Influence of elastic chain in the degradation of orthodontic forces - in vitro study

Abstract

ResumoIntrodução: Os elásticos corrente são acessórios indispensáveis no tratamento ortodôntico, e suas propriedades de grande interesse para o profissional, a fim de obter maior controle sobre os movimentos dos dentes. Objetivo: Avaliar a influência da marca comercial e comprimento da cadeia espaçadora de elásticos corrente na degradação de força. Material e método: Foram utilizadas ligaduras elásticas ortodônticas em cadeia, tipo curto, médio e longo das marcas: Rocky Mountain (RMO), TP e GAC. Os elásticos, contendo elos correspondentes a 12,5 mm, foram tensionados entre pinos de aço na máquina de ensaio universal Instron 4411 até 25 mm. O valor foi anotado. Após a aferição inicial da força, os elásticos foram fixados em placa de resina acrílica e mantidos distendidos a 25 mm. Foram inseridas em recipiente contendo água deionizada e mantidas em estufa a 37 °C. A leitura da força dos elásticos foi feita nos tempos de 24 horas, 48 horas, 7 dias, 14 dias, 21 dias e 28 dias. Os dados foram submetidos ao teste estatístico apropriado, com nível de significância de 5%. Resultado: Os elásticos TP apresentaram força significativamente maior em todos os períodos. Os elásticos GAC e RMO apresentaram forças estatisticamente semelhantes. Os elásticos TP cadeia curta e longa apresentaram força significativamente maior que os elásticos cadeia média. Para GAC e RMO os elásticos curto apresentaram força maior que os médios e este maior que os longos. Conclusão: A cadeia espaçadora e a marca comercial influenciaram nos resultados obtidos, reforçando a importância do conhecimento dos tipos de elástico.Descritores: Elastômeros; ortodontia; elasticidade. AbstractIntroduction: Elastic chains are indispensable accessories in orthodontic treatment. Changes in their properties are of great interest to professionals in order to gain greater control over tooth movements. Objective: Evaluate the influence of trademark and length of the spacer chain on force degradation of elastic. Material and method: We used the following elastic chain types: TP, Rocky Mountain (RMO) and GAC short, medium and long varieties. The elastics, which contained links corresponding to 12.5 mm, were tensioned between steel pins using Instron 4411 universal testing machine up to 25 mm. The value was recorded. After initial measurement of the force, the elastics were fixed on an acrylic resin plate and kept distended to 25 mm. They were inserted in a container with deionized water and kept in an incubator at 37º. The elastic force data was collected at time intervals of 24 hours, 48 hours, 7 days, 14 days, 21 days and 28 days. These records were subjected to an appropriate statistical test, with significance level of 5%. Result: TP elastics showed significantly higher force in all periods. RMO and GAC elastics showed similar elastic forces. Short and long TP elastics exhibited significantly higher strength than the average elastic chain. As regards GAC and RMO, short elastics showed higher than average force values, and higher values than the long type. Conclusion...

Evaluation of degradation of force of esthetic elastomeric chains

“…This refers especially to esthetic elastomers used in adult patients who are highly demanding about the esthetic appearance of orthodontic appliances 3,4 . Elastomer chains can be classified as short, medium or long according to the distance between the links 5,6 . They have the advantages of being practical, hygienic, having elastic memory, being easy to place and comfortable for the patient to use, biocompatible and inexpensive [7][8][9] .…”

“…During orthodontic treatment, it is desirable for the elastics to maintain adequate force, for the purpose of achieving the dental movement desired by the orthodontist. However, the elastomeric chains dissipate a decreasing force 6,13 . To achieve greater efficiency during orthodontic treatment, it is necessary to know about some important factors such as the force applied on the teeth to be moved, because continuous forces obtain better results than intermittent forces 6,13 .…”

“…However, the elastomeric chains dissipate a decreasing force 6,13 . To achieve greater efficiency during orthodontic treatment, it is necessary to know about some important factors such as the force applied on the teeth to be moved, because continuous forces obtain better results than intermittent forces 6,13 . Some authors have suggested prestretching of chain elastics before their clinical application.…”

“…The recommendation is that they should be changed every three weeks, and that elastomeric chains should not be used for a period longer than four weeks. This is because, on an average, the elastics lose 30% of the magnitude of initial force, in addition to the occurrence of bacterial plaque accumulation and chemical interaction with foods and oral fluids 1,6 .…”

“…When evaluating the degradation for force undergone by elastics of the chain type, because of stretching time to which they were submitted 1,6,13,15 , the orthodontist frequently has difficulty in determining the adequate force to be transmitted to the teeth by the elastomeric chains and their time interval of dissipating useful force 13 . In the literature there is a scarcity of studies about the degradation of force of esthetic elastomeric chains.…”