title: Assessment of masticatory performance, bite force, orthodontic treatment need and orofacial dysfunction in children and adolescents.
abstract: OBJECTIVE
  Few studies have evaluated the relationship between morphological and functional characteristics of the masticatory apparatus in young subjects. Thus, the aim of this study was to evaluate masticatory performance (MP), maximal bite force (BF), orthodontic treatment need and orofacial dysfunction in children and adolescents.
  
  
  METHODS
  The sample consisted of 316 subjects of both genders, with an age range 6-16years divided into 4 groups: early mixed, intermediate mixed, late mixed and permanent dentition. MP was evaluated by the individual's ability to comminute a chewable test material in order to determine median particle size (X(50)) and distribution of particles in different sieves ("b"). BF was determined using a digital gnatodynamometer with fork strength of 10mm. Orofacial function and orthodontic treatment need were screened using the Nordic Orofacial Test-Screening (NOT-S) protocol and Index of Orthodontic Treatment Need (IOTN), respectively. The results were submitted to descriptive statistics, normality test, analysis of variance and stepwise multiple linear regression to test relationship between MP and studied independent variables.
  
  
  RESULTS
  Variance of X(50) and b between groups was statistically significant. But evaluation of variables that significantly contributed to MP variation showed that age, body mass index (BMI), BF and the presence of sleep bruxism were negatively related to X(50) and the NOT-S clinical exam scores showed a positive relationship with X(50).
  
  
  CONCLUSIONS
  In the studied sample, age, BMI, BF and the presence of sleep bruxism were related to better MP; but the increase in NOT-S scores was significantly related to poorer MP.
authors.affiliation: Department of Pediatric Dentistry, Piracicaba Dental School, University of Campinas UNICAMP, Piracicaba, Brazil.
authors.forename: Maria Carolina Salomé
authors.initials: MC
authors.lastname: Marquezin
authors.forename: Fernanda Yukie
authors.initials: FY
authors.lastname: Kobayashi
authors.forename: Ana Bheatriz Marangoni
authors.initials: AB
authors.lastname: Montes
authors.forename: Maria Beatriz Duarte
authors.initials: MB
authors.lastname: Gavião
authors.forename: Paula Midori
authors.initials: PM
authors.lastname: Castelo
mesh_terms: D000293:Adolescent; D000367:Age Factors; D001732:Bite Force; D015992:Body Mass Index; D016022:Case-Control Studies; D002648:Child; D003818:Dentition, Mixed; D005145:Face; D005149:Facial Expression; D005260:Female; D006801:Humans; D061326:Index of Orthodontic Treatment Need; D008297:Male; D008310:Malocclusion / Q000145:classification / Q000175:diagnosis; D008409:Mastication / Q000502:physiology*; D009055:Mouth / Q000502:physiology; D053581:Muscle Strength Dynamometer; D009666:Nose / Q000502:physiology; D010316:Particle Size; D012119:Respiration; D020186:Sleep Bruxism / Q000175:diagnosis; D013060:Speech / Q000502:physiology