Bronson Michael R, Lindquist Terry J, Dawson Deborah V
College of Dentistry, University of Iowa, Iowa City, IA 52242, USA.
J Prosthodont. 2005 Dec;14(4):226-32. doi: 10.1111/j.1532-849X.2005.00048.x.
Marginal integrity is a very important element in evaluating a restoration; however, there is no agreement in definition of a clinically acceptable margin. The purpose of this investigation was to examine margin acceptability using an explorer versus the actual marginal gap widths at four locations on uncemented crowns on three extracted teeth using both predoctoral students and prosthodontists as evaluators.
The crown margin evaluation used 16 surfaces of four crowns fitting to three extracted caries-free teeth fitted into a dentiform. The teeth (nos. 14, 20, and 29) were prepared for a full cast (gold) crown using a chamfer finish line configuration, with some margins supragingival and others subgingival. After final impressions and working casts were made, die spacer was applied to the marginal area of the die before waxing to vary the marginal opening. The dentiform was placed in a mannequin in a supine position. Predoctoral students (N = 10) and prosthodontists (N = 9) evaluated each axial surface of each crown in the zone along the margin with an explorer and rated each surface as either "clinically acceptable" or "unacceptable." After casting, the axial marginal openings were measured with Image Pro Software using a digital microscopic image of the surface. Each participant repeated the margin evaluations 6 months later.
Upon casting, marginal gaps ranged from 40 microm to 615 microm. The proportions of prosthodontists and of predoctoral students rating a given surface as "clinically unacceptable" were highly correlated (Spearman rank correlation = 0.81, p= 0.0001). The prosthodontists did not provide more or fewer ratings of clinical acceptability than the students, although kappa results indicated that the prosthodontists might be more consistent among themselves than the student raters. Upon re-evaluation, both groups rated between one and six of the surfaces differently than they had previously: the median number of inconsistencies was 1 for prosthodontists and 3 for predoctoral students. The prosthodontists tended to have fewer inconsistencies than the predoctoral students (0.05 < p < 0.10 Wilcoxon rank sum test), but this was not statistically significant.
The data provided evidence that those surfaces associated with greater margin gaps tended to have a greater proportion of ratings of "clinically unacceptable." The proportion of prosthodontists and predoctoral students rating a margin "clinically unacceptable" were highly correlated. Prosthodontists tended to have fewer inconsistencies than predoctoral students, but that difference was not statistically significant.
边缘完整性是评估修复体的一个非常重要的因素；然而，对于临床上可接受边缘的定义尚无统一标准。本研究的目的是使用探针检查边缘可接受性，并对比在三颗拔除牙齿上未粘结全冠四个位置处实际的边缘间隙宽度，评估者包括牙科博士生和口腔修复科医生。
冠边缘评估使用了四个全冠的16个表面，这些全冠适配于三颗无龋的拔除牙齿并安装在牙模型中。牙齿（14号、20号和29号）采用倒角边缘设计，预备为铸造（金）全冠，部分边缘位于龈上，部分位于龈下。制取终印模和工作模型后，在制作蜡型前在模型的边缘区域涂抹间隙剂以改变边缘开口。将牙模型放置在仰卧位的人体模型中。牙科博士生（N = 10）和口腔修复科医生（N = 9）使用探针评估每个全冠沿边缘区域的每个轴面，并将每个表面评为“临床可接受”或“不可接受”。铸造完成后，使用Image Pro软件通过表面的数字显微镜图像测量轴面边缘开口。每位参与者在6个月后重复边缘评估。
铸造后，边缘间隙范围为40微米至615微米。口腔修复科医生和牙科博士生将给定表面评为“临床不可接受”的比例高度相关（Spearman等级相关性 = 0.81，p = 0.0001）。口腔修复科医生给出的临床可接受评级数量并不比学生多或少，尽管kappa结果表明口腔修复科医生之间的一致性可能比学生评估者更高。重新评估时，两组对1至6个表面的评级与之前不同：口腔修复科医生不一致的中位数为1，牙科博士生为3。口腔修复科医生的不一致情况往往比牙科博士生少（0.05 < p < 0.10，Wilcoxon秩和检验），但这在统计学上并不显著。
数据表明，那些边缘间隙较大的表面往往有更高比例的“临床不可接受”评级。口腔修复科医生和牙科博士生将边缘评为“临床不可接受”的比例高度相关。口腔修复科医生的不一致情况往往比牙科博士生少，但这种差异在统计学上并不显著。
