Do all cells respond identically to the same radiation dose?

• A. Yes
• B. No
• C. Only nerve cells
• D. Only cancer cells vary

Answer: (B)

Different cells respond differently to radiation. A given dose doesn’t affect all cell types the same way because several factors influence how a cell copes with DNA damage. The type of cell and how actively it divides matter a lot—rapidly dividing cells, such as those in the mucosa or bone marrow, are generally more radiosensitive and more likely to undergo cell death or permanent growth arrest at lower doses. In contrast, mature, non-dividing cells like many nerve or muscle cells tend to be more resistant to the same dose.

Another key factor is the cell’s environment and biology. Oxygen presence makes radiation more damaging (the oxygen effect), so well-oxygenated tissues are usually more sensitive than hypoxic ones. The cell’s ability to repair DNA damage also plays a big role; cells with efficient repair mechanisms may survive sublethal damage, while those with repair defects (as in many cancer cells) can be more vulnerable. The dose-rate and the timing of exposure relative to the cell cycle further influence outcomes.

In the context of dentistry, this means the same exposure can have different effects on different tissues—salivary glands, oral mucosa, bone marrow in the jaw, and neural components, for example—leading to a range of responses from repair and survival to cell death. Because of these variations, the statement that all cells respond identically to the same radiation dose is not correct.