Comparison of adhesiv flashfree and conventional ceramic brackets in terms of shear strength and color stability: Invitro study

Aim: The aim of this in vitro study was to evaluate the effect of thermal aging and 5 different solutions on shear bond strength (SBS), color stability and slot surface roughness (SSR) of Flash-Free, APC II and conventional ceramic brackets. Methods: After a total of 210 human premolars were randomly divided into 3 groups, each group was divided into 7 subgroups. Group 1: no treatment, group 2: only thermal cycle (TC), group 3: TC+ dipped in cherry juice for 72 hours, group 4: TC+ 72 hours of immersion in coffee, group 5: 72 hours of cola TC+, group 6: TC+ immersion in artificial gastric acid for 24 hours, group 7: TC+ immersion in artificial saliva for 72 hours. Bond strength values were determined using a universal testing machine. Color stability was evaluated using a Vita Easy Shade spectrophotometer operating based on the CIE Lab color system. A 3D optical profilometer was used to measure the roughness of the bracket slot bases. The ARI index was also determined with a light microscope. Results: It was observed that thermal aging did not have a statistically significant effect on any variable. Coke, coffee, cherry juice, and stomach acid all significantly increased the roughness of the slot surface in all three bracket groups. However, there was no statistically significant difference in the roughness caused by these fluids. The lowest SBS value (13.39 + 3.49 Mpa) was observed in the stomach acid group. However, this lowest SBS value was at a clinically acceptable level. It was observed that gastric acid and cola caused the greatest color change. It also appeared that the discoloration increased as the exposure time increased. Conclusions: There was no significant effect of thermal aging on color change and surface roughness. Liquids with different pH values caused color change and increased surface roughness in APC flash free, APC II and conventional ceramic brackets. Among the three groups, conventional ceramic brackets had the highest bond strength value, while the lowest value was found in APC Flash-free brackets. The bond strength value in all three groups was clinically acceptable even after exposure of gastric acid. Key words: Share strenght, Profilometer, Spectrophotometer