INTRODUCTION
teeth after active orthodontic, low failure rate, mandibular anterior teeth, tooth
Retention of teeth after active orthodontic treatment is usually recommended to overcome the potential of relapse, which can be variable and unpredictable. A Cochrane review found a lack of high-quality evidence to favor one method of retention over another, in terms of stability.Two main designs of bonded retainers are currently in use: 1) rigid round wire bonded to the terminal teeth, which can be the first premolars or the canines; and 2) round multi-strand wire retainer bonded to all teeth in the anterior segment, usually from canine to canine.It has been reported that multi-strand wire retainers are more effective in maintaining individual tooth rotation, compared to the rigid wire retainers, whereas the latter were shown to be more hygienic.Many systematic reviewsA new design of bonded retainer, called Ortho-Flex-Tech™, was recently developed by Reliance Orthodontic Products, Inc. (Itasca, IL, USA). The retainer is a low-profile chain-like design made of stainless steel or gold-plated (14 carat) stainless steel alloy, and usually bonded to the lingual surface of all mandibular anterior teeth, from canine to canine. This wire is rectangular in cross-section (0.974 x 0.402 mm / 0.0383 x 0.0158-in). The manufacturer claims that it has the advantages of easy application (naturally conforms to arch curvature), less chair time, low failure rate (flexible linkage), laboratory cost savings, and improved patient comfort (very low and flat profile). However, to the best of our knowledge, no previous studies have addressed the effectiveness of Ortho-Flex-Tech™ rectangular wire retainer in maintaining the alignment of teeth, its effect on the gingival health and the failure rate. Because the Ortho-Flex-Tech™ retainer is gold-plated and allow for physiologic tooth movement, it is thus hypothesized that it has a more hygienic design and promote less hazard on the gingival health. Additionally, the cross-section of the Ortho-Flex-Tech™ retainer is rectangular in shape, when compared to round multi-strand wire retainer, which could provide more tooth contact surface area and maintain the alignment of the teeth better than the round single point contact wire retainer. 