Carga bacteriana de dentes humanos e efeito da radiação gama sobre o esmalte dental

Orientador : Marines Nobre dos Santos UchoaDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Odontologia de PiracicabaResumo: A radiação gama é letal para microrganismos e parece não causar mudanças morfológicas na superficie do esmalte, sendo uma alternativa para a esterilização dental. No entanto, os dados da literatura não são conclusivos em estabelecer uma dose mínima de radiação gama eficaz para esterilização de dentes humanos armazenados em solução salina fisiológica, já que nas pesquisas que sugerem esta dose não foi executado o processo de validação da eficácia esterilizante da referida dose. Por conseguinte, o presente trabalho se propôs, através de um estudo in vitro, a determinar a carga bacteriana de dentes armazenados em solução salina para posterior escolha da dose de radiação gama capaz de esterilizá-Ios. Este trabalho objetivou também, analisar o efeito da dose de 25 kGy sobre a microdureza de superficie e resistência do esmalte dental humano ao desenvolvimento de cárie in vitro quando submetido a um modelo de ciclagem de desmineralização-remineralização. O estudo consistiu de três fases. Na primeira, foi determinada a carga microbiana em 20 terceiros molares procedentes de três clínicas diferentes e estocados em solução salina estéril. Na segunda fase, 30 metades dentais foram irradiadas, com a dose hospitalar (25 kGy) e outras 30 foram reservadas como controle. Após a irradiação, o grupo irradiado bem como o controle tiveram sua microdureza de superficie mensurada. Na terceira fase, o efeito da radiação gama foi determinado em blocos de esmalte dental planificados e não planificados após os mesmos terem sido submetidos a um modelo de ciclagem de pH. A partir dos valores de microdureza em corte longitudinal do esmalte, foi calculada a perda mineral para cada grupo. Os dados das fases I, II e lII foram analisados respectivamente pelos testes ANOVA, t de Student e por ANOVA e teste de Tukey (nível de significância de 5%). Os resultados mostraram médias de contaminação bacteriana de 5,60 x 106 ±3,10 x 106a para a clínica A; 6,70 x 106 ±1,48 X 106a para a clínica B e 5,74 x 1061: 2,08 X 106a para a C. A média de unidades formadoras de colônia por unidade dentária foi de 5,8 x 106. As médias de dureza de superficie dos grupos controle e irradiado foram respectivamente, 338,35 ±20,11a e 340,76 ±21,68a. As perdas minerais mensuradas nos grupos: não planificado controle; não planificado irradiado; planificado controle e planificado irradiado, foram 547,9 ±135,9a; 425,0 ±171,9a; 909,5 ± 405,5b e 1106,5 ± 343,3b respectivamente. Estes resultados demonstraram que dentes humanos armazenados em solução salina apresentam uma alta carga bacteriana exigindo para sua esterilização uma dose de radiação gama igual ou superior a dose de 25 kGy. Adicionalmente, tal dose alterou a coloração da estrutura dental porém, não interferiu na microdureza de superficie e nem na resistência à produção de cárie in vitro do esmalte dental humanoAbstract: The gamma radiation is lethal for microorganisms and seems not to cause morphologic changes in the enamel's surface, being an alternative for the dental sterilization. However, the data of the literature are not conclusive in establishing an effective minimum dose for sterilization of human teeth stored in physiologic saline solution, since the sterilizing efficacy of this dose has not been validated. Consequently, the purpose of this study was, firstly, to perform an in vitro study to determine the bioburden of teeth stored in saline solution for subsequent choice of gamma radiation minimum dose able to sterilize human unerupted third molars stored in 0,9% NaCI solution. Secondly, analyze the effect of a 25 kGy dose on human dental enamel microhardness, and thirdly, analyze the resistance of irradiated enamel to the development of in vitro caries-like lesion when submitted the a pH cycling model. The study was divided into three phases. In the first one, the bioburden was determined in twenty third molars stored in sterile saline solution. In the second phase, thirty dental halves were irradiated with a hospital dose (25 kGy) and the other 30 halves were reserved as control. Afier irradiation, the irradiated as well as the control group were submitted to microhardness analysis to determine the enamel surface microhardness. In the third phase, the effect of gamma irradiation was determined in abraded and unabraded human dental enamel blocks afier being submitted to a pH-cyc1ing model. Mineralloss values were calculated from cross-sectional microhardness. The data of phases I, II and lII were analysed respectively by ANOVA, t Student test, and by ANOVA and Tukey's test (at 5% level of significance). The results showed that bioburden means was 5,60 x 106 ±3,10 x 3 106a for clinic A; 6,70 x 106 ±1,48 x 106a for clinic B and 5,74 x 106 ± 2,08 X 106a for clinic C. The mean of units forming coIony for teeth unit was 5,8 x 106, The means of surface enameI microhardness for the groups controI and irradiated were respectively, 338,35 ± 20,11a and 340,76 ± 21,68a. The mineral Iosses measured in the groups: unabraded controI; unabraded irradiated; abraded controI and abraded irradiated were 547 ,9 ± 135,9a; 425,0 ±171,9a; 909,5 ± 405,5b and 1106,5 ± 343,3b respectiveIy. These results demonstrated that human teeth stored in saline solution presented a high bioburden demanding a dose equal or higher than 25 kGy for their sterilization. In addition, this dose changed the teeth coloration, however, had no effect on the enamel surface microhardness, neither on enamel resistance to the development of in vitro caries-like lesionMestradoCariologiaMestre em Odontologi

