Schaefer Oliver, Decker Mike, Wittstock Frank, Kuepper Harald, Guentsch Arndt
Policlinic of Prosthetic Dentistry and Material Science, Centre for Dental Medicine, Jena University Hospital, Jena, Germany.
Policlinic of Prosthetic Dentistry and Material Science, Centre for Dental Medicine, Jena University Hospital, Jena, Germany.
J Dent. 2014 Jun;42(6):677-83. doi: 10.1016/j.jdent.2014.01.016. Epub 2014 Feb 6.
To investigate the effects, digital impression procedures can have on the three-dimensional fit of ceramic partial crowns in vitro.
An acrylic model of a mandibular first molar was prepared to receive a partial coverage all-ceramic crown (mesio-occlusal-distal inlay preparation with reduction of all cusps and rounded shoulder finish line of buccal wall). Digital impressions were taken using iTero (ITE), cara TRIOS (TRI), CEREC AC with Bluecam (CBC), and Lava COS (COS) systems, before restorations were designed and machined from lithium disilicate blanks. Both the preparation and the restorations were digitised using an optical reference-scanner. Data were entered into quality inspection software, which superimposed the records (best-fit-algorithm), calculated fit-discrepancies for every pixel, and colour-coded the results to aid visualisation. Furthermore, mean quadratic deviations (RMS) were computed and analysed statistically with a one-way ANOVA. Scheffé's procedure was applied for multiple comparisons (n=5, α=0.05).
Mean marginal (internal) discrepancies were: ITE 90 (92) μm, TRI 128 (106) μm, CBC 146 (84) μm, and COS 109 (93) μm. Differences among impression systems were statistically significant at p<0.001 (p=0.039). Qualitatively, partial crowns were undersized especially around cusp tips or the occluso-approximal isthmus. By contrast, potential high-spots could be detected along the preparation finishline and at central occlusal boxes.
Marginal and internal fit of milled lithium disilicate partial crowns depended on the employed digital impression technique.
The investigated digital impression procedures demonstrated significant fit discrepancies. However, all fabricated restorations showed acceptable marginal and internal gap sizes, when considering clinically relevant thresholds reported in the literature.
研究数字印模程序对体外陶瓷部分冠三维适合性的影响。
制备下颌第一磨牙的丙烯酸模型，以容纳部分覆盖全瓷冠（近中-咬合-远中嵌体预备，所有牙尖降低，颊壁呈圆形肩台边缘线）。在使用二硅酸锂坯块设计和加工修复体之前，使用iTero（ITE）、cara TRIOS（TRI）、带Bluecam的CEREC AC（CBC）和Lava COS（COS）系统进行数字印模。使用光学参考扫描仪对预备体和修复体进行数字化处理。将数据输入质量检测软件，该软件叠加记录（最佳拟合算法），计算每个像素的适合度差异，并用颜色编码结果以辅助可视化。此外，计算平均二次偏差（RMS），并使用单向方差分析进行统计分析。采用Scheffé法进行多重比较（n = 5，α = 0.05）。
平均边缘（内部）差异为：ITE 90（92）μm，TRI 128（106）μm，CBC 146（84）μm，COS 109（93）μm。印模系统之间的差异在p<0.001（p = 0.039）时具有统计学意义。定性地说，部分冠尺寸过小，尤其是在牙尖或咬合-邻面峡部周围。相比之下，沿预备体边缘线和中央咬合盒处可检测到潜在的高点。
铣削二硅酸锂部分冠的边缘和内部适合性取决于所采用的数字印模技术。
所研究的数字印模程序显示出明显的适合度差异。然而，考虑到文献中报道的临床相关阈值时，所有制作的修复体均显示出可接受的边缘和内部间隙尺寸。
