title: Double primary teeth in children under 17 years old and their correlation with permanent successors.
abstract: BACKGROUND
  The existence of double primary teeth associated with further problems in permanent successors may have deleterious effects on occlusion and esthetics. The purposes of this study were to investigate the prevalence of double teeth in a group of Taiwanese children under 17 years old, and to compare the distribution of the different types of double primary teeth and their relationship to permanent successors.
  
  
  METHODS
  A total of 7868 qualified dental records of children under age 17 from the pediatric dental clinic of Chang Gung Memorial Hospital-Kaohsiung Medical Center were selected for this study. Panoramic radiographs were obtained from each child. The distribution of double teeth was investigated according to sex differences, types and clinical positions. The occurrence of double primary teeth and their effects on the permanent dentition were also recorded.
  
  
  RESULTS
  The prevalence of double primary teeth in children under 17 years old in this study was 0.72%. Double primary teeth were found mostly in the mandibular lateral incisors and canines (63.2%). Approximately 56% of cases experienced further problems in the permanent successors. Hypodontia (51.5%) was the most common problem in the permanent successors.
  
  
  CONCLUSIONS
  The close relationship between double primary teeth and permanent successors justifies radiographic examination to evaluate the number and condition of permanent successors and determine a proper treatment plan.
authors.affiliation: Department of Pediatric Dentistry, Chang Gung Memorial Hospital-Kaohsiung Medical Center, Chang Gung University College of Medicine, Kaohsiung, Taiwan.
authors.forename: Chen-Wei
authors.initials: CW
authors.lastname: Wu
authors.forename: Yng-Tzer
authors.initials: YT
authors.lastname: Lin
authors.forename: Yai-Tin
authors.initials: YT
authors.lastname: Lin
mesh_terms: D002648:Child; D002675:Child, Preschool; D019229:Dentition, Permanent; D005260:Female; D006801:Humans; D008297:Male; D014094:Tooth, Deciduous / Q000002:abnormalities*