Influência da solução de armazenagem na desmineralização do esmalte submetido à ciclagem de pH

Extracted human teeth are frequently used for research or educational purposes. Therefore, it is necessary to store them in disinfectant solutions that do not alter dental structures. Thus, this study evaluated the influence of storage solution on enamel demineralization. For that purpose, sixty samples were divided into the following groups: enamel stored in formaldehyde (F1), stored in thymol (T1), stored in formaldehyde and submitted to pH cycling (F2), stored in thymol and submitted to pH cycling (T2). All samples were evaluated by cross-sectional microhardness analysis and had their percentage of mineral volume versus micrometer (integrated area) determined. Differences between groups were found up to 30-µm depth from the enamel surface (p < 0.05), where samples from group T2 were more demineralized. It was concluded that the storage solution influenced the reaction of a dental substrate to a cariogenic challenge, suggesting that formaldehyde may increase enamel resistance to demineralization, when compared to demineralization occurring in enamel stored in thymol solution.Dentes humanos extraídos são freqüentemente utilizados para propósitos educacionais ou de pesquisa. Desta forma, é necessário o armazenamento dos mesmos em soluções desinfetantes que não alterem a estrutura dental. Para tanto, sessenta espécimes foram divididos nos seguintes grupos: esmalte armazenado em formol (F1), armazenado em timol (T1), armazenado em formol e submetido à ciclagem de pH (F2) e armazenado em timol e submetido à ciclagem de pH (T2), sendo avaliados por meio de análise de microdureza longitudinal e tiveram a porcentagem de volume mineral pro micrômetro determinada. Diferenças entre os grupos foram encontradas até a profundidade de 30µm da superfície do esmalte (

