Nanocomposite containing CaF₂ nanoparticles: Thermal cycling, wear and long-term water-aging

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• 作者：Michael D. Weir^a ; Jennifer L. Moreau^a ; Eric D. Levine^b ; Howard E. Strassler^b ; Laurence C. Chow^c ; Hockin H.K. Xu^a ; ^{hxu@umaryland.edu}
• 关键词：Dental nanocomposite ; CaF2 nanoparticles ; Mechanical properties ; Thermal cycling ; Three-body wear ; Water-aging
• 刊名：Dental Materials
• 出版年：2012
• 期刊代码：29_01095641
• 类别：ms
• 出版时间：June, 2012
• 卷：28
• 期：6
• 页码：642-652
• 文件大小：1564 K

摘要

Objectives

Fluoride (F) releasing dental restoratives are promising to promote remineralization and combat caries. The objectives of this study were to develop nanocomposite containing calcium fluoride nanoparticles (nCaF₂), and to investigate the long-term mechanical durability including wear, thermal-cycling and long-term water-aging behavior.

Methods

Two types of fillers were used: nCaF₂ with a diameter of 53 nm, and glass particles of 1.4 渭m. Four composites were fabricated with fillers of: (1) 0%nCaF₂ + 65%glass; (2) 10%nCaF₂ + 55%glass; (3) 20%nCaF₂ + 45%glass; (4) 30%nCaF₂ + 35%glass. Three commercial materials were also tested. Specimens were subjected to thermal-cycling between 5 掳C and 60 掳C for 10⁵ cycles, three-body wear for 4 脳 10⁵ cycles, and water-aging for 2 years.

Results

After thermal-cycling, the nCaF₂ nanocomposites had flexural strengths in the range of 100-150 MPa, five times higher than the 20-30 MPa for resin-modified glass ionomer (RMGI). The wear scar depth showed an increasing trend with increasing nCaF₂ filler level. Wear of nCaF₂ nanocomposites was within the range of wear for commercial controls. Water-aging decreased the strength of all materials. At 2 years, flexural strength was 94 MPa for nanocomposite with 10%nCaF₂, 60 MPa with 20%nCaF₂, and 48 MPa with 30%nCaF₂. They are 3-6 fold higher than the 15 MPa for RMGI (p < 0.05). SEM revealed air bubbles and cracks in a RMGI, while composite control and nCaF₂ nanocomposites appeared dense and solid.

Significance

Combining nCaF₂ with glass particles yielded nanocomposites with long-term mechanical properties that were comparable to those of a commercial composite with little F release, and much better than those of RMGI controls. These strong long-term properties, together with their F release being comparable to RMGI as previously reported, indicate that the nCaF₂ nanocomposites are promising for load-bearing and caries-inhibiting restorations.