Occurrence of malocclusion in attritive environment: a study of a skull sample from southwest Finland.

Occlusal variation and occurrence of malocclusion were examined in a Finnish skull sample derived from the 15th and 16th centuries. The material consisted of 207 adult individuals; 141 maxillas and 159 mandibles, including 93 pairs, were in observable condition. In the skull sample, only dental anomalies were observed; no skeletal malocclusions were found. The frequency of an Angle Class I lateral relationship was 97.7%. The mean values for overjet and overbite were 1.6 and 1.4 mm, respectively. A comparison with present-day Finns revealed that the skull sample showed less variation in all occlusal variables studied. An Angle Class II type occlusion, deep bite, crowding, spacing, and lateral crossbite occurred with significantly lower frequencies in the skull sample than in the present-day Finns. Advanced dental wear in the skull sample shows that a hard and attritive diet was eaten at that time. It is suggested that a dietary transition from hard to soft food is the most probable cause of the increased occlusal variation and high frequency of malocclusion in present-day Finns.