Accuracy Of 3D Printed Models Research Articles

Effect of Support Densites on Accuracy of 3D-Printed Models

Effect of Support Densites on Accuracy of 3D-Printed Models

Comparison of dimensional accuracy of 3D printing model for clear aligner among various orientation types and hollow types

ABSTRACT Purpose The objective of this study was to investigate the effect of printing protocol focusing upon the accuracy of 3D-printed dental models. Materials and Methods In total, 6 groups of 10 identical maxillary dental models (Formlabs dental model resin) were produced with a stereolithography (SLA)-based 3D printer using 6 printing protocols, Group 1: Hollow/Horizontal (HH), Group 2: Hollow/Oblique (HO), Group 3: Hollow/Vertical (HV), Group 4: Non-hollow/Horizontal (NHH), Group 5: Non-hollow/Oblique (NHO) and Group 6: Non-hollow/Vertical (NHV). Deviation analysis (GOM Inspect) using the best-fit algorithm was conducted to assess accuracy. Trueness and precision of 5 tooth types which were further classified by 3 surface points on anterior teeth and 5 surface points on posterior teeth, were calculated. Thereafter, Kruskal–Wallis was conducted to determine if there were any differences in trueness/precision among the 6 printing protocols. Results Accuracy of clear aligner models showed significant differences (p < .05) among the 6 printing protocols. Majority of values were within clinically acceptable limits (<0.2 mm) except for first molars and second molars. HV showed significant worst accuracy while NHH was the best printing protocol. Other groups (HH/NHV/HO/NHO) were ranked in middle. Inaccuracy was varied depending on tooth type and surface points. Second molars showed greatest defects at significant level in all printing groups. Color surface maps of 3D model superimposition demonstrated non-uniform deviations. Conclusions The printing protocols with differences in hollow types and printing orientations can significantly affect the dimensional accuracy of 3D printed models for clear aligner. Overall deviations showed location-specific deviations.

Validation study of 3D-printed anatomical models using 2 PLA printers for preoperative planning in trauma surgery, a human cadaver study

Introduction3D printing contributes to a better understanding of the surgical approach, reduction and fixation of complex fractures. It is unclear how a 3D-printed model relates to a human bone. The accuracy of 3D-printed models is important to pre-bend plates and fit of surgical guides. We conduct a validation study in which we compare human cadavers with 3D-printed models to test the accuracy of 3D printing.MethodsNine specimens were scanned, volume rendered into 3D reconstructions and saved as STL data. All models were in a ratio of 1:1 printed on the Ultimaker 3 and Makerbot Replicator Z18. Two independent observers measured all distances between the K-wires on the human cadavers, 2DCT, 3D reconstruction, Meshlab and both printers. A paired Samples T test was used to compare the measurements between the different modalities.ResultsThe least decrease in average distance in millimetres was seen in “the 3D printed pelvis 1”, − 0.3 and − 0.8% on respectively the Ultimaker and Makerbot when compared with cadaver Pelvis (1) The 3D model of “Hand 2” showed the most decrease, − 2.5 and − 3.2% on the Ultimaker and Makerbot when compared with cadaver hand (2) Most significant differences in measurements were found in the conversion from 3D file into a 3D print and between the cadaver and 3D-printed model from the Makerbot.ConclusionOur 3D printing process results in accurate models suitable for preoperative workup. The Ultimaker 3 is slightly more accurate than the Makerbot Replicator Z18. We advise that medical professionals should perform a study that tests the accuracy of their 3D printing process before using the 3D-printed models in medical practice.

3D-printed upper cervical models: accuracy validation and feasibility study into anterior occiput-to-axis screw fixation on them

Objective To validate the accuracy of 3D-printed upper cervical models and investigate the feasibility of use of the models in anterior occiput-to-axis screw fixation, in an attempt to provide a protocol of pre-operative plan for surgeons. Methods Forty-five adult atlantoaxial CT scans were obtained, imported into Mimics software for 3D reconstruction, successively imported into 3D printer to print the 3D models. Fourteen parameters were measured on both imaging system and 3D-printed models to validate the accuracy of 3D-printed models. Thirty upper cervical CT data were obtained and imported into Mimics software for 3D reconstruction. Cylinders in 1.75 mm radius were drawn to simulate the trajectory of anterior occiput-to-axis screw fixation. Anteroposterior view of the minimum lateral angle (α1) and maximum lateral angle (α2) and lateral view of the minimum posterior angle (β1) and maximum posterior angle (β2) were measured. Mean value of α1 and α2 was calculated as α3 and mean value of β1 and β2 as β3. Meanwhile, the 3D models were printed, and an angle guide device was used to introduce the anterior occiput-to-axis screws into the 3D models in reference to the angles of α3 and β3. Anteroposterior view of lateral angle (α4) and lateral view of posterior angle (β4) were measured. Differences in α3 vs. α4 and β3 vs. β4 were compared. Results All above 14 parameters did not differ significantly between radiographic images and 3D-printed models (P>0.05). Intraclass correlation coefficient (ICC) values of 13 parameters were >0.800. On the 3D digital models, the α3 was (12.6±3.7)° (left) and (12.0±4.2)° (right), and the β3 was (23.9±4.8)° (left) and (23.4±4.9)° (right). On the 3D-printed models, the α4 was (12.0±4.1)° (left) and (12.3±4.1)° (right), and β4 was (23.4±4.2)° (left) and (22.8±4.4)° (right). There were no significant differences in both comparisons of α3 vs. α4 and β3 vs. β4 (P>0.05). Conclusions The 3D printing technique enables accurate fabrication of upper cervical spine. Aided by the 3D reconstruction with screw trajectory simulation and angle guide device, the anterior occiput-to-axis screws are introduced on the 3D-printed models successfully. Key words: Imaging, three-dimensional; Spine; Computer-assisted design