A survey of craniomandibular disorders in 1000 12-year-olds. Study design and baseline data in a follow-up study.

One-thousand-and-eighteen 12-year-old children were chosen by use of preselected screening criteria, and disproportionate sampling to participate in a longitudinal study into the dental and social effects of malocclusion. The data has now been used to investigate the effects of malocclusion and orthodontic treatment on craniomandibular disorders. The sampling method was designed to create sub-groups large enough to study effectively the whole range of malocclusion, even those which have a low prevalence. This report will give baseline data in a longitudinal study. Intra-observer variability on recordings of signs of craniomandibular disorders was tested and reproducibility was found to be on an acceptable level. Almost half the children had signs of CMD, but few of these were severe and overall, only a very small minority of children in this sample required treatment. A preliminary examination has been made into possible relationships between the signs and symptoms of CMD, and significant associations were found between headache and several clinical signs.