Magister Scientiae Dentium - MSc(Dent) / Introduction: Micro-leakage and enamel demineralization is still a major challenge in dental practice. It can lead to formation of demineralization lesions around and beneath the adhesive–enamel interface (Mali et al., 2006). Enamel demineralization adjacent to orthodontic brackets is one of the risks associated with orthodontic treatment. The prevention of demineralization during orthodontic treatment is therefore essential for aesthetic reasons and to circumvent the onset of caries. Aim: To assess micro-leakage and enamel demineralization around orthodontic direct attachments (brackets) using three different orthodontic cements. Materials and methods: In this in-vitro study, intact (non carious) extracted human premolars were used to compare the micro-leakage and enamel demineralization of three different cements (Fuji Ortho LC, Rely X luting 2 and Transbond XT). The dye penetration technique was used to evaluate micro-leakage on extracted human premolars. Micro-hardness testing was performed on 21 teeth to determine enamel demineralization. Sixty teeth were randomly divided into 3 groups of twenty teeth each. Direct attachments were cemented on each tooth using 3 different cements; Fuji Ortho LC (GC Fuji II LC GC Corporation Tokyo, Japan), (group 1), Rely X luting 2 cement (3M ESPE dental product, USA), (group 2), Transbond XT Light Cure (3M Unitek, Monrovia, Calif), (group 3). After the orthodontic direct attachments were fitted, they were exposed to 500 thermo-cycles between 5°C and 55°C, with a dwell time of 15 seconds in a buffered (pH 7) 1% methylene blue dye solution (Grobler et al, 2007). The specimens were viewed under a stereomicroscope (Nikon, Japan) at magnification of 40 times. Photographs of each specimen were taken with a Leica camera (Leica DFC 290 micro-systems, Germany) fitted onto a stereomicroscope. The ACDsee photo editing programme was used to transfer the photographs to a computer to measure the dye penetration along the enamel–adhesive and adhesive–bracket interfaces, both on the gingival and occlusal edge at × 40 magnification. For the demineralization sample, 21 teeth were divided into 3 groups of seven teeth each, where direct attachments were cemented using each of the 3 cements, group 1, Fuji Ortho LC (GC Fuji II LC GC Corporation Tokyo, Japan); group 2, Rely X luting 2 cement (3M ESPE dental product, USA) and group 3, Transbond XT Light Cure (3M Unitek, Monrovia, Calif). A digital hardness tester with Vickers diamond indenter (Zwick RoellIndentec (ZHV; Indentec UK) was used to measure surface micro-hardness of enamel before and after attaching the brackets. Ten indentations were made on the enamel surface of each tooth before bonding the brackets with a 300g load applied for 15 seconds to establish the baseline hardness value. After de-bonding the brackets, the hardness was measured again in the same area as mentioned above to determine the degree of enamel demineralization (softening). Result: The result showed statistically significantly lower levels of micro-leakage for Transbond XT (P= <0.001). The amount of micro-leakage on the margins was significantly higher in the gingival portion (P <0.05) as compared with the occlusal margin. Enamel micro-hardness tests before bonding using the three different cements showed that the variances are not significantly different (Chi-squared = 3.051, df = 2, p-value = 0.218). However, the micro-hardness tests done after bonding and thermo-cycling was statistically significantly different (Chi-squared = 13.435, df = 2, p-value = 0.001). Clearly, the Transbond XT group had less hardness, implying greater demineralization than the Fuji Ortho LC and Rely X luting 2 groups. Two sample t-tests show that mean value for the Fuji Ortho and Rely X luting 2 were not significantly different from each other (t = -0.636, df = 12, p-value = 0.537). The mean value for Transbond XT differed significantly from both the other two means: Transbond XT vs Fuji Ortho LC (t = 3.249, df = 6.9, p-value = 0.014). Transbond XT vs Rely X luting 2 (t = 3.493, df = 6.8, p-value = 0.011). Conclusions: This study showed that Fuji Ortho LC and Rely X luting 2 show more micro-leakage than Transbond XT. However Transbond XT had significant lower micro-leakage, less hardness (greater demineralization) than the Fuji Ortho LC and Rely X luting 2. This may have been due to the fluoride release which significantly reduces demineralization. Therefore the Fuji Ortho LC and Rely X luting 2 may be recommended for prevention of demineralization during orthodontic treatment.

