Nassif Qusay Khaznadar, Alshaarani Fendi Fendi
Department of Fixed Prosthodontics, Faculty of Dentistry, Damascus University, Syria.
Department of Fixed Prosthodontics, Faculty of Dentistry, Al-Hawash Private University, Homs, Syria.
Dent Med Probl. 2020 Apr-Jun;57(2):185-190. doi: 10.17219/dmp/114196.
Marginal fit is the most important criterion in the evaluation of the clinical acceptability of fixed restorations. Due to cement solubility and plaque retention, marginal gaps are potentially harmful to both the teeth and the periodontal tissues.
The aim of the study was to investigate the accuracy of the fit of dental metal-ceramic bridges manufactured with the use of direct metal laser sintering (DMLS), and to explore the effects of porcelain firing on the marginal, axial and occlusal fit of metal-ceramic frameworks.
The study involved 10 patients with 3-unit metal-ceramic restorations produced using the DMLS technique. Using the silicone replica technique, we examined the marginal, axial and occlusal fit of the dental bridges before and after ceramic firing. The Shapiro-Wilks normality test and Student's paired t‑test were implemented to analyze the mean differences in the marginal, axial and occlusal fit of the restorations before and after ceramic firing. A 95% confidence interval (CI) and discrepancy values at the level of 1% and 0.1% (p > 0.05) were applied.
All the mean values of the measurements of marginal (156.08 μm), axial (95.75 μm) and occlusal (252.83 μm) gaps were lower before ceramic veneering than after ceramic veneering, when the mean value for the marginal gap was 178.17 μm, for the axial gap - 106.75 μm and for the occlusal gap - 266.00 μm.
Porcelain firing caused no statistically significant differences in the discrepancy values of marginal, axial and occlusal fit. For clinical application, further improvement of the DMLS system is highly recommended. Marginal gaps in DLSM bridges significantly exceed the permissible inaccuracy values of 100-120 μm for prosthetic restorations.
边缘适合性是评估固定修复体临床可接受性的最重要标准。由于粘结剂溶解性和菌斑滞留，边缘间隙对牙齿和牙周组织都有潜在危害。
本研究旨在调查使用直接金属激光烧结（DMLS）制造的牙科金属烤瓷桥的适合精度，并探讨烤瓷烧制对金属烤瓷框架边缘、轴向和咬合适合性的影响。
本研究纳入10例采用DMLS技术制作3单位金属烤瓷修复体的患者。使用硅橡胶复制技术，我们检查了烤瓷烧制前后牙桥的边缘、轴向和咬合适合性。采用夏皮罗-威尔克正态性检验和学生配对t检验分析烤瓷烧制前后修复体边缘、轴向和咬合适合性的平均差异。应用95%置信区间（CI）以及1%和0.1%水平的差异值（p>0.05）。
在烤瓷贴面之前，边缘（156.08μm）、轴向（95.75μm）和咬合（252.83μm）间隙测量的所有平均值均低于烤瓷贴面之后，烤瓷贴面之后边缘间隙平均值为178.17μm，轴向间隙为106.75μm，咬合间隙为266.00μm。
烤瓷烧制在边缘、轴向和咬合适合性的差异值方面未引起统计学上的显著差异。对于临床应用，强烈建议进一步改进DMLS系统。DLSM桥的边缘间隙显著超过了修复体100 - 120μm的允许误差值。
