A group of 29 individuals, 17-23 years old, with intact teeth, has been compared with a control group with respect to occurrence of mandibular dysfunction. A statistically significant difference between the groups, with a lower frequency and degree of dysfunction among the intact individuals was established. The results suggest that filling therapy per se may be a possible etiological factor in the mandibular dysfunction. Disorders in the masticatory neuromuscular system may arise from an abnormal tactile response to contacts on fillings, including an abnormal pattern of mandibular movement, possibly exceeding the tolerance level of the system.

Signs and symptoms of craniomandibular dysfunction (CMD) and oral parafunctions were re-examined in subjects, 25-26 years of age, 10 years after the first examination. Forty subjects had restored dentitions at both examinations (group F), 18 subjects with previously intact dentitions had had fillings in their teeth during the follow-up period (group FI), and 11 subjects had intact dentitions at both examinations (group I). Signs and symptoms of CMD were more common among the subjects in group F than in the original group of subjects with intact teeth (group 10). In accordance with the first study most of the symptoms were mild and of low frequency. However, frequent symptoms were only found among the subjects in group FI and group F and more severe frequent symptoms only in group F. There was an increase of the symptoms in group FI and group F. Frequent tooth clenching and frequent tongue pressing were more common in group F and there was a statistically significant increase in group FI concerning tooth clenching and tooth grinding and in group F concerning tooth grinding, tooth clenching and tongue pressing. Together with the correlations found between tooth clenching and signs and symptoms of CMD, the findings in this study and the personality study indicate a possible causal relationship between oral parafunctions, signs and symptoms of CMD, personality and fillings. A hypothesis for the possible mechanisms is presented. However, the findings are not conclusive and more studies are necessary, and for further interpretation of the results, studies from other research centres would be of interest.

The attritional dental pattern was studied clinically and on plaster casts in a group of individuals, 17-22 years old, with intact teeth and in a control group with a 'normal' distribution of dental restorations. The following observations were made: 1) all contact areas between occluding teeth exhibited facets; 2) most facets were located on inclines; 3) facets in the fossa bottom occurred oftenest in the control group and often involved fillings; 4) attritional facets on the distal marginal crest of the lower second molars were oftenest found in the control group; 5) denuded dentin in facets occurred oftenest in the control group; and 6) the number of facets and the worn areas were on an average largest in the control group. The findings in this study indicate a difference in the functional activity between the groups and support the hypothesis that dental fillings can induce changes in the neuromuscular pattern of the masticatory system.

A group of 96 individuals, 13 to 15 years of age, with intact teeth was compared with a control group of 129 individuals with dental restorations, with regard to occurrence of mandibular dysfunction. Statistically significant differences between the groups were established at both the anamnestic and the clinical examination, with a lower frequency and degree of dysfunction among those with intact teeth. Conforming with the findings of a previous study on 17- to 23-year-olds, these findings indicate that filling therapy may be associated with mandibular dysfunction.

Recordings of functional variables of the masticatory system were made in 184 subjects, 18-20 years old, 5 years after the first examination. One hundred and six subjects had restored dentitions at both examinations (group F), 35 subjects with previously intact dentitions had received fillings during the follow-up period (group FI), and 43 subjects had intact dentitions at both examinations (group I). In conformity with the first examination 5 years earlier, the subjects in group F had higher scores for dentin facets on the first lower molar. Together with the finding of more frequent attrition on the distal part of the occlusal surface of the second lower molar, this finding indicates more functional or parafunctional activity in restored dentitions. Unilateral contacts in the retruded contact position (RCP) were equally common in all three groups, but the contacts in RCP were more often located in the molar region in group F. The finding at the first examination that interference causing a lateral slide of the mandible between RCP and the intercuspal position (ICP) was commoner in restored dentitions was not confirmed in the present study. Nor did the correlation analysis show any relationship between occlusal factors and signs and symptoms of mandibular dysfunction. However, the differences found between subjects with intact and restored dentitions indicate that the iatrogenic effect of dental filling therapy merits more consideration and more extensive research.