Abstract
This study aimed to evaluate the intaglio surface trueness of interim dental crowns fabricated with three 3-dimensional (3D) printing and milling technologies. Dental crown was designated and assigned as a computer-aided design (CAD) reference model (CRM). Interim dental crowns were fabricated based on CRM using two types of 3D printer technologies (stereolithography apparatus and digital light processing) and one type of milling machine (n = 15 per technology). The fabricated interim dental crowns were obtained via 3D modeling of the intaglio surface using a laboratory scanner and designated as CAD test models (CTMs). The alignment and 3D comparison of CRM and CTM were performed based on the intaglio surface using a 3D inspection software program (Geomagic Control X). Statistical analysis was validated using one-way analysis of variance and Tukey HSD test (α = 0.05). There were significant differences in intaglio surface trueness between the three different fabrication technologies, and high trueness values were observed in the milling group (p < 0.05). In the milling group, there was a significant difference in trueness according to the location of the intaglio surface (p < 0.001). In the manufacturing process of interim dental crowns, 3D printing technologies showed superior and uniform manufacturing accuracy than milling technology.
Highlights
The introduction of dental computer-aided design and computer-aided manufacturing (CAD/CAM) systems in dental clinics is rapidly increasing [1,2,3]
In many previous studies, 3D analysis was performed by an overlapping CAD reference model (CRM), which is the basis of evaluation, and CAD test model (CTM), which is the subject of evaluation, and calculating the distances of the corresponding 3D modeling points [21,22,23]
Except for the occlusal region, there was no significant difference between stereolithography apparatus (SLA) and digital light processing (DLP) in the whole, marginal, and axial regions (Table 1; p > 0.05), but there was a significant difference between the milling and 3D printing group (Table 1; p < 0.05)
Summary
The introduction of dental computer-aided design and computer-aided manufacturing (CAD/CAM) systems in dental clinics is rapidly increasing [1,2,3]. The steps of CAD/CAM workflow are as follows: acquire a virtual work model using a 3-dimensional (3D) scanner and produce a working cast using a 3D printer, milling machine, or design a prosthesis in CAD software without a model and use 3D printing and milling technologies to fabricate dental prostheses [9,10]. This can save time, and the use of a 3D scanner makes accurate and quantitative analysis possible [14]. In many previous studies, 3D analysis was performed by an overlapping CAD reference model (CRM), which is the basis of evaluation, and CAD test model (CTM), which is the subject of evaluation, and calculating the distances of the corresponding 3D modeling points [21,22,23]. The alignment process, overlapping with CRM on software, is an important point in the 3D analysis, and the overlapping process is generally studied via best fit alignment [24]
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