Examination of the impact of various manifacturing methods and surface treatments on the adhesive strength of artificial teeth to prosthetic bases fabricated via 3D printing

Objective: The aim of this study was to evaluate the effect of different surface treatments applied to prefabricated and 3D-printed artificial teeth on the bond strength of 3D-printed denture bases. Method: Artificial teeth were manufactured by two different production methods, prefabricated and 3D printer, and denture bases were produced by 3D printer (n=80). Three different surface treatments were applied to the teeth: sandblasting, liquid methyl methacrylate (MMA) after sandblasting, and argon plasma after sandblasting. No surface treatment was applied to the control group. A total of 8 subgroups were formed with the control groups (n=10). All specimens were thermocycled for 5000 cycles in the range of 5-55 oC and then shear bond strength test was performed in a universal testing machine at a crosshead speed of 0.5 mm/min. Failure types were examined under stereomicroscope. Statistical analysis of the data was performed by two-way ANOVA and Bonferroni test. Results: According to the mean shear bond strength values, the bond strength of 3D printed teeth (6.615±2.574 MPa) was significantly higher than the bond strength of prefabricated teeth (2.944±1.197 MPa) (p<0.001). In the prefabricated tooth groups, the highest bond strength value was observed in the methyl methacrylate group after sandblasting (4,289±1,070 MPa) and the lowest bond strength value was observed in the control group (1,969±0,566 MPa). In the tooth groups manufactured with 3D printer, the highest value was measured in the sandblasting group (8,391±,2,047 MPa) and the lowest value was measured in the argon plasma group after sandblasting (3,532±1,374 MPa). Conclusion: It was observed that the production method and surface treatments of artificial teeth affect the shear bond strength. The bond strength of printed teeth was found to be higher than prefabricated teeth. Liquid methacrylate application after sandblasting on prefabricated teeth and sandblasting application on printed teeth were the surface treatments that increased the bond strength the most. Key words: bond strength, artificial teeth, base, 3D printer, surface treatment