Synthesis Of Novel Antibacterial Dimethacrylate Monomers And Their Potential Application In Dental Resin

Methacrylate-based dental composite materials have been widely used in dentalrestorative treatment because of their excellent adhesion and superior aesthetic qualities.However, methacrylate-based dental composite materials have no antibacterial activity, andthe polymerization shrinkage will lead to the micro-gaps between the restoration and dentin.The bacterial in the micro-gaps between the restorative material and the hybrid layer and theprimed dentin or between the restorative material and hybrid layer will lead to bonding failureand generate secondary caries. Therefore, the investigation of novel methacrylate monomersas dental restorative materials with antibacterial activity attracts more and more attentionresent years. In this study, two series novel quaternary ammonium dimethacrylate monomerswith different alkyl substituent chain length were synthesized and and their potentialapplications in dental restorative materials were also investigated. All the results of this studywere listed as below：1. A novel series quaternary ammonium dimethacrylate monomers (UDMQAs) withdifferent alkyl substituent chain length were synthesized using2-hydroxyethyl methacrylate,isophorone diisocyanate, N-methyl diethanol amine,1-bromododecane,1-bromotetradecane,1-bromohexadecane and1-bromooctadecane as row materials, and their structures wereconfirmed by FT-IR and1H-NMR spectra. A novel series quaternary ammoniumdimethacrylate monomers (IMQs) with different alkyl substituent chain length weresynthesized using2-Isocyanatoethyl Methacrylate, N-methyl diethanol amine,1-bromododecane,1-bromotetradecane,1-bromohexadecane and1-bromooctadecane as rowmaterials, and their structures were confirmed by FT-IR and1H-NMR spectra.2. UDMQAs were used as base resin to replace Bis-GMA in Bis-GMA/TEGDMA dentalresin system. The influence of UDMQAs on properties of the copolymer was studied.Compared with Bis-GMA-based dental resin, UDMQAs-based resin exhibits antibacterialactivity and significantly reduces polymerization shrinkage, the same or higher DC, lower mechanical properties, and higher SOB and SOL. And UDMQA-12-based resin shows thebest synthetically properties of all the UDMQAs-based resin. UDMQA-12was used as resinto replaced Bis-GMA in Bis-GMA/TEGDMA dental resin system partial. The results showedthat30%or more UDMQA-12could endow the dental resin with antibacterial activity whencompared with control resin. With the increased concentration of UDMQA-12, DC becamehigher and polymerization shrinkage, but SOB and SOL of the resin systems became higher,while mechanical properties became lower. Compared with3M Z250, UDMQA-12compositeexhibits antibacterial activity and higher DC, but higher polymerization shrinkage, SOB andSOL, and lower mechanical properties, despite its comprehensive properties were lower thancommercial filling restorative materials still met the ISO standard of dental restorativematerial. UDMQAs-based resin3. Each IMQ was incorporated into Bis-GMA/TEGDMA (50/50, wt/wt) with differentmass ratio to form antibacterial dental resin systems. The influences of the IMQ concentrationand alkyl chain length on properties of the copolymer was studied. With the same mass ratioof IMQs, alkyl chain length had no influence on mechanical properties, DC, SOB and SOL ofthe resin systems, IMQ-18containing polymer had the poorest antibacterial activity and theother IMQs containing polymers showed significant antibacterial activity. The concentrationsof IMQs had no significantly influence on DC of the same IMQ-containing resin. IMQscontaining polymers showed significant antibacterial activity, thought mechanical propertiesdecreased, SOB and SOL increased when the concentrations of IMQs were higher than5%.