Danappanavar Prasanna M, Nanda Zinnie, Bhaskar Mummidi, Gowd Vikas, Molugu Mallikarjun, Reddy K Amarendher, Reddy Rajiv Kumar, Kumar M Ashwini
Department of Oral Pathology, MNR Dental College and Hospital, Sangareddy, Andhra Pradesh, India.
J Contemp Dent Pract. 2011 Nov 1;12(6):434-40. doi: 10.5005/jp-journals-10024-1072.
To determine the resistance failure value of nonprecious metal-ceramic restorations at the incisal edge with varying thickness under different application of load.
An Ivorian central incisor was prepared to receive metal-ceramic crown, which was further duplicated, invested, casted and 72 metal dies were fabricated in Co-Cr alloy. Metal dies were relieved with die spacer, lubricated and wax patterns were prepared for metal copings, which were further invested and casted and 72 metal copings were fabricated. The ceramic materials were used for the study viz. Vita/VMK, IPSd SIGN, and superporcelain. Ceramic built-up was carried out according to manufacturer instructions. Incisal ceramic built-up was carried out with increasing thickness from 2.00 to 2.5 and 3.00 mm.
A total of 72 samples, prepared for the study, were divided into two groups, i.e. group I (36 samples) and group II (36 samples), as per the direction of application of load. The samples were mounted on acrylic block (6 samples/block). A total 12 acrylic blocks were prepared. All the samples were tested using universal testing machine (MTS/USA). The load was applied with crosshead speed of 5 mm/min.
Fracture resistance was found to be highest for the 2.00 mm and lowest for 3.00 mm incisal ceramic thickness samples regardless of the ceramic material in both groups. There was a gradual decrease in fracture resistance as the incisal ceramic thickness increased from 2.00 to 3.00 mm in all samples. Fracture resistance was marginally higher for incisal ceramic build-up of 3 mm thickness on group II metal copings than on group I copings. Fracture resistance was highest for IPSd SIGN followed by that of Vita/VMK-95 and superporcelain.
A 3.00 mm incisal ceramic thickness offered greater fracture resistance in comparison to lower values of incisal thickness; IPSd SIGN offered greatest fracture resistance followed by that of Vita/VMK-95 and superporcelain.
确定不同厚度的非贵金属烤瓷修复体在切缘处，于不同加载方式下的抗折破坏值。
对一颗科特迪瓦中央前牙进行预备以制作金属烤瓷冠，之后进行复制、包埋、铸造，用钴铬合金制作72个金属代型。用代型间隙剂处理金属代型，润滑后制作金属基底冠的蜡型，进一步包埋、铸造，制作72个金属基底冠。研究使用的陶瓷材料有：维他/VMK、IPSd SIGN和超瓷。按照制造商说明进行陶瓷堆塑。切端陶瓷堆塑厚度从2.00毫米增加到2.5毫米和3.00毫米。
为该研究制备的72个样本，根据加载方向分为两组，即I组（36个样本）和II组（36个样本）。样本安装在丙烯酸树脂块上（每个块6个样本）。共制备12个丙烯酸树脂块。所有样本使用万能试验机（美国MTS）进行测试。以5毫米/分钟的十字头速度施加负荷。
无论哪一组，无论使用何种陶瓷材料，切端陶瓷厚度为2.00毫米的样本抗折力最高，3.00毫米的样本抗折力最低。在所有样本中，随着切端陶瓷厚度从2.00毫米增加到3.00毫米，抗折力逐渐降低。II组金属基底冠上切端陶瓷厚度为3毫米的堆塑抗折力略高于I组基底冠。IPSd SIGN的抗折力最高，其次是维他/VMK - 95和超瓷。
与较低的切端厚度相比，3.00毫米的切端陶瓷厚度具有更高的抗折力；IPSd SIGN的抗折力最大，其次是维他/VMK - 95和超瓷。
