ABSTRACT
Introducción: el propósito del presente estudio fue describir los cambios en la postura craneocervical en unapoblación infantil con clase II esquelética por prognatismo mandibular, luego de la utilización de mentonera con placa de acetato inferior para levantar la mordida. Métodos: la muestra consistió de once niños (siete niñas y cuatro niños). A cada niño le fueron tomadas tres radiografías cefálicas laterales en posición natural de cabeza (mirando de frente a un espejo), con ligero contacto oclusal. La primera radiografía (T1) fue tomada antes de iniciar la utilización de la mentonera, la segunda (T2), cuatro meses después de su uso y la tercera (T3), cuatro meses después de retirada. Para el análisis se emplearon medidas lineales y angulares, se realizó análisis descriptivo de las variables y se utilizaron las pruebas de normalidad (Shapiro-Wilk) y Friedman. Resultados: el análisis estadístico no mostró diferencias significativas en ninguna de las variables analizadas, y en ninguno de los momentos evaluados. Conclusión: a pesar de la gran variabilidad individual en la postura craneal, cervical y craneocervical de los niños evaluados, en general no se observaron en esta muestra cambios significativos en la columna cervical, luego del tratamiento con mentonera y placa de acetato inferior que levantaba la mordida.
Introduction: the aim of this study was to describe the changes in the craniocervical posture in children with skeletal class II malocclusion (prognathic mandible) after wearing chincap with lower occlusal bite plane. Methods: the sample consisted of eleven children (7 girls and 4 boys). Three lateral cephalic radiographs were taken for each child with the head in natural position (mirror position), with light occlusal contact. The first radiograph (T1) was taken before wearing the chincap, the second (T2) was taken four months after wearing the appliance and the third (T3) was taken four months after removing the chincap. Specific angular and linear dimensions were used, the comparison within the group was performed using Descriptive Analysis and the Normality (Shapiro-Wilk) y Friedman Signed Rank Test. Results: statistical analysis didnt show significant changes in any of the angular and linear measurements analyzed nor at any of the times studied. Conclusion: even though there is a great individual variability in the cranial, cervical and craniocervical posture of the tested children, in general, there were nostatistical significant changes in cervical posture after treatment with chincap and lower occlusal bite plane.
Subject(s)
Child , Head-Down Tilt , Extraoral Traction AppliancesABSTRACT
Objective:To build a three-dimensional finite element model of child temporomandibular joint including the mandible with chincap,and provide a basic condition for the study of the effects of chincap on the stress distribution of the base of mandible.Methods:The model was constructed from a child who accepted the treatment of chincap by ANSYS 5.6,using the reconstructive technique of spiral CT in combination with the three-dimensional finite element.The model consisted of 20045 bricks and 4442 nodes.On the model,mandible retraction was simulated under the different traction which included the different directions and magnitudes.Results:Three-dimensional model of the `Temporomandibular joint-mandible-chincap system of child' was established,which was better suited for the actual and practical situation of chincap in clinic,and the loading point and the different directions and magnitudes were determined by clinical application.Mechanical changes of various parts of the model in different working conditions could be simulated by means of adding different material properties and boundary conditions.Conclusion:The established model could be used for the study of stress distribution of chincap applying simulation.
ABSTRACT
This study was conducted to investigate the changes in the structural parts of the craniofacial skeleton subsequent to chincap therapy in the juvenile skeletal Class Ill Patients. The subject consisted of 29 Korean children(14 males, 15 females) who had skeletal Class M malocclusion and were undergone chincap therapy from the beginning of the treatment (and an auxiThary upper removable appliance, if necessary). The control group was composed of 21 children(10 males, 11 females) with skeletal Class Ill malocclusion who had no orthodontic treatment. Cephalometric data at the mean age of 7 and 2 years later were analyized by finite element method, and compared between groups by independent group t-test(p<0.05). The results of the present study were as follows; 1. There were no significant changes in the cranial base, posterior face, upper anterior face, ramus, chin and soft tissues by the chincap therapy. 2. The mandibular body showed significant differences in the minimum extention ratio and the overall shape ratio. This means that the vertical direction of growth was retarded by the chincap therapy. 3. The major direction of the growth in the maxillary basal bone was significantly more horizontal in the experimental group, which suggests that the vertical growth of maxilla was inhibited. 4. There was statistical difference in the major direction of the growth of the anterior face between groups. This may be due to the significant difference in the major direction of growth of the lower anterior face, supposed to be resulted from the mandibular rotation and/or displacement by the chincap therapy. The change in the oral functional space seemed to be caused by the same reason. 5. From the standpoint of these results, the retardation of growth, the changes of the growth direction and the morphological changes could be accepted partly, but the major effect of the chincap seems to be the rotation and the displacement of the mandible.
Subject(s)
Humans , Male , Chin , Finite Element Analysis , Malocclusion , Mandible , Maxilla , Skeleton , Skull BaseABSTRACT
The purpose of this study was to investigate the changes in the craniofacial skeleton subsequent to chincap therapy in the juvenile skeletal Class III malocclusion with more appropriate control samples. The experimental group consisted of 29 Korean children(14 males, 15 females) who had skeletal Class III malocclusion with prognathic mandible and were undergone chincap theray from the beginning of treatment. The control. group was composed of 21 Korean children(10 males, 11 females) who had no orthodontic treatment, but with similar skeletal discrepancies to experimental group. Lateral cephalometric radiographs at the age of 7, and 2 years later were analyized and compared with student's t-test(p< 0.05). The results of this study were as follows; 1. The control group without chincap therapy had not shown any improvement of the skeletal discrepancies, but had grown to be much severe. This means that the untreated Class III patient with prognathic mandible would not be corrected by growth For the experimental group with chincap therapy, the anterior-posterior skeletal discrepancies and mandibular prognathism were both improved. 2. Neither significant restraint nor acceleration of growth was found in the cranial base and maxilla by chincap treatment" The inhibition of mandibular growth could not be accepted, but the changes of the direction of growth and morphological changes were found. 4. Vertical growth tendency was increased with chincaP therapy. 5, When putting together the results of the analyses , it seems to be the rotation and displacement of the mandible that the major treatment effects of chincap are. The changes of the direction of growth and the morphological changes also seems to contibute to the treatment effect partly. In summary, the chincap doesn't restrain the mandbbular growth. But, it is considered as a useful treatment modality for correction of skeletal discrepancies and reduction of mandbbnlar prognathism in growing Class Ill patients with madibular prognathism.
Subject(s)
Humans , Male , Acceleration , Malocclusion , Mandible , Maxilla , Prognathism , Skeleton , Skull BaseABSTRACT
The purpose of this study was to predict the response to the chincap therapy from the initial cephalometric measurements and to obtain the indication of chincap therapy. 40 patients selected for this study were classified into two groups by the occlusal stability after completion of permanent dentition and the improvement of facial profile, after chincap therapy. One was good response group which consisted of 25 children and the other was poor response group with 15 patients. Various measurements of the craniofacial structure in the initial lateral cephalogram were calculated and analyzed by t-test and discriminant analysis. The results were as follows: 1. Good response group had more horizontal growth pattern in initial stage of treatment, and the contributing measurements were Bjork sum, anterior-posterior facial height ratio, gonial angle, lower gonial angle and occlusal plane to AB plane angle. 2. The critical points and predictive values of the influential skeletal measurements were calculated. 3. The discriminant function was obtained from three major influential measurements; Bjork sum, gonial angle and occlusal plane to AB plane angle, and this function could discreminate correctly in 85% of this samples.