Graduate student, Department of Restorative Dentistry, School of Dentistry, University of Washington, Seattle, Wash.
Professor, Department of Restorative Dentistry, School of Dentistry, University of Washington, Seattle, Wash.
J Prosthet Dent. 2020 Mar;123(3):514-522. doi: 10.1016/j.prosdent.2019.02.024. Epub 2019 Jul 26.
The adaptation of interim crowns made by subtractive and additive manufacturing has not been well investigated.
The purpose of this in vitro study was to evaluate the internal fit and marginal discrepancy of interim crowns made by different manufacturing methods.
A dentoform mandibular left first molar was prepared for a ceramic crown and scanned for the fabrication of 48 stereolithical resin dies and interim crowns. Group CAM included 16 ZCAD interim crowns made by computer-aided design and computer-aided manufacturing (CAD-CAM) technology; group 3DP, 16 NextDent MFH interim crowns made by digital light processing technology; and group APP, 16 Jet interim crowns manually made by using autopolymerizing acrylic resin and used as controls. The silicone replica technique was used to determine the internal discrepancy volume before definitive cementation. All crowns were cemented with Temp-Bond NE under a 50-N load and bench set for 10 minutes before microcomputed tomographic (μCT) scan assessment. The volume of cement space was measured by using the μCT scan 3-dimensional (3D) images, and gap distance at assigned locations was recorded by using the μCT scan 2-dimensional (2D) images. The marginal discrepancy was measured by the polyvinyl siloxane (PVS) impression technique and using a stereomicroscope. Data were analyzed by ANOVA and the Tukey honestly significant difference tests (α=.05). The association between different measuring techniques was analyzed by the Pearson correlation test.
The gap distance between interim crowns and dies from all 3 groups measured by using the μCT scan 2D images ranged from 0.13 mm to 0.55 mm, with the highest value found at the central occlusal location in group APP. The total average gap distance values recorded for group APP were significantly higher than those for group CAM and group 3DP (P<.05). No significant differences were found in internal discrepancy and cement space volume between group CAM and group 3DP (P>.05). The Pearson correlation test showed a moderate correlation (r=0.69) between the silicone replica technique and the μCT scan technique in determining cement space volume. When the PVS impression technique was used to measure the marginal discrepancy, the mean values obtained from group APP were statistically significantly higher than those from group CAM and group 3DP (P<.05). No statistically significant difference in marginal discrepancy was found between group CAM and group 3DP (P=.70).
Digitally fabricated interim crowns had better internal fit and smaller marginal discrepancy than manually constructed interim crowns. The silicone replica technique and μCT scan technique measurements had a moderate correlation in assessing the adaptation of cemented interim crowns.
通过减法和加法制造的临时冠的适应性尚未得到很好的研究。
本体外研究的目的是评估不同制造方法制作的临时冠的内部适合性和边缘差异。
对下颌左侧第一磨牙进行牙体预备，制作陶瓷冠，并进行扫描，以制作 48 个立体树脂模具和临时冠。组 CAM 包括 16 个 ZCAD 临时冠，由计算机辅助设计和计算机辅助制造（CAD-CAM）技术制成; 组 3DP 由数字光处理技术制成的 16 个 NextDent MFH 临时冠; 组 APP 由自聚物丙烯酸树脂手动制作的 16 个 Jet 临时冠作为对照。在最终粘固前，使用硅橡胶复制技术确定内部差异量。所有冠均在 50-N 负载下用 Temp-Bond NE 粘固，并在 bench 上设置 10 分钟，然后进行微计算机断层扫描（μCT）扫描评估。通过 μCT 扫描 3 维（3D）图像测量粘结剂空间的体积，通过 μCT 扫描 2 维（2D）图像记录指定位置处的间隙距离。使用聚硅氧烷（PVS）印模技术和立体显微镜测量边缘差异。通过方差分析和 Tukey 诚实显着差异检验（α=.05）分析数据。通过 Pearson 相关检验分析不同测量技术之间的相关性。
使用 μCT 扫描 2D 图像测量的三组临时冠和模具之间的间隙距离范围为 0.13-0.55mm，APP 组在中央咬合位置的最高值。APP 组记录的总平均间隙距离值明显高于 CAM 组和 3DP 组（P<.05）。CAM 组和 3DP 组之间的内部差异和粘结剂空间体积无显着差异（P>.05）。Pearson 相关检验显示，在确定粘结剂空间体积时，硅橡胶复制技术和 μCT 扫描技术之间存在中度相关性（r=0.69）。当使用 PVS 印模技术测量边缘差异时，APP 组获得的平均值明显高于 CAM 组和 3DP 组（P<.05）。CAM 组和 3DP 组之间的边缘差异无统计学意义（P=.70）。
数字化制作的临时冠具有更好的内部适合性和更小的边缘差异，而手动制作的临时冠则具有更好的内部适合性和更小的边缘差异。硅橡胶复制技术和 μCT 扫描技术在评估粘结临时冠的适应性方面具有中度相关性。
