| Objective:To evaluate the influence of build orientation and layer thickness on manufacturing accuracy,material consumption,and printing time of complete denture(CD)bases fabricated using digital light processing(DLP)with the aim of providing a reference for the selection of printing strategies in clinical practice.MethodsThe CD base was designed on the basis of a standard maxillary edentulous model.Seventy CD bases were fabricated using a DLP 3D printer(Pro95,Sprint Ray,USA)and printable CD base material(DENTCA Denture Base II,Dentca,USA)at seven build orientations(0°,labial 45°,labial 90°,posterior 45°,posterior 90°,buccal 45°,and buccal90°)and two types of layer thicknesses(50-and 100-μm)(n = 5).All test CD bases were digitalized and superimposed on the reference cast by section-based best-fit alignment.For evaluating manufacturing accuracy,deviation analysis was performed to compare the test data with the reference cast using the “3D Compare” in the 3D metrology software.The printing time and material consumption were calculated using slicing software and recorded,respectively.The two-way ANOVA test was used for accuracy evaluation,and the non-parametric test was used to evaluate printing time and material consumption(α =0.05).Results:Statistically significant differences were found in the manufacturing accuracy(p <0.001),printing time(p < 0.001),and material consumption(p < 0.001)among the build orientation groups.The labial 45 ° and labial 90 ° groups had the best accuracy in the overall intaglio surface,palatal region,residual alveolar ridge,and denture border.In the deviation analysis,the buccal 90° group had the worst accuracy in the overall intaglio surface(0.129 ± 0.011 mm),the residual ridge(0.116 ± 0.015 mm)and the denture border area(0.129 ± 0.011 mm);the posterior 90° group(0.186 ± 0.019 mm)had the worst accuracy in the deviation analysis of the palatal region.The deviation color map intuitively demonstrated the region-specific deviation of CD bases.A positive deviation(impingement)greater than 0.3 mm(dark red)was observed at the maxillary tuberosities in the 0?,P45?,P90?,and B90?groups.Except for the L45? and L90? groups,all other groups showed negative deviations(interspace)in the posterior palatal seal area.Moreover,a negative deviation of > 0.5 mm was observed in the B90? group.The deviation distributions of the base with build orientations of B45?and B90? were asymmetric,potentially leading to an imbalance of the denture under the occlusal force.In contrast,the deviation distribution pattern in the L45?and L90? groups was more compatible with the anatomical characteristics of the edentulous maxilla: it showed a favorable fit or slight positive deviation on the posterior palate and some negative deviation at the torus palatinus and median palatine suture areas.The 90° build orientations required the least material consumption and longest printing time;the labial 45° group consumed the most printing materials;the 0° group required the shortest printing time to fabricate a CD base.Moreover,the layer thickness influenced the printing time(p < 0.001)rather than the accuracy(p = 0.560)and material consumption(p = 1.000).Conclusion:When DLP was used to fabricate the CD bases,the build orientation influenced the manufacturing accuracy,material consumption,and printing time.However,the layer thickness only affected the printing time.Optimizing the build orientation can improve the manufacturing accuracy and reduce the material consumption and printing time of a DLP-printed CD base.The fast-printing setting(100-μm layer thickness)can reduce the printing time without compromising the manufacturing accuracy of the CD base.The L45? and L90? build orientations are recommended based on their satisfactory accuracy as well as the deviation distribution pattern in the color map.If sufficient time is available,the choice of L90? can reduce material consumption.If rapid fabrication is required,the L45? build orientation should be selected. |
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