Efeito da adição de flúor e cálcio no gel clareador a base de peróxido de hidrogênio na penetração, cor e microdureza

The objective of this study was to evaluate the effect of adding calcium ions and fluoride in the formulation of a whitening gel 35% hydrogen peroxide in its penetration through the dental structure, whitening efficacy and surface hardness of dental enamel. 80 teeth bovine incisors were used, which were obtained enamel and dentin disks of the buccal surface with 6mm diameter and 2mm thick (1 mm of enamel and dentin 1mm). The samples were divided into four groups stratified according to the protective substance / remineralizing added to the gel of hydrogen peroxide 35%: Group Ca - Calcium gluconate 0.5%; Group F - Sodium fluoride 0.2%; Group Ca + F - Calcium gluconate 0.5% and Sodium Fluoride 0.2%; Control group - no substance was added. The initial color of the samples and the hardness of the enamel were measured before the bleaching procedures. The specimens from each group were placed on a metallic support on which there was a simulated pulp chamber, which was filled with acetate buffer to collect and stabilize the penetrated peroxide. The respective bleaching treatments were applied 3 times, total of 30 minutes of application. The amount of peroxide which passed through the samples was determined by absorbance spectrophotometry. The hardness of the samples was measured immediately after bleaching. Next, the samples were immersed in artificial saliva for 7 days, after which the final color was evaluated. Data were statistically analyzed adopting a 5% significance level

Efeito da adição de flúor e cálcio no gel clareador a base de peróxido de hidrogênio na penetração, cor e microdureza

The objective of this study was to evaluate the effect of adding calcium ions and fluoride in the formulation of a whitening gel 35% hydrogen peroxide in its penetration through the dental structure, whitening efficacy and surface hardness of dental enamel. 80 teeth bovine incisors were used, which were obtained enamel and dentin disks of the buccal surface with 6mm diameter and 2mm thick (1 mm of enamel and dentin 1mm). The samples were divided into four groups stratified according to the protective substance / remineralizing added to the gel of hydrogen peroxide 35%: Group Ca - Calcium gluconate 0.5%; Group F - Sodium fluoride 0.2%; Group Ca + F - Calcium gluconate 0.5% and Sodium Fluoride 0.2%; Control group - no substance was added. The initial color of the samples and the hardness of the enamel were measured before the bleaching procedures. The specimens from each group were placed on a metallic support on which there was a simulated pulp chamber, which was filled with acetate buffer to collect and stabilize the penetrated peroxide. The respective bleaching treatments were applied 3 times, total of 30 minutes of application. The amount of peroxide which passed through the samples was determined by absorbance spectrophotometry. The hardness of the samples was measured immediately after bleaching. Next, the samples were immersed in artificial saliva for 7 days, after which the final color was evaluated. Data were statistically analyzed adopting a 5% significance level

Argon and Nd:YAG Lasers for Caries Prevention in Enamel

Objective: The aim of this study was to investigate the effect of Nd:YAG and argon laser irradiations on enamel demineralization after two different models to induce artificial caries. Background data: It is believed that the use of the high-intensity laser on the dental structure can lead to a more acid-resistant surface. Materials and methods: Twenty-one extracted human third molars were sectioned into tooth quarters. The quarters were distributed in three groups: Group I (control), untreated; Group II, Nd:YAG laser (60 mJ, 15 pps, 47.77 J/cm(2), 30 sec); and Group III, argon laser (250mW, 12 J/cm(2), 48 sec). Tooth quarters from each group were subjected to two different demineralization models: cycle 1, a 14 day demineralization (pH 4.5; 6 h) and remineralization (pH 7.0; 18 h) solutions, 37 degrees C and cycle 2, 48 h in demineralization solution (pH 4.5). Samples were prepared in slices (60-100 mu m thick) to be evaluated under polarized light microscopy. Demineralization areas were measured (mm(2)) (n = 11). Data were analyzed by ANOVA and Tukey's test (p < 0.05). Results: Means followed by different letters are significantly different: 0.25 A (control, cycle 48 h); 0.18 AB (control, cycle 14 days); 0.17 AB (Nd:YAG, cycle 14 days); 0.14 BC (argon, cycle 48 h); 0.09 BC (Nd:YAG, cycle 48 h), and 0.06 C (argon, cycle 14 days). Conclusions: The argon laser was more effective for caries preventive treatment than Nd: YAG laser, showing a smaller demineralization area in enamel.

