The prevalence of temporomandibular joint dysfunction in the mixed dentition.

A functional and articular examination was carried out of 136 children (70 boys, 66 girls) aged from 6 to 12 years (6 years 1 month to 12 years 9 months), all presenting with a malocclusion in the mixed dentition and who had not yet received orthodontic treatment. The aim of the study was to examine the prevalence of signs of temporomandibular joint dysfunction (TMD) in this population and to evaluate the possible relationship between certain 'individual' parameters and TMD signs. The results showed an elevated prevalence of muscle tenderness, particularly in the lateral pterygoid muscle, which was found to be sensitive in 80.9 per cent of patients. Muscle tenderness had a tendency to increase with age and was greater on the right side. Temporomandibular joint sounds were present in 35.3 per cent of the subjects and more frequent in girls and in older children. Of the children who presented a mandibular deviation on maximal opening (19.8 per cent), 13.2 per cent had a predominance of opening deviation towards the left. Retruded contact position interferences were present in 57.4 per cent of the children and 72.1 per cent presented lateral and protrusive interferences. Assessment of the maximal amplitudes of mandibular movements did not reveal any limitations. These results indicate that few relationships exist between individual parameters and TMD signs.