Michael D Weir1, Jianping Ruan2, Ning Zhang3, Laurence C Chow4, Ke Zhang5, Xiaofeng Chang6, Yuxing Bai7, Hockin H K Xu8. 1. Department of Endodontics, Periodontics and Prosthodontics, University of Maryland School of Dentistry, Baltimore, MD 21201, USA. 2. School of Stomatology, Xi'an Jiaotong University, Xi'an, Shaanxi, China. 3. Department of Endodontics, Periodontics and Prosthodontics, University of Maryland School of Dentistry, Baltimore, MD 21201, USA; Department of Orthodontics, School of Stomatology, Capital Medical University, Beijing, China. 4. Volpe Research Center, American Dental Association Foundation, National Institute of Standards & Technology, Gaithersburg, MD 20899, USA. 5. Department of Endodontics, Periodontics and Prosthodontics, University of Maryland School of Dentistry, Baltimore, MD 21201, USA; Department of Orthodontics, School of Stomatology, Capital Medical University, Beijing, China. Electronic address: tuzizhangke@163.com. 6. School of Stomatology, Xi'an Jiaotong University, Xi'an, Shaanxi, China. Electronic address: changxf@xjtu.edu.cn. 7. Department of Orthodontics, School of Stomatology, Capital Medical University, Beijing, China. Electronic address: byuxing@263.net. 8. Department of Endodontics, Periodontics and Prosthodontics, University of Maryland School of Dentistry, Baltimore, MD 21201, USA; Center for Stem Cell Biology & Regenerative Medicine, University of Maryland School of Medicine, Baltimore, MD 21201, USA; Department of Mechanical Engineering, University of Maryland Baltimore County, Baltimore, MD 21250, USA.
Abstract
OBJECTIVE: Secondary caries is a primary reason for dental restoration failures. The objective of this study was to investigate the remineralization of human dentin lesions in vitro via restorations using nanocomposites containing nanoparticles of amorphous calcium phosphate (NACP) or NACP and tetracalcium phosphate (TTCP) for the first time. METHODS: NACP was synthesized by a spray-drying technique and incorporated into a resin consisting of ethoxylated bisphenol A dimethacrylate (EBPADMA) and pyromellitic glycerol dimethacrylate (PMGDM). After restoring the dentin lesions with nanocomposites as well as a non-releasing commercial composite control, the specimens were treated with cyclic demineralization (pH 4, 1h per day) and remineralization (pH 7, 23h per day) for 4 or 8 weeks. Calcium (Ca) and phosphate (P) ion releases from composites were measured. Dentin lesion remineralization was measured at 4 and 8 weeks by transverse microradiography (TMR). RESULTS: Lowering the pH increased ion release of NACP and NACP-TTCP composites. At 56 days, the released Ca concentration in mmol/L (mean±SD; n=3) was (13.39±0.72) at pH 4, much higher than (1.19±0.06) at pH 7 (p<0.05). At 56 days, P ion concentration was (5.59±0.28) at pH 4, much higher than (0.26±0.01) at pH 7 (p<0.05). Quantitative microradiography showed typical subsurface dentin lesions prior to the cyclic demineralization/remineralization treatment, and dentin remineralization via NACP and NACP-TTCP composites after 4 and 8 weeks of treatment. At 8 weeks, NACP nanocomposite achieved dentin lesion remineralization (mean±SD; n=15) of (48.2±11.0)%, much higher than (5.0±7.2)% for dentin in commercial composite group after the same cyclic demineralization/remineralization regimen (p<0.05). SIGNIFICANCE: Novel NACP-based nanocomposites were demonstrated to achieve dentin lesion remineralization for the first time. These results, coupled with acid-neutralization and good mechanical properties shown previously, indicate that the NACP-based nanocomposites are promising for restorations to inhibit caries and protect tooth structures.
OBJECTIVE: Secondary caries is a primary reason for dental restoration failures. The objective of this study was to investigate the remineralization of human dentin lesions in vitro via restorations using nanocomposites containing nanoparticles of amorphous calcium phosphate (NACP) or NACP and tetracalcium phosphate (TTCP) for the first time. METHODS:NACP was synthesized by a spray-drying technique and incorporated into a resin consisting of ethoxylated bisphenol A dimethacrylate (EBPADMA) and pyromellitic glycerol dimethacrylate (PMGDM). After restoring the dentin lesions with nanocomposites as well as a non-releasing commercial composite control, the specimens were treated with cyclic demineralization (pH 4, 1h per day) and remineralization (pH 7, 23h per day) for 4 or 8 weeks. Calcium (Ca) and phosphate (P) ion releases from composites were measured. Dentin lesion remineralization was measured at 4 and 8 weeks by transverse microradiography (TMR). RESULTS: Lowering the pH increased ion release of NACP and NACP-TTCP composites. At 56 days, the released Ca concentration in mmol/L (mean±SD; n=3) was (13.39±0.72) at pH 4, much higher than (1.19±0.06) at pH 7 (p<0.05). At 56 days, P ion concentration was (5.59±0.28) at pH 4, much higher than (0.26±0.01) at pH 7 (p<0.05). Quantitative microradiography showed typical subsurface dentin lesions prior to the cyclic demineralization/remineralization treatment, and dentin remineralization via NACP and NACP-TTCP composites after 4 and 8 weeks of treatment. At 8 weeks, NACP nanocomposite achieved dentin lesion remineralization (mean±SD; n=15) of (48.2±11.0)%, much higher than (5.0±7.2)% for dentin in commercial composite group after the same cyclic demineralization/remineralization regimen (p<0.05). SIGNIFICANCE: Novel NACP-based nanocomposites were demonstrated to achieve dentin lesion remineralization for the first time. These results, coupled with acid-neutralization and good mechanical properties shown previously, indicate that the NACP-based nanocomposites are promising for restorations to inhibit caries and protect tooth structures.
Authors: Hong Chen; Yunhao Tang; Michael D Weir; Lei Lei; Radi Masri; Christopher D Lynch; Thomas W Oates; Ke Zhang; Tao Hu; Hockin H K Xu Journal: RSC Adv Date: 2019-12-17 Impact factor: 4.036
Authors: Yuncong Li; Xiaoyi Hu; Yang Xia; Yadong Ji; Jianping Ruan; Michael D Weir; Xiaoying Lin; Zhihong Nie; Ning Gu; Radi Masri; Xiaofeng Chang; Hockin H K Xu Journal: Dent Mater Date: 2018-06-21 Impact factor: 5.304
Authors: Abdulrahman A Balhaddad; Anmar A Kansara; Denise Hidan; Michael D Weir; Hockin H K Xu; Mary Anne S Melo Journal: Bioact Mater Date: 2018-12-18
Authors: Ning Zhang; Ke Zhang; Xianju Xie; Zixiang Dai; Zeqing Zhao; Satoshi Imazato; Yousif A Al-Dulaijan; Faisal D Al-Qarni; Michael D Weir; Mark A Reynolds; Yuxing Bai; Lin Wang; Hockin H K Xu Journal: Nanomaterials (Basel) Date: 2018-06-01 Impact factor: 5.076
Authors: Ke Zhang; Suping Wang; Chenchen Zhou; Lei Cheng; Xianling Gao; Xianju Xie; Jirun Sun; Haohao Wang; Michael D Weir; Mark A Reynolds; Ning Zhang; Yuxing Bai; Hockin H K Xu Journal: Bone Res Date: 2018-10-22 Impact factor: 13.567