# Long-Term CBCT Evaluation of Mandibular Third Molar Changes after Distalization in Adolescents
###### Abstract  
Introduction: This study aimed to evaluate mandibular molar changes after distalization using Class III elastics and modified C-palatal plates (MCPPs) in the maxilla and to use CBCT to specifically analyze the third-molar position after long-term retention in adolescents. Methods: The sample consisted of 65 mandibular third molars from 35 subjects, divided into two groups. Twenty-six of the third molars were from fourteen adolescent patients with Class I bimaxillary protrusion (mean age, 12.8 years) who had undergone bilateral maxillary distalization using an MCPP and mandibular distalization with Class III elastics with non-extraction treatment. For the control group, 39 third molars from 21 Class I normal-occlusion subjects were used. In the treated group, CBCT images were taken before distalization (T1), after molar distalization (T2), and at a long-term observation point (6.1 \(\pm\) 2.7 years) (T3). Repeated measures ANOVA and a post hoc test with Bonferroni correction were used to analyze significant differences in the positions at the three points in time. Results: There were 2.3 and 1.7 mm of distal movement at the crown of the mandibular first and second molars, with distal tipping of 5.2\({}^{\circ}\) and 5.3\({}^{\circ}\), respectively, and 3.0\({}^{\circ}\) of distal tipping of the third molars. Comparing the treated group with the control group at T3, there was a significant change in the angularation of the third molars (_p_ < 0.001). In the long-term, the third molars from the treated group showed a downward and buccal position after distalization. Conclusions: In the long term, the developing mandibular third molar buds had downward and buccal positional changes after total attach distalization. These findings suggest the need for clinicians to consider the possibility of the impaction of developing third molars after mandibular total arch distalization in adolescents. Keywords:distalization; mandibular molars; temporary skeletal anchorage devices +
Footnote †: journal: _Sciences_  
Currently, however, temporary skeletal anchorage devices (TSADs) have become an important modality in orthodontics, reducing the need for extraction while allowing the distalization of the maxillary dentition [3; 4; 5]. A promising non-extraction treatment modality to consider for the correction of bimaxillary protrusion is molar distalization. To reduce bimaxillary protrusion, maxillary molar distalization should be performed concurrently with mandibular molar distalization. [PERSON] et al. [4] reported that with microimplant-aided sliding mechanics, crowding could be resolved while improving facial esthetics by retracting the lips with the distalization of the maxillary and mandibular posterior teeth without extraction. [PERSON] et al. [6] demonstrated a novel technique to treat bimaxillary protrusion using miniscrews to extract only an impacted third molar without the extraction of the premolars. In other cases, miniplates, as well as miniscrews, were efficiently used for total mandibular arch distalization. [PERSON] et al. [7] presented improved lip protrusion, and retrolcination of the upper and lower incisors was achieved with non-extraction treatment using a modified C-palatal plate (MCPP) and intermaximillary elastics in a bimaxillary patient (Figure 1). [PERSON] et al. [1] reported that the miniplate is a useful tool for moving mandibular molars distally to correct anterior crossbite or mandibular anterior crowding. Further, [PERSON] et al. [8] evaluated the differences in treatment effects between arch distalization using buccal miniscrews and ramal plates in the mandibular dentition. They suggested that the ramal plates presented more molar distalization than could be achieved with buccal miniscrews. Traditionally, Class III elastics have been used to correct protrusions of the mandibular dentition.