熔融沉积成形下颌全口义齿聚乳酸蜡型的打印精度与组织面适合性初探

Quantitative evaluation of printing accuracy and tissue surface adaptation of mandibular complete denture polylactic acid pattern fabricated by fused deposition modeling technology

目的定量评价熔融沉积成形（fuseddepositionmodeling，FDM）下颌全口义齿聚乳酸蜡型的打印精度及组织面适合性，为FDM的临床应用提供依据。方法扫描1副标准上下颌无牙颌石膏模型及骀托。用自主研发的全口义齿设计软件进行下颌全口义齿计算机辅助设计（computeraideddesign，CAD），用自主研发的FDM三维打印机打印下颌全口义齿聚乳酸蜡型10个。进行表面光学扫描，分别获得蜡型数据、石膏模型数据和蜡型就位于石膏模型上的整体数据。在Geomagic2013软件中，应用N点配准命令，将蜡型数据配准于CAD数据，分析三维打印的整体偏差；应用最佳拟合配准命令，将石膏模型数据和蜡型数据分别配准于整体数据，分析由就位误差导致的石膏模型表面与蜡型组织面间的三维间隙量，并分为主承托区、副承托区和边缘封闭区3个功能区，方差分析比较各功能区三维间隙量的差异。结果与CAD数据相比，FDM三维打印下颌全口义齿聚乳酸蜡型的整体偏差为（0．013±0．004）mill；蜡型组织面与石膏模型的整体三维间隙量为（0．164±0．033）mm；其中主承托区为（0．165±0．045）mm，副承托区为（0．153±0．027）mm，边缘封闭区为（0．186±0．043）mm（F=1．857，P=0．175〉0．05）。结论应用自主研发的FDM三维打印机和专用打印工艺，可打印下颌全口义齿聚乳酸蜡型，其打印精度与组织面适合性可满足临床应用要求。

Objective To quantitatively evaluate the adaptation of polylactic acid （PLA） pattern of mandibular complete denture fabricated by fused deposition modeling （FDM） technology. Methods A mandibular complete denture digital model was designed through a complete denture design software based on a pair of standard maxillomandibular edentulous plaster model and their occlusion bases. Ten PLA mandibular complete dentures were printed with a FDM machine. The dentures were scanned with and without the plaster model using a three-dimensional （3D） scanner. In Geomagic software, the scanning data of printed dentures were registered to its computer aided design （CAD） data, and the printing error wasanalyzed using the multipoint registration command. For quantitatively evaluating the adaptation of the denture, the data of plaster model and PLA denture were registered to the whole data of denture located in the plaster model using the best-fit alignment command, the 3D deviation of the plaster model and tissue surface of the denture represent the space between them. The overall area was separated into three parts： primary stress-bearing area, secondary stress-bearing area and border seal area, and the average deviations of these three parts were measured. The values were analyzed using analysis of variance. Results Compared with the CAD data, the printing error was （0.013±0.004） mm. The overall 3D deviation between PLA denture and plaster model was （0.164±0.033） mm, in which the primary stress-bearing area was （0.165± 0.045） mm, the secondary stress-bearing area was （0.153±0.027） mm, the border seal area was （0.186± 0.043） mm. These showed a good fit in the majority parts of the FDM denture to the piaster model. No statistically significant difference was observed between the three areas （F=1.857, P=0.175〉0.05）. Conclusions Combined with the 3D scanning, CAD and FDM technology, a FDM 3D printing process of complete denture for injection moulding can be established. As a result, high efficiency and low cost can be used to print out the complete denture, to lav the basis for further clinical annlications.