The correct term for horizontally blocked wisdom teeth should be horizontally blocked wisdom teeth. Some horizontally blocked wisdom teeth are exposed, but only partially erupted and not fully grown out, while other horizontally blocked wisdom teeth fail to erupt at all.
Horizontal wisdom teeth are more common, meaning that the relationship between the long axis of the blocked wisdom tooth and the long axis of the adjacent second molar is horizontal. In addition to being categorized according to the angle of obstruction, blocked wisdom teeth can also be categorized according to the relationship between the blocked wisdom teeth and the jaw plane, as follows.
1. High level obstruction: the jaw plane of the blocked wisdom tooth is at or above the jaw plane of the second molar.
2. Intermediate obstruction: the jaw plane of the wisdom tooth is located between the jaw plane of the second molar and the cervical line.
3. Low level obstruction: the jaw plane of the wisdom tooth is lower than the cervical line of the second molar.
In the above categorization, horizontally high and horizontally intermediate wisdom teeth can be seen in the oral cavity, i.e. partially erupted. Horizontally low blocked wisdom teeth are often unable to erupt because of gingival coverage.