Temporomandibular joint pathological changes in the prehistoric New Zealand Maori and Moriori

Diseases and disorders of the temporomandibular joint are commonly encountered clinically. This has lead to most temporomandibular research focusing upon the pathologies that affect the joint and their proposed aetiologies. Little of this research has been conducted on the prehistoric Polynesians. Therefore, this study was developed in order to determine the type and pattern of any temporomandibular pathologies in the prehistoric Maori and Moriori and to investigate their possible aetiologies. For this study a sample of 89 prehistoric Maori and Moriori skulls were used. All temporomandibular pathologies were recorded by type, location, and severity. Where possible, the ecological and geographical provenance of each individual was recorded and their sex and age estimated. This enabled an analysis of whether the prevalence and severity of temporomandibular degeneration varied between provenances or sexes, and if the occurrence of temporomandibular pathology increased with age. The condition of the dentition was also recorded for each individual as the dentition has been implicated in many previous studies to be an aetiological factor in temporomandibular degeneration. The dental conditions examined include; tooth loss, tooth attrition, inflammation or infection of the alveolar bone, dental caries, and fem root planes. Finally, the presence of any congenital or developmental anomalies and condylar enthesophytes were recorded in order to investigate if these conditions had any relationship to the occurrence of temporomandibular degeneration. A high prevalence of temporomandibular degenerative joint disease was found in this sample. No primary relationship was seen between age, congenital or developmental anomalies, condylar enthesophytes and temporomandibular degeneration. Furthermore, despite a high proportion of these individuals having very worn teeth, with consequent infection and tooth loss, no primary relationships were found between the selected dental conditions and temporomandibular degeneration either. However, a significant association was found between the sex of the individual and temporomandibular pathology, with males being more frequently and severely affected than the females. This appeared to be due to differences in dietary type between the sexes resulting in more severe biomechanical loading in the males. It is suggested that the high prevalence of temporomandibular degeneration recorded may be caused by excessive biomechanical loading possibly resulting from the diet or as a consequence of the Polynesian morphology. Interestingly, over one third of the sample had grooving in at least one fossae. It is proposed that this grooving may have either a hereditary component, or result from a specific morphological variation that is present in the prehistoric Maori and Moriori