Orientador: Lívia Maria Andaló Tenuta / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba / Made available in DSpace on 2018-08-18T14:38:08Z (GMT). No. of bitstreams: 1 Kusano_SandroCarvalho_M.pdf: 956275 bytes, checksum: f7babc0a1138faa960f02a6d9ca0a048 (MD5) Previous issue date: 2011 / Resumo: O Fluoreto (F) interfere com o desenvolvimento de cárie dental quando presente no meio bucal, reduzindo a desmineralização e ativando a remineralização da estrutura dental. Embora ambos os mecanismos estejam envolvidos na redução da perda mineral na presença de F, não foi encontrado nenhum estudo in situ que avaliasse a importância relativa de cada um deles na inibição do desenvolvimento de cárie. Desta forma, foi realizado um estudo in situ, cruzado e cego, com o objetivo de avaliar o efeito do momento de uso do dentifrício fluoretado, i.e., antes ou após desafios desmineralizantes diários (para simular efeito na redução da desmineralização ou ativação da remineralização, respectivamente), na perda mineral do esmalte e dentina radicular. Doze voluntários utilizaram dispositivos intrabucais palatinos contendo 3 blocos de esmalte e 3 de dentina radicular hígidos e com dureza de superfície previamente determinada, durante 3 fases de 14 dias cada. Os blocos foram fixados 1 mm abaixo do nível do dispositivo e cobertos por uma tela plástica para favorecer o acúmulo de biofilme dental, e foram expostos à sacarose 20% 8x/dia. Os voluntários realizaram os seguintes tratamentos: G1 - dentifrício placebo (nãofluoretado) três vezes/dia (grupo controle); G2 - dentifrício fluoretado pela manhã (7:00), antes dos desafios desmineralizantes diários, e dentifrício não-fluoretado nas escovações seguintes; e G3 - dentifrício fluoretado à noite (entre 20:00 e 21:00), após os desafios desmineralizantes, e dentifrício não-fluoretado nas duas escovações anteriores. A desmineralização do esmalte e dentina radicular foi avaliada pela porcentagem de perda de dureza de superfície (%PDS). Também foi avaliada a concentração de fluoreto incorporado aos blocos dentais (fluorapatita). Os resultados de %PDS dos tratamentos com dentifrício fluoretado diferiram do grupo controle (p<0,05), tanto para o esmalte (G1=72,0%±20,8; G2=41,6%±21,5; G3=30,0%±15,8) quanto para a dentina (G1=76,5%±9,3; G2=61,8%±11,8; G3=48,4±19,1), sendo que na dentina, a %PDS foi menor (p<0,05) no grupo tratado com dentifrício fluoretado após os desafios desmineralizantes. A concentração de F nos blocos de esmalte não diferiu entre os grupos tratados com dentifrício fluoretado (p>0,05), no entanto, foi significativamente maior no grupo tratado com dentifrício fluoretado após os desafios desmineralizantes, quando comparado ao grupo controle (p<0,05). Nos blocos de dentina, os grupos tratados com dentifrício fluoretado apresentaram concentrações significativamente maiores quando comparados ao grupo controle (p<0,05), entretanto não diferiram entre si (p>0,05). Os resultados do presente estudo sugerem que o dentifrício fluoretado é mais eficaz na redução da cárie através da ativação da remineralização do esmalte e dentina radicular, do que pela inibição da sua desmineralização / Abstract: Fluoride (F) interferes with dental caries development when present in oral environment, reducing dental demineralization and enhancing its remineralization. Although both mechanisms are related to the reduction of mineral loss in the presence of F, no experimental study which evaluated the relative importance of each mechanism on the inhibition of development of dental caries was found. Thus, this in situ, crossover and blind study was performed to evaluate the effect of the period of F dentifrice use, i.e., either before or after daily cariogenic challenges (to simulate either the effect on the reduction of demineralization or on the enhancement of remineralization, respectively), on enamel and root dentin remineralization. Twelve volunteers wore palatal appliances containing three sound enamel slabs and three sound root dentin slabs, with surface hardness previously determined, during three phases of 14 days each. Dental slabs were fixed 1 mm underneath the level of the appliance and covered by a plastic mesh to allow dental biofilm accumulation, and exposed to sucrose 20% 8x/day. The volunteers performed the following treatments: G1 - placebo toothpaste (non-fluoride) three times/day (control group); G2 - fluoride toothpaste in the morning (7:00), before cariogenic challenges, and non-fluoride toothpaste in the next two toothbrushings; and G3- fluoride toothpaste at night (between 20:00 and 21:00), after cariogenic challenges, and non-fluoride toothpaste in the previous two toothbrushings. Enamel-dentin demineralization was evaluated by percentage of surface hardness loss (%SHL). F uptake by enamel and dentin was also determined (as fluorapatite). %SHL data in groups treated with fluoride toothpaste differ from control group (p<0.05), for both enamel (G1=72.0%±20.8; G2=41.6%±21.5; G3=30.0%±15.8) and dentin (G1=76.5%±9.3; G2=61.8%±11.8; G3=48.4±19.1). For dentin, %SHL was lower (p<0.05) in the group using fluoride toothpaste after cariogenic challenges. F concentration in enamel slabs did not differ between groups using fluoride toothpaste (p>0.05), however, it was significantly higher in the group treated with fluoride toothpaste after cariogenic challenges compared to control group (p<0.05). For dentin slabs, groups using fluoride toothpaste showed significantly higher F concentration compared to control group (p<0.05), but no difference was observed between each other (p>0.05). The findings of this study suggest that F from toothpaste is more effective to reduce caries by enhancing enamel-dentine remineralization than by reducing their demineralization / Mestrado / Cariologia / Mestre em Odontologia