Photodynamic Effects of Curcumin Against Cariogenic Pathogens

Background data: The presence of Streptococcus mutans and Lactobacillus acidophilus in dental structure is an indicator of a cariogenic biofilm. Photodynamic therapy is a technique that involves the activation of photosensitizers by light in the presence of oxygen, resulting in the production of reactive radicals capable of inducing cell death. Reduction of bacteria levels can provide additional means of preventing dental caries. Objective: The present study evaluated the susceptibility of planktonic cultures of S. mutans (ATCC 25175) and L. acidophilus (ATCC-IAL-523) from the Adolfo Lutz Institute (IAL) to photodynamic therapy after sensitization with curcumin and exposure to blue light at 450 nm. Methods: Bacterial suspensions of S. mutans and L. acidophilus isolated (as single species) and combined (multspecies) were prepared and then evaluated. Four different groups were analyzed: L-D- (control group), L-D+ (drug group), L+D- (light group), and L+D+ (photodynamic therapy group). Two different concentrations of curcumin were tested (0.75 and 1.5 g/L) associated with a 5.7 J/cm(2) light emission diode. Results: Significant decreases (p < 0.05) in the viability of S. mutans were only observed when the bacterial suspensions were exposed to both curcumin and light. Then, reductions in viability of up to 99.99% were observed when using 1.5 g/L of the photosensitizer. The susceptibility of L. acidophilus was considerably lower (21% and 37.6%) for both curcumin concentrations. Conclusions: Photodynamic therapy was found to be effective in reducing S. mutans and L. acidophilus on planktonic cultures. No significant reduction was found for L-D+, proving the absence of dark toxicity of the drug.

Thermal alteration and morphological changes of sound and demineralized primary dentin after Er:YAG laser ablation

The purpose of this study was to assess the influence of Er:YAG laser pulse repetition rate on the thermal alterations occurring during laser ablation of sound and demineralized primary dentin. The morphological changes at the lased areas were examined by scanning electronic microscopy (SEM). To this end, 60 fragments of 30 sound primary molars were selected and randomly assigned to two groups (n = 30); namely A sound dentin (control) and B demineralized dentin. Each group was divided into three subgroups (n = 10) according to the employed laser frequencies: I4 Hz; II6 Hz, and III10 Hz. Specimens in group B were submitted to a pH-cycling regimen for 21 consecutive days. The irradiation was performed with a 250 mJ pulse energy in the noncontact and focused mode, in the presence of a fine water mist at 1.5 mL/min, for 15 s. The measured temperature was recorded by type K thermocouples adapted to the dentin wall relative to the pulp chamber. Three samples of each group were analyzed by SEM. The data were submitted to the nonparametric Kruskal-Wallis test and to qualitative SEM analysis. The results revealed that the temperature increase did not promote any damage to the dental structure. Data analysis demonstrated that in group A, there was a statistically significant difference among all the subgroups and the temperature rise was directly proportional to the increase in frequency. In group B, there was no difference between subgroup I and II in terms of temperature. The superficial dentin observed by SEM displayed irregularities that augmented with rising frequency, both in sound and demineralized tissues. In conclusion, temperature rise and morphological alterations are directly related to frequency increment in both demineralized and sound dentin. Microsc. Res. Tech., 2011. (c) 2011 Wiley Periodicals, Inc.

