| Abstract: |
This dissertation research project investigates resorptive defects of the lingual surface of the human mandible, commonly called Stafne's defects or static bone cavities, in an osteological sample of 1,598 human mandibles. These asymptomatic, non-healing osseous defects were reported predominately in middle-aged males, with a sex ratio of about 7:1 clinically, and 12:1 in osteological mandibles, and were documented in the medical, radiological and anthropological literature in approximately 0.3% individuals of all ancient and modern human groups. Surgery, biopsy, and radiographic analyses revealed that the vast majority of Stafne's defects, which in osteological specimens can measure more than 3 cm in length, contain normal submandibular gland tissue, fatty tissue, muscle, lymph or vascular tissue. These findings lead many researchers to conclude that Stafne's defects form in one of four ways
(1) either during embryonic development of the mandible and contain entrapped or aberrant salivary gland tissue
or (2) as a result of enlargement of adjacent soft tissues, especially the submandibular gland
or (3) pressure erosion by the facial artery
or (4) simple (Mendelian) inheritance. A review of the literature revealed few testable hypotheses and definitive findings on these defects other than the sex of individuals and frequencies of occurrence. The major research questions addressed in this research are the relationship of mandible size (allometry) and pre-mortem loss of the mandibular molars to the occurrence, sex of the individual, size and genetic basis of Stafne's defects. The present study reveals (1) A statistically significant relationship between Stafne's defects and sex of the individual
(2) No statistically significant relationship between the occurrence of Stafne's defects and mandible size when controlling for sex
(3) No correlation between the size of Stafne's defects and mandible size
(4) No relationship between the occurrence of Stafne's defects and the pre-mortem loss of one or more of the mandibular molars
and (5) The observed frequencies of Stafne's defects fit the expected frequency for a single X-linked recessive trait. This research provides potentially significant information for researchers and furthers our understanding of allometry, skeletal plasticity and the formation, occurrence, size and genetic basis of Stafne's defects in human mandibles.
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