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Purpose: The purpose of this study was to investigate the accuracy of removable partial denture frameworks fabricated by 3D-printed pattern casting (AM-Cast) and selective laser sintering (SLS) under different conditions with a reinforcement bar. Methods: A partially edentulous model was scanned with a dental laboratory scanner, and CAD software was used to design the framework. Reinforcement bars (n=0-2) were set on the lingual side of the framework. 3D scanning of the fabricated frameworks by AM-Cast and SLS was performed, and the obtained data were overlapped with the design data. The differences in shape among setting conditions of the bar were statistically compared using the Bonferroni method after the Kruskal-Wallis test. Results: The ranges in differences of the AM-Cast-0, AM-Cast-1, and AM-Cast-2 were-0.167 to 0.128 mm,-0.101 to 0.105 mm, and-0.185 to 0.015 mm, respectively. The ranges of SLS-0, SLS-1, and SLS-2 were-0.166 to 0.035 mm,-0.182 to 0.049 mm, and-0.138 to 0.038 mm, respectively. Large discrepancies were observed at the joining area of the lingual bar on the right side of the AM-Cast. A significant difference was found between the AM-Cast-0 and AM-Cast-1, and between the AM-Cast-0 and AM-Cast-2. Conclusions: The setting conditions of the reinforcement bar affected the accuracy of the lingual bar in the AM-Cast; however, no effect was observed on the displacement of the central area of the lingual bar in SLS. Setting a single reinforcing bar on the retentive latticework contributed to improving the accuracy of the lingual bar in the AM-Cast but not the displacement of the central area of the lingual bar in SLS.

Background: The purpose of this study was to compare the displacement of tooth arrangement in dentures fabricated by additive manufacturing (AM) and heat curing. Methods: Three-dimensional (3D) scanning was performed for edentulous jaw models. After the teeth were arranged, 3D scanning for the wax denture was performed. Heat-cured dentures were fabricated with heat-cure polymer resin. Based on data obtained by subtracting the model data from wax denture data, AM dentures were fabricated from ultravioletcured acrylic resin. Accuracy was verified by superimposing heat-cured and AM dentures on the tooth region data from the wax dentures and measuring displacement of the tooth arrangement. Results: In the maxillary dentures, the amount of tooth displacement for the heat-cured dentures and for the AM dentures ranged from À0.08 to +0.06 mm and from À0.25 to +0.06 mm respectively. A significant difference was observed between two dentures. In the mandibular dentures, the amount of tooth displacement for the heat-cured dentures and for the AM dentures ranged from À0.09 to +0.07 mm and from À0.03 to +0.07 mm respectively. No significant difference was observed between two dentures. Conclusions: The artificial teeth of the maxillary dentures fabricated by AM showed a greater displacement compared to those by heat curing.

The inner lattice structures were added to the stem of an artificial femoral joint to obtain optimal mechanical properties similar to those of cortical bone in orthopedics. Consequently, the elastic modulus was successfully reduced to one-fifth of that of conventional implants [15]. SLS technology enables the addition of inner structures, unlike conventional processes, leading to localized changes in mechanical properties.