Clinical strategies for esthetic excellence in anterior tooth restorations: understanding color and composite resin selection

Direct composite resin restorations have become a viable alternative for patients that require anterior restorative procedures to be integrated to the other teeth that compose the smile, especially for presenting satisfactory esthetic results and minimum wear of the dental structure. Technological evolution along with a better understanding of the behavior of dental tissues to light incidence has allowed the development of new composite resins with better mechanical and optical properties, making possible a more artistic approach for anterior restorations. The combination of the increasing demand of patients for esthetics and the capacity to preserve the dental structure resulted in the development of different incremental techniques for restoring fractured anterior teeth in a natural way. In order to achieve esthetic excellence, dentists should understand and apply artistic and scientific principles when choosing color of restorative materials, as well as during the insertion of the composite resin. The discussion of these strategies will be divided into two papers. In this paper, the criteria for color and material selection to obtain a natural reproduction of the lost dental structures and an imperceptible restoration will be addressed.

[Dens invaginatus. Review of the literature and diagnostic and therapeutic guidelines]

Dens invaginatus is a clinically relevant malformation of teeth resulting from an infolding of enamel and dentine into the dental structure during tooth formation, hence the former denomination "dens in dente". The dens invaginatus shows multiple morphological variations of crown and root formation. This frequently leads to caries, pulpal and periodontal involvement with necrosis and loss of attachment. Therefore, early diagnosis and prevention are of utmost importance. Due to the complexity of the malformation, treatment options in former days were limited. This article presents a profound review of the literature regarding etiology, epidemiology and histology. It discusses clinical appearance and diagnosis and it provides guidelines for decision-making and treatment of invaginated teeth.

Cheek Tooth Extraction Via a Minimally Invasive Transbuccal Approach and Intradental Screw Placement in 54 Equids

OBJECTIVE: To describe (1) preoperative findings and surgical technique, (2) intraoperative difficulties, and (3) postoperative complications and long-term outcome of equine cheek tooth extraction using a minimally invasive transbuccal screw extraction (MITSE) technique. STUDY DESIGN: Retrospective case series. ANIMALS: Fifty-four equids; 50 horses, 3 ponies, and 1 mule. METHODS: Fifty-eight MITSE procedures were performed to extract cheek teeth in 54 equids. Peri- and intraoperative difficulties, as well as short- (<1 month) and long-term (>6 months) postoperative complications were recorded. Followup information was obtained through telephone interviews, making specific inquiries about nasal discharge, facial asymmetry, and findings consistent with surgical site infection. RESULTS: Preoperative findings that prompted exodontia included 50 cheek teeth with apical infections, 48 fractures, 4 neoplasia, 2 displacements, and 1 supernumerary tooth. Previous oral extraction was attempted but had failed in 55/58 (95%) animals because of cheek tooth fracture in 28, or insufficient clinical crown for extraction with forceps in 27. MITSE was successful in removing the entire targeted dental structure in 47/58 (81%) procedures. However, MITSE failed to remove the entire targeted dental structure in 11/58 (19%) procedures and was followed by repulsion in 10/11 (91%). Short-term postoperative complications included bleeding (4/58 procedures, 7%) and transient facial nerve paralysis (4/58 procedures, 7%). Owners were satisfied with the functional and cosmetic outcome for 40/41 (98%) animals with followup. CONCLUSION: MITSE offers an alternate for cheek tooth extraction in equids, where conventional oral extraction is not possible or has failed. Overall, there was low morbidity, which compares favorably with invasive buccotomy or repulsion techniques

