confidence: 99%