effect of saliva contamination on microleakage beneath bonded brackets: a comparison between two moisture-tolerant bonding systems

objectives: this study aimed to evaluate the effects of saliva contamination on the metallic bracket microleakage bonded with two moisture-tolerant bonding systems. materials and methods:  ninety freshly extracted premolar teeth were randomly divided into six groups of 15 with the following treatments: g1 (control): after acid etching, assure primer and assure adhesive were applied to non-contaminated enamel surfaces. g2 (contaminated after etching): the etched enamel surface was exposed to saliva, then assure primer and assure adhesive were applied. g3 (contaminated after priming): saliva contamination was done after application of assure primer. the exact same procedures were applied to groups g4 to g6 except that timp primer and transbond plus adhesive system were used.   to measure the microleakage score, the teeth were stained with 2% methylene blue for 24 hours, sectioned and examined under a stereomicroscope at ×16 magnification. data analysis was performed using fisher’s exact test. results: in dry conditions, assure and tmip were not significantly different in terms of microleakage scores.  all contaminated groups exhibited higher microleakage score at the enamel/adhesive interface compared to the bracket/adhesive interface (p< 0.01). in wet conditions, assure groups showed higher microleakage at the enamel-adhesive interface compared to the tmip groups (p<0.05). at the bracket-adhesive interface, the microleakage scores were not significantly different in saliva contaminated groups compared to the controls. conclusion: saliva contamination caused greater microleakage at the enamel-adhesive interface compared to the adhesive-bracket interface.