3Dプリントされた部分床フレームワークの真実性：印刷パラメータと保管条件の調査

The computer-aided design and computer-aided manufacturing (CAD-CAM) of removable partial denture (RPD) frameworks provides a cost-effective alternative to conventional techniques. However, the accuracy of printed patterns can be influenced by printing parameters and storage conditions, leading to distortions that may compromise RPD retention and longevity.

The purpose of this in vitro study was to evaluate the effects of printing parameters (layer thickness and support diameter) and storage conditions (storage after 7 days and light exposure) on the trueness of 3-dimensionally (3D) printed RPD frameworks by digital superimposition.

A Kennedy Class II modification 2 maxillary cast was scanned to design an RPD framework. Frameworks were printed in castable resin with a digital light processing printer using 25- or 50-µm layers and 200- or 600-µm supports (n=6 per group). Half of the specimens underwent 7 days of storage in a light box simulating daylight; the others were kept in a lightproof box for the same time. Frameworks were scanned immediately after printing and after storage, and deviations at 12 locations were calculated by superimposing the scans onto the original design. The 2-way ANOVA with the Tukey post hoc test was applied (α=.05).

Trueness varied across framework locations and was significantly influenced by layer thickness and support diameter (P<.05). Frameworks printed with 25-µm layers and 200-µm supports showed the lowest deviation (0.098 ±0.052 mm). Support diameter had a greater effect than layer thickness. Storage by itself increased deviations at rest seats, while the light box conditioning also affected the minor connector, base, and major connector regions (P<.05).

Under the conditions of this study, trueness varied significantly across sites in printed RPD frameworks. Printing parameters of 25-µm layers and 200-µm supports showed the greatest dimensional accuracy. Seven-day storage in a light box introduced additional deviations.