Erosive Effect of Analgesics on Primary Tooth Enamel - An in Vitro Study

Objective:&nbsp;To evaluate in vitro erosive effect of analgesics on primary tooth enamel.&nbsp;Material and Methods:&nbsp;The pH and the titratable acidity measurements of the medicines were performed in triplicate using a digital pH meter. Enamel slabs of primary teeth flat and polished were selected by initial surface microhardness analysis. Medications were selected and specimens were assigned into five groups (n=12): Dalsy; Magnopyrol; Paracetamol; Tylenol; and distilled water (negative control). Specimens were immersed in 5 ml of each group solution for 30 min, 4x/day for three days and stored in artificial saliva at 37 °C between immersions and at night. Final microhardness was determined. The data were submitted to One-way ANOVA and Tukey's test. Scanning electron microscopy (SEM) analysis was performed in three specimens of each group.&nbsp;Results:&nbsp;Medicines showed acidic pH and mean values of titratable acidity ranged from 1.46 to 11.66 ml of 0.1N NaOH. The mineral loss of Magnopyrol was statistically significant in relation to the control group (p&lt;0.01). Magnopyrol showed higher values when compared to Tylenol (p&lt;0.05). SEM images displayed microstructure alterations in the Paracetamol group.&nbsp;Conclusion:&nbsp;Despite the low pH values, only Magnopyrol showed greater enamel softening. Paracetamol demonstrated morphological changes in primary tooth enamel

Influence of environmental conditions on properties of ionomeric and resin sealant materials

OBJECTIVES: The aim of this study was to determine the effect of environmental conditions on the degradation of ionomeric and resin sealant materials. MATERIAL AND METHODS: FluroShield, Vitremer, and Ketac Molar disc-shaped specimens (n=18/material) were prepared, polished, subjected to initial hardness and roughness readings. Six discs of each material were randomly assigned to one of three different storage solutions: 0.3% citric acid (CA), demineralization solution (DE), and remineralization solution (RE). The specimens were individually immersed in 3 mL of the test solutions, which were daily changed. After 15 days of storage, new surface roughness and hardness readings were done. Fluoride release in the solutions was measured within 15 days. Data were analyzed by ANOVA and Tukey's and Contrast tests (&#945;=0.05). RESULTS: The storage in CA increased the roughness of Vitremer and Ketac Molar. A significant reduction in hardness was observed for all materials after storage in all solutions. For all materials, the greatest amounts of fluoride release occurred during the 1st day. FluroShield presented the same patterns of fluoride release in all solutions. Ketac Molar and Vitremer released the highest amounts of fluoride in the CA solution. CONCLUSIONS: Ionomeric materials are more susceptible to degradation than resin-based materials under acidic conditions. Acidic conditions lead to a higher fluoride release from ionomeric materials

Chitosan microparticles loaded with essential oils inhibit duo-biofilms of Candida albicans and Streptococcus mutans

Oral candidiasis is a common fungal infection that affects the oral mucosa, and happens when Candida albicans interacts with bacteria in the oral microbiota, such as Streptococcus mutans, causing severe early childhood caries. C. albicans and S. mutans mixed biofilms are challenging to treat with conventional antimicrobial therapies, thus, new anti-infective drugs are required. Objective: This study aimed to test a drug delivery system based on chitosan microparticles loaded with geranium and lemongrass essential oils to inhibit C. albicans and S. mutans mixed biofilms. Methodology: Chitosan microparticles loaded with essential oils (CM-EOs) were obtained by spray-drying. Susceptibility of planktonic were performed according CLSI at 4 to 2,048 µg/mL. Mixed biofilms were incubated at 37ºC for 48 h and exposed to CM-EOs at 256 to 4,096 µg/mL. The antimicrobial effect was evaluated using the MTT assay, with biofilm architectural changes analyzed by scanning electron microscopy. RAW 264.7 cell was used to evaluate compound cytotoxicity. Results: CM-EOs had better planktonic activity against C. albicans than S. mutans. All samples reduced the metabolic activity of mixed C. albicans and S. mutans biofilms, with encapsulated oils showing better activity than raw chitosan or oils. The microparticles reduced the biofilm on the slides. The essential oils showed cytotoxic effects against RAW 264.7 cells, but encapsulation into chitosan microparticles decreased their toxicity. Conclusion: This study demonstrates that chitosan loaded with essential oils may provide an alternative method for treating diseases caused by C. albicans and S. mutans mixed biofilm, such as dental caries

Chitosan microparticles loaded with essential oils inhibit duo-biofilms of Candida albicans and Streptococcus mutans

