Effect of different liquids on APC flash-free ceramic bracket’s color stability, shear bond strength, and slot surface roughness

Abstract Objective: The aim of this in vitro study was to evaluate the effect of thermal aging and five different discolouring solutions on the shear bond strength (SBS), discoloration, and slot surface roughness (SSR) of Flash-Free ceramic brackets. Methods: A total of 70 human premolar teeth were randomly divided into seven groups: group 1: no procedure was performed; group 2: Only thermal cycling (TC); group 3: TC + immersion in cherry juice for 72 hr; group 4: TC + immersion in coffee for 72 hr; Group 5: TC + immersion in Coke for 72 hr; group 6: TC + immersion in artificial gastric acid for 24 hr; group 7: TC + immersion in artificial saliva for 72 hr. SBS values were determined by using a universal testing machine. The discolouration was evaluated using a Vita Easy Shade spectrophotometer which is based on the International Commission on Illumination system (CIE Lab colour system). A 3D optical profilometer was used to measure the roughness of the bracket slot bases. Results: Coke, coffee, cherry juice, and gastric acid all significantly increased slot surface roughness. There was, however, no statistically significant difference in the roughness caused by these liquids. The lowest SBS value was observed in the gastric acid group. Gastric acid and Coke were observed to induce the largest colour change. Conclusions: Thermal aging and different liquids cause discolouration and increased surface roughness on APC flash-free brackets. The adhesive bond strength was clinically acceptable even after immersion in gastric acid.