RESUMEN
INTRODUCTION: The mandibular condylar surface is made up of four layers, i.e., an external layer composed of dense connective tissue, followed by a layer of undifferentiated cells, hyaline cartilage and bone. Few studies have demonstrated the behavior of the condylar cartilage when the mandible is positioned posteriorly, as in treatments for correcting functional Class III malocclusion. OBJECTIVE: The aim of this study was to assess the morphologic and histological aspects of rat condyles in response to posterior positioning of the mandible. METHODS: Thirty five-week-old male Wistar rats were selected and randomly divided into two groups: A control group (C) and an experimental group (E) which received devices for inducing mandibular retrusion. The animals were euthanized at time intervals of 7, 21 and 30 days after the experiment had began. For histological analysis, total condylar thickness was measured, including the proliferative, hyaline and hypertrophic layers, as well as each layer separately, totaling 30 measurements for each parameter of each animal. RESULTS: The greatest difference in cartilage thickness was observed in 21 days, although different levels were observed in the other periods. Group E showed an increase of 39.46% in the total layer, reflected by increases in the thickness of the hypertrophic (42.24%), hyaline (46.92%) and proliferative (17.70%) layers. CONCLUSIONS: Posteriorly repositioning the mandible produced a series of histological and morphological responses in the condyle, suggesting condylar and mandibular adaptation in rats.
Asunto(s)
Cartílago/crecimiento & desarrollo , Maloclusión de Angle Clase III/fisiopatología , Cóndilo Mandibular/crecimiento & desarrollo , Retrognatismo/fisiopatología , Animales , Cartílago/anatomía & histología , Masculino , Cóndilo Mandibular/anatomía & histología , Ratas , Ratas Wistar , Estadísticas no ParamétricasRESUMEN
INTRODUCTION: The mandibular condylar surface is made up of four layers, i.e., an external layer composed of dense connective tissue, followed by a layer of undifferentiated cells, hyaline cartilage and bone. Few studies have demonstrated the behavior of the condylar cartilage when the mandible is positioned posteriorly, as in treatments for correcting functional Class III malocclusion. OBJECTIVE: The aim of this study was to assess the morphologic and histological aspects of rat condyles in response to posterior positioning of the mandible. METHODS: Thirty five-week-old male Wistar rats were selected and randomly divided into two groups: A control group (C) and an experimental group (E) which received devices for inducing mandibular retrusion. The animals were euthanized at time intervals of 7, 21 and 30 days after the experiment had began. For histological analysis, total condylar thickness was measured, including the proliferative, hyaline and hypertrophic layers, as well as each layer separately, totaling 30 measurements for each parameter of each animal. RESULTS: The greatest difference in cartilage thickness was observed in 21 days, although different levels were observed in the other periods. Group E showed an increase of 39.46% in the total layer, reflected by increases in the thickness of the hypertrophic (42.24%), hyaline (46.92%) and proliferative (17.70%) layers. CONCLUSIONS: Posteriorly repositioning the mandible produced a series of histological and morphological responses in the condyle, suggesting condylar and mandibular adaptation in rats.
INTRODUÇÃO: a superfície do côndilo da mandíbula é constituída por quatro camadas: uma externa (constituída de tecido conjuntivo denso), seguida pela camada de células indiferenciadas, cartilagem hialina e osso. Poucos estudos demonstraram o comportamento da cartilagem condilar quando a mandíbula é posicionada posteriormente, como na terapia para correção de Classe III funcional. OBJETIVO: o objetivo desse trabalho foi avaliar os aspectos morfológicos e histológicos do côndilo de ratos, em resposta ao posicionamento posterior da mandíbula. MÉTODOS: foram selecionados 30 ratos Wistar, machos, com cinco semanas de vida, aleatoriamente divididos em dois grupos: grupo controle (GC) e grupo experimental (GE), que recebeu dispositivos para induzir a retrusão mandibular. Os animais foram sacrificados após 7, 21 e 30 dias de experimento. Para a análise histológica, foi realizada a mensuração da espessura condilar total, incluindo as camadas proliferativa, seriada e hipertrófica, assim como cada camada separadamente, totalizando 30 medições para cada parâmetro, de cada animal. RESULTADOS: a maior diferença na espessura da cartilagem foi observada em 21 dias, apesar de serem verificados níveis diferentes nos demais períodos. Em GE, foi possível observar um aumento de 39,46% na camada total, representado pelo aumento na espessura das camadas hipertrófica (42,24%), seriada (46,92%) e proliferativa (17,70%). CONCLUSÕES: o reposicionamento posterior da mandíbula produziu uma série de respostas histológicas e morfológicas no côndilo, e sugerem a ocorrência de uma adaptação condilar e mandibular em ratos.
