Viet Anh Nguyen, Thi Thanh Thanh Huyen Le, Mai Phuong Nguyen, Thi Ngan Dang
In adults treated with four-premolar extractions, lingual appliances were associated with greater maxillary incisor retroclination than labial appliances, whereas mandibular incisor inclination, vertical pattern, and lip position were similar. Appliance selection should therefore consider maxillary torque control, especially when lingual treatment is chosen for esthetic reasons.
PURPOSE: Evidence comparing the dentofacial effects of lingual and labial fixed appliances in adults treated with four-premolar extractions is limited, particularly when skeletal anchorage is considered. This study compared posttreatment incisor inclination, vertical pattern, and lip position between the two appliance types by analyzing lateral cephalograms.
METHODS: This retrospective comparative study included 118 adults treated in one private practice (59 with lingual, 59 with labial fixed appliances). Primary outcomes were posttreatment maxillary incisor to sella-nasion angle (U1-SN) and mandibular incisor to mandibular plane angle (IMPA). Secondary outcomes were sella-nasion to gonion-gnathion angle (SN-GoGn), upper lip to esthetic line distance (UL-E), and lower lip to esthetic line distance (LL-E). Outcomes were compared using analysis of covariance adjusted for the pretreatment value, Angle classification, crowding, and the number of temporary anchorage devices (TADs). Sensitivity models additionally adjusted for age, sex, and treatment duration.
RESULTS: Adjusted posttreatment U1-SN was lower in the lingual group than in the labial group (adjusted difference, -4.40°; 95% confidence interval [CI] -6.46 to -2.35; P < 0.001). No significant between-group differences were found for IMPA (0.05°; P = 0.957), SN-GoGn (0.39°; P = 0.336), UL‑E (-0.31 mm; P = 0.336), or LL‑E (-0.13 mm; P = 0.759). Sensitivity analyses supported the same pattern.
CONCLUSION: In adults treated with four-premolar extractions, lingual appliances were associated with greater maxillary incisor retroclination than labial appliances, whereas mandibular incisor inclination, vertical pattern, and lip position were similar. Appliance selection should therefore consider maxillary torque control, especially when lingual treatment is chosen for esthetic reasons.