Orientador: Luís Roberto Marcondes Martins / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba / Made available in DSpace on 2018-08-18T14:18:22Z (GMT). No. of bitstreams: 1 Santos-Caldeira_MilenaMariaPierre_M.pdf: 1500767 bytes, checksum: 7089c23fae597d1c4940deba6843ad02 (MD5) Previous issue date: 2011 / Resumo: A presente pesquisa objetivou avaliar in situ o potencial anticariogênico de cimento de ionômero de vidro convencional na prevenção da desmineralização de esmalte e dentina, sozinho ou sob ação de dentifrício fluoretado. Foi realizado um estudo cego, cruzado, de indução de cárie, em blocos dentais obtidos a partir de terceiros molares humanos hígidos, pelo acúmulo de biofilme e exposição à sacarose, conduzido em 2 fases clínicas de 14 dias cada. O estudo foi fatorial 2 x 2 cruzado sendo: (1) Tratamento em 2 níveis, bloco dental com restauração de cimento de ionômero de vidro convencional (GI) e bloco dental hígido (ST); (2) Dentifrício em 2 níveis, fluoretado (FD) e não fluoretado (NF). Foi avaliado o efeito dos fatores nas variáveis de resposta: área de perda de dureza (?S) (quantitativamente) e microscopia de luz polarizada (qualitativamente), considerando esmalte e dentina individualmente. Os grupos experimentais foram obtidos pela associação dos fatores em estudo e atribuídos aos voluntários. Os voluntários utilizaram dispositivo intraoral com 2 blocos dentais referentes a cada tratamento, alternando, aleatoriamente, o tipo de dentifrício em cada fase. Os voluntários (n=7) foram considerados unidades experimentais para todas variáveis em estudo. Sobre as amostras no dispositivo intraoral foi acumulado biofilme dental e induzido alto desafio cariogênico pela exposição à solução de sacarose 20% sobre o biofilme 8x/dia, com os dispositivos fora da cavidade bucal. Após cada fase experimental foi avaliada, por microdureza longitudinal, a área de perda de dureza por ?S, em esmalte e dentina, e as amostras foram analisadas sob microscopia de luz polarizada quanto à desmineralização. Após análise estatística (ANOVA com arranjo fatorial dos níveis dos fatores, e Teste de Tukey), não foi encontrada interação dos fatores avaliados (p>0,05). Foi observada menor desmineralização em esmalte e dentina após o uso de FD do que NF (p<0,05). Quanto à comparação entre GI e ST, maior desmineralização para ST foi encontrada em esmalte (p<0,01), contudo não foram encontradas diferenças entre GI e ST para o substrato dentinário (p>0,05). A microscopia por polarização revelou maior porcentagem de sinais de desmineralização para ST+NF (64,28%) e GI+NF (50%), e menor porcentagem de desmineralização aparente para GI+FD (28,57%) seguido por ST+FD (42,85%). Concluiu-se que a presença de dentifrício fluoretado proporcionou menores áreas de desmineralização, proveu efeito anticárie sob todas condições estudadas, e, que a associação do cimento de ionômero de vidro convencional ao dentifrício fluoretado levou à menor porcentagem de desmineralização aparente nas imagens de microscopia de luz polarizada. Independente de dentifrício, restaurações de ionômero de vidro apresentaram efeito anticárie em esmalte / Abstract: The aim of this study was to assess in situ anticaries potential of conventional glass ionomer cement (GIC) to prevent enamel and dentine demineralization either alone or in combination with a fluoride (F) regimen. A randomized, blind, crossover design for caries induction was carried out in 2 phases of 14 days each. This study was a 2 x 2 cross-over factorial design as follows: (1) Material Treatment at 2 levels, dental slabs restored with glass ionomer cement (GI) and sound tooth slabs (ST); and (2) Dentifrice at 2 levels, F dentifrice (FD) and non-F dentifrice (NF). The effect of the factors on the response variables was evaluated: hardness loss area (?S) (quantitative assessment) and light polarized microscopy (qualitative), concerning enamel and dentine, individually. The experimental groups obtained from the association of those factors were assigned to the volunteers. In each experimental phase, volunteers used a palatal device loaded with two dental slabs from each treatment group, using FD or NF depending on the experimental phase. Volunteers (n=07) were considered experimental units for all variables being studied. Biofilm was allowed to accumulate on the slabs, and a high cariogenic challenge was provided by exposing the biofilm/slab sets to a 20 % sucrose solution 8 times/day extra-orally. After each experimental phase was evaluated the integrated area of hardness loss as a function of lesion depth (?S) in enamel and dentine by cross-sectional microhardness, and demineralization was observed by light polarized microscopy. After statistical analysis (ANOVA and Tukey test), for both dental substrates no significant interaction between the factors was found (p>0.05). Also, for enamel and dentin FD provided lower demineralization than NF (p<0.05). For material treatment, higher enamel demineralization was found for ST compared to GI (p<0.01), but no differences were found between GI and ST in dentin substrate (p>0.05). By PLM was observed that the largest percentage of apparent demineralization occurred in NF+ST group (64.28%) and GI+NF (50%), and lowest apparent demineralization percentage occurred in GI+FD (28.57%) followed by ST+FD (42.85%). In concluded, fluoride dentifrice showed lower demineralization areas, and anticaries effect of FD was proven under all conditions studied. And, the association of conventional glass ionomer cement with fluoride dentifrice led to a lower percentage of apparent demineralization lesions in images of polarized light microscopy. Independent of dentifrice, glass-ionomer restorations showed anticaries effect on enamel / Mestrado / Dentística / Mestre em Clínica Odontológica