Técnicas de alongamento coronário

Introdução: O alongamento coronário é um procedimento que pode envolver, ou não, técnicas cirúrgicas, e que tem como principal objetivo aumentar o tamanho da coroa clínica, assim como devolver a estética, a forma e a função às arcadas dentárias. Este procedimento realiza-se, ou por motivos estéticos ou motivos restauradores. Ultimamente, os motivos estéticos têm vindo a ganhar importância e são eles que, muitas da vezes, levam os pacientes às consultas de medicina dentária. O sorriso gengival é um desses motivos, e pode ser causado, entre outras razões por, uma erupção passiva alterada ou/e um excesso vertical maxilar. Estas são as etiologias que serão descritas neste trabalho. O aumento coronário realiza-se, também, quando há a necessidade de reabilitar um dente, quer seja com resinas compostas ou com coroas. Este, deve sempre respeitar os limites biológicos do periodonto, nomeadamente o espaço biológico. A invasão deste espaço pode por em risco a manutenção da saúde do periodonto e a viabilidade do tratamento a longo prazo, por isto, preconiza-se que deve ser deixado um espaço de 3mm, desde a crista óssea até a margem restauradora. As técnicas de alongamento coronário enumeradas e definidas ao longo desta tese são: a gengivectomia, o retalho apicalmente posicionado e a erupção dentária forçada. Cada uma delas possui as suas indicações e contra-inidcaçoes. A gengivectomia é realizada quando não há necessidade de recontorno ósseo, pelo contrário, quando essa necessidade existe opta-se pelo retalho apicalmente posicionado. A erupção forçada é uma alternativa ao alongamento cirúrgico e aplica-se, normalmente a dentes não restauráveis mas com estrutura dentária sã abaixo do da crista óssea. Um ótimo diagnóstico é o essencial para a escolha da técnica de aumento coronário que melhor se adequa a cada caso. Objetivo: O objetivo desta revisão bibliográfica tem por base a pesquisa das técnicas de alongamento coronário, começando por perceber a anatomia do periodonto, as alterações que nele acontecem antes e depois dos procedimentos de alongamento coronário, a descrição e a comparação dos mesmos. Materiais e métodos: Para a realização desta revisão foram utilizados os principais motores de busca de dados científicos como a PubMed, B-on, Medline, Scielo, Google Académico e ainda o repositório on-line da Universidade Fernando Pessoa. Foram utilizadas as seguintes palavras chaves: “altered passive eruption”, “gingivectomy”, “gingivoplasty”, “apically repositioned flap”, “surgical crown lengthening”, “biologic width”, “mucogengival junction”, “forced eruption”, “prostethic dentistry”, “gummy smile”, resultando num pesquisa de 45 artigos e duas obras literarátias de interesse. Conclusões: Foi possível concluir que existem varias técnicas de alongamento coronário, cada uma adequada a cada caso e verificou-se que existem vários motivos pelo qual se realiza essa técnica.

Cárie secundária e propriedades antibacterianas dos materiais restauradores

Grande parte do tempo clínico do Médico Dentista é, atualmente, gasto a substituir restaurações dentárias realizadas no passado devido a fraturas ou fenómenos de cárie secundária. Pesquisou-se, assim, para a realização desta monografia em diferentes bases de pesquisa acerca dos fenómenos de cárie e cárie secundária. Um dos objetivos desta revisão bibliográfica estudar a microbiologia associada á cárie secundária, a histopatologia da lesão, o diagnóstico e os problemas associados ao diagnóstico. pretende-se, também, nesta monografia devido á sua pertinência investigar o potencial bacteriostático e bactericida dos diversos materiais disponíveis e em que situações esse efeito é potenciado, de modo a auxiliar o clinico na sua decisão no momento de restauração dentária, procurando prevenir ou adiar a necessidade de efetuar uma nova restauração. Para a realização desta monografia foram realizadas pesquisas nos motores de busca PubMed, B-on, Science Direct e Sci-elo. Depois de selecionados os artigos com interesse e com a utilização de seguintes palavras-chave e combinações de palavras sendo que no final foram selecionados 58 Artigos, dentro dos últimos 10 anos na língua portuguesa e na língua inglesa. Apesar da microbiologia e dos fenómenos histopatológicos de desenvolvimento da lesão estarem bem documentados, não existe consenso no que toca ao diagnóstico e tratamento das lesões. Existem diversos métodos de diagnóstico ao alcance da prescrição do Médico Dentista, sendo que, no entanto, nem todos estão indicados para o diagnóstico de lesões de cárie. Face á grande variedade de materiais restauradores e sistemas adesivos existentes no mercado torna-se imperativo que o Médico Dentista tenha os conhecimentos necessários sobre o potencial antibacteriano desses mesmos materiais. Sendo, assim, capaz de concluir mediante a situação apresentada: as vantagens, desvantagens e potencialidades dos diversos materiais á sua disposição na prevenção de lesões de cárie inicial e cárie secundária, aumentando a sobrevivência das peças dentárias. Conclui-se que a cárie secundária não é um fenómeno exclusivo a nenhum tipo de material forrador, ou restaurador não existindo também nenhum material capaz de efetuar com elevadas taxas de sucesso a sua prevenção. Contudo, atualmente, vem-se procurando a utilização de materiais que proporcionem um maior selamento da estrutura dentária, diminuindo a microinfiltração e consequentemente diminuindo os fenómenos de cárie secundária.

