Department of Endodontics, Prosthodontics and Operative Dentistry, University of Maryland Dental School, Baltimore, Maryland 21201, USA.
J Biomed Mater Res B Appl Biomater. 2010 Feb;92(2):332-40. doi: 10.1002/jbm.b.31519.
The two main challenges facing dental composite restorations are secondary caries and bulk fracture. Previous studies developed whisker-reinforced Ca-PO(4) composites that were relatively opaque. The objective of this study was to develop an esthetic glass particle-reinforced, photo-cured calcium phosphate composite. Tetracalcium phosphate (TTCP) particles were incorporated into a resin for Ca and PO(4) release, while glass particles provided reinforcement. Ion release and mechanical properties were measured after immersion in solutions with pH of 7, 5.5, and 4. For the composite containing 40% mass fraction of TTCP, incorporating glass fillers increased the strength (p < 0.05). Flexural strength (Mean +/- SD; n = 6) at 30% glass was 99 +/- 18 MPa, higher than 54 +/- 20 MPa at 0% glass (p < 0.05). Elastic modulus was 11 GPa at 30% glass, compared to 2 GPa without glass. At 28 days, the released Ca ion concentration was 4.61 +/- 0.18 mmol/L at pH of 4, much higher than 1.14 +/- 0.07 at pH of 5.5, and 0.27 +/- 0.01 at pH of 7 (p < 0.05). PO(4) release was also dramatically increased at cariogenic, acidic pH. The TTCP-glass composite had strength 2-3 fold that of a resin-modified glass ionomer control. In conclusion, the photo-cured TTCP-glass composite was "smart" and substantially increased the Ca and PO(4) release when the pH was reduced from neutral to a cariogenic pH of 4, when these ions are most needed to inhibit tooth caries. Its mechanical properties were significantly higher than previous Ca, PO(4), and fluoride releasing restoratives. Hence, the photo-cured TTCP-glass composite may have potential to provide the necessary combination of load-bearing and caries-inhibiting capabilities.
牙科复合修复体面临的两个主要挑战是继发龋和大块骨折。以前的研究开发了相对不透明的晶须增强 Ca-PO(4)复合材料。本研究的目的是开发一种美观的玻璃颗粒增强、光固化磷酸钙复合材料。四钙磷酸盐（TTCP）颗粒被掺入树脂中以释放 Ca 和 PO(4)，而玻璃颗粒则提供增强。在 pH 值分别为 7、5.5 和 4 的溶液中浸泡后，测量离子释放和机械性能。对于含有 40%质量分数 TTCP 的复合材料，加入玻璃填料可提高强度（p < 0.05）。在 30%玻璃的情况下，弯曲强度（Mean +/- SD;n = 6）为 99 +/- 18 MPa，高于 0%玻璃时的 54 +/- 20 MPa（p < 0.05）。弹性模量在 30%玻璃时为 11 GPa，而无玻璃时为 2 GPa。在 28 天时，在 pH 值为 4 时释放的 Ca 离子浓度为 4.61 +/- 0.18 mmol/L，远高于 pH 值为 5.5 时的 1.14 +/- 0.07 mmol/L 和 pH 值为 7 时的 0.27 +/- 0.01 mmol/L（p < 0.05）。在致龋酸性 pH 值下，PO(4)的释放也大大增加。与树脂改性玻璃离聚物对照剂相比，TTCP-玻璃复合材料的强度提高了 2-3 倍。综上所述，光固化 TTCP-玻璃复合材料在 pH 值从中性降低到致龋的 4 时具有“智能”特性，并且显著增加了 Ca 和 PO(4)的释放，而当 pH 值降低到致龋的 4 时，这些离子是抑制龋齿最需要的。其机械性能明显高于以前的 Ca、PO(4)和氟化物释放修复体。因此，光固化 TTCP-玻璃复合材料可能具有提供必要的承载能力和抑制龋齿能力相结合的潜力。
