RESUMO
INTRODUCTION: The purposes of this study were to determine (1) how masticatory performance changes with age, (2) whether masticatory performance differs between the sexes, and (3) whether patterns of masticatory performance differ among subjects with various types of malocclusion. METHODS: A total of 450 children and adolescents (244 boys, 206 girls) were assigned to 4 age cohorts (ages 6, 9, 12, and 15 years) and followed for 3 consecutive years. The subjects were selected based on having about equal numbers of boys and girls, and about equal numbers of subjects with normal occlusion and Class I and Class II malocclusions. Masticatory performance was assessed by using the artificial food CutterSil (Heraeus Kulze, South Bend, Ind). The peer assessment rating index was used to quantify the severity of the malocclusions. RESULTS: Median particle size (MPS) decreased significantly from 6 to 17 years of age. There were no statistically significant differences in MPS between the 3 occlusal groups, but there were significant sex differences, with girls having smaller MPS than boys. Multilevel analysis showed greater decreases in MPS between 6 and 9 years, and after 12 years of age, than between 9 and 12 years of age. There were no significant correlations between MPS and the weighted peer assessment rating index. MPS showed significant intercorrelations between measures of MPS obtained at years 1, 2, and 3, with correlations tending to be highest for the oldest age cohort. CONCLUSIONS: Masticatory performance improves with age, and the changes appear to be influenced by the loss of the deciduous teeth during the late mixed dentition phase of dental development. Although there are limited sex differences in masticatory performance among subjects 6 to 17 years of age, mild forms of Class I and Class II malocclusions have little or no effect on masticatory performance.
Assuntos
Mastigação/fisiologia , Adolescente , Fatores Etários , Algoritmos , Criança , Estudos de Coortes , Oclusão Dentária , Dentição Mista , Feminino , Seguimentos , Humanos , Estudos Longitudinais , Masculino , Má Oclusão Classe I de Angle/classificação , Má Oclusão Classe I de Angle/fisiopatologia , Má Oclusão Classe II de Angle/classificação , Má Oclusão Classe II de Angle/fisiopatologia , Modelos Dentários , Tamanho da Partícula , Fatores Sexuais , SiliconesRESUMO
This study describes the development of a system for quantification of human biting forces by (1) determining the mechanical properties of an epoxy resin reinforced with carbon fiber, (2) establishing the transducer's optimal dimensions to accommodate teeth of various widths while minimizing transducer thickness, and (3) determining the optimal location of strain gages using a series of mechanical resistance and finite element (FE) analyses. The optimal strain gage location was defined as the position that produced the least difference in strain pattern when the load was applied by teeth with two different surface areas. The result is a 7.3-mm-thick transducer with a maximum load capacity beyond any expected maximum bite force (1500N). This system includes a graphic interface that easily allows acquisition and registration of bite force by any health-sciences or engineering professional.
Assuntos
Força de Mordida , Transdutores/normas , Fenômenos Biomecânicos , Módulo de Elasticidade , Análise de Elementos Finitos , Humanos , Estresse MecânicoRESUMO
This study analysed how bolus hardness and size affect within-subject variability of chewing cycle kinematics. Two independent prospective studies were performed; both tracked chin movements using an optoelectronic recording system. Computer programs identified each subject's ten most representative cycles, and multilevel modelling procedures were used to estimate variances. One study evaluated 38 subjects who chewed 1, 2, 4 or 8 g of gum presented in random order. The second study evaluated 26 subjects who chewed approximately 2.5 g of harder (670 g) or softer (440 g) gum, also presented in random order. In terms of bolus size, the 2g and 1g boluses produced the least and greatest relative within-subject variability, respectively; the largest differences were found for cycle duration and excursions. Within-subject variability when chewing the harder gum was consistently greater than when chewing the softer gum, except for lateral movement towards the balancing side. Because bolus hardness and bolus size influence within-subject variability differently, they must be taken into consideration when designing experiments to study masticatory kinematics. We conclude that a 2g bolus of soft gum should be used in studies of chewing cycle kinematics in order to reduce within-subject variability and increase statistical power.