Most of these problems are because of small jaw size and comparatively larger teeth size, so teeth either project out or if the lip muscles are strong, teeth become irregularly aligned. Why such things occur, there are two main explanations:
1.Some times it is told that genetically the person may get small jaw size from mother and big teeth from father.
2. But more important as we see, most of people don’t eat enough hard food. Present day kids eat a lot of chocolates and soft pressure cooked food, this does not give any exercise to jaws and its muscles, and jaws remain small in size and can not accommodate all the teeth.