Abstract Oral candidiasis is a common fungal infection that affects the oral mucosa, and happens when Candida albicans interacts with bacteria in the oral microbiota, such as Streptococcus mutans, causing severe early childhood caries. C. albicans and S. mutans mixed biofilms are challenging to treat with conventional antimicrobial therapies, thus, new anti-infective drugs are required. Objective This study aimed to test a drug delivery system based on chitosan microparticles loaded with geranium and lemongrass essential oils to inhibit C. albicans and S. mutans mixed biofilms. Methodology Chitosan microparticles loaded with essential oils (CM-EOs) were obtained by spray-drying. Susceptibility of planktonic were performed according CLSI at 4 to 2,048 µg/mL. Mixed biofilms were incubated at 37ºC for 48 h and exposed to CM-EOs at 256 to 4,096 µg/mL. The antimicrobial effect was evaluated using the MTT assay, with biofilm architectural changes analyzed by scanning electron microscopy. RAW 264.7 cell was used to evaluate compound cytotoxicity. Results CM-EOs had better planktonic activity against C. albicans than S. mutans. All samples reduced the metabolic activity of mixed C. albicans and S. mutans biofilms, with encapsulated oils showing better activity than raw chitosan or oils. The microparticles reduced the biofilm on the slides. The essential oils showed cytotoxic effects against RAW 264.7 cells, but encapsulation into chitosan microparticles decreased their toxicity. Conclusion This study demonstrates that chitosan loaded with essential oils may provide an alternative method for treating diseases caused by C. albicans and S. mutans mixed biofilm, such as dental caries

