title: Perceptions of dental professionals and laypeople to altered maxillary incisor crowding.
abstract: BACKGROUND
  The aim of this study was to determine how sensitive dental specialists and laypeople are to maxillary incisor crowding when viewed from the front.
  
  
  METHODS
  Computer technology was used to create a series of photographs of the incisors of a smiling woman viewed from the front. The photographs showed varying degrees of maxillary incisor crowding classified according to Little's irregularity index (LII). The incisors illustrated in the photos were ranked on a scale from perfect alignment to severely crowded. The rating was done by 4 groups of people: orthodontists, general dentists, laypeople with experience of orthodontic treatment, and laypeople with no history of orthodontic treatment.
  
  
  RESULTS
  The orthodontists and the general dentists noted misalignment of 1 central incisor when the LII reached 1.5 mm, whereas the laypeople with or without experience of orthodontic treatment were sensitive to 2.0 mm of crowding. When the LII reached 2.0 mm for 1 lateral incisor, it triggered the orthodontists to consider providing orthodontic treatment, whereas this degree of irregularity was ignored by the general dentists and laypeople. When both central incisors were misaligned, the orthodontists were sensitive to the fact at 2.0 mm of LII, whereas the general dentists and the laypeople with experience of orthodontic treatment became sensitive at 3.0 mm of LII, and the laypeople with no history of orthodontic treatment were sensitive at 4.0 mm of LII. When both lateral incisors were misaligned, the orthodontists noted the crowding at an LII of 3.0 mm, the general dentists became sensitive at an LII of 4.0 mm, whereas both the laypeople with experience of orthodontic treatment and the laypeople with no history of orthodontic treatment ignored it. When the crowding of all maxillary incisors reached an LII of 4 mm, both the orthodontists and the general dentists were alerted to the fact, but both the laypeople with experience of orthodontic treatment and the laypeople with no history of orthodontic treatment were sensitive only to a total incisor crowding equal to an LII of 6.0 mm.
  
  
  CONCLUSIONS
  Orthodontists are more critical than other groups when evaluating the misalignment of the maxillary incisors. It appears that the central incisors play a more important role than do the lateral incisors when dental crowding impacts smile esthetics. For all observer groups, it also appears that people are more sensitive to the misalignment of a single tooth than they are to the same level of crowding distributed over multiple teeth.
authors.affiliation: Formerly, clinical assistant professor, Department of Orthodontics, State University of New York, Buffalo, NY; currently, professor and chairman of Orthodontics, School of Stomatology, Hebei Medical University, Shijiazhuang, Hebei, China.
authors.forename: Wensheng
authors.initials: W
authors.lastname: Ma
authors.affiliation: Professor and chairman, Department of Orthodontics, State University of New York, Buffalo, NY.
authors.forename: Brian
authors.initials: B
authors.lastname: Preston
authors.affiliation: Private practice, Gifu-Shi, Gifu, Japan.
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Asai
authors.affiliation: Resident, Department of Orthodontics, State University of New York, Buffalo, NY.
authors.forename: Huiyan
authors.initials: H
authors.lastname: Guan
authors.affiliation: Clinic director and assistant professor, Department of Orthodontics, State University of New York, Buffalo, NY. Electronic address: gguan@buffalo.edu.
authors.forename: Guoqiang
authors.initials: G
authors.lastname: Guan
mesh_terms: D000328:Adult; D001291:Attitude of Health Personnel; D001294:Attitude to Health; D003815:Dentists / Q000523:psychology*; D004955:Esthetics, Dental; D005260:Female; D005792:General Practice, Dental; D006801:Humans; D007180:Incisor / Q000473:pathology*; D008297:Male; D008310:Malocclusion / Q000473:pathology / Q000523:psychology*; D008437:Maxilla / Q000473:pathology*; D009970:Orthodontics; D023861:Photography, Dental; D012904:Smiling; D019228:Tooth Crown / Q000473:pathology; D055815:Young Adult