Class 1, 2, and 3 Bites
These are the primary method by which the bite is classified. Class 1 is “normal” occlusion, while Class 2 is typically referred to as an overbite and Class 3 is typically referred to as an underbite.
The classification system relies largely on the position of the molars, as (like indicated in the above graphic) the crowding and misplacement of the front teeth is so common that they can overjet or underjet haphazardly. Regardless, an overjet (top incisors farther out than lower) is still a typical symptom of Class II bites while an underjet (bottom teeth farther out than bottom teeth) is still typical of Class III bites.
While the class system refers to how far forward (anterior) or backward (posterior) the equivalent top and bottom teeth are to each other, a Cross Bite refers to the Buccal (outward, to cheeks) and Lingual (Inward, to tongue) relationship two corresponding upper and lower teeth have to each other. Cross Bites can be present anywhere along the dental arch, from posterior (molar) cross bites to anterior (incisor) cross bites, and even single tooth crossbites. The Cross Bites can occur on one side or both.