The effect of combination of xylitol and fluoride varnish on microbial biofilm and saliva in fixed orthodontic patients: a randomized clinical trial

Evaluation of effect of combination of Xylitol and Fluoride on Streptococcusmutans and lactobacillus around orthodontic brackets

Clinical trial with control group, with parallel groups , three-way blind ,randomized ,randomization with using software

120 participants will be recruited from orthodontic patients attending the orthodontic clinic at the Dental Faculty of Shiraz University of Medical Science. Before the intervention, saliva sample and biofilm sample from around the patient orthodontic bracket will be taken, then varnish will be applied to all maxillary and mandibular teeth. The patients will be requested not to eat or drink for 2 hours and not to brush their teeth until the next day. The varnish procedure will be repeated after 1 month. Then, after 2 weeks, saliva sample and biofilm sample from around the patient orthodontic bracket will be taken again.

Inclusion criteria: Male and female subjects Age between 12 and 30 years old Permanent dentition Good general health No anti-inflammatory or antibiotic medications taken in the month before the study No chewing gum or mouthwash use in the last week and during the study Brushing twice daily with fluoride toothpaste No active or untreated caries lesions or gingival inflammation exclusion criteria : Treatment with antibiotics, steroids or any medication known to cause dry mouth in the last 3 months Poor oral hygiene Active periodontal disease Sever crowding of anterior teeth that would be likely to interfere with cleaning of tooth surface Smoking History of mouth breathing

1- Fluoride group: dental varnish with 5% NaF 2- Xylitol group: dental varnish with 10% xylitol 3- Combination group: dental varnish contained 5% NaF+10% xylitol 4-Control group: placebo

Number of Streptoccus mutans and Lactobacillus bacteria

Block randomization method will be used with block size of 8, using online software (RANDOM.ORG) to allocate patients to four experimental groups with a 1:1:1:1 ratio. Following the random sequence generation, random numbers will be allocated to each patient in sealed opaque envelopes. Before the varnish application, the envelope will be opened to disclose the assigned treatment.

All varnishs will be spilled into identical tubes that will be color coded by the first investigator, so the clinician who assigns the intervention, the patients, laboratory technician, and the statistician will be all blind to the treatment groups.