High-dose anticancer chemotherapy and total body irradiation during childhood can damage developing teeth

Research published by the University of Helsinki, Finland, indicates that cytostatic and radiation therapies administered before stem cell transplantation often damage children's permanent teeth.

Detrimental effects of cytostatic and radiation therapies on dental development have been known for a long time, but knowledge about the dental consequences of high-dose anticancer therapy preceding stem cell transplantation has so far been scarce. Paivi Holtta, Licentiate in Dentistry, from the Institute of Dentistry, University of Helsinki, has studied the effects of high-dose anticancer chemotherapy and total body irradiation on the development of permanent teeth.

Tooth development is a genetically controlled chain of events that can be disturbed by various environmental factors. The development of permanent teeth begins as early as the 20th week of gestation and continues until the age of 14 to 15 years with the exception of wisdom teeth, which still continue their development for several years. All this time teeth are vulnerable to developmental aberrations.

The children examined in the current study, treated for cancer or aplastic anemia, had received stem cell transplantation at the age from 1 to 9.4 years, preceded with a high-dose anticancer chemotherapy and, in most cases, with total body irradiation. In her research, Hölttä studied how many of the treated children lacked permanent teeth or had unusually small teeth, and how often dental roots were poorly developed.

The results indicated that 31% of the treated children lacked permanent teeth (as opposed to 8% of the Finnish population), when wisdom teeth were excluded. Lack of permanent teeth was most frequent (77%) among children who had been less than three years old at stem cell transplantation. The highest number of missing teeth was 12. Those who had been over five years of age at stem cell transplantation lacked only wisdom teeth. A significant finding was that a high-dose anticancer chemotherapy alone caused a lack of permanent teeth nearly as often as when combined with total body irradiation, which, however, slightly increased the number of missing teeth.

The children also had a high frequency of microdontia, teeth smaller than normal (44% as opposed to 2% of the Finnish population). Microdontia was common among children under five years of age at stem cell transplantation and rare among others. Surprisingly, high-dose anticancer chemotherapy caused microdontia in all those who had been treated when under three years old. Total body irradiation did not increase the number of microdontia patients or microdontic teeth.

Developmental aberrations in dental roots were found in all the children in the study. Some of them had minor changes visible in a few teeth only, while others had severe damage in all their teeth. Total body irradiation increased the number of damaged roots. The children who had only received high-dose anticancer chemotherapy had root damage in over half of their teeth, but the damage was not as severe as with those who had also received total body irradiation.

The lack of several permanent teeth and their small size affect the development of occlusion and the growth of the jaws. Short and sometimes almost non-existent roots may not endure masticatory forces, and periodontal infections may result in an early loss of short-rooted teeth. "We still don't know about the long-term consequences of the treatments, which is why the monitoring of the patients should be continuous and centralised. Cooperation between specialists in children's haematology and oncology and specialists in various fields of dentistry is of fundamental importance in providing for these children the best possible dental care in the future," Päivi Hölttä says.