Introduction: The Atraumatic Restorative Treatment (ART) is based on the indirect pulp capping technique. In these techniques, the infected dentine is removed and a glass ionomer cement (GIC) restoration is placed on remnant demineralized dentine to allow remineralization to occur. There is some evidence from in vitro and in vivo studies that fluoride and strontium diffuse into demineralized dentine (Kitasako, Nakajima et al. 2003); Smales 2005; Ngo 2006), and may contribute to remineralization. However, it is proposed that the mineral ions diffusing from dentinal tubular fluid also contribute. Shellis (1994) and Ozok (2004) recently demonstrated that infused surrogated dentinal fluid could decrease the depth of demineralization in dentine under an acidic challenge. Objectives: This study aimed to investigate the role of Simulated Dentine Tubule Fluid (SDTF) in remineralization of the remnant demineralized dentine using an in vitro model of the ART technique. Material and method: An apparatus was developed to achieve fluid flow into the pulp chambers of molar crowns, and thus into the dentine tubules at the same hydrostatic pressure as operates in vivo. A pilot study was carried out which demonstrated that the dye can diffuse into the dentine tubules when both artificial and natural caries are present, thus validating the method. A further pilot study demonstrated that SDTF could reduce the level of calcium lost in dentine under an acidic challenge, which agreed with Shellis and Ozok’s findings. Moreover, in the presence of the SDTF, the remineralization of demineralized dentine increased with exposure to a remineralizing solution. The main experiment of this study was to investigate whether SDTF can enhance remineralization of demineralized dentine using an in vitro ART simulation method. In this experiment, Class 1 cavities of similar dimension were cut in 18 extracted, intact third molar teeth. These teeth were painted with nail varnish leaving the dentine floors exposed for generation of artificial caries (6 teeth each for 7 days, 14 days and 21 days of demineralization). Half of the demineralized cavity floor was protected with nail varnish providing a control and test side. The cavity was restored in Fuji IX which enabled a direct contact between demineralized dentine on the test half of the cavity floor and Fuji IX. A reservoir of SDTF was connected to supply SDTF under prescribed hydrostatic pressure to each pulp chamber for 21 days during which ion exchange was proceeding between GIC and demineralized dentine as demonstrated by Ngo (2005). Teeth were then detached from the system, sectioned and prepared for analysis by Electron Probe to determine profiles of Ca, P, F and Sr across the demineralized dentine under the GIC restoration. The results from this experiment, while showing an increase in calcium in the test over control side of the lesion, also showed an increase of calcium levels on both test and control side. This suggested a need to modify the model to provide evidence of the increase in calcium and other elements above the baseline profiles originally present in the demineralized dentine. The modified model was developed which sectioned the teeth into halves. Each half of the tooth was treated as an individual sample in separated experiments where one was supplied with SDTF and the other with De-ionized Distilled Water. Based on the assumption that the mineral contents in two halves of the same tooth initially were similar, any increase in mineral contents in either half of the tooth could be considered as an indication of remineralization. Other experiments were carried out to investigate the interaction between the SDTF to calcium rich materials which were applied to the demineralized dentine, and to investigate the effect of longer exposure time on remineralization. In the first experiment, Ketac Molar was used as an alternative restorative material which is calcium based restorative material. In the second experiment, CPP-ACP was applied to the demineralized dentine before placement of composite resin or glass ionomer cement restorations. In the third experiment, the exposure time of demineralized dentine under Fuji IX restoration to SDTF was increased to six weeks to look at the effect of longer periods of exposure to SDTF on overall remineralization. Results: Both the initial and enhanced models showed the effectiveness of SDTF on remineralization in vitro under GIC restorations. The results provided evidence of an initial positive equilibrium gradient between SDTF and demineralized dentine. The placement of a GIC restoration provided an added gradient in terms of calcium concentration between SDTF and the adjacent GIC restoration. If the calcium level in the restoration was higher than that in the SDTF, as occurred with Ketac Molar, the diffusion of calcium into demineralized dentine was diminished. This also occurred in the presence of CPP-ACP. In the presence of CPPACP, the calcium/phosphorus ratios in the demineralized dentine (adjacent to the restoration) was reduced and nearer to the ratio in calcium deficient apatite. However, the longer exposure time of the demineralized dentine to GIC restoration in the presence of the SDTF increased remineralization. Conclusion: Dentinal tubule fluid contributes significantly to remineralization of the partially demineralized dentine in this model of the ART technique. However, the level of remineralization is very sensitive to factors affecting the concentration gradients between critical structural elements with the SDTF and the restoration. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1325244 / Thesis (Ph.D.) -- University of Adelaide, School of Dentistry, 2008

