Available online 14 May 2024

Author links open overlay panel, AbstractStatement of problem

Evidence is lacking on the influence of different designs of bulb support structures on the accuracy of 3-dimensional (3D) printed obturators.

Purpose

The purpose of this in vitro study was to evaluate the influence of various infill designs (hollow, honeycomb, and gyroid) for the bulb of an obturator on the accuracy and weight of digital light projection (DLP) 3D printed maxillary obturators.

Material and methods

A maxillary obturator was virtually designed and used to obtain 3 digital reference files which were defined based on the design of the infill support structure within the bulb: hollow, honeycomb, and gyroid. The resultant standard tessellation language (STL) files were used to fabricate the obturators using a DLP 3D-printer in FREEPRINT denture resin material (n=10 per each group design). The fitting surfaces of all printed specimens (n=30) were digitized using a laboratory scanner, and the scan STL files were exported to the Geomagic control X program for dimensional accuracy analysis (trueness and precision) using the digital subtraction technique. One-way analysis of variance (ANOVA) was used for analysis (α=.05)

Results

Quantitative analysis revealed no significant difference in root mean square estimate (RMSE) values among the test groups for trueness (P=.326) and precision (P=.140). Hollow bulb design was significantly lighter in weight than both honeycomb and gyroid infill designs (P<.001). Colormaps revealed increased areas of negative deviation around the circumference of the bulb wall in the hollow design compared with both the gyroid and honeycomb groups and the close surface matching of fitting surfaces in the 3 groups.

Conclusions

The lack of significant difference in accuracy among the tested groups and the significantly lighter hollow design obturator compared with honeycomb and gyroid designs favors the selection of the hollow bulb design in the digital fabrication of maxillary obturators.

Section snippetsMATERIAL AND METHODS

An edentulous maxillary model available in the preclinical laboratory, Department of Prosthodontics, College of Dentistry, King Saud University was used for the digital design of the obturator. The model was digitized using a laboratory scanner (T310; Medit), and the resultant digital data were exported in standard tessellation language (STL) format. The STL files were used to design a complete denture base using a digital design software program (exocad; Align).

The digital file of the designed

RESULTS

Descriptive statistics, including the mean and standard deviation of trueness, precision, and weight of the obturators with different bulb infill designs, are shown in Table 1. The 1-way ANOVA revealed no significant difference in RMSE values among the test groups (F (2,27) =1.169, P=.326) and (F (2,27) =2.114, P=.140) for trueness and precision, respectively.

A significant difference was found in weight among the test groups (F (2,27) =20.36, P<.001). The Tukey post hoc test showed that the

DISCUSSION

The null hypothesis that the design of the bulb support structure would not affect the accuracy or weight of the printed obturators was partially accepted as there was no significant difference in the accuracy of obturators with different bulb designs. However, the hollow bulb design was significantly lighter compared with the other 2 designs (P<.001). The increased application of 3D printing for the fabrication of maxillofacial prosthetics calls for the optimization of the fabrication

CONCLUSIONS

Based on the findings of this in vitro study, the following conclusions were drawn:

1.

The presence of infill support structure within the bulb did not influence the accuracy of DLP printed maxillary obturators.

2.

The lack of significant difference in accuracy among the tested groups and the significantly lighter hollow design obturator compared with the honeycomb and gyroid designs would favor its application during the digital fabrication of maxillary obturators.

CRediT authorship contribution statement

Reham Osman: Conceptualization, Data curation, Formal analysis, Investigation, Methodology, Software, Validation, Visualization, Roles/Writing - original draft, Writing - review and editing. Nawal Alharbi: Conceptualization, Data curation, Formal analysis, Funding acquisition, Investigation, Methodology, Software, Validation, Visualization, Roles/Writing - original draft, Writing - review and editing.

Acknowledgments

The authors thank Dr Amr el Khadem for his assistance with designing the obturator prosthesis.

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