Avaliação das alterações nos tecidos moles, do tempo de retração e da movimentação de incisivos, caninos e molares em casos de extrações de pré-molares
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Data
2019-02-22
Autores
Schneider, Patricia Pigato [UNESP]
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
Os fechamentos dos espaços das extrações pode ser realizados utilizando duas técnicas principais: retração em massa (RM) ou retração em duas etapas (RDE). Os objetivos principais destes estudos foram avaliar a retração dos incisivos, as mudanças nos tecidos moles e o tempo de retração entre RM e RDE; bem como as taxas de movimentação dos caninos e molares superiores durante a primeira etapa de fechamentos dos espaços utilizando a RDE. A amostra foi composta por modelos, telerradiografias cefalométricas em norma lateral e oblíqua de 45º obtidos antes e durante o tratamento ortodôntico de 48 pacientes biprotrusos cujo os tratamentos foram realizados com extrações de quatro primeiros pré-molares. Todos os pacientes da amostra haviam sido alocados aleatoriamente para o grupo de tratamento utilizando RM (n = 24) ou RDE (n = 24). A retração dos incisivos e as alterações nos tecidos moles foram avaliadas por meio de radiografias cefalométricas em norma lateral do pré-tratamento (T1) e pós-tratamento (T2). Para análise do tempo de retração, o tamanho dos pré-molares foram medidos nos modelos e os dados, referentes ao atendimento clínico, foram coletados dos prontuários nos seguintes tempos: data do início da retração (T1) e data do término do fechamento de espaço (T2). Os movimentos dos caninos e molares superiores foram analisados através das radiografias cefalométricas oblíquas em 45º obtidas antes da retração (T0) e durante o tempo de fechamento dos espaços das extrações: 1º (T1), 3º (T3), 5º (T5) e 7º (T7) mês. Os testes não paramétricos, o método de Kaplan Meier e a análise de regressão linear foram utilizados para análise estatística. Os resultados mostraram que a quantidade de retração dos incisivos e as alterações nos tecidos moles não foram estatisticamente diferentes entre os grupos. Entretanto, o tempo de retração apresentou diferenças significativas entre a RM e RDE. Enquanto o RM levou entre 12,1 e 13,8 meses, o RDE levou entre 24,7 e 26,8 meses para fechar os espaços das extrações. Durante a RDE, as taxas de movimentação dos caninos e molares maxilares foram significativamente maiores durante o 1º mês de retração, no qual foi de 1,32mm para as cúspides dos caninos e 0,82mm para as cúspides dos molares. Após o 1º mês de retração, ambos iniciaram uma fase linear em que as taxas de movimentação mensais permaneceram constantes até o final do período de retração, estimado em média de 0,58 mm para as cúspides dos caninos e 0,30 mm para as cúspides dos molares. As principais conclusões obtidas com estes estudos são que as duas técnicas de retrações proporcionam quantidade similares de retração dos incisivos e mudanças nos tecidos moles. Entretanto, a RDE irá requerer de 1,8 a 2,2 vezes mais tempo para fechar os espaços das extrações do que a RM. Além disso, o 1º mês de retração é o período de maiores taxas de movimentação para ambos, caninos e molares, durante a primeira etapa dos fechamentos dos espaços utilizando a RDE. Após esse período, as taxas de movimentação mensal destes dentes são constantes até o 7º mês de retração.
