Multiple choice general knowledge Which is the non-contagious disease that is the most common in the world? Sinus Diabetis Ulcer Tooth Decay Reveal answer Fill a bubble to check yourself D Correct answer Explanation Tooth decay (dental caries) is one of the most widespread non-contagious diseases globally, affecting people of all ages. It results from bacteria breaking down tooth enamel and is largely preventable through proper oral hygiene.