Indiana University-Purdue University Indianapolis (IUPUI) / Erosive tooth wear (ETW) is a growing dental condition often associated with aging. This in-vitro project comprised three studies aiming to investigate the impact of tooth age on ETW susceptibility and prevention. In the first study, un-identified extracted premolars were collected and had their ages estimated using validated dental forensic methods. The premolars were examined to investigate the relationship between age and presence and severity of ETW, as well as other main dental-hard tissues conditions. ETW, dental caries, fluorosis, extrinsic staining and tooth color were evaluated using established clinical indices. In the second study, the tooth age impact on ETW susceptibility and response to preventive treatments (Sn+F, NaF, and de-ionized water control) were evaluated using representative samples from the initial study. Enamel and dentin specimens were prepared and subjected to daily erosion-treatmentremineralization cycling procedure. Surface loss (SL) was determined during and after the cycling, by optical profilometry. Similar protocol was adopted in the third study with the addition of toothbrushing abrasion to the model, in order to explore the interplay between age and toothpaste abrasivity on erosion-abrasion development. SL was measured during and after the erosion-toothbrushing-remineralization cycling. The relationships between age and the investigated variables were assessed using linear regression models. In conclusion: 1. The presence and severity of ETW, dental caries, and extrinsic staining increased with age, while of enamel fluorosis decreased. Tooth also showed to be darker with age. 2. Susceptibility of enamel and dentin to demineralization increased with age. Sn+F showed the highest anti-erosive efficacy, and was not affected by age. NaF showed lower efficacy on dentin, which increased with age. 3. Enamel and dentin SL increased with toothpaste abrasivity level. Dentin SL also increased with age. Age effect on enamel SL was observed only with low abrasive toothpaste. Age-related changes on enamel and dentin affected ETW development. / 2020-05-17

Incipient caries lesions or white spot lesions are one of the most common clinical problems resulting from orthodontic treatment with fixed appliances. Literature has shown that infrared photothermal radiometry and modulated luminescence (PTR-LUM), used by The Canary System for caries detection, is capable of monitoring artificially created carious lesions and their evolution during demineralization. Recently, a water-based calcium aluminate glass ionomer luting cement, Ceramir, has shown bioactive surface apatite formation that may influence local remineralization. This in vitro study’s objective was to evaluate effects of bioactive cement on enamel demineralization around orthodontic brackets compared to composite resin cement. A sample of 32 caries-free extracted human teeth was collected under an IRB-exempt protocol. Orthodontic brackets were cemented to each tooth with either Transbond XT or Ceramir. A 3x3 mm window adjacent to the bracket was created with acid-resistant varnish f / Oral Biology

Indiana University-Purdue University Indianapolis (IUPUI) / Fluoride prevents caries by decreasing demineralization and promoting remineralization of enamel crystals during lesion formation and progression. The chemical, morphological, and histologic characteristics of teeth with fluorosis may alter the response of enamel to fluoride during the caries process. However, the effectiveness of fluoride in fluorosed teeth has not been thoroughly studied. Therefore, the current study utilized an in-vitro net remineralization model to study differences between fluorosed and sound enamel with regards to caries lesion remineralization and progression. Hypotheses: There is no significant difference in the effectiveness of fluoride to enhance caries lesion remineralization between fluorosed and non-fluorosed (sound) teeth after changes in enamel fluorescence relative to the lesion baseline. Objectives: The primary objective is to investigate the relative fluoride response of caries lesions created in sound and fluorosed teeth of varying severities under remineralizing conditions in vitro. Secondary objectives: a) To investigate the impact of the presence and severity of enamel fluorosis on caries lesion formation, and b) To investigate the acquired acid resistance of pH-cycled lesions relative to their fluorosis severity. Materials and Methods: Three hundred sixty (360) extracted human molars (sound and fluorosed) were collected and divided into four main groups based on their TF score (0; 1; 2; 3), with sample size of n = 45 per group. Each group was divided into two subgroups: no fluoride/placebo and fluoride/treatment. Artificial caries lesions were created on the teeth and pH-cycled for 20 days using a net remineralization model. The lesions were assessed to determine differences in acquired acid resistance. Quantitative light-induced fluorescence (QLF) was used throughout the study to determine changes in enamel fluorescence relative to a sound enamel window, thereby providing information about enamel de- or remineralization. The results of this study demonstrated that enamel fluorosis levels had a significant effect on lesion remineralization after pH cycling (p > 0.05). The teeth with moderate dental fluorosis had a significantly better response to remineralization and more resistance to a subsequent acid challenge than sound teeth in the presence of fluoride. / indefinitely.

