Hujoel PP, Bollen AM, Noonan CJ, del Aguila MA. Antepartum dental radiography and infant low birth weight. JAMA. 2004 Apr 28;291(16):1987-93. doi: 10.1001/jama.291.16.1987. PMID: 15113817.
Context: Both high- and low-dose radiation exposures in women have been associated with low-birth-weight offspring. It is unclear if radiation affects the hypothalamus-pituitary-thyroid axis and thereby indirectly birth weight, or if the radiation directly affects the reproductive organs.
Objective: To investigate whether antepartum dental radiography is associated with low-birth-weight offspring.
Design: A population-based case-control study.
Participants and setting: Enrollees of a dental insurance plan with live singleton births in Washington State between January 1993 and December 2000. Cases were 1117 women with low-birth-weight infants (<2500 g), of whom 336 were term low-birth-weight infants (1501-2499 g and gestation > or =37 weeks). Four control pregnancies resulting in normal-birth-weight infants (> or =2500 g) were randomly selected for each case (n = 4468).
Main outcome measures: Odds of low birth weight and term low birth weight by dental radiographic dose during gestation.
Results: An exposure higher than 0.4 milligray (mGy) during gestation occurred in 21 (1.9%) mothers of low-birth-weight infants and, when compared with women who had no known dental radiography, was associated with an adjusted odds ratio (OR) for a low-birth-weight infant of 2.27 (95% confidence interval [CI], 1.11-4.66, P =.03). Exposure higher than 0.4 mGy occurred in 10 (3%) term low-birth-weight pregnancies and was associated with an adjusted OR for a term low-birth-weight infant of 3.61 (95% CI, 1.46-8.92, P =.005).
Conclusion: Dental radiography during pregnancy is associated with low birth weight, specifically with term low birth weight.
Hwang SY, Choi ES, Kim YS, Gim BE, Ha M, Kim HY. Health effects from exposure to dental diagnostic X-ray. Environ Health Toxicol. 2018 Dec;33(4):e2018017. doi: 10.5620/eht.e2018017. Epub 2018 Nov 21. PMID: 30661338; PMCID: PMC6341170.
The purpose of this review is to summarize the results of studies on of the association between exposure to dental X-rays and health risk. To perform the systematic review, We searched the PUBMED, EMBASE, and MEDLINE databases for papers published before December 15, 2016. A total of 2 158 studies, excluding duplicate studies, were found. Two reviewers independently evaluated the eligibility of each study. The final 21 studies were selected after application of exclusion criteria. In terms of health outcomes, there were 10 studies about brain tumors, 5 about thyroid cancer, 3 about tumors of head and neck areas, and 3 related to systemic health. In brain tumor studies, the association between dental X-ray exposure and meningioma was statistically significant in 5 of the 7 studies. In 4 of the 5 thyroid-related studies, there was a significant correlation with dental diagnostic X-rays. In studies on head and neck areas, tumors included laryngeal, parotid gland, and salivary gland cancers. There was also a statistically significant correlation between full-mouth X-rays and salivary gland cancer, but not parotid gland cancer. Health outcomes such as leukemia, low birth weight, cataracts, and thumb carcinomas were also reported. In a few studies examining health effects related to dental X-ray exposure, possibly increased risks of meningioma and thyroid cancer were suggested. More studies with a large population and prospective design are needed to elaborate these associations further.
Preston-Martin S, Thomas DC, White SC, Cohen D. Prior exposure to medical and dental x-rays related to tumors of the parotid gland. J Natl Cancer Inst. 1988 Aug 17;80(12):943-9. doi: 10.1093/jnci/80.12.943. PMID: 3398070.
Findings from this population-based study in Los Angeles County suggest, for the first time, that tumors of the parotid gland are related to prior exposure to diagnostic medical and dental radiography. Responses to interviews with 408 patients with a parotid tumor (269 benign tumors and 139 malignant tumors) were compared to responses of 408 neighborhood controls. Cumulative exposure of the parotid gland from diagnostic radiography was associated with a dose-related increase in risk of malignant tumors (P for trend less than .05; relative risk for exposure to greater than or equal to 50 rad = 3.4; 95% confidence interval = 1.02-11.46). Benign tumors showed a weaker positive association, and exposure before age 20 to a major diagnostic examination (full-mouth or panoramic dental radiography or medical radiography to the head) increased risk (relative risk = 1.8; confidence interval = 1.13-2.91). This study also confirmed the association of malignant tumors with prior radiation treatment to the head or neck; 28% of these tumors are attributable to exposure of the parotid gland from diagnostic and therapeutic radiation.
Memon A, Godward S, Williams D, Siddique I, Al-Saleh K. Dental x-rays and the risk of thyroid cancer: a case-control study. Acta Oncol. 2010 May;49(4):447-53. doi: 10.3109/02841861003705778. PMID: 20397774.
The thyroid gland is highly susceptible to radiation carcinogenesis and exposure to high-dose ionising radiation is the only established cause of thyroid cancer. Dental radiography, a common source of low-dose diagnostic radiation exposure in the general population, is often overlooked as a radiation hazard to the gland and may be associated with the risk of thyroid cancer. An increased risk of thyroid cancer has been reported in dentists, dental assistants, and x-ray workers; and exposure to dental x-rays has been associated with an increased risk of meningiomas and salivary tumours.
Methods: To examine whether exposure to dental x-rays was associated with the risk of thyroid cancer, we conducted a population-based case-control interview study among 313 patients with thyroid cancer and a similar number of individually matched (year of birth +/- three years, gender, nationality, district of residence) control subjects in Kuwait.
Results: Conditional logistic regression analysis, adjusted for other upper-body x-rays, showed that exposure to dental x-rays was significantly associated with an increased risk of thyroid cancer (odds ratio = 2.1, 95% confidence interval: 1.4, 3.1) (p=0.001) with a dose-response pattern (p for trend <0.0001). The association did not vary appreciably by age, gender, nationality, level of education, or parity.
Discussion: These findings, based on self-report by cases/controls, provide some support to the hypothesis that exposure to dental x-rays, particularly multiple exposures, may be associated with an increased risk of thyroid cancer; and warrant further study in settings where historical dental x-ray records may be available.
