title: The risk of healing complications in primary teeth with intrusive luxation: A retrospective cohort study.
abstract: OBJECTIVE
  Intrusive luxation is a frequent injury in the primary dentition. Complications such as ankylosis or pulp necrosis (PN) and infection with periapical inflammation may affect the developing permanent tooth if not diagnosed and treated in time. The aim of this study was to report the risk of PN, pulp canal obliteration (PCO), infection-related resorption (IRR), ankylosis-related resorption (ARR) and premature tooth loss (PTL) in primary teeth following intrusive luxation, and to identify possible risk factors for PN and PTL.
  
  
  METHODS
  A retrospective analysis of a cohort comprising 149 patients 194 intruded primary incisors. No treatment was performed. The follow-up programme included examination after 4 weeks, 8 weeks, 6 months, 1 year, and at 6 years of age. The minimum follow-up period was 1 year or until time of tooth loss.
  
  
  METHODS
  The Kaplan-Meier and Aalen-Johansen methods were employed along with Cox regression analysis. The level of significance was 5%.
  
  
  RESULTS
  Risks estimated after 3 years: PCO 38.9% (95% CI: 31.8-46.0), PN 24.2% (95% CI: 17.7-30.6), IRR 8.8% (95% CI: 4.5-13.1), ARR 3.6% (95% CI: 1.0-6.2) and PTL 39.4% (95% CI: 31.2-47.5). Most teeth (83.7%) spontaneously re-erupted within the first year. Most complications were diagnosed within the first year. The risk of PN was lowest in patients less than 2 years of age. The degree of intrusion or a concomitant crown fracture did not affect the risk of PN or PTL.
  
  
  CONCLUSIONS
  Over 80% of the intruded primary teeth re-erupted spontaneously. However, nearly one-third of the teeth showed complications such as pulp infection/periapical inflammation or ankylosis, which could potentially affect the development of the permanent incisor. Therefore, patients should be monitored regularly, especially during the first year after injury, to diagnose and treat complications in time.
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: School of Oral health Care, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Nadia
authors.initials: N
authors.lastname: Yousaf
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: D002675:Child, Preschool; D003718:Denmark; D005260:Female; D006801:Humans; D007180:Incisor / Q000000981:diagnostic imaging / Q000293:injuries*; D007223:Infant; D008297:Male; D012189:Retrospective Studies; D012306:Risk; D014084:Tooth Avulsion / Q000150:complications* / Q000000981:diagnostic imaging; D014094:Tooth, Deciduous / Q000000981:diagnostic imaging / Q000293:injuries*
keywords: dental trauma; intrusion injury; primary teeth; pulp necrosis; root resorption