Czarnecka Beata, Kruszelnicki Anna, Kao Anthony, Strykowska Marta, Nicholson John W
Department of Biomaterials and Experimental Dentistry, University of Medical Sciences, ul Bukowska 70, 60-812 Poznań, Poland.
School of Sport, Health & Applied Science, St Mary's University College, Twickenham, Middlesex TW1 4SX, United Kingdom.
Dent Mater. 2014 Dec;30(12):e301-5. doi: 10.1016/j.dental.2014.05.008. Epub 2014 Jun 17.
To study the interfaces between model cavities prepared in teeth and four glass ionomer cements (two conventional and two resin-modified).
Ten non-cavitated molars and premolars were used and, in each, two 3mm deep slot preparations were created on opposing sides of the tooth. The teeth were conditioned as appropriate, then restored using the open sandwich technique, using a conventional glass ionomer (Fuji IX, Ketac Molar) or resin modified glass ionomer (Fuji II LC or N100), followed by completion with composite resin. The teeth were then embedded in a transparent acrylic resin and cut parallel to the long axis through both restorations, using a low speed diamond wheel saw. Samples were evaluated using a metallographic light microscope (100×). Three areas were assessed: the axial wall, the axial gingival line angle and the cavo-surface line angle. Bonding was categorized as inadequate or adequate based on the appearance and inadequate bonding was further studied and classified. Data were analysed statistically using the McNamara analysis.
The majority of materials failed to make adequate contact with the axial wall, and there were also flaws at the axial/gingival line angle in several samples. By contrast, the cavo-surface line angle was generally soundly filled and the materials showed intimate contact with the tooth surface in this region. The most serious inadequacy, though, was not lack of intimate contact and/or adhesive bond, but the presence of perpendicular cracks in 30% of the Fuji II LC samples which extended into the underlying dentin.
The problems of placement and dentin cracking experienced with these materials demonstrate that adhesive bond strength alone cannot be used as the criterion of success for restorative materials. In fact good adhesion can, in certain cases, promote cracking of the dentin due to stresses within the material, an outcome which is undesirable.
研究在牙齿中制备的模型洞与四种玻璃离子水门汀（两种传统型和两种树脂改良型）之间的界面。
使用十颗未患龋的磨牙和前磨牙，每颗牙齿相对的两侧制备两个3毫米深的槽形洞。对牙齿进行适当处理，然后采用开放三明治技术，使用传统玻璃离子水门汀（富士IX、Ketac Molar）或树脂改良玻璃离子水门汀（富士II LC或N100）进行修复，随后用复合树脂完成修复。然后将牙齿嵌入透明丙烯酸树脂中，使用低速金刚石砂轮锯沿长轴平行切割穿过两个修复体。使用金相光学显微镜（100倍）对样本进行评估。评估三个区域：轴壁、轴龈线角和洞缘角。根据外观将粘结分为不足或充分，对不足的粘结进行进一步研究和分类。使用麦克纳马拉分析对数据进行统计学分析。
大多数材料未能与轴壁充分接触，几个样本的轴龈线角也存在缺陷。相比之下，洞缘角通常填充良好，材料在该区域与牙齿表面紧密接触。然而，最严重的不足并非缺乏紧密接触和/或粘结，而是30%的富士II LC样本中存在垂直裂纹，这些裂纹延伸至下方的牙本质。
这些材料所经历的放置问题和牙本质开裂表明，仅粘结强度不能用作修复材料成功的标准。事实上，在某些情况下，良好的粘结可能会因材料内部应力而促进牙本质开裂，这是一个不良结果。
