Slow-acting Amine Polymerization Accelerators. Para-dimethylaminobenzoic Acid and Its Ethyl Ester
J. M. ANTONUCCI, R. J. PECKOO,t C. SCHRUHL,tt and E. E. TOTH J Dent Res 60(7): 1325-1331, July 1981 National Bureau of Standards, Washington, DC 20234
From theoretical considerations both paradimethylaminobenzoic acid and its ethyl ester would be expected to be slow-acting polymerization accelerators. Using these relatively slow-acting amine accelerators with a fast-polymerizing monomer system, it was possible to formulate composite materials having acceptable setting times at 37°C and excellent diametral tensile strengths.
Introduction. Dental monomers, such as those used in composite, sealant, cement, and denturebase materials, are commonly polymerized under ambient conditions by means of an initiator system consisting of benzoyl peroxide (BP) and a tertiary aromatic amine accelerator such as N,N-dimethyl-ptoluidine.
1. Although it comprises only a minor part of these dental materials, the amine accelerator can exert a significant influence on the properties of-the hardened material (e.g., esthetics, mechanical strength, and general clinical performance).
2. For example, the inherent color instability of the usual amine accelerators can lead to the development of undesirable colors in the finished dental material. In addition, although they have not been identified as causing a serious toxicity . Certain commercial materials and equipment are identified in this article to specify the experimental procedure. In no instance does such identification imply recommendation or endorsement by the National Bureau of Standards or that the materials and equipment identified are necessarily the best available for the purpose. problem when properly used in dental and medical applications, the common tertiary aromatic amine promoters are not ideally biocompatible.
3. From tertiary structure-property considerations, the commercially available tertiary aromatic amines, 4-N,N-dimethylaminobenzoic acid (4-DMAB) and its ethyl ester (4-EDMAB), would be expected to be slow-acting accelerators with enhanced oxidative and color stabilities due to the electron withdrawal character of their respective para substituents. Both 4-DMAB and 4-EDMAB, by analogy with their respective parent compounds,
4-aminobenzoic acid (a vitamin B and an anticanitic and sunscreen agent) and ethyl 4- aminobenzoate (the local anesthetic, benzocaine) should have excellent biocompatibilities. 4. The object of this study was to ascertain the feasibility of using these amines as polymerization accelerators for dental composite restorative and sealant materials.
Received for publication July 15, 1980. Accepted for publication September 11, 1980 tCo-op student, College of Notre Dame, Baltimore, MD Student Participating in American University Internship Program Work described in this article was supported by NIDR/NBS Interagency Agreement #YO1-DE- 40015.