# Long-Term Stability of Class II Malocclusion Treated with Maximly Molar Distalization
## 4 Discussion  
In the management of dental Class II malocclusion, the two primary treatment modalities traditionally include maxillary molar distalization and the extraction of two premolars in the upper arch. However, in recent years, there has been a noticeable decline in the frequency of extraction-based treatments--particularly those involving four premolars or even just two maxillary premolars in Class II cases. This trend is largely attributed to increasing esthetic demands and the growing adoption of alternative orthodontic strategies, such as maxillary expansion techniques, distalization appliances, temporary anchorage devices (TADs), and the more frequent application of interproximal enamel reduction [29]. In addition, maxillary molar distalization holds a significant role in clear aligner therapy due to its high level of predictability [30]. Despite being a commonly employed procedure in orthodontics with various available techniques, maxillary molar distalization lacks sufficient long-term follow-up research in the literature. A recent systematic review [31] confirmed this scarcity, identifying only nine relevant articles, of which only five included follow-up periods of at least four years and just three involved more than 20 distalization patients. In the present study, long-term outcomes were assessed in 40 patients who completed fixed orthodontic treatment following maxillary molar distalization, with an average post-treatment follow-up period of 6.1 years. Since the evaluated group consisted of growing individuals, the significant increases observed in both the SNA and SNB angles during the treatment and follow-up periods can be attributed more to the ongoing craniofacial growth of the mandible and maxilla rather than the direct effect of the treatment itself [32]. Notably, the ANB angle remained unchanged in our study, indicating that the correction of Class II malocclusion was largely due to denotaalveolar compensation rather than skeletal change. This finding aligns with studies by [PERSON] et al. [17], [PERSON] et al. [19], and [PERSON] et al. [21], who reported similar patterns of limited skeletal changes and the preservation of the maxillomandibular skeletal relationship. Although the distalization mechanics temporarily increased the SN-MP angle during treatment, this returned to baseline post-treatment. This finding closely aligns with the earlier results of [PERSON] et al. [19]. It has also been claimed that the distalization mechanics did not change the vertical craniofacial growth pattern [17]. In the study by [PERSON] et al. [20], it was observed that the lower anterior facial height decreased significantly as a result of maxillary arch distalization and remained relatively constant throughout the retention period. However, these findings may not be directly comparable to our results due to methodological differences. In particular, the inclusion of adult patients in their study and the use of a different distalization protocol may explain the inconsistency in the vertical skeletal changes. In this study, it was expected that both during the distalization phase and throughout the follow-up period, the maxilla and mandible, along with their associated dentition, would move anteriorly as a whole. Indeed, the fact that the distance from the maxillary molar to the vertical reference plane (U6-Y) did not significantly change--and even increased slightly--in the records taken immediately after distalization suggests that the effects of distalization were masked by concurrent growth. However, the average increase of 1.76 mm in the distance between the maxillary molars and the ANS, along with an approximately 2.5 mm improvement in the molar relationship following distalization, indicates that the maxillary molars were substantially distalized. During the fixed orthodontic treatment and subsequent follow-up period, as the maxilla and mandible continued to move anteriorly, a relapse of 0.31 mm occurred. As a result, the remaining net distalization was reduced to 1.45 mm.