Yewei Xin, Yaqiu Chen, Feng Qiu, Chang Liu, Xiaojing Sun, Qian Jiang
Anterior open bite (AOB) is a challenging vertical malocclusion that requires careful control of posterior vertical dimension, and when it is combined with first molar loss, restoration of posterior occlusal support may require either prosthetic replacement or orthodontic molar protraction. This case report describes the treatment of a 22-year-old male patient with AOB and compromised first molars who underwent extraction of Teeth 16, 26, and 46 followed by long-distance molar protraction with clear aligners; similar nonprosthetic approaches have been reported for patients with missing first molars, although clear aligner treatment remains less predictable for complex tooth movements and extraction-space closure. During space closure, mesial tipping and aligner off-tracking were managed with long-arm molar uprighting springs used as auxiliary devices, because molar protraction requires appropriate moment-to-force control to reduce uncontrolled crown tipping and improve root paralleling. After 41 months and 82 aligner sets, the extraction spaces were substantially closed, the anterior overbite and overjet were improved, and the facial profile became more harmonious, supporting previous observations that adult AOB correction with aligners may be achievable when vertical control and auxiliary biomechanics are carefully managed. Because root resorption and enamel opacities occurred during treatment, this report also discusses the biological limitations and risk-control considerations of long-distance molar protraction in an adult patient, as prolonged orthodontic tooth movement, extraction-space closure, and aligner or fixed-appliance therapy may be associated with adverse effects such as external apical root resorption and white spot lesions.