Probing the dual function of a novel tertiary amine compound in dentin adhesive formulations

Abstract

Objectives A novel tertiary amine compound containing three methacrylate-urethane groups was synthesized for application in dentin adhesives. The synthesis, photopolymerization kinetics, and leaching were examined in an earlier study using this novel compound as the co-initiator (0.5 and 1.75 wt% based on the total resin mass). The objective of this work was to investigate the potential of TUMA (8-(2-(((2-(methacryloyloxy)ethyl)carbamoyl)oxy)propyl)-6,10-dimethyl-4,12-dioxo-5,11-dioxa-3,8,13-triazapentadecane-1,15-diyl bis(2-methylacrylate)) to serve simultaneously as a co-initiator and co-monomer (15 to 45 wt% based on the total resin mass) in dentin adhesive formulations. The polymerization kinetics, water sorption and dynamic mechanical properties of these novel formulations were determined. Materials and method The monomer system contained Bisphenol A glycerolate dimethacrylate (BisGMA), 2-hydroxyethylmethacrylate (HEMA) and TUMA (synthesized in our lab) at the mass ratio of 45/55-x/x. Two photoinitiator (PI) systems were compared. One initiator system contains three components: camphorquinone (CQ), diphenyliodonium hexafluorophosphate (DPIHP) and ethyl-4-(dimethylamino) benzoate (EDMAB) and the second initiator system contains CQ and DPIHP. The control adhesive formulations are: C0-3: HEMA/BisGMA 45/55 w/w and 3-component PI and C0-2: HEMA/BisGMA 45/55 w/w and 2-component PI. These controls were used as a comparison to the experimental adhesive resins (Ex-3 or Ex-2), in which x represents the weight percentage of synthesized co-monomer (TUMA) to replace part of BisGMA. The control and experimental adhesive formulations were photo-polymerized and compared with regard to the degree of conversion (DC), polymerization rate (Rp), water sorption and dynamic mechanical analysis (DMA) under both dry and wet conditions. Results C0-3 and Ex-3 formulations had similar DC, while the DC of Ex-2 formulation was higher than C0-2. The DC was similar when comparing the two- component with the three-component photoinitiator system when TUMA was used at the same concentration. DMA under dry conditions shows higher rubbery storage modulus for all experimental formulations, while storage modulus at rubbery region under wet conditions was decreased as compared with control (C0-3). There was no statistically significant difference for the DMA results under both dry and wet conditions when comparing two- and three-component initiator systems with the same TUMA concentration. Significance The newly synthesized TUMA could serve simultaneously as a co-monomer and co-initiator in the absence of commercial co-initiator. This study provides information for the future development of new co-monomer/co-initiator for dentin adhesives and dental composites.

Fabrication of hybrid crosslinked network with buffering capabilities and autonomous strengthening characteristics for dental adhesives

“…In our previous study, amine-functionalized co-monomers have been introduced into the dental adhesive resin and the copolymers showed a long-term neutralization capacity [34,53,63,64]. In the present work, with the incorporation of amine functionalized poly-merizable component (SNM), the copolymers showed promising neutralization capacity, which could offer the benefit of maintaining the neutral pH at the localized micro-environment of the restorative material/tooth interface.…”

Modulating pH through lysine integrated dental adhesives

“…The preparation of the adhesive formulations has been reported [15–17]. There are two experimental adhesive formulations with 2.5 and 5.0 wt % of lysine, respectively.…”

“…The preparation of the round-beam shaped polymer specimens for dynamic mechanical analysis and thermogravimetric analysis has been reported previously [17]. In brief, resin was first injected into glass-tubing molds with a diameter of 1 mm (Fiber Optic Center, Inc., part no.…”

“…As described previously [17], the viscoelastic properties of the dental adhesives were characterized using DMA Q800 (TA Instruments, New Castle, USA) with a 3-point bending clamp. The cylinder beam specimens (1mm× 15mm) were divided into two groups.…”

“…In our previous work [14–17], amine-containing dental adhesives have been developed to buffer the acidic micro-environment and to enhance the lifetime of dental composite restorations. However, due to incomplete amine monomer conversion, there is a concern that amine-containing cytotoxic species could be leached.…”