###### Abstract
Although all these appliances could achieve maxillary molar distalization, there are some concerns in their clinical usage. Firstly, the activation unit of the majority of these devices is palatally positioned and relatively bulky, which could lead to patient discomfort. Previous studies showed that, compared to patients with buccal orthodontic appliances, patients with lingual appliances experience discomfort for a longer time [22; 23; 24]. Patients with lingual appliances also reported higher speech difficulties, soft tissue irritations, and chewing difficulty than those with buccal appliances [25]. In addition, due to the poor accessibility, the lingual technique is more challenging in terms of treatment approach and needs longer chairside time when compared with the labial technique [26]. Thus, when the activation/reactivation procedures need to be performed intraorally at the palatal area, it necessitates a lot of expertise and time from the orthodontists and good cooperation from the patients. For a patient with a smaller mouth open range or one who cannot hold their mouth wide open, activating the palatal appliance intraorally becomes a very difficult task. Secondly, for some designs of palatal appliances, the amount of activation that each appliance can achieve is limited by how the appliances were fabricated. For instance, the Jones jig, first class appliance, and distal jet function by having the molar tubes slide on the palatal/buccal arm. Thus, the length of the palatal/buccal arm extended distally is the limitation of the total activation of the appliance. If the arm is not long enough to achieve the treatment objectives, a second appliance is needed, which not only increases the lab cost but also prolongs the treatment time. Thirdly, certain palatal devices do not allow unilateral distalization. For example, a modified C-palatal plate has a modified transpalatal arch (TPA) connecting left and right molars rigidly. While connecting the TPA with the palatal temporary anchorage devices (TAD) supported plate by power chains or NiTi springs, a similar amount of distalization force will be applied to the molars on both sides [27]. Thus, in the scenario that only unilateral distalization is needed, or different amounts of distalization are planned for left and right sides, such appliances do not meet clinical needs. Fourthly, although buccal alveolar TADs supported mechanics could be utilized to achieve both bilateral and unilateral molar distalization, the local anatomic structure (such as maxillary sinus floor, adjacent tooth roots) [28; 29; 30] and bone quality [31] sometimes limit the usage of maxillary buccal alveolar TADs. Last but not least, the high complexity of the palatal appliances requires better hand skills of the lab technicians and longer fabrication time. To improve the chairside treatment efficiency and increase the patients' comfort level during the treatment, new intra-arch molar distalizers are needed. The current manuscript intends to introduce a novel and effective maxillary molar distalization appliance--a modified Nance appliance technique that is simple to be fabricated, delivered, and activated. In addition, it is comfortable for the patients.