Chen Hong, Tang Yunhao, Weir Michael D, Lei Lei, Masri Radi, Lynch Christopher D, Oates Thomas W, Zhang Ke, Hu Tao, Xu Hockin H K
State Key Laboratory of Oral Diseases, Department of Preventive Dentistry, West China Hospital of Stomatology, Sichuan University Chengdu Sichuan 610041 China
Department of Advanced Oral Sciences and Therapeutics, University of Maryland Dental School Baltimore MD 21201 USA
RSC Adv. 2019 Dec 17;9(71):41672-41683. doi: 10.1039/c9ra09220j. eCollection 2019 Dec 13.
Secondary caries at the restoration-tooth margins is a main reason for dental restoration failures. Gene-modification for () and composites containing dimethylaminohexadecyl methacrylate (DMAHDMA) and nanoparticles of amorphous calcium phosphate (NACP) all have the potential to suppress bacterial acids and promote remineralization. However, there has been no report of their effects on marginal caries-inhibition and enamel hardness. The objective of this study was to investigate the effects of gene-modification and DMAHDM-NACP composite restoration on enamel demineralization and hardness at the margins under biofilm acids for the first time. Parent and gene-deleted were tested side by side. The bioactive composite contained 3% DMAHDM and 30% NACP. Mechanical properties and calcium (Ca) and phosphate (P) ion releases were measured. Colony-forming units (CFU), MTT, lactic acid and polysaccharide of biofilms were evaluated. Demineralization of bovine enamel with composite restorations was induced biofilms, then enamel hardness was measured. The dual strategy of combining -deletion with DMAHDM+30NACP: (1) achieved the strongest biofilm-inhibition, with the greatest reduction in biofilm CFU by 6 logs; (2) decreased biofilm lactic acid and polysaccharide production by more than 80%; (3) achieved enamel hardness that was 140% higher than that of a commercial fluoride-releasing composite under 30 days of biofilm acids. Therefore, the novel dual approach of gene-deletion and DMAHDM+NACP nanocomposite is promising to inhibit secondary caries at the margins and increase the longevity of tooth restorations.
修复体与牙齿边缘处的继发龋是牙齿修复失败的主要原因。对（）进行基因改造以及含有甲基丙烯酸十六烷基二甲胺（DMAHDMA）和无定形磷酸钙纳米颗粒（NACP）的复合材料都具有抑制细菌酸和促进再矿化的潜力。然而，尚未有关于它们对边缘龋抑制和牙釉质硬度影响的报道。本研究的目的是首次研究基因改造和DMAHDM-NACP复合修复对生物膜酸作用下边缘处牙釉质脱矿和硬度的影响。对亲本和基因缺失的（）进行了并排测试。生物活性复合材料含有3%的DMAHDM和30%的NACP。测量了其机械性能以及钙（Ca）和磷（P）离子的释放情况。评估了生物膜的菌落形成单位（CFU）、MTT、乳酸和多糖。用复合修复体诱导牛牙釉质在生物膜作用下脱矿，然后测量牙釉质硬度。将基因缺失与DMAHDM + 30NACP相结合的双重策略：（1）实现了最强的生物膜抑制作用，生物膜CFU最大减少了6个对数级；（2）使生物膜乳酸和多糖产量降低了80%以上；（3）在生物膜酸作用30天的情况下，牙釉质硬度比市售含氟复合材料高出140%。因此，基因缺失和DMAHDM + NACP纳米复合材料这种新型双重方法有望抑制边缘处的继发龋并延长牙齿修复体的使用寿命。
