Effect of chlorhexidine varnish application on streptoococcus mutans colonisation in adolescents with fixed orthodontic appliances.

The aim of this prospective study was to evaluate the re-colonisation pattern of Streptococcus mutans (MS) in highlevel MS-colonised patients with fixed orthodontic appliances following 40% chlorhexidine varnish application prior to bracket placement. The subjects of this single-blinded clinical trial were 13-14year-old adolescents (N = 14) with significant orthodontic treatment need, a high salivary MS count but without any carious lesions. Baseline MS levels were determined by the cultivation of saliva collected from each subject using strips developed for this purpose (Strip-mutans, Orion Diagnostica, Espoo, Finland). Prior to the bonding of orthodontic brackets, 40% chlorhexidine varnish (EC 40, Explore, Nijmegen, Netherlands) was applied to all teeth for 10 minutes. The re-colonisation of MS was assessed at one, two, four and six week time periods. The data obtained were subjected to a repeated measures design. Chlorhexidine varnish reduced salivary MS significantly at the first, second and fourth weeks compared to baseline values. Significant MS suppression lasted less than six weeks and MS colonisation gradually returned to baseline level. Repeated application of chlorhexidine varnish in orthodontic patients with high MS levels may be beneficial throughout fixed appliance orthodontic treatment.