Maxillary incisors initial position and soft-tissue changes in Class II malocclusion extraction protocols

• Ano de defesa: 2016
• Autor(a) principal: Mendes, Lucas Marzullo
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: eng
• Instituição de defesa: Biblioteca Digitais de Teses e Dissertações da USP
• Palavras-chave em Português: Andrews Element II; Class II malocclusion; Elemento II de Andrews; Extração de pré-molares; Maloclusão de Classe II; Non-extraction; Normal occlusion; Oclusão normal; Premolar extraction; Revisão sistemática; Seis Elementos; Sem extração; Six Elements; Soft-tissue; Systematic review; Tecidos mole
• Link de acesso: https://www.teses.usp.br/teses/disponiveis/25/25144/tde-09122021-110010/

Introduction: Differences in long-term and posttreatment attractiveness between Class II treatment protocols motivated these studies. Element II demonstrated that well-balanced faces have maxillary incisors positioned in an individually calculated anteroposterior relationship with the forehead. Thus, it was used to investigate the initial characteristics of the patients. Moreover, to evaluate the soft-tissue changes with extraction protocols, a systematic review was performed searching PubMed, Web of Science, Embase, Scopus and Cochrane electronic databases. Results: The CII group had forward incisors AP position when compared to the NO group. Also, the incisors AP positions in the extraction subgroups were forward when compared to the NE subgroup. Statistically significant soft-tissue changes reported included nasolabial angle (NLA) increasing from 2.4 to 5.40 degrees in the 2-premolar extraction protocol and from 1 to 6.84 degrees in the 4-premolar extraction protocol. Retrusion of the upper and lower lips were also verified, with less retraction of the lower lip in the 2-premolar extraction group. Conclusions: Class II subjects presented the maxillary incisors significantly more protruded than normal occlusion subjects. Class II division 1 extraction subgroups demonstrated significantly more protruded incisors as compared to the non-extraction subgroup. When Class II division 1 malocclusion is treated with premolar extractions, the NLA increases and the lips are retracted. However, there is less retraction of the lower lip in the 2- maxillary premolar extraction protocol.