title: Traumatic intrusion of primary teeth and developmental defects in successor teeth.
abstract: METHODS
  This was a clinical observational study of primary incisor trauma, in children of under 4 years of age at the time of injury, with a 7-year follow up period. COHORT SELECTION: Children treated for intrusive injuries (as defined by World Health Organization guidelines) of primary incisors in a paediatric clinic. EXPOSURE MEASUREMENT: Patient's age, sex, cause of trauma, site and number of primary teeth involved, and nature of immediate treatment were recorded. Photographs and radiographs were taken. At 6-12-month intervals clinical and radiographical examinations recorded the process of re-eruption, and any post-traumatic changes to the intruded primary teeth: namely, pulpal necrosis, root resorption, ankylosis, or obliteration of the pulp canal. Developmental defects were recorded on the fully erupted successor teeth, namely enamel hypoplasia, malformation of tooth and/ or root, and site of eruption.
  
  
  METHODS
  Chi-squared tests were used to determine significant differences between the patient's age at diagnosis; subsequent changes to the intruded primary teeth; and any developmental defects in the successor teeth.
  
  
  RESULTS
  Complete data were obtained over a 7-year followup period, for 78 children (138 teeth) who were aged between 12 and 48 months at initial examination. Thirty-six of these teeth, in 23 children, were extracted at the first visit because of extensive lateral luxation as well as intrusion. Of the remaining (unextracted at initial visit) 102 intruded primary incisors, 78% fully re-erupted, 15% partially re-erupted, and only 7% remained impacted. Post-traumatic consequences were recorded in 54% of the teeth. Over half of the permanent successors (74 out of the initial sample of 138 traumatised primary incisors) were found to have one or more developmental disturbances: enamel hypoplasia (28.3% of all incisors); dilacerations (16.7% of all incisors); or ectopic eruption (16.7% of all incisors).
  
  
  CONCLUSIONS
  The study did not find any correlation between the child's age at the time of the intrusion injury and the frequency of subsequent developmental disturbances.
authors.affiliation: Preventive and Children's Dentistry Section, Dundee Dental Hospital and School, University of Dundee, Dundee, Scotland, UK.
authors.forename: Nicola P T
authors.initials: NP
authors.lastname: Innes