SUMMARY Purpose To establish a method to improve the accuracy of a dental chair-side fused deposition modelling (FDM) printer and assess the internal adaptation of full crown casting patterns produced by the FDM printer. Method A Lingtong dental three-dimensional (3D) printer (Beijing SHINO Company, China), was used to fabricate six cubes. Deviation analysis was performed between the 3D scanned data and the designed cube data. Fifteen crowns (Group LT) of the right maxillary first molar were printed. A DDP 3D printer (Group EV) and a milling machine (Group ZT) were used to produce the same crowns as controls. Results Compared with the designed cube, the 3D deviation of 73.75% points was within 0.1 mm. The calibration parameters (CP) of the X, Y, and Z directions were 1.005, 0.998, and 1.000, respectively. Based on the CP, the X and Y directions of the printer were adjusted in the software to compensate for the mechanical errors. The crowns were fabricated using different types of equipment to evaluate the accuracy of printing by the 3D dental printer. The internal gap of each crown was measured using a silicone replica and the 3D analysing method. In Group LT, the internal gap of the marginal, axial, and occlusal areas were 0.030 ± 0.019, 0.092 ± 0.019, and 0.023 ± 0.009 mm, respectively. In the marginal and occlusal areas, Group EV exhibited the smallest internal discrepancy, whereas in the axial area, Group ZT achieved the smallest. Only LT and ZT achieved internal spaces in the marginal area without statistical significance to the prescribed parameters (p>0.05). Conclusion The crown cannot be placed on the preparation if the printer is not calibrated. This study revealed the inability to produce full crown casting patterns with similar internal adaptations using different machines for fabrication. None of the three groups could reproduce the prescribed internal space. Combined with CAD/CAM technology, 3D printing technology has been gradually applied in stomatology.