⽛釉質發育不全的古病理及組織學研究和研究⽅法的討論——以⼗三⾏考古遺址的⼈體⾻骼爲例

Abstract

牙釉質發育不全是人類社會中，尤其是古代社會，常見的齒科疾病，在生物考古學中常作為評估個體年幼時期的健康狀況和生存壓力的古病理學指徵。然牙釉質的生長過程是生物發育過程中最複雜的程序之一， 想要從牙釉質發育不全這一病症的觀察結果提取更多能應用於生物考古學研究的資訊，勢必要對牙釉質的發育生長和牙釉質發育不全的發生機制有更深入的瞭解。本文將首先對牙釉質發育不全及其病因進行介紹和定義，同時說明牙釉質發育不全的不同表現，再進一步針對其中的線性釉質發育不全進行討論。為了闡明牙釉質發育不全的發生機制，本文也將對牙釉質的組織學進行詳細的分析說明，以論述這些組織學結構對牙釉質生長的影響，及如何決定牙釉質發育不全這一病理學指徵被學者觀察到的形式。 除了介紹牙釉質發育不全這一病理學現象以何形式被考古學者進行詮釋，本文也對國內外、從過去至今的牙釉質發育不全的觀察鑒定方法進行梳理，闡明這一病症的發病年齡、發病頻率、發病時長及患病週期等資訊如何從觀察鑒定結果中被汲取。與此，著重介紹 MicroPolySharp 電腦程序並說明該程序的背後邏輯——將牙釉面輪廓圖像轉化成個體的患病時長和週期，意即藉由計算將距離數據轉換成時間信息，對牙釉質發育不全進行鑒定的同時保證了其結果的客觀性。 最後再以十三行考古遺址出土的人體骨骼為樣本進行觀察鑒定，並以此為例說明宏觀觀察方法的不足之處，以及應用微觀觀察法的必要性。十三行遺址（距今 1800-500 年）是臺灣北部極具代表性的金屬器時代考古學遺址，自 1990 年起執行的搶救發掘工作出土了至少 300 具墓葬，本次研究僅以該遺址H 區出土的 8 具人骨遺留作為觀察樣本，說明在應用宏觀觀察法時，所面對的困難與其觀察結果的主觀性，討論這些難題的成因。與此同時，論述 MicroPolySharp 電腦程序如何克服這些難題、更客觀的觀察鑒定方法產出的數據和資訊有何益處，以及在牙釉質發育不全之研究中微觀觀察方法的重要性。

Enamel hypoplasia is a dental pathology commonly seen in human societies, especially in ancient societies. In bioarchaeology, enamel hypoplasia is often used as a paleopathological indicator to evaluate health status and to quantify systemic nutritional stress of individuals in their early ages. However, the incremental growth of enamel is one of the most complicated processes in human biological development. In order to extract more information applicable to bioarchaeological studies, in-depth understanding of the process of enamel growth histologically is a necessity. In this thesis, firstly, I define enamel hypoplasia and elucidate the differing etiologies of its appearance, while also introducing the different manifestations of it on various tooth classes. To clarify the mechanisms of enamel hypoplasia, this thesis also provides a detailed discussion on the histology of enamel and how this impacts the examination of it as a pathological indicator in bioarchaeology. In addition to reviewing the interpretations of enamel hypoplasia by bioarchaeologists, this thesis also reviews the methods of identification and examination of enamel hypoplasia from past till present and also explains how the information concerning of age of onset, frequency, stress duration, etc. can be extracted from macroscopic and microscopic observations. Furthermore, in this thesis, I pay attention to the recent development of the MicroPolySharp method, yet also elaborate the logic supports the methodology that assured the objectivity of application. Instead of estimation, MicroPolySharp relied on converting enamel surface profile scans that represents the variations of perikymata across the affected tooth crown into the duration and chronology of defects, in other words, turning the data of distance to the information of time by calculation while the objectivity is promised in the process of examination. I then offer observations of skeletal samples from the Shihsanhang site. The Shihsanhang site is a representative Metal Age prehistoric archaeological site of northern Taiwan that dates ca. 1800 BP - 500 BP. At least 300 burials were unearthed during the rescue excavations started in 1990. This thesis examines eight individuals from burials in Area H of the site to give an idea of the differences in results between macroscopic and microscopic methodologies for observing enamel hypoplasia. It highlights the difficulties and consequences of applying macroscopic methodologies, especially the subjectivity inherent in those methodologies, and also looks at the problems of not understanding the causes of the observed pathologies. The benefits and importances of applying the MicroPolySharp method is then be discussed to demonstrate how the programme helps to improve the objectivity during the process of examination and, furthermore, how the reliability of the data retrieved from more objective methods provides better opportunities for further interpretation.