The use of CO2 laser in dental caries prevention

Orientador: Marines Nobre dos Santos UchoaTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Odontologia de PiracicabaResumo: A irradiação do esmalte dental com laser de CO2, especialmente se associada ao flúor, aumenta a resistência deste substrato ao desafio ácido. Deste modo, esta tese, constituída por 3 artigos, teve por objetivos: (1) descrever as características do laser de CO2 e revisar a literatura disponível enfocando seus efeitos na prevenção de cárie em esmalte e dentina, bem como discutir os efeitos deste mesmo laser quando associado ao flúor; (2) investigar, in vitro, o efeito do laser de CO2 (? = 10,6 µm), com duas densidades de energia, na inibição da desmineralização ao redor de restaurações de resina composta; (3) avaliar in situ os efeitos combinados de um TEA (Transversely Excited Atmospheric-pressure) laser de CO2 (? = 9,6 µm) e do dentifrício fluoretado na desmineralização do esmalte dental humano. No estudo 1, a literatura científica pertinente ao assunto foi pesquisada usando a base de dados medline e busca manual de referências citadas em artigos científicos. No estudo 2, preparos cavitários realizados com ponta diamantada em esmalte hígido tiveram seu ângulo cavo-superficial irradiado com laser de CO2 com 8 ou 16 J/cm2. Através de microdureza em corte longitudinal, avaliou-se a perda mineral in vitro dos grupos experimentais e controle no esmalte ao redor da restauração. No estudo 3, foi testado in situ o efeito do laser de CO2 com 1,5 J/cm2 associado ou não à utilização de dentifrício fluoretado na prevenção de cárie dentária. Avaliou-se a perda mineral do esmalte dental humano nos grupos experimentais e controle. Os resultados dos estudos 2 e 3 foram analisados estatisticamente pelos testes ANOVA e Tukey com nível de significância fixado em 5%. A análise da literatura apresentada no artigo 1 mostrou que pode haver um futuro promissor para o laser de CO2 na prevenção de cárie dentária tendo seu efeito preventivo potencializado quando utilizado em associação a compostos fluoretados. Os resultados do artigo 2 demonstraram que o laser utilizado foi efetivo na inibição da desmineralização do esmalte ao redor de restaurações de resina composta (p < 0,05) e que o aumento da energia não potencializou o efeito do laser. No terceiro estudo, observou-se que os tratamentos com laser e/ou dentifrício fluoretado foram capazes de inibir a desmineralização do esmalte in situ, tendo sido observado o melhor resultado de inibição da desmineralização quando o laser foi associado à utilização de dentifrício fluoretado. Em conclusão, os resultados desses estudos indicam que o laser de CO2 é capaz de inibir a desmineralização do esmalte dental humano em situações de alto desafio cariogênico in vitro e in situ, apresentando efeito sinérgico quando associado ao flúorAbstract: The irradiation of dental enamel by CO2 laser, especially if combined with fluoride, increases the enamel acid resistance. Thus, this thesis, comprised by 3 manuscripts, aimed: (1) to describe the characteristics of the CO2 laser and to review the literature with regard to its effects on caries inhibition in enamel and dentin. Another aim of this review is to discuss the effects of the CO2 laser in combination with fluoride; (2) to investigate, in vitro, the effect of a carbon dioxide laser (? = 10.6 µm), with two energy densities, on the enamel inhibition of demineralization around composite restorations; (3) to assess in situ the combined effects of a 9.6 µm TEA (Transversely Excited Atmospheric-pressure) CO2 laser and fluoride dentifrice on the demineralization of human dental enamel. In study 1, the scientific literature related to the issue was searched using medline and manual tracing of references cited scientific papers. In study 2, cavity preparations performed with diamond bur on sound enamel had their cavo surface angle irradiated with CO2 laser using 8 or 16 J/cm2. In vitro mineral loss, in experimental and control groups, was evaluated in the enamel around the restoration. In manuscript 3, the in situ caries preventive effect of the CO2 laser, with 1.5 J/cm2, associated or not to fluoridated dentifrice, was tested. In the human dental enamel, mineral loss was evaluated, by cross-sectional microhardness, in experimental and control groups. The results of studies 2 and 3 were analyzed by ANOVA and Tukey test. The literature analysis presented in study 1 showed that there can be a promising future for CO2 laser in caries prevention and its preventive effect is improved when associated to fluoride products. The results of study 2 demonstrated that the laser used was effective in inhibiting enamel demineralization around the composite restorations (p < 0.05). In the third manuscript, it was observed that the treatments with laser and/or fluoridated dentifrice were able to inhibit the in situ enamel demineralization and the best demineralization inhibition result was observed when laser was combined with fluoridated dentifrice use. In conclusion, the results of these studies suggest that CO2 laser is able of inhibiting enamel demineralization, in in vitro and in situ high cariogenic challenge situations, showing synergic effect with fluorideDoutoradoCariologiaDoutor em Odontologi

Effect of chlorhexidine on the bond strength of a self-etch adhesive system to sound and demineralized dentin

This study evaluated the effect of a 2% chlorhexidine-based disinfectant (CHX) on the short-term resin-dentin bond strength of a self-etch adhesive system to human dentin with different mineral contents. Dentinal mineralization was tested at 4 levels (sound, and after 2, 4, or 8 days of demineralization-remineralization cycles) and disinfectant at 2 levels [deionized water (DW, negative control) and CHX]. Dentin demineralization induced by pH-cycling was characterized by cross-sectional hardness (CSH). Each dentin surface was divided into halves, one treated with DW and the other with CHX (5&#8197;minutes). Each surface was bonded with a self-etch adhesive system and restored. The specimens were sectioned and subjected to microtensile bond testing. CSH and microtensile bond strength (&#181;TBS) data were analyzed by regression analysis and ANOVA-Tukey tests (&#945; = 5%), respectively. The groups treated with CHX resulted in mean &#181;TBS similar to those found for the groups in which the dentin was exposed to DW (p = 0.821). However, mean &#181;TBS were strongly influenced by dentin mineralization (p < 0.05): the bond strength found for sound dentin was lower than that found for dentin cycled for 8 days, which was even lower than the bond strengths for dentin cycled for 2 or 4 days. The results suggest that the degree of dentin demineralization affects the bond strength of self-etching adhesives, but the use of CHX does not modify this effect