title: Microdontia and hypodontia of premolars and permanent molars in childhood cancer survivors after chemotherapy.
abstract: BACKGROUND
  Adverse long-term general and dental health effects of cancer and cancer therapy during childhood have been reported.
  
  
  OBJECTIVE
  To examine the association between chemotherapy before the age of 8 years and (1): microdontia; (2): hypodontia of premolars and permanent molars.
  
  
  METHODS
  In The Danish Registry of Childhood Cancer (DBCR), we identified 203 children who met the following inclusion criteria: (1) age below 8 years at the start of treatment; (2) age between 12 to 18 years upon dental examination; (3) had received chemotherapy The exclusion criterion was radiotherapy to the head and neck. A total of 150 children fulfilled the inclusion criteria. As controls, a random sample of 193 age-matched unexposed children was included.
  
  
  RESULTS
  Microdontia was found in a total of 88 teeth in 29 (19.3%) of the 150 children who had been exposed to chemotherapy, while none of the controls had microdontia of premolars or permanent molars (difference: 19.3%; 95% CL: 13.5%; 26.4%). The earlier the exposure, the more frequent was microdontia. We found a total of 27 missing premolars and permanent molars in 14 (9.3%) of the exposed children and a total of 18 missing premolars and permanent molars in 8 (4.1%) of the controls (difference: 5.2%; 95% CL: -0.1%; 11.3%).
  
  
  CONCLUSIONS
  The present study confirms findings from previous studies that chemotherapy, especially in very young children, causes microdontia and hypodontia of premolars and permanent molars.
authors.affiliation: Department of Pediatric Dentistry, School of Dentistry, Faculty of Health Sciences, Aarhus University, Aarhus C, Denmark.
authors.forename: Lisbeth Bønløkke
authors.initials: LB
authors.lastname: Pedersen
authors.forename: Niels
authors.initials: N
authors.lastname: Clausen
authors.forename: Henrik
authors.initials: H
authors.lastname: Schrøder
authors.forename: Malene
authors.initials: M
authors.lastname: Schmidt
authors.forename: Sven
authors.initials: S
authors.lastname: Poulsen
mesh_terms: D000293:Adolescent; D000367:Age Factors; D000848:Anodontia / Q000139:chemically induced*; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000009:adverse effects*; D001342:Autonomic Nervous System Diseases / Q000188:drug therapy; D001641:Bicuspid / Q000002:abnormalities*; D016022:Case-Control Studies; D002648:Child; D003718:Denmark; D006801:Humans; D007680:Kidney Neoplasms / Q000188:drug therapy; D007938:Leukemia / Q000188:drug therapy; D008113:Liver Neoplasms / Q000188:drug therapy; D008223:Lymphoma / Q000188:drug therapy; D008963:Molar / Q000002:abnormalities*; D009369:Neoplasms / Q000188:drug therapy*; D009423:Nervous System Neoplasms / Q000188:drug therapy; D017741:Survivors