Dental restorations represent one of the conceptually simplest biomaterials - essentially requiring the restoration of mechanical function in an aesthetically acceptable manner. Yet, despite that conceptual simplicity, an array of complex and often conflicting material, biological, curing and reaction properties necessitate a series of suboptimal solutions. Hundreds of millions of restorations are performed each year and premature failure of these restorations results in the need for a far greater number of restorations, including the occasional removal of additional healthy tooth structure. The need for simple, biocompatible, easily manipulated aesthetic dental restoratives has pushed the community towards polymeric composites that are readily reacted in situ, generally by photoinitiation, to yield a high modulus, high strength composite structure that is tooth-like in appearance. Despite the importance of these materials, the resin (i.e., the polymerizable component) phase of these systems has remained largely unchanged since its introduction several decades ago. The common use of dimethacrylate-based resins for dental restorative materials is plagued by critical problems;they do not achieve complete conversion of the methacrylates and thus leave a great deal of material that can be extracted into the oral environment. Further, these materials are prone to significant shrinkage and shrinkage stress that arises during the polymerization/curing process that is used to set the material. Thus, here, we propose a revolutionary new approach to dental materials based on the nucleophile- catalyzed thiol-vinyl sulfone network forming reaction. The proposed thiol-vinyl sulfone dental composite system will significantly improve upon the biological, chemical reaction and mechanical behavior of traditional methcrylate based composite systems. Based on exciting preliminary results that demonstrate the ability to achieve complete functional group conversion via this highly efficient, rapid reaction;appropriate mechanical behavior from the polymers formed;low shrinkage and stress;and the elimination of enzymatically reactive functional groups from the resin, we hypothesize that resins formed by this thiol-vinyl sulfone reaction represent ideal candidates as dental restorative materials. The overall aim is to develop and evaluate dental composites based on the nucleophile catalyzed thiol-vinyl sulfone Michael addition reaction that will include the development of appropriate monomers and functionalized fillers, the development of highly reactive photoinitiator systems for these resins, and the demonstration of acceptable fatigue, extractables, biocompatibility, degradation and other essential short- and long-term composite behavior. Ultimately, the overall aim is to establish these thiol-vinyl sulfone-based composites as a disruptive change in the dental composite field. We will demonstrate over the course of this grant period that these materials are capable of achieving more than a two-fold increase in service lifetime based on dramatically reduced extractables, swelling, degradation and wear in longterm, environmentally challenging testing conditions.

Public Health Relevance

We propose to implement the thiol-vinyl sulfone reaction as a means for curing dental restorative materials. Though used for nearly 50 years and in 65% of tooth restorations, composite materials presently suffer from severe issues associated with extractables, degradation, shrinkage induced stresses and mechanical failure that limits their average service life to less than eight years. Here, this disruptive approach to dental restorative materials will form restorations with much higher conversion, dramatically reduced extractables, elimination of degradable chemical structures, and significantly lower shrinkage stress. As such, we estimate that these materials would lead to at least a doubling in the service life of composite restorations

National Institute of Health (NIH)
National Institute of Dental & Craniofacial Research (NIDCR)
Research Project--Cooperative Agreements (U01)
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Special Emphasis Panel (ZDE1)
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Drummond, James
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University of Colorado at Boulder
Engineering (All Types)
Biomed Engr/Col Engr/Engr Sta
United States
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Zhang, Xinpeng; Xi, Weixian; Wang, Chen et al. (2016) Visible-Light-Initiated Thiol-Michael Addition Polymerizations with Coumarin-Based Photobase Generators: Another Photoclick Reaction Strategy. ACS Macro Lett 5:229-233
Podgórski, Maciej; Becka, Eftalda; Claudino, Mauro et al. (2015) Ester-free thiol-ene dental restoratives--Part A: Resin development. Dent Mater 31:1255-62
Podgórski, Maciej; Becka, Eftalda; Claudino, Mauro et al. (2015) Ester-free thiol-ene dental restoratives--Part B: Composite development. Dent Mater 31:1263-70
Podgórski, Maciej; Becka, Eftalda; Chatani, Shunsuke et al. (2015) Ester-free Thiol-X Resins: New Materials with Enhanced Mechanical Behavior and Solvent Resistance. Polym Chem 6:2234-2240
Podgórski, M; Wang, C; Bowman, C N (2015) Multiple shape memory polymers based on laminates formed from thiol-click chemistry based polymerizations. Soft Matter 11:6852-8
Xi, Weixian; Peng, Haiyan; Aguirre-Soto, Alan et al. (2014) Spatial and Temporal Control of Thiol-Michael Addition via Photocaged Superbase in Photopatterning and Two-Stage Polymer Networks Formation. Macromolecules 47:6159-6165
Podgórski, Maciej; Chatani, Shunsuke; Bowman, Christopher N (2014) Development of glassy step-growth thiol-vinyl sulfone polymer networks. Macromol Rapid Commun 35:1497-502