title: Maxillary first molar agenesis and other dental anomalies.
abstract: OBJECTIVE
  To explore the association of maxillary first molar agenesis with other dental anomalies in Japanese orthodontic patients.
  
  
  METHODS
  A total of 32 subjects with one or two congenitally missing maxillary first molars (group M) were selected and divided into group 1M (12 subjects with one maxillary first molar missing) and group 2M (20 subjects with two maxillary first molars missing). As controls, 32 sex-matched subjects without agenesis of maxillary first molars were collected (group C). Panoramic and periapical radiographs, cephalograms, study models, intraoral photographs, and anamnestic data were used to identify anomalies of permanent teeth. Chi-square, Fisher's exact, Kruskal-Wallis, and Steel-Dwass tests were used to make statistical comparisons.
  
  
  RESULTS
  The prevalence rates of tooth agenesis other than the maxillary first molars and advanced tooth agenesis, with third molars excluded, were significantly higher in group 2M than in group C. The absence of second premolars was most common. The prevalence rate of third molar agenesis was significantly higher in groups 1M and 2M than in group C. The occurrence of symmetrical agenesis of the mandibular third molars was particularly notable in group 2M as compared to group 1M, in which maxillary third molar agenesis was predominant. There was no significant association between maxillary first molar agenesis and other dental anomalies, except for agenesis of teeth other than maxillary first molars.
  
  
  CONCLUSIONS
  Agenesis of maxillary first molars is associated with a higher prevalence of other permanent tooth agenesis and advanced tooth agenesis.
authors.affiliation: The Nippon Dental University Niigata Hospital, Niigata, Japan.
authors.forename: Ryota
authors.initials: R
authors.lastname: Abe
authors.forename: Toshiya
authors.initials: T
authors.lastname: Endo
authors.forename: Shohachi
authors.initials: S
authors.lastname: Shimooka
mesh_terms: D000293:Adolescent; D000848:Anodontia / Q000150:complications* / Q000000981:diagnostic imaging; D016022:Case-Control Studies; D002508:Cephalometry; D016009:Chi-Square Distribution; D002648:Child; D005260:Female; D005671:Fused Teeth / Q000150:complications; D006801:Humans; D008297:Male; D008310:Malocclusion / Q000150:complications; D008437:Maxilla; D008963:Molar / Q000002:abnormalities*; D008964:Molar, Third / Q000002:abnormalities; D011859:Radiography; D018709:Statistics, Nonparametric; D014071:Tooth Abnormalities / Q000150:complications / Q000000981:diagnostic imaging; D014079:Tooth Eruption, Ectopic / Q000150:complications; D014096:Tooth, Supernumerary / Q000150:complications