A multicenter, prospective, randomized trial of pain and discomfort during maxillary expansion: Leaf expander versus hyrax expander

Background: Pain suffered by the young patient is the most frequent symptom during orthodontic treatment and is the one that most frightens children and causes worry in their families. Aim: To investigate pain perception and function impairment during the first week of activation of two palatal expansion screws. Design: A total of 101 subjects were randomly divided into two groups: RME group included patients treated with the standard hyrax expansion screw and LEAF group included patients treated with Leaf Expander appliance. Pain intensity was assessed via the Wong-Baker scale. A questionnaire on oral function impairments was also compiled by the patients. Results: The Pain Scale analysis showed that patients in the RME group suffered from a significantly higher level of pain than those in the LEAF group (88.6% vs 25%, P <.01). RME group showed highest pain indexes from day 1 to day 4 (51.4% RME vs 9.7% LEAF suffered at least once from strong pain in the first 4 days, P <.01). Furthermore, oral functions were similarly affected in both groups. Conclusions: Pain reported during maxillary arch expansion is influenced by clinical activation protocol and by the screw type. Patients treated with Leaf Expander reported significantly lower pain level in the first 7 days of treatment.