Self-perceived pain in Hyrax versus other maxillary expansion orthodontic appliances: a systematic review of clinical studies

To evaluate self-perceived pain levels in the Hyrax compared to other types of maxillary expansion (ME) appliances in growing patients.

An unrestricted search of indexed databases and manual searching were performed up to October 2022. Randomized controlled trials (RCTs) comparing the Hyrax appliance with other ME appliances were included. Data screening, extraction, and Risk of Bias (RoB) assessment with the Cochrane tool were performed by two authors.

Six RCTs were included. The number of participants in the included RCTs ranged between 34 to 114 and included both male and female growing patients. Various tools were used to measure self-perceived pain including the Graphic Rating Scale for Pain, the Wong–Baker Faces Pain Scale, the Numerical Rating Scale, the visual analogue scale, and a questionnaire. One RCT reported that pain intensity in patients treated with the Hyrax was higher than in the Haas appliance, with a statistically significant difference limited to the first day. Two RCTs reported that pain intensity in patients treated with the Leaf expander was lower than in the Hyrax during the first 7 days of treatment. Two RCTs reported no significant differences in pain intensity between the Hyrax and other ME appliances. One RCT reported that pain intensity in patients using the computer-guided skeletal ME appliance was higher than in the Hyrax appliance at the first day after expansion. Four RCTs had a high RoB, and two RCTs had a moderate RoB.

Within the limitations of the present systematic review and based on the currently available evidence, it is challenging and inconclusive to identify the best maxillary expansion appliances, regarding pain levels for growing patients.