Objectives: The aim of this study is to investigate the effect of photobiomodulation therapies on root resorption compared with the placebo group. Materials and Methods: 30 patients, who were admitted to the …………. University Faculty of Dentistry Orthodontics Department for treatment, with an indication of upper right 1st premolar tooth extraction was included. Before the individuals' orthodontic treatment, 0.022 slot MBT brackets and tubes were placed on the maxillary 1st premolar and molar. A 150g buccal tipping force was applied to the 1st premolar. Individuals were then randomly divided into 3 groups. For the first group; laser application was performed with a 810 nm GaAlAs laser device at 0,3,7,14,21 and 28 days to 8 J/cm2. Second group; an LED application according to the manufacturer's instructions with a 850 nm wavelength and 20 mW/cm2 output power for 10 minutes per day during the experiment. Third group; a placebo therapy was completed whereby a laser device that did not make active pulses was used. At the end of four weeks, the amount of root surface resorption was compared using micro-CT imaging after the extraction of the teeth.

Inclusion Criteria:

• No history of orthodontic treatment
• No systemic disease or craniofacial anomaly
• No dental trauma and tooth with root resorption
• Having good oral hygiene
• No periodontal disease (no more than 3mm pocket)
• No restored or endodontically untreated upper right 1st premolar teeth
• Having the maxillary right 1st premolar tooth extraction indication of orthodontic treatment

Exclusion Criteria:

• Problems in patient compliance
• Inadequate oral hygiene
• Development of any medical problem making orthodontic treatment contraindicated during the study period