title: The risk of healing complications in primary teeth with concussion or subluxation injury-A retrospective cohort study.
abstract: OBJECTIVE
  Traumatic dental injuries in the primary dentition occur frequently. Long-term complications may potentially cause damage to the permanent successor. The aim of this study was to report the risk of pulp necrosis (PN), pulp canal obliteration (PCO), repair-related resorption (RRR), infection-related resorption (IRR), ankylosis-related resorption (ARR), and premature tooth loss (PTL) in primary teeth following concussion and subluxation injuries, and to identify possible risk factors for PN, PCO, and PTL following subluxation.
  
  
  METHODS
  The study was a retrospective analysis of a cohort comprising 31 patients (36 teeth) with concussion injury and 174 patients (241 teeth) with subluxation injury. No treatment was performed. The follow-up program included examination after 4 weeks, 8 weeks, 6 months, 1 year, and when the patients were 6 years of age. Minimum follow up was 1 year or until the time of tooth loss.
  
  
  METHODS
  Kaplan-Meier and Aalen-Johansen methods and Cox regression analysis. Level of significance was set at 5%.
  
  
  RESULTS
  Risk estimated after one year. Concussion: PCO 8.6% (95% CI: 0-17.9), PN 5.7% (95% CI: 0-13.4), PTL 5.6% (95% CI: 0-13.4). Subluxation: PCO 23.2% (95% CI: 17.8-28.6), PN 8.3% (95% CI: 4.8-11.8), IRR 2.6% (95% CI: 0.5-4.6), PTL 9.5% (95% CI: 5.0-14.1). Most complications (95%) were diagnosed within the first year. Most cases of PN (65%) and PTL (85%) were seen in patients aged 4 years or more.
  
  
  CONCLUSIONS
  Primary teeth with concussion or subluxation injury carry a low risk of PN and infection with periapical inflammation, root resorption, and PTL. Nearly all complications were diagnosed within the first year after the injury. The risk of PTL was highest in patients more than 4 years of age at the time of injury.
authors.affiliation: Resource Centre for Rare Oral Diseases, Department of Oral and Maxillo-Facial Surgery, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark.
authors.forename: Eva
authors.identifier: http://orcid.org/0000-0003-0859-7262
authors.initials: E
authors.lastname: Lauridsen
authors.affiliation: Department of Public Health, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Paul
authors.initials: P
authors.lastname: Blanche
authors.affiliation: Pediatric Dentistry and Clinical Genetics, Department of Odontology, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Catharina
authors.initials: C
authors.lastname: Amaloo
authors.affiliation: Resource Centre for Rare Oral Diseases, Department of Oral and Maxillo-Facial Surgery, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark.
authors.forename: Jens O
authors.initials: JO
authors.lastname: Andreasen
mesh_terms: D001424:Bacterial Infections / Q000209:etiology*; D002675:Child, Preschool; D003790:Dental Pulp Necrosis / Q000209:etiology*; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D012189:Retrospective Studies; D012306:Risk; D012391:Root Resorption / Q000209:etiology*; D020254:Tooth Ankylosis / Q000209:etiology*; D014084:Tooth Avulsion / Q000150:complications*; D016388:Tooth Loss / Q000209:etiology*; D014094:Tooth, Deciduous / Q000293:injuries*
keywords: concussion; dental trauma; premature tooth loss; primary teeth; pulp necrosis; subluxation