[pt] A partir dos anos 70 constatou-se a formação de uma massa aderida às paredes do canal radicular, após a instrumentação, que foi denominada smear layer. Esta camada é composta de material orgânico e inorgânico, tecido pulpar e bactérias, e contribui para obliterar os túbulos dentinários. A remoção desta camada melhora a adaptação entre o material obturador e as paredes dentinárias, elimina bactérias, limpa e alarga os túbulos. Essa remoção é realizada por soluções quelantes, mas a substância e o tempo ideais permanecem desconhecidos. Os quelantes atuam removendo Cálcio da microestrutura dentinária. No presente estudo, foi analisado o poder quelante de MTAD, HEBP e EDTA sobre a dentina coronária, avaliando a fração de área tubular aberta (AreaP) e a massa de Cálcio quelado (MNC (Ca)). Três hipóteses foram propostas e testadas: Não existe diferença entre os quelantes quanto a AreaP (H1) e quanto a MNC(Ca) (H2); existe correlação entre AreaP e MNC(Ca) (H3). Através de Microscopia Óptica Co-localizada (MCL) foram capturadas imagens de vários campos de cada amostra, em diferentes tempos de ataque ácido. Uma seqüência de processamento e análise de imagens foi utilizada para medir AreaP versus tempo, para cada quelante. Esta análise foi complementada qualitativamente com Microscopia Eletrônica de Varredura (MEV). As medidas de MNC(Ca) foram realizadas por Espectroscopia de Absorção Atômica (AA) sobre as soluções quelantes utilizadas no experimento de MCL. H1 foi negada, com MTAD sendo o mais potente e HEBP o menos potente dos quelantes. Os resultados de MEV corroboram os resultados de MCL. Os resultados de AA apresentaram grande dispersão, mas indicam que H2 é falsa. H3 foi rejeitada. / [en] In the 70's it was discovered that after instrumentation of the root canal there was the formation of a smear layer, attached to the walls of the canal. This layer is composed of organic and inorganic material, pulp tissue and bacteria, and contributes to the obliteration of the dentine tubules. The removal of this layer improves the adaptation of the filling material to the dentine walls, eliminates bacteria, cleans and enlarges the tubules. Smear layer removal is achieved through the use of chelators but the ideal substance and application time remain unknown. Chelators act through the removal of Calcium from the dentine microstructure. In the present study, the chelating power of MTAD, HEBP and EDTA on coronal dentine was analyzed through the measurement of the area fraction of open tubules (AreaP) and of the chelated Calcium mass (MNC(Ca)). Three hypotheses were proposed and tested: There is no difference between chelators regarding AreaP (H1) and regarding MNC(Ca) (H2); there is correlation between AreaP and MNC(Ca) (H3). Images of several fields of each sample, for different chelation times, were acquired through Co-Site Optical Microscopy (CSOM). An image processing and analysis sequence was employed to measure AreaP versus time, for each chelator. This analysis was qualitatively complemented by Scanning Electron Microscopy (SEM). Measurements of MNC(Ca) were obtained by Atomic Absorption Spectroscopy (AA) from the chelator solutions used during the CSOM experiments. H1 was denied, with MTAD found to be the most powerful chelator while HEBP was the weakest. SEM results corroborate these findings. AA results showed wide dispersion but indicate that H2 is false. H3 was rejected.

