Stability of first and second premolars extraction space closure

• Ano de defesa: 2018
• Autor(a) principal: Mayara Rizzo
• Orientador(a): Guilherme dos Reis Pereira Janson
• Banca de defesa: Marcos Roberto de Freitas, Francyle Simões Herrera Sanches, Danilo Pinelli Valarelli
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: eng
• Instituição de defesa: Universidade de São Paulo
• Programa de Pós-Graduação: Ciências Odontológicas Aplicadas
• País: BR
• Link de acesso: https://doi.org/10.11606/T.25.2018.tde-19072018-145926

Premolars are the most commonly extracted teeth to provide space to correct crowding and excessive labial protrusion. After treatment, the extraction spaces have to remain closed. Nevertheless, several studies have shown that there is a tendency for some relapse even in patients finished with an adequate occlusion. The objective of this study was to compare the stability of extraction space closure of the first and second premolars. A sample 72 patients´ dental casts were divided into two groups. Group 1, comprised 29 patients (116 extraction spaces) were treated with first premolar extractions at a mean initial age of 13.78 years and group 2, comprised 43 patients (100 extraction spaces) were treated with second premolar extractions at a mean initial age of 15.20 years. The dental casts obtained at pretrement, posttreament and a between 3 to 4 years postretention were digitized using a 3- dimensional scanner (R700; 3Shape,Copenhagen, Denmark). Chi-Square tests were used to compare the numbers of open and closed extraction spaces after treatment and at long-term posttreatment. T tests were used to compare the amount of spaces at posttreatment and at the long-term posttreatment stages. These tests were also performed in subgroups with completely closed extraction sites at posttreatment. The groups showed similar numbers of extraction sites reopening. First and second premolar extraction space closure present a similar tendency for reopening. Considering only the cases that showed completely closed extraction spaces in the final dental models, extraction space reopening was larger in the first premolar extraction group in the maxillary arch.