Amine Accelerators for Methacrylate Resin Systems

Abstract

Tertiary aromatic amines were synthesized with various nitrogen and ring substituents. They were compared with commercial homologues using composites based on dimethacrylate monomer formulations containing benzoyl peroxide. Equiinolar amounts of the different amines were the only variables. Although accelerating ability was a function of both ring and nitrogen substitution, color stability was influenced more by the substituents on the ring than by the substituents on the nitrogen.Previous reports have shown that a relationship exists between the structure of an aromatic tertiary amine and the color stability of the methacrylate polymer containing the amine.12 The color stability decreases in the order shown in the illustration. The hardened specimens containing NNdimethyl-sym-m-xylidine (DMSX) [also referred to as DMDA (NN-dimethyl-3,5-dimethylaniline) previously3] had the lightest color and were the most color stable.The purpose of this investigation was to prepare and evaluate aromatic amines of similar general structure, but with greater molecular weights than accelerators now in use. Increased molecular size might reduce solubility in tissue fluids and thus lessen ease of diffusion into the pulp or other tissues.4 Use of amines with such properties should lower toxicities and produce less pulpal irritations in comparison with the

Colour-stability and gloss-retention of silorane and dimethacrylate composites with accelerated aging

“…Additionally, colourstability of resin-composites may be affected by chemical differences of resin components, such as polymeric structure and photo-initiator system. [17][18][19][20] The aim of this study was to evaluate the colour-stability and the gloss-retention of commercial resin-composites with accelerated aging. The working hypothesis tested was that accelerated photo-aging might induce colour and gloss changes in different commercial resin-composites over time.…”

Influence of viscosity and amine content on CC conversion and color stability of experimental composites

“…recognized that excess amine causes color instability because of the eventual formation of oxidative products from unreacted co-initiator molecules [9]. Another, and more recent, explanation for that effect considers the dependency on the photoinitiator consumption and viscosity development during the polymerization [7,16].…”

“…Although a direct correlation between co-initiator concentration and polymerization efficiency might be considered, it is known that above certain concentration limits, amines may act as retarders since excess amine may trap initiating radicals by termination reactions [6,8]. Excess amine might also cause color instability because of the eventual formation of oxidative products [9][10][11].…”

New Amine Accelerators for Composite Restorative Resins

“…Based on hardening times, the approximate order of the accelerating ability of the respective amines is: DMAPAA > N,Ndimethyl-sym-xylidine > N,N-dimethyl-ptoluidine -DMAG > MDMAPAA >> DHEPT. 3. Maximum strength for the cured composites is obtained over a narrow concentration range of acceleration in the monomer.…”