Addison Owen, Marquis Peter M, Fleming Garry J P
Biomaterials Unit, University of Birmingham, School of Dentistry, St. Chad's Queensway, Birmingham B4 6NN, UK.
Dent Mater. 2007 Apr;23(4):461-8. doi: 10.1016/j.dental.2006.03.002. Epub 2006 Apr 18.
Hydrofluoric (HF) acid etching increases the bond strength between composite resin and porcelain surfaces and has been advocated as a pre-cementation technique for ceramic restorations. The internal surface flaw distribution which is implicated in the premature failure of ceramic restorations is modified by the etching process and little agreement exists amongst researchers as to the appropriate etching regime. The purpose of the current study was to examine the impact of HF acid concentration and etching time on the performance of a low fusing feldspathic porcelain.
Sets of 30 Vitadur-Alpha dentin porcelain discs (15 mm diameter, 0.9 mm thickness) were etched with HF acid of three different concentrations (5, 10 and 20%) and for three different etching periods (45, 90 and 180s). Mean flexure strengths, standard deviations and the associated Weibull moduli (m) and characteristic stress (sigma(0)) were determined using bi-axial flexure (ball on ring). Contact profilometry was utilised to characterise the roughness of the etched porcelain surfaces.
A univariate general linear analysis of means revealed a significant reduction in the mean strength values of the as-fired control compared with groups subjected to HF acid etching. Further significance (P<0.05) was discovered with the impact of acid concentration. Altering etching time also resulted in changes in the reliability of the fracture strength data. Contact profilometry demonstrated an increase in surface roughness following HF acid etching and an increase in roughness associated with increasing HF concentration.
Etching of feldspathic porcelain is a dynamic process and the impact is dependent on substrate constitution, surface topography, acid concentration and etching time. A significant reduction of the flexural strength of a low fusing feldspathic porcelain has been demonstrated to result from etching and clear evidence exists that the nature of surface flaw modification is a function of etching time and HF acid concentration. Favourable combinations of HF acid concentration and etching time have been identified which enhance the reliability of the porcelain utilised although variability in clinical technique will result in the reduced reliability of porcelain laminate restorations in function.
氢氟酸蚀刻可提高复合树脂与瓷表面之间的粘结强度，并且已被提倡作为陶瓷修复体的一种粘结前技术。陶瓷修复体过早失效所涉及的内表面缺陷分布会因蚀刻过程而改变，并且研究人员对于合适的蚀刻方案尚未达成共识。本研究的目的是检验氢氟酸浓度和蚀刻时间对低熔长石质瓷性能的影响。
用三种不同浓度（5%、10%和20%）的氢氟酸对30组维它灵 - α型牙本质瓷盘（直径15毫米，厚度0.9毫米）进行蚀刻，并蚀刻三个不同的时间段（45秒、90秒和180秒）。使用双轴弯曲试验（环上球法）测定平均挠曲强度、标准差以及相关的威布尔模量（m）和特征应力（σ(0)）。利用接触轮廓仪来表征蚀刻后瓷表面的粗糙度。
单因素均值一般线性分析显示，与经过氢氟酸蚀刻的组相比，烧制后的对照组平均强度值显著降低。酸浓度的影响具有进一步的显著性（P<0.05）。改变蚀刻时间也会导致断裂强度数据可靠性的变化。接触轮廓仪显示，氢氟酸蚀刻后表面粗糙度增加，且粗糙度随氢氟酸浓度增加而增大。
长石质瓷的蚀刻是一个动态过程，其影响取决于基底组成、表面形貌、酸浓度和蚀刻时间。已证明蚀刻会导致低熔长石质瓷的挠曲强度显著降低，并且有明确证据表明表面缺陷改性的性质是蚀刻时间和氢氟酸浓度的函数。已确定了氢氟酸浓度和蚀刻时间的有利组合，这提高了所用瓷的可靠性，尽管临床技术的差异会导致瓷贴面修复体在功能上的可靠性降低。
