Ethyl‐4‐(Dimethylamino) benzoate initiation of the spontaneous polymerization of aqueous acidic adhesive formulations in the presence of a base

Bai, Xueshi; Wu, Ningjing; Liu, Yi; Zhang, Ying; Wang, Yong

doi:10.1002/app.39368

Cited by 2 publications

(8 citation statements)

References 22 publications

(30 reference statements)

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“…At higher viscosity, the polymeric species involving termination is retarded, whereas monomer-involving initiation is less affected, leading to faster autoacceleration. At fixed light exposure (15 s), the adhesives at a higher HAp level arrived at the auto-acceleration stage sooner, consistent with our previous findings that higher HAp content facilitated initiation of the 2MP-4E acid-amine pair (Zhang and Wang 2012;Bai et al 2013). Clearly, the null hypothesis that BT-RPAAC does not occur in inadequately light-cured adhesives has to be rejected in vitro.…”

Section: Discussionsupporting

confidence: 85%

“…To our knowledge, only in the 1990s were there investigations of carboxyl-bearing secondary/ tertiary amines (e.g., N-phenylglycine, N-phenyliminodiacetic acid) in dentin bonding (Antonucci et al 1992;Farahani et al 1997;Schumacher et al 1997). However, these amines share the same drawback of regular chemical initiators in spontaneity possibly due to the coexistence of acid and amine on the same molecule so that the acid-amine balance is always maintained (Bai et al 2013). In comparison, the system under our examination has far more acid (2MP) than amine (4E), which necessitates additional base (HAp), resulting in user-controlled initiation.…”

Section: Discussionmentioning

confidence: 99%

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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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Section: Discussionsupporting

confidence: 85%

Section: Discussionmentioning

confidence: 99%

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

et al. 2015

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“…It is believed that the initiation mechanism is associated with the tertiary amine (4E) and acid (acidic monomer) complex, mediated by a base trigger (HAp). 21,22 Radical polymerization initiated by amine-acid complex has been reported previously [28,29] in dental bonding research. However, in these studies, the amines used are carboxyl-containing amines (e.g., N-phenylglycine, N-phenyliminodiacetic acid), which contain amine and acid on the same molecule.…”

Section: Discussionmentioning

confidence: 83%

“…The superior performance of 10-MDP has made it one of the most popular monomers in self-etch adhesives. According to previous studies, 21,22 the interaction between acidic monomer 2MP and tertiary amine 4E, concentration of both 4E and HAp, and the acidity of the selfetch adhesive played critical roles in the occurrence of this kind of self-cure. Thus, it is totally unknown if self-cure of other acidic monomers, especially those used in commercial self-etch adhesives, would happen using this 4E-HAp system.…”

Section: Introductionmentioning

confidence: 92%

“…Previously we reported a very unique spontaneous polymerization phenomenon of bis [2-(methacryloyloxy)ethyl] phosphate (2MP) mediated by ethyl 4-(dimethylamino)benzoate (4E) and hydroxyapatite (HAp) [21,22]. This new initiation system induced self-cure of 2MP monomer at low pH and could be a good solution to dual-cure of acidic self-etch adhesives [23].…”

Section: Introductionmentioning

confidence: 97%

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Tertiary amine and tooth mineral hydroxyapatite facilely trigger self-cure of 10-MDP based adhesives

Liu

Wang

2019

International Journal of Adhesion and Adhesives

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The present work aims to investigate if a novel self-cure system, mediated by tertiary amine ethyl 4-(dimethylamino)-benzoate (4E) and tooth mineral hydroxyapatite (HAp), would trigger polymerization of model adhesives based on a popular self-etch monomer, 10methacryloyloxydecyl dihydrogen phosphate (10-MDP). The effect of 4E and HAp contents on degree of conversion (DC), polymerization rate (Rp), and induction period (IP) was investigated. The occurrence of such self-cure phenomenon in adhesives that underwent prior inadequate light cure was also evaluated. Model self-etch adhesives were prepared by using a monomer mixture of 10-MDP with 2-hydroxyethyl methacrylate at1:1 wt. ratio. 4E (0.3-1.3 wt%), and HAp (0.5-2 wt %) were added to the mixture. Benzoylperoxide and N,N-dihydroxyethyl-p-toluidine were used as conventional chemical-cure system, and trimethylbenzoyl-diphenylphosphine oxide as light-curing photoinitiator. The polymerization processes and mechanical properties of model adhesives were evaluated by real time ATR/FT-IR and nanoindentation, respectively. The 4E-HAp system successfully triggered self-cure of 10-MDP based model adhesives. DC, Rp and IP were apparently affected by both 4E and HAp contents. DC of self-cure of the model adhesives was much higher than that of the conventional chemical-cure system. 4E-HAp initiated self-cure further boosted DC to ~100% regardless of prior light exposure, and significantly improved elastic modulus and hardness, thus provided a novel polymerization method to effectively salvage curing of the adhesives after inadequate light-cure.

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Ethyl‐4‐(Dimethylamino) benzoate initiation of the spontaneous polymerization of aqueous acidic adhesive formulations in the presence of a base

Cited by 2 publications

References 22 publications

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

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

Tertiary amine and tooth mineral hydroxyapatite facilely trigger self-cure of 10-MDP based adhesives

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