Detection modalities that can evaluate the early stages of dental caries are indispensable. The purpose of this thesis is to evaluate the efficacy of photothermal radiometry and modulated luminescence (PTR-LUM) to non-destructively detect and quantify simulated enamel caries. Two experiments were performed based on the PTR-LUM detection mode: back-propagation or transmission-mode. Artificial demineralized lesions were created in human molars and a subset was further exposed to an artificial remineralizing solution. PTR-LUM frequency scans were performed periodically during de/re-mineralization treatments. PTR data was fitted to a theoretical model based on optical and thermal fluxes in enamel to extract opto-thermophysical parameters. Lesion validation was performed using transverse microradiography (TMR). Optical and thermal properties changed with the development and repair of the caries lesions while theory-derived thicknesses paralleled those determined microradiographically. These trends coupled with the uniqueness-of-fit of the generated parameters illustrate the efficacy of PTR- LUM to non-destructively detect and quantify de/re-mineralized lesions.

Detection modalities that can evaluate the early stages of dental caries are indispensable. The purpose of this thesis is to evaluate the efficacy of photothermal radiometry and modulated luminescence (PTR-LUM) to non-destructively detect and quantify simulated enamel caries. Two experiments were performed based on the PTR-LUM detection mode: back-propagation or transmission-mode. Artificial demineralized lesions were created in human molars and a subset was further exposed to an artificial remineralizing solution. PTR-LUM frequency scans were performed periodically during de/re-mineralization treatments. PTR data was fitted to a theoretical model based on optical and thermal fluxes in enamel to extract opto-thermophysical parameters. Lesion validation was performed using transverse microradiography (TMR). Optical and thermal properties changed with the development and repair of the caries lesions while theory-derived thicknesses paralleled those determined microradiographically. These trends coupled with the uniqueness-of-fit of the generated parameters illustrate the efficacy of PTR- LUM to non-destructively detect and quantify de/re-mineralized lesions.

Made available in DSpace on 2015-05-14T12:56:03Z (GMT). No. of bitstreams: 1 arquivototal.pdf: 946361 bytes, checksum: 1766fac9ee5a060f38a21f6c3c424890 (MD5) Previous issue date: 2014-03-27 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The aim of this study was to compare artificial carious enamel lesions induced with an acid gel containing large amounts of organic matter and artificial carious lesions induced by an acidic solution (with little organic constituent) regarding organic volume and permeability (&#61537;d). Thirty teeth (twenty third molar and ten molars with inactive white spot lesions) were divided into three groups. In order to induce artificial caries, ten teeth were exposed to an acid gel containing hydroxyethylcellulose 2% and 50 mM lactic acid at pH 4.5 (Gel; n = 10) while the other ten teeth a demineralizing solution (0,1 mM lactic acid, 11.7 mM of calcium, chloroform 0.5% v/v, 6 mM phosphate, pH 4.5) (Solution; n = 10). As a control group, the teeth containing white spot lesions were also analyzed (Natural Caries, n = 10). Three points were analyzed in each sample at the surface layer in each lesion at 50&#956;m intervals. The results obtained in each of the three groups were compared with theoretical mathematical found values in the literature as a way to standardize the comparison. Finally, variations in organic volume (Ratio &#61538;) and permeability (Ratio &#61537;d) in relation to predicted values were compared between groups. For variable Ratio &#61538;, there was a significant difference between the gel and solution [p<0.0001, ANOVA; Effect Size (ES)=1.84] and between solution and the natural caries (p=0.001, ANOVA; ME=0.46). Similarly, the values of Ratio &#61537;d between Gel/Solution (p<0.0001, Mann-Whitney, ES=0.96) and Solution/Natural caries (p<0.0001; Mann-Whitney; ME=1.15) differed significantly. There was no statistically significant difference between the groups Gel and Natural Caries for Ratio &#61538; (p=0.585, ANOVA, ES=0.30) and the Ratio &#61537;d (p=0.940, Mann-Whitney, ES=0.01). It was concluded that, as in natural decay, the surface layer of artificial carious enamel lesions created with organic acid gel showed higher organic matter and lower permeability compared to those induced in acidic solution. / O objetivo deste estudo foi comparar lesões cariosas artificiais de esmalte induzidas com gel ácido contendo grande quantidade de matéria orgânica e lesões cariosas artificiais induzidas com solução ácida com pouco constituinte orgânico, quanto ao volume orgânico e à permeabilidade (&#61537;d). Trinta dentes (vinte terceiros molares inclusos e dez molares com lesão de mancha branca inativa) foram distribuídos em três grupos. Com o intuito de se induzir cárie artificial, dez dentes inclusos foram expostos a um gel ácido de hidroxietilcelulose 2% e ácido lático 50 mM com pH 4,5 (Gel; n=10) e os outros dez a uma solução desmineralizante (0,1 mM de ácido lático, 11,7 mM de cálcio, clorofórmio 0,5% v/v e 6 mM de fosfato, com pH 4,5) (Solução; n=10). Como grupo controle, os dentes contendo lesões de mancha branca também foram analisados (Cárie Natural; n=10). De cada amostra analisou-se três pontos da camada superficial da lesão, em intervalos de 50 &#956;m. Os pontos analisados em cada um dos três grupos foram comparados com valores teóricos estabelecidos matematicamente na literatura, como forma de padronizar as comparações. E, por fim, as variações de volume orgânico (Razão &#61538;) e permeabilidade (Razão &#61537;d) em relação a valores previstos foram comparadas entre os grupos. Para a variável Razão &#61538;, houve diferença significante entre os grupos Gel e Solução [p<0,0001, ANOVA; Magnitude do efeito (ME)=1,84] e entre Solução e Cárie Natural (p=0,001; ME=0,46; ANOVA). Da mesma forma, os valores da Razão &#61537;d do cruzamento Gel/Solução (p<0,0001, Mann-Whitney; ME=0,96) e Solução/Cárie Natural (p<0,0001, Mann-Whitney; ME=1,15) diferiram de maneira significativa. Não houve diferença estatisticamente significante entre os grupos Gel e Cárie Natural para a Razão &#61538;&#61472;(p=0,585; ANOVA; ME=0,30) e a Razão &#61537;d (p=0,940; Mann-Whitney; ME=0,01). Concluiu-se que, semelhantemente à cárie natural, a camada superficial das lesões cariosas artificiais de esmalte criadas com gel ácido apresentaram maior volume orgânico e menor permeabilidade, comparadas às induzidas em solução ácida.