The extraction space closing can be performed using two main retraction techniques: en masse retraction (ER) or two-step retraction (TSR). The main objectives of these studies were to evaluate incisor retraction, soft tissue changes and retraction time between ER and TSR; as well as the movement rates of the maxillary canines and molars during the first step of space closing using the TSR. The sample consisted of models, lateral and oblique cephalometric radiographs at 45º obtained before and during the orthodontic treatment of 48 adult patients with bimaxillary protrusion whose treatments were performed with extractions of four first premolars. All patients had been randomly allocated to either ER (n=24) group or TSR (n=24) group. Both incisor retraction and soft tissue changes were evaluated using pretreatment (T1) and posttreatment (T2) lateral cephalometric radiographs. To analyze the retraction time, the size of the premolars were measured in the models and data were collected from the clinical records in the following times: retraction start date (T1) and space closure completion date (T2). Both maxillary canine and molar movements were analyzed by oblique cephalometric radiographs at 45º taken before the retraction (T0) and during the follow-up of extraction space closing time: on the 1st (T1), 3rd (T3), 5th (T5) and 7th (T7) month. The principal investigator traced, superimposed and digitized all cephalograms from the lateral and oblique cephalometric radiographs at 45º using DFPlus®. The nonparametric tests, Kaplan Meier method and linear regression analysis were used for statistical analysis. The results showed that the amount of incisor retraction and soft tissue changes showed no significant differences between the two groups. However, the retraction time presented significant differences between ER and TSR. While the ER took about 12.1 and 13.8 months, the TSR took about 24.7 and 26.8 months to close the extraction spaces. During the TSR, the maxillary canine and molar movement rates were significantly greater during the 1st month of retraction at which it were of 1.32mm for the canine cusps and 0.82mm for the molar cusps. After the 1st month of retraction, both of them started a linear phase in which monthly movement rates remained constant until the end of the follow-up time, estimated on average of 0.58 mm for the canine cusps and 0.30 mm for the molar cusps. The main conclusions from these studies are that the two retraction techniques, ER and TSR, provide similar amount of incisor retraction and changes in the soft tissues. However, the TSR will require between 1.8 and 2.2 more time than ER to close the extraction spaces. In addition, the 1st month of retraction is period of greatest movements of canines and molars during the first step of space closing with TSR. After this time, the monthly movement rates are constant until the 7th retraction month.
The extraction space closing can be performed using two main retraction techniques: en masse retraction (ER) or two-step retraction (TSR). The main objectives of these studies were to evaluate incisor retraction, soft tissue changes and retraction time between ER and TSR; as well as the movement rates of the maxillary canines and molars during the first step of space closing using the TSR. The sample consisted of models, lateral and oblique cephalometric radiographs at 45º obtained before and during the orthodontic treatment of 48 adult patients with bimaxillary protrusion whose treatments were performed with extractions of four first premolars. All patients had been randomly allocated to either ER (n=24) group or TSR (n=24) group. Both incisor retraction and soft tissue changes were evaluated using pretreatment (T1) and posttreatment (T2) lateral cephalometric radiographs. To analyze the retraction time, the size of the premolars were measured in the models and data were collected from the clinical records in the following times: retraction start date (T1) and space closure completion date (T2). Both maxillary canine and molar movements were analyzed by oblique cephalometric radiographs at 45º taken before the retraction (T0) and during the follow-up of extraction space closing time: on the 1st (T1), 3rd (T3), 5th (T5) and 7th (T7) month. The principal investigator traced, superimposed and digitized all cephalograms from the lateral and oblique cephalometric radiographs at 45º using DFPlus®. The nonparametric tests, Kaplan Meier method and linear regression analysis were used for statistical analysis. The results showed that the amount of incisor retraction and soft tissue changes showed no significant differences between the two groups. However, the retraction time presented significant differences between ER and TSR. While the ER took about 12.1 and 13.8 months, the TSR took about 24.7 and 26.8 months to close the extraction spaces. During the TSR, the maxillary canine and molar movement rates were significantly greater during the 1st month of retraction at which it were of 1.32mm for the canine cusps and 0.82mm for the molar cusps. After the 1st month of retraction, both of them started a linear phase in which monthly movement rates remained constant until the end of the follow-up time, estimated on average of 0.58 mm for the canine cusps and 0.30 mm for the molar cusps. The main conclusions from these studies are that the two retraction techniques, ER and TSR, provide similar amount of incisor retraction and changes in the soft tissues. However, the TSR will require between 1.8 and 2.2 more time than ER to close the extraction spaces. In addition, the 1st month of retraction is period of greatest movements of canines and molars during the first step of space closing with TSR. After this time, the monthly movement rates are constant until the 7th retraction month.
Descrição
Palavras-chave
Ortodontia, Fechamento de espaço ortodôntico, Tempo para o tratamento, Procedimentos de ancoragem ortodôntica, Orthodontic, Orthodontic space closure, Time to treatment, Anchorage procedures orthodontics.