title: Smoothness of molar movement during gum chewing in children with primary dentition.
abstract: The purpose of this study was to test the null hypothesis that molar movement during gum chewing in children with primary dentition is as smooth as in adults. Twenty-two healthy children with primary dentition and 23 healthy adult females participated in this study. Mandibular movement during gum chewing was recorded using an optoelectronic analysis system with six degrees-of-freedom at 100 Hz, and 10 cycles were selected for analysis. Normalized jerk cost (NJC) at the incisors and working and balancing molars were calculated in each phase (i.e., opening, closing and occlusal level phases) for each chewing cycle. The NJC of the working side molar in children was larger than in adults in both the opening and occlusal phases. Inter-individual variances of the NJC in each phase in children and adults were smaller than corresponding intra-individual variances, except for the NJC during the occlusal phase of adults for the working and balancing side molars. The inter- and intra-individual variances of the NJC during the closing phase were the smallest in each phase for both children and adults. This indicates that the jaw movements of children with primary dentition are more variable, less smooth, and faster than that of adults.
authors.affiliation: Section of Pediatric Dentistry, Division of Oral Health, Growth, and Development, Kagoshima University, Graduate School of Dental Sciences, Japan.
authors.forename: Chiaki
authors.initials: C
authors.lastname: Yamada-Ito
authors.forename: Issei
authors.initials: I
authors.lastname: Saitoh
authors.forename: Kohtaro
authors.initials: K
authors.lastname: Yashiro
authors.forename: Emi
authors.initials: E
authors.lastname: Inada
authors.forename: Tomoaki
authors.initials: T
authors.lastname: Maruyama
authors.forename: Kenji
authors.initials: K
authors.lastname: Takada
authors.forename: Tomonori
authors.initials: T
authors.lastname: Iwasaki
authors.forename: Haruaki
authors.initials: H
authors.lastname: Hayasaki
authors.forename: Youichi
authors.initials: Y
authors.lastname: Yamasaki
mesh_terms: D002638:Chewing Gum; D002675:Child, Preschool; D005260:Female; D006801:Humans; D016014:Linear Models; D008297:Male; D008334:Mandible / Q000502:physiology*; D008409:Mastication / Q000502:physiology*; D008963:Molar / Q000502:physiology*; D009068:Movement; D014094:Tooth, Deciduous / Q000502:physiology*; D055815:Young Adult
chemical_list: D002638:Chewing Gum