Evaluation of anchor loss of upper incisor after distalization of maxillary posterior teeth with clear aligners in adult patients

Class II malocclusions are one of the most common anomalies in orthodontic practice. One of the most common strategies used in the nonextraction treatment of Class II molar relations is distalization of the maxillary molars. In recent years, various intraoral devices have been developed to reduce dependence on patient compliance. However, even these devices can cause undesirable tipping of maxillary molars or loss of anchorage in anterior incisors during distalization. In order to distalize the maxillary molars, the anterior teeth are usually supported, and during sequential distalization, the upper incisors are tipped even more mesially in the first place. Nowadays, orthodontic treatment with clear aligners has become an increasingly common choice due to the increasing number of adult patients seeking more aesthetic and comfortable alternatives to traditional orthodontic treatments. In this prospective study, it was aimed to perform distalization with clear aligners in patients with class II malocclusion and to determine the loss of anchorage in the upper incisors during the treatment (the mesial movement of the incisors) and to eliminate the deficiency of this subject in the literature. A total of 24 patients over the age of 18 were included in our study. The patients were randomly divided into two groups as 30% and 50% sequenced distalization groups. Measurements on digital scanning models and cephalometric films taken at the beginning (T0) and at the end of distalization (T1) were compared within and between groups, and skeletal, dental and soft tissue changes were evaluated. In the lateral cephalometric analyzes performed at the end of distalization, no significant skeletal change was noted. When we look at the dental measurements; While it was determined that the maxillary molars moved by tipping to the distal significantly and the upper incisors were displaced in the anterior direction, it was observed that there was no significant change in the vertical movements of the teeth. In soft tissue measurements, it was determined that the upper lip was protruded and the nasolabial angle decreased in both groups. In the comparison between groups, anterior teeth were found to be significantly more protruded and proclined in the 30% sequenced distalization group. In the digital model analysis performed at the end of distalization, it was observed that while the posterior teeth moved significantly distally in both groups, the anterior teeth lost anchorage. There was an increase in the transves width between the posterior teeth. In addition, while the posterior teeth were distalized, they also underwent distopalatal rotation. No significant difference was found between the measurements in the comparisons between the groups. As a result of our study, it was found that distalization could be performed successfully with clear aligners, but anchorage was lost in the anterior region in response to the distalization movement, and this anchorage loss was higher in the 30% sequenced distalization group.