Rodrigues Renata Cristina Silveira, Ribeiro Ricardo Faria, de Mattos Maria da Gloria Chiarello, Bezzon Osvaldo Luiz
Dental Materials and Prosthesis Department, Ribeirão Preto School of Dentistry, São Paulo University, São Paulo, Brazil.
J Prosthet Dent. 2002 Sep;88(3):290-6. doi: 10.1067/mpr.2002.128128.
The interest in using titanium to fabricate removable partial denture (RPD) frameworks has increased, but there are few studies to support its use.
The objective of this study was to compare circumferential RPD clasps made of commercially pure titanium and identical clasps made of 2 different cobalt (Co)-chromium (Cr) alloys by testing insertion/removal and radiographically inspecting the casts for defects.
On refractory casts that represent a partially edentulous mandibular right hemi-arch segment, 36 frameworks were cast from commercially pure titanium (n = 12) and 2 Co-Cr alloys (n = 12 each) with identical prefabricated patterns and the manufacturer-designated investment and casting technique. Each group was divided into 2 subgroups, corresponding to .25-mm and .50-mm undercuts, respectively. No polishing procedures were performed to ensure uniformity. Only nodules and burs were carefully removed with tungsten burs under magnification when necessary. The specimens were radiographed and subjected to an insertion/removal test simulating 5 years of framework use. The data were subjected to analysis of variance and the Tukey complementary test (P<.01) to compare the retentive forces of RPDs made with the different materials. The Student t test (P<.01) was used to compare the retentive forces of RPDs fabricated with the same alloy with different undercuts.
A total of 20% of the titanium specimens demonstrated porosity, showing casting difficulties, and any defect detected on the clasps determined the sample replacement. For Co-Cr alloys, casting difficulties were not found. The data were subjected to analysis of variance and the Tukey complementary test to compare materials for the same undercut. For the .25-mm undercut, no significant difference was found between Magnum and Rematitan alloys; they were both different from the Remanium alloy (P<.01). For the.50-mm undercut, no significant difference was found between Co-Cr alloys; they were both different from Rematitan alloy (P<.01). The Student t test used to compare the same alloys with different undercuts showed no significant difference between Remanium with .25-mm and .50-mm undercuts. For Magnum and Rematitan alloys, there was a significant difference between different undercuts (P=.01).
Within the limitations of this simulation study, the results suggest that commercially pure titanium clasps maintained retention over a simulated 5-year period, with lower retention force than identical Co-Cr clasps.
使用钛来制作可摘局部义齿（RPD）支架的兴趣有所增加，但支持其使用的研究较少。
本研究的目的是通过测试义齿的插入/取出情况，并对模型进行射线照相检查是否存在缺陷，来比较由商业纯钛制成的环形RPD卡环与由两种不同钴（Co）-铬（Cr）合金制成的相同卡环。
在代表下颌右侧部分牙列缺失半牙弓节段的耐火模型上，用商业纯钛（n = 12）和两种Co-Cr合金（各n = 12），采用相同的预制模型以及制造商指定的包埋材料和铸造技术铸造36个支架。每组再分为两个亚组，分别对应0.25毫米和0.50毫米的倒凹。未进行抛光处理以确保一致性。必要时，仅在放大条件下用钨钢车针小心去除瘤状物和毛刺。对标本进行射线照相，并进行模拟支架使用5年的插入/取出测试。对数据进行方差分析和Tukey补充检验（P<0.01），以比较不同材料制成的RPD的固位力。使用Student t检验（P<0.01）比较相同合金不同倒凹制成的RPD的固位力。
总共20%的钛标本显示有孔隙，表明铸造困难，卡环上检测到的任何缺陷都决定样本更换。对于Co-Cr合金，未发现铸造困难。对数据进行方差分析和Tukey补充检验，以比较相同倒凹情况下的材料。对于0.25毫米倒凹，Magnum合金和Rematitan合金之间未发现显著差异；它们与Remanium合金均不同（P<0.01）。对于0.50毫米倒凹，Co-Cr合金之间未发现显著差异；它们与Rematitan合金均不同（P<0.01）。用于比较相同合金不同倒凹的Student t检验显示，Remanium合金0.25毫米和0.50毫米倒凹之间无显著差异。对于Magnum合金和Rematitan合金，不同倒凹之间存在显著差异（P = 0.01）。
在本模拟研究的局限性内，结果表明商业纯钛卡环在模拟5年期间保持了固位力，但其固位力低于相同的Co-Cr卡环。
