Variation in health care, whether it be in terms of the utilisation of resources, observed health outcomes, costs, quality or access to health care is a well recognised and ever present feature of the modern day health care system. Health care variations challenge basic assumptions about the nature of the health care economy and raise questions about efficiency, equity and where best to direct policy instruments in health care markets. Despite the vast literature documenting variation, and the many discussions around ways to reduce variations in health care markets, the field of dental care has received little interest, in comparison to that of general medical care. This thesis will address this gap and will analyse the variation observed in a specific dental care treatment (dental radiographs) within NHS Scotland, with particular emphasis on the contribution of both dentist and patient unobserved heterogeneity. The thesis takes its focus from two strands of the literature; the underlying theoretical aspect draws on the literature concerning the theory of incentives and physician agency, whilst the empirical component makes use of recent advances in micro-econometric methods, documented in the labour economics literature. Although the thesis is predominantly an empirical analysis, the estimation strategy combines ideas from both the theoretical and empirical literature. A matched patient provider dataset from NHS Scotland is used to conduct an analysis of the variation in dental radiographs, in the presence of, and controlling for unobserved dentist and patient heterogeneity. The results indicate that the remuneration structure alone has little or no impact on the treatment decision to provide a radiograph. When a dentist changes from being on a fixed salary contract to being paid on a fee-for-service basis, they are in fact less likely to provide a radiograph. This result changes in the presence of insurance (identified as being when patients are exempt from the patient charge) and indicates that when the self employed dentist can identify the patient as being exempt, they are more likely to provide a radiograph. This result provides some support for the theory that in the presence of insurance, financial incentives do influence the treatment decision. A final result of the study highlights the importance of accounting for unobserved patient and provider heterogeneity, a factor that has had little attention in the healthcare literature. The results suggest that patient variation, as opposed to the variation across dentists, is much more important in explaining total variation. This is a similar result to that found in both the labour and education literatures.

Philosophiae Doctor - PhD / A technique was developed for the assessment of forensic identification using dental radiographs. The technique involved the digitisation of dental radiographs, cutting of a horizontal section from an antemortem radiograph and superimposing it over the same geographic location on the postmortem radiograph. The technique was useful in vitro and in an in vitro mock mass disaster. It was accurate within both the paediatric and permanent dentition and not useful in subjects with changing dentitions (mixed dentition). Image density (with and without optical enhancement) did not prove to be an impediment to the technique although extremes of image contrast did. Within the range of dental xray generators settings, contrast could be altered in a manner to allow matching. Differences in the vertical angulation of the x-ray beam did not influence the technique although horizontal angulation was a critical factor. Alterations in focal-film distance did not adversely affect the use of this technique. The three different scanning systems used were .all adequate for the purpose of the technique and the images could be compressed and transferred with little difficulty. Analysis of a group of actual Coroner's cases proved the technique to be useful in a timely fashion, for actual field identifications with minimal inter and intra operator error.

Exploration of the internal structures of teeth is complex and has the potential to add greatly to existing information about the lifecourse of archaeological individuals, but has yet to realize its full interpretative value as an avenue of bioarchaeological inquiry. This thesis consists of three papers that focus on the potential for internal dental structures to provide important information on chronological age, and physiological alterations linked to vitamin D deficiency. The first paper used SEM, microscopic imaging, and histological investigation of tooth dentin to determine the presence of mineralisation defects, observed as interglobular dentin (IGD) (spaces following incremental lines) in living (with known medical history) and archaeological individuals with clear healed rickets. This paper demonstrated that incremental bands of IGD are indicative of vitamin D deficiency. The second paper expands identification of those with deficiency by quantifying morphological changes in pulp chambers of living and archaeological individuals. Pulp chambers were radiographed, evaluated histologically, and measured. Those with evidence of past vitamin D deficiency displayed constricted or chair shaped pulp horns. This radiographic technique provides a non-destructive tool to identify individuals that experienced childhood vitamin D deficiency. The role vitamin D plays in the development of IGD over the lifecourse requires that accurate age estimates be conducted on older as well as younger adults. The third paper used a new version of pulp/tooth area ratios to provide an accurate estimation of age-at-death in older adults (50+). ImageJ software was used to calculate areas on sectioned teeth and results provided a mean absolute error (MAE) of ±3.9 years in older adults. The results described in this thesis contribute to broader topics of discussion in anthropology, such as investigating health and metabolic disease in human populations, and adds to the ongoing discussion and evaluation of age-at-death techniques used to extend our ability to study the lifecourse of archaeological individuals. / Dissertation / Doctor of Philosophy (PhD) / Teeth record life events and the three papers in this thesis use dental structures to provide methodological foundations to evaluate the occurrence and severity of vitamin D deficiency in early life. The potential long-term consequences of such events are investigated through accurate recognition of older adults. Vitamin D regulates skeletal health by mediating calcium absorption and phosphorous homeostasis and deficiency is recognised as an important health concern. Accurate identification of older adults is also a widely recognised problem in skeletal studies. Age-at-death estimation in older individuals was calculated and the exploration of abnormal pulp chamber shape and mineralisation defects in tooth dentin was done to determine vitamin D status in both younger and older individuals. This research established that internal dental structures enables past episodes of vitamin D deficiency to be recognized in cases where skeletal indicators are not clear and permits increased precision in age-at-death estimations in the older individual.

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