IRCT201309239086N2 IRCT 2013-11-09 Faculty of dentistry, Hamedan University of Medical Sciences Antimicrobial effect of nano silver particles Effect of application of nano-silver particles in acrylic base plate of orthodontic removable retainers on oral microflora 2013-11-01 anticipated 60 Complete https://irct.ir/trial/9708 interventional Randomization: Randomized, Blinding: Single blinded, Placebo: Not used, Assignment: Parallel, Purpose: Prevention. N/A Dental caries. Intervention 1: Control group: received conventional orthodontic retainer and The patient was instructed to use her/his retainer full-time except when eating and brushing.Oral hygene will be instructed for all patients, including brushing with toothpaste containing fluoride . Dental biofilm sample of upper arch at the time of retainer delivery and after 50 days use of retainer(end of study) will be obtained for colony count and evaluated in culture medium.Also at the end of study upper removable retainer will be sent for candida assessment. Intervention 2: Intervention group: similar as control group but they will receive removable orthodontic retainer containing nano silver particle and patient was instructed to use her/his retainer full-time except when eating and brushing. Oral hygene will be instructed for all patients, including brushing with toothpaste containing fluoride . Dental biofilm sample of upper arch at the time of retainer delivery and after 50 days use of retainer(end of study) will be obtained for colony count and evaluated in culture medium.Also at the end of study upper removable retainer will be sent for candida assessment.