Comparisons of maxillary incisor retraction effects for patients with first premolar extractions between Damon Q and Invisalign(®): A retrospective study

Torque control of maxillary incisors is very important in maxillary protrusion patients with first premolars extraction, but the efficacy of maxillary incisor retraction of clear aligners is still controversial now. This retrospective study was aimed to compare the retraction effects between Damon Q and Invisalign(®) appliances in patients with first premolar extractions. 59 patients (33 cases with Damon Q and 26 cases with Invisalign(®)) with first premolar extraction were selected in this study. Subsequently, patients of each group were allocated into three subgroups according to the pretreatment value of U1-NA (°). The retraction effects of maxillary incisors and upper lips were accessed by the variations of cephalometric, overbite and overjet measurements. Treatment duration with Invisalign(®) (31.4 ± 6.4 months) was longer than Damon Q (27.7 ± 6.3 months) (P = .03). The angular measurements, U1-NA (°) and U1-SN (°) showed more lingual crown inclinations in Invisalign(®) group than Damon Q group (P ≤ .04). When evaluating linear measurements, the retractions of the maxillary incisors and upper lip positions showed no significant differences (P ≥ .13). Invisalign(®) group also showed more lingual crown retractions and labial root deviations compared to Damon Q group in subgroup Ⅲ (P ≤ .037). As regards to the molar relationship, Invisalign(®) displayed less Class Ⅰ molar relationship than Damon Q group. The increased overbite of anterior incisors was also showed in the Invisalign(®) treatment group (P ≤ .047). Invisalign(®) was not sufficiently effective in retracting maxillary incisors compared with Damon Q appliances. Invisalign(®) led to more lingual inclination movement and increased overbite.