O objetivo geral deste estudo foi avaliar o efeito do íon ferro na inibição da erosão de dentes bovino e humano provocada por bebidas ácidas, em estudos in vitro e in situ. O estudo foi realizado em três etapas. No 1° subprojeto, foi avaliado, in vitro, o efeito de concentrações crescentes de ferro na dissolução do pó de esmalte bovino, quando adicionado à Coca-Cola® e à Sprite Zero®. A concentração de ferro, para a qual foi observada inibição de perda de fósforo, foi utilizada nos experimentos seguintes. Para se determinar a quantidade de esmalte dissolvido foi analisado o fósforo por método colorimétrico. Os dados foram analisados por ANOVA e teste de Tukey (p<0,05). No 2º subprojeto (in vitro), blocos de esmalte bovino foram expostos a 4 ciclos de desmineralização em Coca-Cola®, contendo ou não 10 mmol/L de ferro (experimental e controle, respectivamente). Cada ciclo de desmineralização foi seguido por um ciclo de remineralização em saliva artificial. O 3º subprojeto foi constituído por um estudo in situ, cruzado, no qual 10 voluntários utilizaram dispositivos palatinos, contendo 2 blocos de esmalte e 2 de dentina humanos durante 2 fases de 5 dias cada. A diferença entre estas fases foi a adição ou não de ferro a 10 mmol/L ao refrigerante tipo cola, antes da imersão do dispositivo na mesma. Os voluntários imergiram os dispositivos por 5 minutos em 150 mL de Coca-Cola®, contendo ou não ferro, 4 vezes ao dia. O efeito do ferro na inibição da erosão, tanto do 2º como do 3º subprojetos, foi avaliado pela %PDS e análise de desgaste. Os dados foram analisados usando teste t (p<0,05). Resultados: Subprojeto 1- quando ferro a 30 e 60 mmol/L foi adicionado à Coca-Cola®, uma redução na dissolução do pó de esmalte foi observada quando comparado ao controle (11 e 17%, respectivamente), enquanto concentrações menores não tiveram nenhum efeito. Com relação à Sprite Zero®, concentrações de ferro acima de 10 mmol/L não tiveram efeito significativo, enquanto concentrações maiores aumentaram significativamente a dissolução do pó de esmalte. Subprojeto 2- O ferro a 10 mmol/L reduziu significativamente o desgaste, mas aumentou significativamente a %PDS dos blocos de esmalte submetidos à erosão in vitro pela Coca-Cola®. Subprojeto 3- Para o esmalte, houve uma redução significativa no desgaste e uma redução não significativa na %PDS, quando o ferro foi utilizado foi diminuída, embora não significativamente. Para a dentina, houve redução significativa no desgaste e aumento significativo na %PDS quando da utilização do ferro. Assim, concluiu-se que o íon ferro pode reduzir a erosão de dentes bovino e humano provocada por bebidas ácidas, sendo esta ação dependente do tipo de ácido presente na bebida. / The general aim of this study was to evaluate the effect of iron ion on inhibition of the erosion of bovine and human teeth submitted to acidic drinks, using in vitro and in situ protocols. The study was conducted in 3 steps. At the first subproject, it was evaluated, in vitro, the effect of increasing iron concentrations on the dissolution of bovine enamel powder when added to Coke® or Sprite Zero®. The iron concentration for which an inhibition of enamel dissolution was observed was used in the subsequent experiments. The average concentration of phosphate released was analysed spectrophotometrically. Data were analyzed using ANOVA and Tukey?s test (p<0.05). In the second subproject, 24 specimens of bovine enamel were randomly assigned to 2 groups (experimental and control). They were exposed in vitro to 4 cycles of demineralization in Coke® containing or not 10 mmol/L of iron (experimental and control groups, respectively). Each demineralization cycle was followed by a remineralization cycle in artificial saliva. As for the third subproject, in an in situ crossover protocol, 10 volunteers wore palatal devices containing human 2 enamel and 2 dentin blocks during two 5-day crossover phases. The difference between these phases was the addition or not of iron at 10 mmol/L in Coke® before the immersion of the devices. The volunteers immersed the devices for 5 minutes in 150 mL of cola drink, containing or not iron, 4 times per day. The effect of iron on the inhibition of erosion in subprojects 2 and 3 was evaluated by %SMH and wear analysis. Data were analyzed using t test (p<0.05). Results: Subproject 1 - when iron at 30 and 60 mmol/L was added to Coke®, a significant reduction in the dissolution of powdered enamel was observed when compared to control (11 and 17%, respectively), while lowering iron concentrations did not have any effect on enamel powder dissolution. Regarding Sprite Zero®, iron concentrations up to 10 mmol/L had no significant effect, while higher concentrations significantly increased enamel powder dissolution. Subproject 2- Iron at 10 mmol/L significantly reduced the wear, but significantly increased the %SMH of enamel blocks submitted to in vitro erosion by Coke®. Subproject 3- For enamel, when iron was used, a significant reduction in the wear and a non-significant reduction in the %SMH were observed. For dentin, the use of iron significantly reduced the wear but significantly enhanced the %SMH. Hence, we concluded that iron ion may reduce the erosion of bovine and human teeth caused by acidic drinks, depending on the type of acid present in the beverage.

