Uniform TitleMicro-raman spectroscopy of caries lesion formation in dental enamel
NameDadlani, Deepa (author), Mann, Adrian (chair), Shreiber, David (internal member), Langrana, Noshir (internal member), Lehman, Richard (outside member), Rutgers University, Graduate School - New Brunswick,
DescriptionCaries lesions form by a complex process of chemical interactions between dental enamel and its environment. They can cause cavities and pain, and are expensive to fix. Lesions form by slow demineralization over many months, even years. It is hard to characterize in vivo as a result of environmental factors and remineralization by ions in the oral cavity. In this thesis the process of demineralization was carried out in vitro and micro-Raman spectroscopy used to investigate and characterize the lesion's chemistry. Demineralization occurs by diffusion across the depth of the lesion of mineral ions via interstitial spaces in the dental enamel. Hydroxyl ions are initially lost by acidic attack, which increases the interstitial space. The demineralization is retarded by diffusion processes in the opposite direction, and a balance in the charges of the ions must be maintained. Having multiple ions diffusing simultaneously is termed &amp;amp;#08220;coupled diffusion&amp;amp;#08221;. A subsurface highly demineralized region is formed, but this can be remineralized.
Micro-Raman spectroscopy is a powerful tool for studying material composition by exciting chemical bonds in the sample. Using micro-Raman to characterize the chemical composition of lesions may help in developing preventative measures to stop their formation. Raman (λ=785 nm) was used to characterize lesions grown over 5, 7, 9, 11 and 14 days. The amide I peak at ~1605 cm-1, which has not been observed previously, was seen in the maturing lesions. The extreme demineralization in these lesions enables the organic peaks to be seen rather than the normally stronger mineral peaks. Analysis of crystallinity shows that there is always a reduction in mineral content with distance below the enamel surface, but this becomes magnified as the lesion matures. Type B carbonate substitution for phosphate ions can also be examined with Raman. Correcting for crystallinity shows that both carbonate and phosphate ions are lost at the same rate during demineralization.
In summary, micro-Raman is an effective and relatively easy tool to use in lesion characterization. It also has the advantage that it can be used to identify changes in both the mineral and protein phases of enamel.
NoteIncludes bibliographical references (p. 53-55).
CollectionGraduate School - New Brunswick Electronic Theses and Dissertations
Organization NameRutgers, The State University of New Jersey
RightsThe author owns the copyright to this work.