Microdontia and hypodontia of premolars and permanent molars in childhood cancer survivors after chemotherapy

International Journal of Paediatric Dentistry 2012; 22: 239–243 Background.  Adverse long‐term general and dental health effects of cancer and cancer therapy during childhood have been reported. Aim.  To examine the association between chemotherapy before the age of 8 years and (1): microdontia; (2): hypodontia of premolars and permanent molars. Material and 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%). Conclusion.  The present study confirms findings from previous studies that chemotherapy, especially in very young children, causes microdontia and hypodontia of premolars and permanent molars.