title: A new concept of mandibular dental arch forms with normal occlusion.
abstract: BACKGROUND
  Because it is important to maintain dental arch dimensions during orthodontic therapy, all possible dental arch forms must be evaluated.
  
  
  METHODS
  A mathematical method associated with a polynomial function was used to evaluate the dental arch forms of 63 mandibular models of Brazilian adolescents in the permanent dentition with normal occlusion. A bead was glued to each tooth to simulate an orthodontic accessory and help in the measurement of distances between the center of the bead to the x- and y-axes. The dental casts were digitized, and images were plotted on a computer program to obtain the sixth-degree polynomial and the graph of this function. These segments were organized into 8 groups according to the form of the anterior curve of the dental arch; these were named forms A through H. Each group was subdivided into 3 subgroups: small, medium, and large sizes.
  
  
  RESULTS
  Form A was the most frequently observed at 22%, whereas form G was observed in only 2% of the total sample. Forms A, B, C, D, E, and F had more curve segments in medium size, and forms G and H had more curves in small size. A mean dental arch curve was calculated; however, this form coincided with form C, which had an incidence of 10%.
  
  
  CONCLUSIONS
  The mandibular dental arch is represented by 23 forms; thus, a normal dental arch cannot be represented by only 1 simple arch form.
authors.affiliation: Methodist University of São Paulo, São Bernardo do Campo, São Paulo, Brazil. tarcilatrivino@uol.com.br
authors.forename: Tarcila
authors.initials: T
authors.lastname: Triviño
authors.forename: Danilo Furquim
authors.initials: DF
authors.lastname: Siqueira
authors.forename: Marco Antonio
authors.initials: MA
authors.lastname: Scanavini
mesh_terms: D000293:Adolescent; D000328:Adult; D002508:Cephalometry / Q000379:methods; D002648:Child; D003724:Dental Arch / Q000033:anatomy & histology*; D003768:Dental Occlusion, Centric; D019229:Dentition, Permanent; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D008297:Male; D008334:Mandible / Q000033:anatomy & histology*; D008954:Models, Biological; D012016:Reference Values