#orthodontics
The study of the development of face & jaw, & how irregularities in development may lead to malocclusion (an abnormal relationship between upper & lower teeth, or between teeth in same jaw). The most commonly occurring problem is overcrowding, which may cause teeth to splay outward or inward, or twist out of alignment with each other. 


This in turn, apart from looking unattractive, can lead to an increased susceptibility to decay & gum disease, because irregular teeth are more difficult to clean effectively.
Correction of such irregularity may require extraction of some teeth & wearing of a brace to realign the remaining teeth.