Long-term comparison of occlusal relapse in cases treated with and without premolar extraction

• Ano de defesa: 2020
• Autor(a) principal: Silva, Paula Patrícia Cotrin da
• 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: Estabilidade; Extrações dentárias; Má oclusão; Malocclusion; Recidiva; Relapse; Stability; Tooth extraction
• Link de acesso: https://www.teses.usp.br/teses/disponiveis/25/25144/tde-22102021-123836/

Objective: The aim of this study was to compare the occlusal relapse in nonextraction and extraction orthodontic treatments in the long-term. Material and methods: The sample comprised 57 Class I and Class II malocclusion patients were divided into 2 groups: Group 1: 16 patients treated nonextraction, with mean initial, final and longterm posttreatment ages of 13.20, 15.07 and 50.32 years, respectively. Mean treatment and long-term follow-up times were 1.86 and 35.25 years. Group 2: 41 patients treated with 4-premolars extraction, with mean initial, final and long-term posttreatment ages of 13.31, 15.63 and 53.60 years, respectively. Mean treatment and long-term follow-up times were 2.32 and 37.96 years. Dental casts were obtained and digitized at pretreatment (T1), posttreatment (T2) and long-term posttreatment (T3) stages. The following measurements were obtained: Little irregularity Index, arch length and perimeter, intercanine, interpremolar and intermolar widths, PAR and OGS indexes. The subjects also answered an on-line questionnaire on the esthetic and occlusal self-perception at T3. Intergroup comparison was performed with independent t tests. Results: At the long-term, all arch dimensions, except intercanine width, were significantly smaller in the extraction group. Both groups showed similar amount of relapse and arch dimension changes in the long-term, except for the mandibular arch perimeter. The percentage of mandibular anterior crowding relapse was significantly greater in nonextraction (84.46%) than in extraction group (44.66%). PAR index improved with treatment and relapsed at the long-term in both groups. Nonextraction group showed greater relapse according to OGS index than extraction cases. Nonextraction patients perceived more changes in alignment over time than extraction individuals, but overall satisfaction was similar. Conclusions: There was no difference in the amount of long-term relapse of anterior crowding and transversal arch dimensions in cases treated with and without extraction. The percentage of relapse of mandibular anterior crowding was significantly higher in the nonextraction than in the extraction group. Mandibular arch perimeter showed more decrease in the long-term in extraction cases. The nonextraction group showed more occlusal relapse and perceived more changes in alignment over time, but overall patient satisfaction was similar for both groups.