A total of 152 subjects will be recruited and randomly assigned into three groups. First group will have a square 8-stranded 0.673x0.268 mm retainer wire bonded in mandibular teeth after completing the active phase of comprehensive orthodontic treatment with fixed appliances. Retainer will be bonded on lingual site canine to canine on each tooth. Second group will have a round 6-stranded 0.40 mm retainer in mandible. Third group will be without fixed retainer, only with thermoplastic vacuum-formed removable Essix retainer in mandible.~Subjects will be examined before orthodontic treatment (T0), upon completion of treatment (T1), six months in retention (T2), two years (T3) and three years in retention (T4). Changes in intercanine width, relapse (unexpected tooth movements), retainer failure, accumulation of biofilm, calculus and gingivitis will be assessed.
Objective is to assess changes of dentition and periodontium, and hygiene in retention after the end of the active phase of orthodontic treatment, and relationship with gender, type of retention appliance, pre-therapeutic condition of dentition and duration of active phase of treatment.