Interproximal grooving and task activity in Australia.

Interproximal grooving was recorded in 85 nineteenth century aboriginal skulls from Swanport in South Australia. One or more grooved teeth were noted in 41% of individuals, but the frequency of grooving in males was twice that in females. Distal surface grooving was noted in 93 teeth in contrast to only five instances of mesial grooving. The lesions were similar in appearance to those reported in many other populations--confined primarily to the premolar-molar region, located at the cementoenamel junction, directed horizontally, and usually clean-cut and free of caries. Stripping of animal sinews between the clenched posterior teeth has been recorded on film as a common task activity in traditional aboriginal society. In our opinion, task activity and not toothpicking was the likely cause of the observed interproximal grooving in the aboriginals.