Comparação de materiais usados na confeção de facetas dentárias

A demanda na procura da reabilitação estética é um dos focos da história da humanidade ao longo das eras, mas que teve a sua acentuação nestes últimos dois séculos. Sendo a face um dos pontos que nos permite avaliar esteticamente uma pessoa, cabe ao médico dentista, como um dos profissionais que trabalha nessa zona do corpo humano, avaliar e procurar satisfazer as necessidades estéticas da população. Assim, por parte dos profissionais de Medicina Dentária, tem de haver uma procura constante para a satisfação das exigências estéticas, não só no conhecimento como no aprimoramento da técnica. Nos últimos tempos, com a necessidade de desenvolvimento de materiais para colmatar a cada vez maior busca para a perfeição estética, as facetas surgiram como tratamento de excelência. O presente trabalho teve como objectivo a comparação entre resina composta e cerâmica, na elaboração de restaurações estéticas. Para os dois tipos de materiais foram avaliados a estética e o comportamento biomecânico. Foram comparados benefícios e desvantagens, contra-indicações, indicações, plano de tratamento, diagnóstico e procedimentos clínicos dos dois materiais, utilizados na confecção das facetas cerâmicas e de resina composta. Foram utilizados os seguintes parâmetros de comparação: biocompatibilidade, adaptação marginal, preparação, resistência, cor, acabamento, potencial de reparação, custo e estética. A utilização de facetas cerâmicas tem sido um dos principais focos de desenvolvimento da Medicina Dentária no âmbito científico. A sua utilização permite uma maior predictibilidade e uma maior longevidade clínica. A sua qualidade estética, resistência à fractura, biodisponibilidade e estabilidade de cor, são as suas maiores vantagens na utilização clínica. Em sentido inverso, as facetas de resina composta apresentam menor custo, maior resistência à abrasão, possibilidade de reparação fácil e menor desgaste de estrutura dentária durante a sua preparação. Contudo apresentam menor estabilidade de cor. Portanto, torna-se esclarecedor que a escolha do material a utilizar na confecção de facetas, deve ser adaptada às especificidades de cada caso.

The effect of the solute on the structure, selected mechanical properties, and biocompatibility of Ti-Zr system alloys for dental applications

New titanium alloys have been developed with the aim of utilizing materials with better properties for application as biomaterials, and Ti-Zr system alloys are among the more promising of these. In this paper, the influence of zirconium concentrations on the structure, microstructure, and selected mechanical properties of Ti-Zr alloys is analyzed. After melting and swaging, the samples were characterized through chemical analysis, density measurements, X-ray diffraction, optical microscopy, Vickers microhardness, and elasticity modulus. In-vitro cytotoxicity tests were performed on cultured osteogenic cells. The results showed the formation essentially of the α′ phase (with hcp structure) and microhardness values greater than cp-Ti. The elasticity modulus of the alloys was sensitive to the zirconium concentrations while remaining within the range of values of conventional titanium alloys. The alloys presented no cytotoxic effects on osteoblastic cells in the studied conditions. © 2013 Elsevier B.V. All rights reserved.

The Influence of Small Quantities of Oxygen in the Structure, Microstructure, Hardness, Elasticity Modulus and Cytocompatibility of Ti-Zr Alloys for Dental Applications

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Diabetes triggers the loss of tooth structure associated to radiographical and histological dental changes and its evolution to progressive pulp and periapical lesions in rats

