Introduction: The high prevalence of orthodontic treatment in young people makes the associated radiation to the head and neck of potential public-health significance. In this study, we estimated secular changes (1963-2003) in age-specific organ doses associated with orthodontic care and collective organ doses in the United States in 1999. Methods: A survey of radiographic records at 1 university clinic was combined with published estimates to provide organ-specific radiation doses. Collective organ doses were estimated from the 1999 US Nationwide Evaluation of X-ray Trends and published orthodontic utilization surveys. Results: Before 1992, orthodontic care in a university setting was associated with mean doses of 7.0 milligrays (mGy) to the thyroid, 0.8 mGy to the red bone marrow, 2.7 mGy to the brain, 13.2 mGy to the salivary glands, and 5.1 mGy to the bone. After 1992, the doses decreased to 2.8 mGy to the thyroid, 0.3 mGy to the red bone marrow, 0.7 mGy to the brain, 6.2 mGy to the saliva glands, and 2.4 mGy to the bone. Around 1999, the collective doses associated with orthodontic care in the United States in patients less than 19 years of age were 400 Gy to the red bone marrow and 3800 Gy to the thyroid. Conclusions: Orthodontic care, in part due to its high prevalence, potentially contributes significantly to the diagnostic radiation burden in those less than 19 years old in the United States.

Obtaining lifetime diagnostic radiation histories in head and neck cancer studies is often challenging due to the almost universal lack of centralized registries on X-ray utilization in medicine and dentistry. Both the common nature of orthodontics and the young age at which orthodontics typically occurs make it important to quantify what diagnostic radiographs are typically taken during orthodontic therapy. The aim of this study was to assess the number and type of radiographic films associated with one episode of orthodontic therapy in an educational setting. Charts stored in an orthodontic clinic at one academic setting were randomly sampled, and the type and number of radiographic examinations were tallied for the 325 individuals who were in orthodontic therapy for at least one year. Being under orthodontic therapy for one or more years was associated with a median number of seven extra-oral radiographs and twenty-four intra-oral radiographic films. The extra-oral radiographs included three panoramic radiographs and three cephalometric radiographs. Less than 10 percent of the variability was explained by factors such as age, gender, calendar year, surgical orthodontic therapy, and duration of therapy. Head and neck cancer etiology studies should take into account the ionizing radiation during episodes of orthodontic care. The substantial variability in radiographic practices in orthodontics could be reduced by research into clinical utility and by establishing guidelines.

The thyroid is among the more radiosensitive organs in the body. The goal of this study was twofold: (1) to evaluate age-related changes in what is exposed to ionizing radiation in the neck area, and (2) to assess thyroid shield presence in cephalometric radiographs