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

Abstract

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.

Risk Factors for Maxillary Central Incisors Torque Loss in Orthodontic Treatment of Premolar Extraction Cases with Clear Aligners：a retrospective study

“…[20,24]Conversely, other studies concluded that torque measurements obtained from cephalometric are predictable for clinical purposes. [7] The cephalometric analysis (T0-T1) shows that CAs are effective in retracting the maxillary incisors and improving the pro le, which is consistent with previous studies. [7]However, the angle changes of the maxillary incisors decreased by 11.68° from T0-T1, and the post-U1-NA(°)was less than the standard deviation of the normal mean, indicating that CAs were not effective in controlling incisor torque in extraction cases.…”

“…[7] The cephalometric analysis (T0-T1) shows that CAs are effective in retracting the maxillary incisors and improving the pro le, which is consistent with previous studies. [7]However, the angle changes of the maxillary incisors decreased by 11.68° from T0-T1, and the post-U1-NA(°)was less than the standard deviation of the normal mean, indicating that CAs were not effective in controlling incisor torque in extraction cases. It is possible that the overtreatment design or movement steps were not considered.The current study results indicate that there is greater upper anterior retraction in CAs.When the crown is lingually inclined ,the root will be labially inclined,which increases the risk of creating or deteriorating bone fenestration during orthodontic treatment.…”

“…However, restarting is a means of correction, while not being e cient, and multiple restarts can result in longer correction times than a xed correction. [7,28] The extraction pattern in our study varied, with the extraction of premolars being one of the most common strategies to retract proclined incisors and reduce lip protrusion. [8, 29,30]One study reports that more signi cant tipping occurs around the extraction of the second premolar than around the rst premolar [31] because extraction of the second premolars involves more anchorage loss.…”

“…[5,6] Despite the increasing range of clear aligner treatments, movements such as anterior torque control in premolar extraction cases remain challenging. [7] The control of incisor torque is crucial in orthodontic treatment, particularly in extraction cases. [8] Achieving optimal torque is essential for both smile aesthetics and proper anterior guidance.…”

Long-term bone remodeling of maxillary anterior teeth with post-treatment alveolar bone defect in adult patients with maxillary protrusion: a prospective follow-up study

“…The inclusion criteria were as follows: age > 18 years, maxillary protrusion (Class I or Class II molar relationship, 2° < ANB angle < 8°, U1-NA angle > 22.8° [ 17 ], upper lips positioned in advance of the E-line), extraction of four first premolars, undergone maxillary anterior teeth retraction during orthodontic treatment, at least one maxillary anterior tooth diagnosed with PBD or LBF after orthodontic treatment, available CBCT scans before and after orthodontic treatment, and wearing a removable thermoplastic retainer during retention period. The exclusion criteria were as follows: missing maxillary anterior teeth, maxillary anterior teeth with root canal treatment and crown, significant reopening of the extraction site or crowding during the retention period, periodontal inflammation, systemic disease, and smoker.…”