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Frente ao aumento da prevalência da erosão dental e das dificuldades de controle de seus possíveis fatores etiológicos (químicos, biológicos e comportamentais) é de fundamental importância o estabelecimento de medidas no sentido de diminuir o progresso ou evitar a instalação da erosão dental ou ainda reverter lesões de erosão já estabelecidas. Assim, o objetivo deste estudo é avaliar o potencial remineralizador de dentifrícios com compostos bioativos no esmalte dental submetido a desafios erosivos de diferentes severidades. A variável de resposta, alteração mineral, foi avaliada quantitativamente pelo método de mensuração de fluorescência do substrato dental (QLF). Os tratamentos remineralizadores avaliados foram: saliva (controle) e 5 dentifrícios (Flúor, Recaldent, Recaldent+F, Novamin®, Novamin®+F) em três condições experimentais relacionadas à severidade do desafio erosivo (1h, 4h e 8 h e diferentes momentos de análise (baseline, desafio erosivo, 1ºdia, 7ºdia, 14ºdia). As unidades experimentais foram compostas de 180 fragmentos dentais de incisivos bovinos com dimensões 4 x 4 x 3 mm. As amostras foram distribuídas entre os grupos experimentais sendo n=10. Para a realização dos desafios erosivos os espécimes foram imersos em suco de laranja de acordo com os tempos experimentais. A análise estatística confirmou que os tempos de imersão utilizados, 1 hora, 4 horas e 8 horas, causaram diferentes graus de erosão no esmalte dental: suave, moderado e severo respectivamente. A aplicação dos diferentes tratamentos remineralizadores foi realizada diariamente por meio da imersão dos espécimes em recipientes contendo suspensão de dentifrícios. O grupo controle permaneceu imerso em saliva artificial que era substituída diariamente. Foram realizadas mensurações referentes ao processo remineralizador pelo método QLF nos momentos experimentais baseline, erosão, 1ºdia, 7ºdia e 14ºdia. Foram realizadas análises estatísticas distintas para cada severidade de desafio erosivo (suave, moderado e severo). Nenhum dos tratamentos propostos foi capaz de remineralizar totalmente as lesões erosivas independentemente da severidade, sendo que o a associação dos compostos bioativos Recaldent e Flúor apresentou maior potencial remineralizador. / The increasing prevalence of dental erosion besides the difficulty of controlling its etiological factors (chemical, biological and behavioral) indicate the fundamental importance for the establishment of measures to slow the progression, prevent the installation of dental erosion or even reverse the process. Thus, the purpose of this study was to evaluate the remineralizing potential of bioactive compounds in dentifrices with enamel subjected to erosive challenges of different severities. The mineral changes were evaluated by Quantitative Ligth-induced Fluorescence (QLF). The remineralizing treatments consisted in saliva (control) and 5 toothpaste (Fluoride, Recaldent, Recaldent+F, Novamin®, Novamin®+F) in three experimental conditions according to the severity of erosive challenge (1h, 4h and 8 h) and different analysis periods (baseline, erosive challenge, 1th day, 7th day and 14th day). The experimental units consisted of 180 bovine incisors fragments with dimensions 4 x 4 x 3 mm. The samples were distributed among the experimental groups (n = 10). Erosive challenges were performed by samples immersing in orange juice according to the experimental times. Different immersion times, 1 hour, 4 hours and 8 hours, promoted different erosion severities on dental enamel: mild, moderate and severe respectively confirmed by statistical analysis. Application of different remineralizing treatments was performed daily by immersing the specimens in vials containing toothpastes suspensions. Control group remained immersed in artificial saliva which was daily replaced. QLF measurements concerning remineralizing process were performed at experimental times, baseline, erosion, 1th, 7th and 14th days. Statistics analyses were performed for each erosive challenge severity separately (mild, moderate and severe). None of the treatments proposed were capable of fully remineralizing regardless erosive lesions severity. Recaldent and Fluoride association presented the highest remineralizing potential among bioactive compounds.