Dentre as estratégias de tratamento de lesões incipientes de cárie, no estágio de mancha branca ativa, o infiltrante resinoso tem sido empregado, preenchendo os poros do esmalte e impedindo a sua progressão. O objetivo deste trabalho foi avaliar o efeito do infiltrante de cárie (Icon®) sobre lesões cariosas artificiais produzidas por diferentes protocolos e a eficiência deste tratamento após novo desafio ácido por modelos experimentais in vitro e in situ, utilizando a microdureza de superfície (MS) e longitudinal (ML). Na fase in vitro, lesões cariosas artificiais foram produzidas em 45 espécimes de esmalte bovino (6x4mm) através de três diferentes protocolos (ciclagem DES-RE, gel MC e solução MHDP). Os espécimes foram tratados com o infiltrante e submetidos a novo desafio ácido por ciclagem DES-RE. Este delineamento resultou em 4 condições em um mesmo espécime: hígida (H), após a desmineralização (D), após o tratamento com o infiltrante (I) e após o novo desafio ácido (N). Na fase in situ, 15 voluntários usaram dispositivos palatinos contendo dois espécimes por 14 dias, induzindo a lesão por meio de gotejamento de solução de sacarose 8x/dia. Nas duas fases, a MS e ML foram avaliadas em todas as condições dos espécimes até 220&#x3BC;m. Os dados foram coletados e processados pela porcentagem da diferença com os valores iniciais da condição hígida para serem analisados estatisticamente de acordo com ANOVA (medidas repetidas) e teste de Tukey (p<0,05). No estudo in vitro e in situ todos os protocolos de desmineralização foram capazes de produzir lesões de cárie de subsuperfície. Todos os protocolos in vitro promoveram perda de dureza de superfície maior que 75%, enquanto o protocolo in situ promoveu quase 40%. Há uma redução da perda de dureza à medida que a profundidade aumenta em todos os casos, sendo as particularidades mais observadas até 50 &#x3BC;m. O infiltrante avaliado em todas as condições foi capaz de re-equilibrar parcialmente a dureza interna, entretanto sua resistência e efeito após o novo desafio ácido apresentou-se limitado. / Among the strategies for early caries lesions treatment as active white spot, the resin infiltrant has been employed filling the enamel pores and preventing their progression. The aim of this study was to evaluate the effect of caries infiltrant (Icon®) on artificial carious lesions produced by different protocols, and the efficiency of this treatment after new challenge acid by in vitro and in situ experimental models, using the surface microhardness (SH) and cross-sectional microhardness (CSH). In the in vitro phase, artificial carious lesions were performed on 45 enamel bovine specimens (6x4mm) by three different protocols (DE-RE cycling, MC gel and MHDP solution). The specimens were treated with the infiltrant and subjected to a new challenge by DE-RE cycling. This design resulted in four conditions at the same specimen: sound (S), after demineralization (D), after the treatment with infiltrant (I) and after the new acid challenge (N). In the in situ phase, 15 volunteers wore intraoral appliances containing two specimens for 14 days, inducing the lesion formation by sucrose solution dripping 8x/day. In both models, SH and CSH were evaluated in all conditions of the specimens up to 220&#x3BC;m. Data were collected and processed as percentage from the difference to each condition compared to sound stage to be statistically analyzed with ANOVA (repeated measures) and Tukey test (p <0.05). For all tested conditions, demineralization protocols were able to produce subsurface carious lesions. All in vitro protocols promoted hardness loss higher than 75% while in situ protocol promoted almost 40%. There is a reduction in the hardness loss as the depth increases, in which the main differences can be noticed up to 50&#x3BC;m. The infiltrant evaluated in all conditions was able to partially re-balance the internal hardness, however its strength and effect after the new challenge acid had been limited.

