Available online 1 December 2022

Author links open overlay panelAbstractStatement of problem

Studies on the movement of artificial teeth during the manufacturing of computer-aided design and computer-aided manufacturing (CAD-CAM) complete dentures using the custom disk method with milled recesses and on whether the movement is within a clinically acceptable range are lacking.

Purpose

The purpose of this in vitro study was to assess the trueness and precision of the artificial teeth on custom disks the recesses of which were manufactured using a milling machine and to compare the results with the recesses manufactured using a 3-dimensional (3D) printer.

Material and methods

Four types of artificial teeth (maxillary left central incisors [Max-L1], mandibular left central incisors [Man-L1], maxillary left first premolars [Max-L4], and maxillary left first molars [Max-L6]) were prepared. Milling data were created, and 3 of each type of tooth were attached to each disk made up of 3 concentric circles (large, medium, and small). Five each of the 3D-printed custom disks and custom disks with milled recesses were milled based on the milling data. Standard tessellation language data were obtained through cone beam computed tomography and superimposed by using a CAD software program. Mean absolute error (MAE) values were calculated to assess trueness and precision; MAE values of artificial teeth in custom disks with milled recesses and 3D-printed custom disks were statistically compared by using the 2-way analysis of variance test with 2 factors, 2 types of custom disks and 4 types of artificial teeth, and the Tukey post hoc comparison (α=.05).

Results

Regarding position trueness, the MAE value of Man-L1 on the milling custom disk was significantly lower than that of the 3D-printed custom disk (P<.001), whereas the MAE values of Max-L4 and Max-L6 on the milling custom disk were significantly higher than those on the 3D-printed custom disk (P<.001). No significant difference was found in the MAE value of the position trueness of Max-L1 between the milling and 3D-printed custom disks. Regarding position precision, the MAE values of Max-L1, Man-L1, and Max-L4 on the milling custom disk were significantly lower than those on the 3D-printed custom disks (P=.002, P<.001, P=.025, respectively). However, no significant difference was seen in the MAE value of position precision of Max-L6 between the milling and 3D-printed custom disks (P=.180)

Conclusions

Movement of artificial teeth during the manufacture of dentures using the custom disk method and custom disks with milled recesses was within a clinically acceptable range.

Section snippetsMaterial and methods

The experiment is depicted in a flow chart (Fig. 1). Standard tessellation language (STL) data for artificial teeth were obtained by scanning prefabricated artificial teeth (Velasia SA Antieria, Velasia SA Posteria; SHOFU Dental Corp) with a scanner (NeWay; Open Technologies). Milling data were produced in accordance with a previous study.14 Four types of artificial teeth (maxillary left central incisors [Max-L1], mandibular left central incisors [Man-L1], maxillary left first premolars

Results

Two-way ANOVA results indicated that types of disks and types of artificial tooth factors, including interaction between the factors, were statistically significant (P<.05). Tables 1 and 2 show the MAE values of position trueness and precision of artificial teeth on milled and 3D-printed custom disks.

Regarding position trueness, the MAE value of Man-L1 on the milling custom disk was significantly lower than that of the 3D-printed custom disk (P<.001). In contrast, MAE values of Max-L4 and

Discussion

The MAE position trueness values of 3 types of artificial teeth except Man-L1 with a milled custom disk were higher than those with a 3D-printed custom disk. In addition, the position trueness of Max-L4 and Max-L6 with a milled custom disk was significantly lower than that of a 3D-printed custom disk; only the position trueness of Man-L1 with a milling custom disk was significantly higher than that of a 3D-printed custom disk. Three-dimensional printing has no restrictions on the shapes to be

Conclusions

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

1.

The trueness and precision of artificial teeth on the 3D-printed custom disks were higher for posterior than for anterior teeth.

2.

No significant difference was found in the precision among the 4 types of artificial teeth on the milled custom disks.

3.

The precision of artificial teeth on milled custom disks was higher than on 3D-printed disks.

4.

The movement of artificial teeth during the manufacturing of dentures using

CRediT authorship contribution statement

Yumika Soeda: Methodology, Investigation, Visualization, Writing – original draft. Yuriko Komagamine: Conceptualization, Supervision, Writing – review & editing. Manabu Kanazawa: Data curation, Funding acquisition. Tamaki Hada: Formal analysis, Software. Maiko Iwaki: Validation. Shunsuke Minakuchi: Resources, Project administration.

Acknowledgments

The authors thank Dr Awutsadaporn Katheng, Dr Toshio Arakida, and Dr Ryosuke Otake for their support in this study. The authors also thank DGSHAPE Corporation for milling the dentures.

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© 2022 by the Editorial Council for The Journal of Prosthetic Dentistry.