Effects of attritive diet on craniofacial morphology: a cephalometric analysis of a Finnish skull sample

The purpose of the present study was to analyse cephalometrically the effects of a high-attrition environment on craniofacial morphology. The material consisted of lateral cephalograms of 32 Finnish crania and of a control sample of 50 present-day Finns. The skull sample represented Finns who had lived in the city of Turku during the 15th and 16th centuries. Marked dental attrition was seen in the skulls; the dentition of the control individuals was virtually unworn. The gonial angle, and the angle between the mandibular base and nasal floor were significantly smaller in the skull sample than in the present-day sample. In addition, the upper incisors were more palatally inclined, and the angle between the axes of the upper and lower incisors was significantly larger in the skull sample. The configuration of the cranial base, and the relationship of the clivus to the nasal floor and ramus were similar in both samples. The results indicate that intensive mastication affects mandibular growth by advancing its anterior rotation. The large interincisal angle was caused, almost equally, by the lingual tipping of the upper incisors and the anterior rotation of the mandible. It is suggested that anterior rotation is the natural growth direction of the mandible. However, several functional disturbances, including reduced masticatory stimulation due to modern diet, may promote more posteriorly directed growth.