Frente ao aumento da prevalência da erosão dental e das dificuldades de controle de seus possíveis fatores etiológicos (químicos, biológicos e comportamentais) é de fundamental importância o estabelecimento de medidas no sentido de diminuir o progresso ou evitar a instalação da erosão dental ou ainda reverter lesões de erosão já estabelecidas. Assim, o objetivo deste estudo é avaliar o potencial remineralizador de dentifrícios com compostos bioativos no esmalte dental submetido a desafios erosivos de diferentes severidades. A variável de resposta, alteração mineral, foi avaliada quantitativamente pelo método de mensuração de fluorescência do substrato dental (QLF). Os tratamentos remineralizadores avaliados foram: saliva (controle) e 5 dentifrícios (Flúor, Recaldent, Recaldent+F, Novamin®, Novamin®+F) em três condições experimentais relacionadas à severidade do desafio erosivo (1h, 4h e 8 h e diferentes momentos de análise (baseline, desafio erosivo, 1ºdia, 7ºdia, 14ºdia). As unidades experimentais foram compostas de 180 fragmentos dentais de incisivos bovinos com dimensões 4 x 4 x 3 mm. As amostras foram distribuídas entre os grupos experimentais sendo n=10. Para a realização dos desafios erosivos os espécimes foram imersos em suco de laranja de acordo com os tempos experimentais. A análise estatística confirmou que os tempos de imersão utilizados, 1 hora, 4 horas e 8 horas, causaram diferentes graus de erosão no esmalte dental: suave, moderado e severo respectivamente. A aplicação dos diferentes tratamentos remineralizadores foi realizada diariamente por meio da imersão dos espécimes em recipientes contendo suspensão de dentifrícios. O grupo controle permaneceu imerso em saliva artificial que era substituída diariamente. Foram realizadas mensurações referentes ao processo remineralizador pelo método QLF nos momentos experimentais baseline, erosão, 1ºdia, 7ºdia e 14ºdia. Foram realizadas análises estatísticas distintas para cada severidade de desafio erosivo (suave, moderado e severo). Nenhum dos tratamentos propostos foi capaz de remineralizar totalmente as lesões erosivas independentemente da severidade, sendo que o a associação dos compostos bioativos Recaldent e Flúor apresentou maior potencial remineralizador. / The increasing prevalence of dental erosion besides the difficulty of controlling its etiological factors (chemical, biological and behavioral) indicate the fundamental importance for the establishment of measures to slow the progression, prevent the installation of dental erosion or even reverse the process. Thus, the purpose of this study was to evaluate the remineralizing potential of bioactive compounds in dentifrices with enamel subjected to erosive challenges of different severities. The mineral changes were evaluated by Quantitative Ligth-induced Fluorescence (QLF). The remineralizing treatments consisted in saliva (control) and 5 toothpaste (Fluoride, Recaldent, Recaldent+F, Novamin®, Novamin®+F) in three experimental conditions according to the severity of erosive challenge (1h, 4h and 8 h) and different analysis periods (baseline, erosive challenge, 1th day, 7th day and 14th day). The experimental units consisted of 180 bovine incisors fragments with dimensions 4 x 4 x 3 mm. The samples were distributed among the experimental groups (n = 10). Erosive challenges were performed by samples immersing in orange juice according to the experimental times. Different immersion times, 1 hour, 4 hours and 8 hours, promoted different erosion severities on dental enamel: mild, moderate and severe respectively confirmed by statistical analysis. Application of different remineralizing treatments was performed daily by immersing the specimens in vials containing toothpastes suspensions. Control group remained immersed in artificial saliva which was daily replaced. QLF measurements concerning remineralizing process were performed at experimental times, baseline, erosion, 1th, 7th and 14th days. Statistics analyses were performed for each erosive challenge severity separately (mild, moderate and severe). None of the treatments proposed were capable of fully remineralizing regardless erosive lesions severity. Recaldent and Fluoride association presented the highest remineralizing potential among bioactive compounds.