ultrasound: a treatment in which deep heat is applied to an affected area to relieve soreness or improve mobility. In dentistry, ultrasound can be used to treat temporomandibular disorders.
underbite: when the lower jaw protrudes forward causing the lower jaw and teeth to extend out beyond the upper teeth.
unerupted tooth: a tooth that has not pushed through the gum and assumed its correct position in the dental arch.
veneer: an artificial filling material, usually plastic, composite, or porcelain, that is used to provide an aesthetic covering over the visible surface of a tooth. This is most often used on front teeth.
wisdom teeth: third (last) molars that usually erupt at age 18-25.
xerostomia: dry mouth or decrease in the production of saliva.
X-rays: high frequency light (or radiation) that penetrates different substances with different rates and absorption. In dentistry, there are typically four types of X-rays: periapical, bite-wing, occlusal, and panoramic.