Sobrinho L C, de Lima A A, Consani S, Sinhoreti M A, Knowles J C
Area Materiais Dentários, Faculdade de Odontologia de Piracicaba, UNICAMP, Piracicaba, SP, Brasil.
Braz Dent J. 2000;11(1):11-7.
The purpose of this paper was to study the influence of curing tip distance on Knoop hardness values, at different depths, of two composites, Z100 and Silux Plus. Specimens (5 mm in diameter and 2.5 mm in height) were prepared in a copper mold, covered with mylar strip and polymerized for 40 s, at 3 tip-to-composite surface distances: 0 mm (surface contact), 6 and 12 mm, utilizing an XL 3000 curing unit, with 750 mW/cm2 power. The specimens were then stored at 37 degrees C for 24 h. Knoop hardness values were measured using a microhardness tester, with a load of 50 g for 30 s for each indentation. Four specimens were made for each distance and composite and eighteen indentations were made of each specimen. The results were submitted to analysis of variance and Tukey test at 5% significance level. The results indicated that 1) composite Z100: the larger the curing tip distance in relation to the composite, the lower the Knoop hardness values; 2) Silux Plus: increasing the curing tip distance did not produce a statistically significant difference in the Knoop hardness values; however, at 6 and 12 mm, the deeper layers showed lower Knoop hardness values in relation to the surface; 3) Z100: statistically superior in relation to Silux Plus at all three curing tip distances and at all depths (P < 0.05).
本文旨在研究固化头距离对两种复合材料Z100和Silux Plus在不同深度下努氏硬度值的影响。在铜模具中制备直径5毫米、高2.5毫米的试样，用聚酯薄膜条覆盖，并使用XL 3000固化单元，在3种固化头与复合材料表面的距离下进行40秒的聚合，功率为750毫瓦/平方厘米，这3种距离分别为：0毫米（表面接触）、6毫米和12毫米。然后将试样在37摄氏度下储存24小时。使用显微硬度计测量努氏硬度值，每次压痕施加50克载荷，持续30秒。每种距离和复合材料制备4个试样，每个试样进行18次压痕。结果进行方差分析和Tukey检验，显著性水平为5%。结果表明：1）复合材料Z100：相对于复合材料，固化头距离越大，努氏硬度值越低；2）Silux Plus：增加固化头距离在努氏硬度值上未产生统计学显著差异；然而，在6毫米和12毫米时，较深层相对于表面显示出较低的努氏硬度值；3）Z100：在所有三种固化头距离和所有深度下，相对于Silux Plus在统计学上更优（P < 0.05）。
