Análise do movimento de molares, caninos e incisivos, sobremordida e perda de ancoragem, em pacientes classe I biprotrusos, tratados com extração de 4 primeiros pré-molares e retração em duas etapas
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Data
2022-03-03
Autores
Ledra, Ingrid Muller
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
Este estudo retrospectivo com amostra derivada de um ensaio clínico randomizado com amostra por seleção prospectiva avaliou a perda de ancoragem dentária e a sobremordida em indivíduos biprotrusos que foram submetidos a extração dos quatro primeiros pré-molares e cujo fechamento de espaços foi realizado com mecanismos de retração por deslizamento. Foram selecionadas 144 telerradiografias de uma amostra de 24 pacientes adultos Classe I de Angle, com protrusão dentoalveolar de maxila (Mx) e mandíbula (Md) e apinhamento máximo 4mm por arco dentário. Esta amostra foi tratada com a extração dos quatro primeiros pré-molares e retração de caninos (R1) e incisivos (R2) em duas etapas (R2E). Para análise foram utilizadas cefalogramas obtidos por meio do traçado das radiografias cefalométrica de 45 graus direita e esquerda, obtidos pré (T0), pós retração de canino (T1) e após o fechamento completo dos espaços das extrações (T2). Todos os cefalogramas foram sobrepostos e digitalizados no software DFPlus®. Para análise estatistica foi realizado teste T de student. Os resultados mostraram que o maior movimento mesial dos molares ocorre na etapa R1 e que nesta mesma etapa não houve significancia estatística na movimentação dos incisivos no sentido antero posterior e na movimentação vertical dos incisivos superiores. Na etapa R2 existe um aumento significativo da sobre mordida em 60%. Movimento mesial dos molares e inclinação descontrolada dos caninos. Com este estudo podemos concluir que o movimento de distalização do canino é o principal responsável por movimento mesial dos molares na R2E, que existe aumento do overbite nas duas etapas da retração, sendo este maior em R2 e que somente a curva de spee acentuada ou reversa não é suficiente para neutralizar as forças colaterais de extrusão presentes na R2 da retração anterior na técnica R2E por mecânica de deslize.
This is a retrospective study derived from a randomized clinical trial sample with a prospective selection that evaluated the loss of dental anchorage and overbite in biprotruding patients who underwent extraction of the four first premolars and closed spaces with retraction mechanisms. 144 cephalograms were selected from a sample of 24 Angle Class I adult patients, with dentoalveolar protrusion of the maxilla (Mx) and mandible (Md) and maximum crowding of 4 mm per dental arch. This sample was treated with extraction of the four first premolars and retraction of canines (R1) and incisors (R2) in two steps (R2E). For analysis, cephalograms were used by tracing of cephalometric radiographs of 45 degrees right and left, obtained before (T0), after canine retraction (T1) and after complete closure of the extraction spaces (T2). All cephalograms were superimposed and digitized using the DFPlus® software. For statistical analysis, Student's T test was performed. The results showed that the greatest mesial movement of the molars occurs in stage R1 and was no statistical significance in the movement of the incisors in the anteroposterior direction and in the vertical movement of the maxillary incisors. In step R2 there is a significant increase in overbite by 60%. Mesial movement of molars and uncontrolled tipping of canines. With this study we can conclude that the movement of canine distalization is the main responsible for the mesial movement of the molars in R2E and that there is an increase in the overbite in both stages of retraction, which is greater in R2 and that only the accentuated or reversed spee curve is not sufficient to neutralize the collateral forces of extrusion present in the R2 of the previous retraction in the R2E technique by sliding mechanics.
This is a retrospective study derived from a randomized clinical trial sample with a prospective selection that evaluated the loss of dental anchorage and overbite in biprotruding patients who underwent extraction of the four first premolars and closed spaces with retraction mechanisms. 144 cephalograms were selected from a sample of 24 Angle Class I adult patients, with dentoalveolar protrusion of the maxilla (Mx) and mandible (Md) and maximum crowding of 4 mm per dental arch. This sample was treated with extraction of the four first premolars and retraction of canines (R1) and incisors (R2) in two steps (R2E). For analysis, cephalograms were used by tracing of cephalometric radiographs of 45 degrees right and left, obtained before (T0), after canine retraction (T1) and after complete closure of the extraction spaces (T2). All cephalograms were superimposed and digitized using the DFPlus® software. For statistical analysis, Student's T test was performed. The results showed that the greatest mesial movement of the molars occurs in stage R1 and was no statistical significance in the movement of the incisors in the anteroposterior direction and in the vertical movement of the maxillary incisors. In step R2 there is a significant increase in overbite by 60%. Mesial movement of molars and uncontrolled tipping of canines. With this study we can conclude that the movement of canine distalization is the main responsible for the mesial movement of the molars in R2E and that there is an increase in the overbite in both stages of retraction, which is greater in R2 and that only the accentuated or reversed spee curve is not sufficient to neutralize the collateral forces of extrusion present in the R2 of the previous retraction in the R2E technique by sliding mechanics.
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Palavras-chave
Má oclusão, Procedimentos de ancoragem ortodôntica, Ortodontia corretiva, Malocclusion, Orthodontic anchorage procedures, Orthodontics corrective