Jefferies Steven, Lööf Jesper, Pameijer Cornelis H, Boston Daniel, Galbraith Colin, Hermansson Leif
Professor, Department of Restorative Dentistry, Kornberg School of Dentistry, Temple University, Philadelphia, Pennsylvania.
Director of Research, Doxa Dental AB, Uppsala, Sweden.
Compend Contin Educ Dent. 2013 Nov-Dec;34 Spec No 8:8-14.
New dental cement formulations require testing to determine physical and mechanical laboratory properties.
To test an experimental calcium aluminate/glass-ionomer cement, Ceramir C and B (CC and B), regarding compressive strength (CS), film thickness (FT), net setting time (ST) and Vickers hardness. An additional test to evaluate potential dimensional change/expansion properties of this cement was also conducted.
CS was measured according to a slightly modified ISO 9917:2003 for the CC and B specimens. The samples were not clamped while being exposed to relative humidity of great than 90 percent at 37 degrees C for 10 minutes before being stored in phosphate-buffered saline at 37 degrees C. For the CS, four groups were tested: Group 1-CC and B; Group 2-RelyX Luting Cement; Group 3-Fuji Plus; and Group 4-RelyX Unicem. Samples from all groups were stored for 24 hours before testing. Only CCandB was tested for ST and FT according to ISO 9917:2003. The FT was tested 2 minutes after mixing. Vickers hardness was evaluated using the CSM Microhardness Indentation Tester using zinc phosphate cement as a comparison material. Expansion testing included evaluating potential cracks in feldspathic porcelain jacket crowns (PJCs).
The mean and standard deviation after 24 hours were expressed in MPa: Group 1 equals 160 plus or equal to 27; Group 2 equals 96 plus or equal to 10; Group 3 equals 138 plus or equal to 15; Group 4 equals 157 plus or equal to 10. A single-factor ANOVA demonstrated statistically significant differences between the groups (P less than 0.001). Pair-wise statistical comparison demonstrated a statistically significant difference between Groups 1 and 2. No statistically significant differences were found between other groups. The FT was 16.8 plus or equal to 0.9 and the ST was 4.8 plus or equal to 0.1 min. Vickers hardness for Ceramir C and B was 68.3 plus or equal to 17.2 and was statistically significantly higher (P less than 0.05) than Fleck's Zinc Phosphate cement at Vickers hardness of 51.4 plus or equal to 10. There was no evidence of cracks due to radial expansion in PJCs by the Ceramir C and B cement.
All luting cements tested demonstrated compressive strengths well in excess of the ISO requirement for water-based cements of no less than 50 MPa. Ceramir C and B showed significantly higher CS than RelyX Luting Cement after 24 hours, but was not significantly higher than either Fuji Plus or RelyX Unicem. The ST and FT values of CC and B conform to and are within the boundaries of the requirements of the standard. Surface hardness was statistically higher than and comparable to zinc phosphate cement. There was no evidence of potentially clinically significant and deleterious expansion behavior by this cement. All cements tested demonstrated acceptable strength properties. Within the limits of this study, Ceramir C and B is deemed to possess physical properties suitable for a dental luting cement.
新型牙科水门汀配方需要进行测试以确定其物理和力学实验室性能。
测试一种实验性铝酸钙/玻璃离子水门汀Ceramir C和B（CC和B）的抗压强度（CS）、薄膜厚度（FT）、净凝固时间（ST）和维氏硬度。还进行了一项额外测试以评估该水门汀的潜在尺寸变化/膨胀性能。
根据对ISO 9917:2003稍作修改的方法测量CC和B样本的CS。样本在37℃下暴露于相对湿度大于90%的环境中10分钟且不夹紧，然后储存在37℃的磷酸盐缓冲盐水中。对于CS测试，分为四组：第1组 - CC和B；第2组 - RelyX Luting水门汀；第3组 - Fuji Plus；第4组 - RelyX Unicem。所有组的样本在测试前储存24小时。仅根据ISO 9917:2003对CC和B进行ST和FT测试。混合后2分钟测试FT。使用CSM显微硬度压痕测试仪评估维氏硬度，并以磷酸锌水门汀作为对比材料。膨胀测试包括评估长石质烤瓷全冠（PJC）中潜在的裂纹。
24小时后的平均值和标准差以MPa表示：第1组等于160±27；第2组等于96±10；第3组等于138±15；第4组等于157±10。单因素方差分析显示各组之间存在统计学显著差异（P＜0.001）。两两统计比较显示第1组和第2组之间存在统计学显著差异。其他组之间未发现统计学显著差异。FT为16.8±0.9，ST为4.8±0.1分钟。Ceramir C和B的维氏硬度为68.3±17.2，在维氏硬度为51.4±10时，与Fleck磷酸锌水门汀相比具有统计学显著更高（P＜0.05）。没有证据表明Ceramir C和B水门汀会导致PJC因径向膨胀出现裂纹。
所有测试的粘结水门汀显示出的抗压强度远超过ISO对水性水门汀不低于50 MPa 的要求。24小时后Ceramir C和B显示出比RelyX Luting水门汀显著更高的CS，但不比Fuji Plus或RelyX Unicem显著更高。CC和B的ST和FT值符合标准要求且在其范围内。表面硬度在统计学上高于磷酸锌水门汀且与之相当。没有证据表明该水门汀存在潜在的临床显著且有害的膨胀行为。所有测试的水门汀显示出可接受的强度性能。在本研究的范围内，Ceramir C和B被认为具有适合牙科粘结水门汀的物理性能。