Asunto(s)
Animales , Masculino , Ratas , Cartílago/crecimiento & desarrollo , Maloclusión de Angle Clase III/fisiopatología , Cóndilo Mandibular/crecimiento & desarrollo , Retrognatismo/fisiopatología , Cartílago/anatomía & histología , Cóndilo Mandibular/anatomía & histología , Ratas Wistar , Estadísticas no ParamétricasRESUMEN
OBJECTIVE: To determine whether dentofacial deformities influence maximal isometric bite force in affected individuals compared to a control group. DESIGN: A total of 125 volunteer adult patients attended at a hospital participated in the study. Of these, 44 had a confirmed diagnosis of class II deformity (GII: 13 men and 31 women; mean age: 27 years) and 81 had class III deformity (GIII: 35 men and 46 women; mean age 25 years), all of them with indication of orthognathic surgery and under orthodontic treatment. Fifty adult volunteers (CG: 17 men and 33 women; mean age: 22 years) with no alterations of dental occlusion or clinical signs of temporomandibular joint dysfunction participated as controls. Maximal isometric bite force was measured with an electronic gnathodynamometer alternately positioned on each side of the dental arch in the region of the molar teeth and the subjects were instructed to bite it as strongly as possible, with the value being recorded in Newtons. Individuals with good understanding of oral language and with no cognitive or neuromuscular deficits were selected. Data were analysed statistically by the mixed effects model. RESULTS: There was no statistically significant difference (P>.05) in maximal isometric bite force between subjects with class II and class III dentofacial deformities, although the values for both groups were lower than those of control individuals. CONCLUSION: Dentofacial deformity affected maximal isometric bite force regardless of its pattern.
Asunto(s)
Fuerza de la Mordida , Maloclusión de Angle Clase III/terapia , Maloclusión Clase II de Angle/terapia , Ortodoncia Correctiva , Adolescente , Adulto , Femenino , Humanos , Contracción Isométrica/fisiología , Masculino , Maloclusión Clase II de Angle/fisiopatología , Maloclusión de Angle Clase III/fisiopatología , Diente Molar/fisiopatología , Prognatismo/fisiopatología , Prognatismo/terapia , Retrognatismo/fisiopatología , Retrognatismo/terapia , Adulto JovenRESUMEN
Class II skeletal malocclusion and respiratory disorders owing to the obstruction of the upper airway at early growth stages have been correlated. The retro/micrognathism can be treated with functional appliances. However, the effects of an early functional orthopedic treatment on the airway dimensions have not been evaluated before the growth peak. Therefore, the objective of this study was to evaluate the changes in the airway dimensions of class II retrognathic children who received treatment with either Klammt or Bionator on a pre-pubertal stage. The sample consisted of 50 lateral cephalograms of class II retrognathic patients in a pre-puberal stage, before and after the use of a Klammt or Bionator II treatment for 1 year. The data were evaluated by Student's t-test or Mann-Whitney test, and significance was set at 5% (P < 0·05). When the measurements before and after treatment were compared, a statistically significant increase in the airway dimensions was found at the space where the adenoid tissue was located. The only airway dimensions that increased after treatment with functional appliances were the ones located at the nasopharynx. The adenoid tissue is still in the peak of growing at the ages of the subjects included in this study. However, the measurements along the nasopharynx increased when compared with the initial ones. Still, similar retrospective and prospective studies are needed at older stages.