Text

theses

Inflammation of the gums and tooth decay are conditions that, if detected early enough, can be corrected or reversed. There is therefore a need for minimally invasive, accurate assessment of dental and periodontal tissue in order to achieve prompt diagnosis and treatment. Optical coherence tomography (OCT) is an emerging non-invasive, non-ionizing imaging modality that provides cross-sectional images of tissue, up to several millimeters in depth with micrometer level resolution. The underlying hypothesis of this thesis is that biological alterations to oral tissues result in changes in light scattering behavior which could be quantified by OCT. In vitro bovine tooth samples were demineralized in 30% H3PO4 for exposure times ranging from 0 to 5 seconds. Volume OCT scans were taken and the mean backscattered intensity as a function of depth was generated for each exposure time. Microhardness indentation measurements were also recorded. A significant negative correlation (p < 0.05) was found between OCT surface peak intensity (dB) and Knoop hardness number (KHN). Ten human subjects underwent OCT imaging before and after dry brushing the gingiva to induce inflammation. Mean backscattered OCT intensity versus depth plots were generated from pre- and post-brushing images. The slope of a linear fit to the intensity vs depth plot, and the area under the curve (AUC) were determined for epithelium and the lamina propria layers and compared between baseline and post-treatment. No appreciable factor change in either the fitted slope or AUC were measured for the epithelium (p > 0.05) and no appreciable factor change in the AUC was measured for the lamina propria (p > 0.05). There was a significant factor change in slope for the lamina propria region (p < 0.05). The in vitro demineralization study established a relationship between OCT signal intensity and the current gold-standard of microhardness testing, suggesting that OCT may be able to quantify demineralization in vivo. The in vivo gingival study led to the development of the necessary protocols and software to perform measurements in future studies. Together, these studies provide support for further development of OCT as a diagnostic tool for the in vivo assessment of dental diseases.

ETD_7227

M.S.

Includes bibliographical references

by Christine Charles Sahyoun

doi:10.7282/T3ZK5JTX

ETD graduate

The author owns the copyright to this work.