title: The not-so-harmless maxillary primary first molar extraction.
abstract: BACKGROUND
  Premature loss of primary molars has been associated with space loss and eruptive difficulties, especially when the loss occurs to the primary second molars and when it occurs early. This has not been thought to be the case for primary first molars.
  
  
  METHODS
  The author revisited 13 cases from an earlier study on the effects of premature loss of maxillary primary molars. These longitudinal cases were scrutinized, using serial panoramic radiographs, to explain the irregular response in terms of dental migration. The author presents two case reports.
  
  
  RESULTS
  In the earlier study, the author used digitized study casts and the concept of D + E space--the space occupied by the primary first and second molars--to describe the dental migration that occurred after premature tooth loss. Using analysis of variance on data generated using an instrument capable of measuring in tenths of millimeters, the author produced findings regarding the amount of space loss, rate of space loss, effect of age at loss, amount of space regained at the time of replacement by the permanent tooth and effect on Angle's classification. Finally, the author created a simulation describing directional change; this revealed that the maxillary primary first molar loss resulted in a mesial displacement of the permanent canine during eruption.
  
  
  CONCLUSIONS
  When the maxillary primary first molar is lost prematurely, the first premolar erupts in a more mesial direction than normal, as a result of the mesial incline of the primary second molar, and consumes the space of the permanent canine, which becomes blocked out.
  
  
  CONCLUSIONS
  Rather than use a space maintainer after the premature loss of the maxillary primary first molar, the author suggests, clinicians can choose from a number of other options for preventing the first premolar from erupting too far in a mesial direction.
authors.forename: W M
authors.initials: WM
authors.lastname: Northway
mesh_terms: D000293:Adolescent; D000704:Analysis of Variance; D001641:Bicuspid / Q000503:physiopathology; D002648:Child; D002675:Child, Preschool; D003481:Cuspid / Q000503:physiopathology; D003724:Dental Arch / Q000473:pathology*; D006801:Humans; D021621:Imaging, Three-Dimensional; D008334:Mandible; D008437:Maxilla; D008644:Mesial Movement of Teeth / Q000209:etiology* / Q000517:prevention & control; D008963:Molar / Q000601:surgery*; D014078:Tooth Eruption / Q000502:physiology; D014081:Tooth Extraction / Q000009:adverse effects*; D014094:Tooth, Deciduous / Q000601:surgery*