Imagine a brick wall where a brick is missing, and the bricks around the hole slowly fall into the space. The entire wall eventually becomes unstable. The same thing happens with missing teeth. The space created by the loss of a tooth causes the adjacent teeth to drift out of position which alters your bite. Left untreated, that tooth gap changes the ability to chew effectively, articulate clearly, and causes the facial muscles to fall into the empty space creating a hollowing out of the cheeks.