Effect of conventional and digital methods and aging on the shear bond strength of orthodontic brackets with temporary crowns based on aged PMMA

Shear bond strength (SBS) of orthodontic brackets bonded to temporary crowns (TC) was investigated. TC were manufactured using conventional and digital methods (CAD/CAM milling, 3D printing) and then subjected to cyclic aging (5, 000 cycles). Surface roughness (Ra) and contact angle of polished and abrasive blasted TC were determined before and after aging. Data analysis was performed using one-way ANOVA and repeated measures, and LSD in post-hoc tests (α=0.05). After surface treat ment, there was a significant increase in Ra of conventional and milled TC (p<0.001), while 3D printed showed a slight increase in Ra (p=0.073). The contact angle of polished TC surfaces was significantly different (p>0.05), and after surface treatment the differences in contact angle were small (p<0.001). Aesthetic orthodontic brackets bonded to temporary crowns, regardless of the production method, have adequate bond strength before and after aging, with the exception of 3D printed TCs after aging.