What is the primary concern regarding radiation exposure in patients under the age of 10?

The primary concern regarding radiation exposure in patients under the age of 10 is indeed the risk of long-term somatic stochastic effects. Children are more susceptible to the long-term consequences of radiation because their cells are rapidly dividing, and they have a longer lifespan ahead of them during which these effects may manifest. Stochastic effects, which include cancer and genetic mutations, are probabilistic in nature and can occur without a safe threshold of exposure. As children grow, any damage done to their DNA caused by radiation can increase their lifetime risk of developing cancer.

Considering the other options, while immediate effects of radiation might be a concern for certain exposures, they are generally less of an issue in the context of dental radiography, where doses are low. Overexposure to x-ray machinery is typically controlled through safety protocols and guidelines, which help mitigate this risk effectively. Increased dental caries, while a valid health concern for children, is not directly related to radiation exposure and does not address the specific issue of long-term effects that arise from radiation. Thus, the correct focus rests on the potential long-term risks associated with radiation exposure in this vulnerable age group.