The position of the dentition in the mandible and its possible relation to orthodontic abnormalities

A method used to study human evolution has compared different positions of the lower dentition in relation to the position of the mandibular condyle in the sagittal plane. The method is modified here and, with data from the Burlington Growth Study, used to describe a normal range of positions for the human lower dentition in relation to the condyle from the ages of 4 to 20 years. Measurements of a randomly selected group of orthodontically treated patients showed that in about one half of them the lower dentition was outside the normal range before treatment. The effect of treatment was to move the dentition randomly toward or away from a normal position. It is concluded that the new cephalometric measurement described here could help in the diagnosis and treatment of orthodontic patients.