Efficiency of Upper Arch Expansion with the Invisalign System

Abstract

Objectives To investigate the efficiency and movement pattern of upper arch expansion using Invisalign aligners. The correlation between the amount of designed expansion and the efficiency of bodily expansion was evaluated, as were the initial molar torque and efficiency of bodily expansion. Materials and Methods Twenty Chinese adult patients who underwent arch expansion with Invisalign aligners were included in this study. Records of pretreatment (T0 stage) and immediately after completing the expansion phase (T1 stage) were collected, including digital models and cone-beam computed tomography. Dolphin 3D, Geomagic Studio 12.0, and Meazure software were employed to measure data and calculate differences between the expected and actual outcomes. Results There were significant differences between the expected and actual expansion amounts (P< .05). The average expansion efficiencies of the upper canine crown, first premolar crown, second premolar crown, and first molar crown were 79.75 ± 15.23%, 76.1 ± 18.32%, 73.27 ± 19.91%, and 68.31 ± 24.41%, respectively. The average efficiency of bodily expansion movement for the maxillary first molar was 36.35 ± 29.32%. Negative correlations were found between preset expansion amounts and the efficiency of bodily expansion movement (P < .05), and between initial maxillary first molar torque and efficiency of bodily expansion movement (P < .05). Conclusions Aligners could increase the arch width, but expansion was achieved by tipping movement. The evaluation of initial position and preset of sufficient root-buccal torque of posterior teeth were necessary due to the lower efficiency of bodily buccal expansion by the Invisalign system.

Maxillary arch development with Invisalign system:

“…Only a few previous studies 18,19,22,23 analyzed dentoalveolar expansion with CAT. In 2001, Vlaskalic and Boyd 30 reported that buccal expansion can be achieved within a range of 2 to 4 mm in each quadrant to reduce the risk of gingival recession and relapse.…”

“…The ongoing search for innovation in orthodontics has boosted the emergence of appliances designed to offer patients more comfort, a shorter treatment time, ability to secure better oral hygiene, and greater patient acceptance. 16 Since the introduction of clear aligner treatment (CAT) as an esthetic alternative to traditional orthodontics, it has been reported [17][18][19][20][21][22][23][24][25] that CAT was able to correct dentoalveolar crossbite and to achieve interarch transverse coordination. With conventional fixed appliances, maxillary expansion occurs by tipping the teeth in a buccal direction, both in the posterior and the anterior regions.…”

Aparelhos ortodonticos invisíveis: uma revisão

“…A manutenção das compensações dentárias ou a criação de compensações dentárias são frequentemente realizados quando uma má oclusão de Classe III é tratada apenas com a utilização de sistemas de tratamento ortodonticos. Quando a cirurgia é considerada, é necessário realizar uma descompensação dentária antes da cirurgia , Duncan et al, 2016, Zhou et al, 2019.…”

“…Aprovado o planejamento virtual, a próxima etapa é a impressão digital dos alinhadores, que correspondem a um conjunto de moldeiras sequenciais de material plástico termomoldável transparente e removíveis, são feitos sob medida para cada etapa do tratamento (Boyd, 2008). Podem ser necessários de seis (6) a quarenta e oito (48) alinhadores (Zhou et al, 2019).…”

“…Outro estudorelataram uma precisão média de 59,3% para os movimentos anteriores de torque (50,3%), redução de rotação pré-molar (39,95%), e distalização molar (87,65%) . Por outro lado, Zhou et al, (2019) observaramuma precisão de apenas 35,8% numa amostra onde apenas caninos foram avaliadas. Estudos recentes, não foram encontradas diferenças clinicamente significativas entre o que se esperava do tratamento com aparelhos invisíveis e removíveis conforme o planejamento virtual e os resultados alcançados (Drake et al, 2012;Krieger et al, 2012;Houle et al, 2017).…”