So, when an orthodontist evaluates a person's bite and tooth positions, he or she is comparing the current positioning versus the Six Keys of Occlusion. Occlusion basically means the way the teeth fit together.
Angle's Six Keys to Occlusion
|Key I – Molar Relationship|
|Key II – Crown Angulation (tip)|
|Key III – Crown Inclination (torque)|
|Key IV – Rotation|
|Key V – Spacing|
|Key VI – Curve of Spee|
The photo above illustrates dental casts with ideal occlusion (inter-digitation of teeth) and ideal overbite/overjet.
The following link provides a great explanation and pictures for each of the Six Keys:
So, when many patients think they should be finished with treatment when their teeth are straight, just remember that orthodontists are specially trained to go the distance and achieve both a great looking smile and a bite that fits together and functions in the most ideal way. Orthodontists also evaluate jaw relationships, anterior/posterior and vertical positioning of the teeth relative to the face, and soft tissue form (lips especially), but the Six Keys truly are the key to the best orthodontic treatment in most cases.