How Effective Are Non-Frictional Techniques Compared to Sliding Techniques in the Retraction of Upper Anterior Teeth When Using Buccal Fixed-Appliance Therapy? A Systematic Review

Methods for retracting the anterior teeth are divided into frictional methods and non-frictional methods. However, evidence regarding the superiority of one technique over the other is still lacking in the available literature. Therefore, we aimed to evaluate the current evidence regarding the effectiveness of frictional methods of anterior teeth retraction compared to the non-frictional ones. The extracted data included the mechanism of application of the retraction force and its intensity, the observation period, follow-up records, and outcome measures. Ten studies were included in this review; the results did not favor a specific technique regarding the rate of orthodontic tooth movement and loss of anchorage during canine retraction, although a preference was shown for the sliding technique in the rate of en-masse retraction (0.74 versus 0.39 mm/month) and the anchorage control during the retraction of the incisors (0.5 versus 0.1 mm/month). The control of the incisor's torque during the en-masse retraction was higher when frictionless techniques were used (-12° versus -7°). Regarding the rate of orthodontic tooth movement, the non-frictional technique is characterized by a high sensitivity to the quality of the design, and the sliding technique was generally effective. As for controlling the torque of the incisors, the preference is for the non-frictional technique. Overall, there is a need to conduct more studies with an appropriate design.