The aim of this study was to evaluate the putative influence of diabetes without metabolic control in the loss of tooth structure as well as histological changes in dentin and pulp tissue in rats. Diabetes was induced in Wistar rats (n=25) by intravenous administration of alloxan (42mg/kg). Diabetic and non-diabetic control rats were evaluated at 1, 3, 6, 9 and 12 months of follow-up. In order to evaluate the presence and progression of dental caries and periapical lesions, hemimandibles were removed and submitted to radiographical, histological, and morphometrical procedures. Dental caries were detected after radiographical and histological evaluations in diabetic group from the third month of diabetes onset, increasing gradually in frequency and severity in periods. Diabetic rats dental pulps also presented significant reduction in volume density of collagen fibers and fibroblasts at third month, parallel with a trend towards the increase in inflammatory cells volume density. Diabetic rats presented a generalized pulp tissue necrosis after 6 months of diabetes induction. Moreover, periapical lesions were not detected in control group, while these lesions were observed in all rats after 3, 6, 9, and 12 months of diabetes induction. Uncontrolled diabetes seems to trigger the loss of tooth structure, associated to histological dental changes and mediates its evolution to progressive severe pulp and periapical lesions in rats. Therefore, diabetes may be considered a very important risk factor regarding alterations in dental pulp, development of dental caries, and periapical lesions.

The significance of brittle reaction layers in fusing of dental ceramics to titanium

This thesis comprises four intercomplementary parts that introduce new approaches to brittle reaction layers and mechanical compatibility of metalloceramic joints created when fusing dental ceramics to titanium. Several different methods including atomic layer deposition (ALD), sessile drop contact angle measurements, scanning acoustic microscopy (SAM), three-point bending (TPB, DIN 13 927 / ISO 9693), cross-section microscopy, scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDS) were employed. The first part investigates the effects of TiO2 layer structure and thickness on the joint strength of the titanium-metalloceramic system. Samples with all tested TiO2 thicknesses displayed good ceramics adhesion to Ti, and uniform TPB results. The fracture mode was independent of oxide layer thickness and structure. Cracking occurred deeper inside titanium, in the oxygen-rich Ti[O]x solid solution surface layer. During dental ceramics firing TiO2 layers dissociate and joints become brittle with increased dissolution of oxygen into metallic Ti and consequent reduction in the metal plasticity. To accomplish an ideal metalloceramic joint this needs to be resolved. The second part introduces photoinduced superhydrophilicity of TiO2. Test samples with ALD deposited anatase TiO2 films were produced. Samples were irradiated with UV light to induce superhydrophilicity of the surfaces through a cascade leading to increased amount of surface hydroxyl groups. Superhydrophilicity (contact angle ~0˚) was achieved within 2 minutes of UV radiation. Partial recovery of the contact angle was observed during the first 10 minutes after UV exposure. Total recovery was not observed within 24h storage. Photoinduced ultrahydrophilicity can be used to enhance wettability of titanium surfaces, an important factor in dental ceramics veneering processes. The third part addresses interlayers designed to restrain oxygen dissolution into Ti during dental ceramics fusing. The main requirements for an ideal interlayer material are proposed. Based on these criteria and systematic exclusion of possible interlayer materials silver (Ag) interlayers were chosen. TPB results were significantly better in when 5 μm Ag interlayers were used compared to only Al2O3-blasted samples. In samples with these Ag interlayers multiple cracks occurred inside dental ceramics, none inside Ti structure. Ag interlayers of 5 μm on Al2O3-blasted samples can be efficiently used to retard formation of the brittle oxygen-rich Ti[O]x layer, thus enhancing metalloceramic joint integrity. The most brittle component in metalloceramic joints with 5 μm Ag interlayers was bulk dental ceramics instead of Ti[O]x. The fourth part investigates the importance of mechanical interlocking. According to the results, the significance of mechanical interlocking achieved by conventional surface treatments can be questioned as long as the formation of the brittle layers (mainly oxygen-rich Ti[O]x) cannot be sufficiently controlled. In summary in contrast to former impressions of thick titanium oxide layers this thesis clearly demonstrates diffusion of oxygen from sintering atmosphere and SiO2 to Ti structures during dental ceramics firing and the following formation of brittle Ti[O]x solid solution as the most important factors predisposing joints between Ti and SiO2-based dental ceramics to low strength. This among other predisposing factors such as residual stresses created by the coefficient of thermal expansion mismatch between dental ceramics and Ti frameworks can be avoided with Ag interlayers.