Embora se aceite que as lesões cervicais não cariosas tenham uma etiologia multifatorial, as contribuições relativas dos vários agentes etiológicos permanecem obscuras. O presente estudo propõe um modelo que simula a formação de lesões não cariosas em laboratório e estuda a influência específica de cada tipo de tensão no dano provocado ao esmalte e/ou à dentina. A face vestibular de incisivos bovinos foi cortada em forma de palito com 18 mm x 3 mm x 3 mm. Cada palito recebeu um entalhe na região cervical da parede voltada para a polpa, com o objetivo de direcionar a concentração de tensões para a junção esmalte-dentina. Os corpos de prova (n=108) protegidos com verniz ácido resistente, exceto numa faixa de 1,5 x 18 mm da superfície vestibular, foram divididos em dois grupos, um imerso em solução de ácido acético pH 4,5 e o outro imerso em água destilada. Cada grupo foi dividido em três subgrupos (n=18), dos quais, dois deles sofreram carregamento estático de 800gf em dobramento, um para provocar tração e outro para compressão na região da junção esmalte-cemento, e o terceiro não foi submetido a carregamento. Após 72h de ensaio os palitos foram lavados, desidratados e embebidos em resina acrílica. Em cada grupo de 18 espécimes, 06 foram cortados no sentido longitudinal e 12 no sentido transversal do palito, obtendo-se lamelas de 0,05 mm. As lamelas foram fotografadas em microscópio de luz, e foi medida a profundidade de perda e/ou desmineralização de dentina e esmalte. Os dados obtidos foram submetidos à análise de variância ANOVA, seguida pelo teste de Tukey com 5% de significância. Para comparações entre diferentes regiões do mesmo corpo de prova, foi utilizado o teste t pareado. Foi avaliada também a ocorrência de trincas e fraturas. Não foram encontrados danos nas lamelas dos palitos imersos em água destilada. Nos espécimes seccionados transversalmente a profundidade de desmineralização do esmalte sob tração foi de 158±18m, significativamente maior que a dos demais grupos (138±21m para sem carga e 129±16m para compressão). A profundidade de desmineralização e perda de dentina nos palitos submetidos à tração foi 186±23m, seguidos de 160±20m nos palitos sem carga e 140±27m nos palitos sob compressão. Nos cortes longitudinais foram realizadas medidas da profundidade de desmineralização do esmalte em três pontos: na junção esmalte-dentina (E1), a 3,5 mm (E2) e a 7,0 mm (E3) desta junção. A profundidade de desmineralização do esmalte nos espécimes sob tração foi significativamente maior na região cervical (E1) que nas demais regiões. Para os corpos de prova que sofreram compressão, as regiões E1 e E2 não apresentaram diferença significativa entre si, porém a região E3 teve desmineralização significantemente menor às outras. Nos corpos de prova sem tensão só houve diferença significativa entre os dois extremos (E1 e E3). Foram observadas trincas e fraturas no esmalte cervical apenas nos espécimes submetidos à tração. Parece lícito concluir que a tensão influi na ação do ácido sobre os tecidos dentários, sendo que a tração aumenta significativamente os danos e a compressão tende a reduzi-los. / Although it is accepted that non-carious cervical lesions have a multifactorial etiology, the relative contributions of several etiological agents remain unclear. This study proposes a model which simulates the formation of non-carious lesions in laboratory and studies the specific influence of each kind of tension in the damage caused to the enamel and/or the dentin. The buccal surface of bovine incisor was cut in the stick form measuring 18mm x 3mm x 3mm. Each stick received a groove in the cervical region of the wall facing the pulp aiming to guide the tension concentration to the dentin-enamel junction. The specimens (n=108) protected with resistant acid varnish, except in a 1.5mm x 18mm labial surface range, were divided into two groups, one immersed in acetic acid solution pH 4.5 and the other in distilled water. Each group was divided into three subgroups (n = 18), in which, two of them suffered 800gf static load on folding, one for tensile and the other for compression in the enamel-cement junction region, and the third did not suffer loading. 72h after the trial, the sticks were washed, dehydrated and embedded in acrylic resin. In each group of 18 specimens, 06 were cut in the longitudinal direction and 12 in the transversal one of the stick, getting 0.05mm lamellae. The lamellae were photographed in light microscope, and the depth of loss and/or demineralization of enamel and dentin was measured. Te data were analyzed by ANOVA variance, followed by the Tukey test with 5% significance. For comparisons between different regions of the same specimen, the paired t test was used. It was also evaluated the occurrence of cracks and fractures. No damages were found in the lamellae sticks immersed in distilled water. In specimens cut transversely, the depth of enamel demineralization under tensile was 158±18m, significantly higher than the other groups (138±21m for unloaded and 129±16m for compression). The depth of demineralization and dentin loss in sticks submitted for tensile was 186±23m, followed by 160±20m for the unloaded sticks and 140±27m for the sticks under compression. In the longitudinal cut, measures of the enamel demineralization depth were made in three points: the enamel-dentin junction (E1), 3.5 mm (E2) and 7.0 mm (E3) of this junction. The enamel demineralization depth in specimens under tensile was significantly higher in the cervical region (E1) than in other regions. For the specimens that suffered compression, the regions E1 and E2 did not show significant difference between themselves, but the E3 region showed demineralization significantly lower than the others. In specimens without tension, there was only significant difference between the two extremes (E1 and E3). Cracks and fractures in the cervical enamel were observed specimens only in the specimens under tensile. It seems reasonable to conclude that tension influences in the acid action on the dental tissues, and that tensile increases significantly the damage and compression tends to reduce them.