What is a common sign of impacted third molars?

Impacted third molars, often known as wisdom teeth, occur when these teeth do not have enough space to emerge normally in the mouth. A common sign of this condition is the prevention of tooth eruption, which is accurately reflected in the chosen answer. When third molars are impacted, they remain trapped beneath the gums or in the jawbone, inhibiting their ability to erupt fully. This can cause a variety of issues, including pain, infection, and potential damage to adjacent teeth.

The other options, while they may present in dental issues, are not specific indicators of impacted third molars. Excessive tooth decay can happen for various reasons and isn't a direct result of impaction. Painful jaw clicking often relates to temporomandibular joint disorders rather than directly to impacted molars, and swollen gums, although it can accompany tooth issues, is not exclusive to impaction and can arise from different dental conditions. The prevalence of such symptoms illustrates how impaction can lead to a wide range of oral health challenges, but the direct consequence of impacted third molars is indeed the prevention of their eruption.