Dimorphism in Dental Tissues: Sex differences in Archaeological Individuals for Multiple Tooth Types

ObjectivesDimorphism in the dentition has been observed in human populations worldwide. However, research has largely focused on traditional linear crown measurements. As imaging systems, such as micro-computed tomography (micro-CT), become increasingly more accessible, new dental measurements such as dental tissue size and proportions can be obtained. This research investigates the variation of dental tissues and proportions by sex in archaeological samples.Materials and MethodsUpper and lower first incisor to second premolar tooth rows were obtained from 30 individuals (n=300), from 3 archaeological samples. The teeth were micro-CT scanned and surface area and volumetric measurements were obtained from the surface meshes extracted. Dental wear was also recorded and differences between sexes determined.ResultsEnamel and crown measurements were found to be larger in females. Conversely, dentine and root measurements were larger in males.DiscussionThe findings support the potential use of dental tissues to estimate sex of individuals from archaeological samples, whilst also indicating that individuals aged using current dental ageing methods may be under- or over-aged due to sex differences in enamel thickness.

Wisdom Tooth Formation as a Method of Estimating Age in a New Zealand Population

Dental ageing relies on assumptions aboutthe progression of tooth development from the middletrimester to adulthood and relative stability of thisprocess in the face of adverse dietary, hormonal, diseaseor nutritional factors. Most studies of dental ageingemploy the method of Demirjian et al., (1973), which isbased upon an assessment of crown and root formationstages from dental radiographs. Unfortunately, thismethod has a ceiling effect at age 16, when the secondmolar attains full maturity. The aim of our study was toextend the window of ageing by using the developmentof the third molar teeth. Panoramic radiographs of 207(105 males) children aged between 7 years, 6 months and18 years formed the basis of this study. Upper and lowerleft wisdom teeth were scored according to Demirjian et al. (1973) by a single examiner. Intra-examiner reliabilitywas evaluated by repeat scoring of a randomly selected(10%) sample one week after the initial staging. Theseshowed a consistency of 76% for the mandibular data and95% for the maxillary data, giving an overall percentageof 85%. When the re-scored teeth were not consistentwith their original score, this differed only by one stage.In this population males were advanced in their thirdmolar development and this trend was more markedfor maxillary than mandibular wisdom teeth. Hence, theNew Zealand population examined, males were moreadvanced in their third molar development and thistrend was more marked for maxillary than mandibularteeth.

A Comparison of Tooth Eruption and Wear and Dental Cementum Techniques in Age Determination of New Zealand Feral Pigs.

This study evaluates dental ageing techniques for feral pigs in northern South I., New Zealand. Ages of pigs were estimated by three techniques: tooth eruption and replacement on criteria calibrated from pen-reared American-bred European wild pigs; tooth eruption, development, and wear calibrated from known-age feral pigs from the study area; and annular growth in cementum of molariform teeth. All age estimations showed strong agreement with each other and with known ages. The eruption and replacement criteria were most useful for ageing pigs less than 30 months old, whereas the other two criteria were more suited to ageing pigs more than 30 months old. All permanent teeth of New Zealand feral pigs erupted 1-2 months earlier than in European and Malayan wild pigs, and permanent premolars erupted up to 4 months earlier than in Japanese wild pigs. Earlier eruption may reflect early onset of maturity in New Zealand pigs. The clarity of annuli observed varied between animals, but generally increased with age. Pigs from unforested habitat had a higher percentage of clearly defined annuli than those from forested habitat. This may be explained by a climatic or dietary factor.