The Effectiveness of Low-level Laser Therapy in Orthodontic Retention for Periodontal-compromised Patients

LLLT will be performed by a diode gallium-aluminum-arsenide (Ga-Al-As) laser with a 940-nm wavelength (Ezlase; Biolase Technology Inc., Irvine, CA) and delivered by a quadrant-sized probe which cover the region from the central incisor to the first molar on the test side. The laser probe will be 1 cm from the soft tissue around the test tooth at the gingival margin and alveolar mucosa covering the root area using a setting of 800 milliwatt in a continuous wave. Each tooth will receive 30 seconds of exposure, with no more than 8.6 J/cm2 of energy delivered. In addition, a spot-size laser probe will be applied for 30 seconds 5 mm from the cervical dentin with an output power of 700 milliwatt to reduce tooth sensitivity.

All participants included will wear fixed lingual retainer and removable retainers in the post-orthodontic retention period and their previous orthodontic treatment will be carried out by one operator using preadjusted appliances with bonded 0.022×0.028-inch2 brackets/buccal tubes and 0.014-inch Nickel Titanium (NiTi) archwires as the first archwires.