Academic literature on the topic 'Carbamide peroxide bleaching'

SUMMARY Objective This study evaluated the differences in enamel color change, surface hardness, elastic modulus, and surface roughness between treatments with four bleaching gels containing carbamide peroxide (two at 10% and one each at 35%, and 45%) and two bleaching gels containing hydrogen peroxide (two at 40%). Methods Enamel specimens were bleached and color changes were measured. Color change was calculated using either ΔE or the Bleaching Index (BI). Then, surface hardness, elastic modulus, and surface roughness of the enamel specimens were evaluated. All measurements were performed at baseline and directly after the first bleaching treatment for all carbamide peroxide– and hydrogen peroxide–containing bleaching gels. In addition, final measurements were made 24 hours after each of a total of 10 bleaching treatments for carbamide peroxide bleaching gels, and 1 week after each of a total of three bleaching treatments for hydrogen peroxide bleaching gels. Results After the last bleaching treatment, respective ΔE scores were 17.6 and 8.2 for the two 10% carbamide peroxide gels, 12.9 and 5.6 for the 45% and 35% carbamide peroxide gels, and 9.6 and 13.9 for the two 40% hydrogen peroxide gels. The respective BI scores were −2.0 and −2.0 for the two 10% carbamide peroxide gels, −3.5 and −1.5 for the 45% and 35% carbamide peroxide gels, and −2.0 and −3.0 for the two 40% hydrogen peroxide gels. Each bleaching gel treatment resulted in significant whitening; however, no significant difference was found among the gels after the last bleaching. Whitening occurred within the first bleaching treatments and did not increase significantly during the remaining treatments. Surface hardness significantly decreased after the last bleaching treatment, when 10% carbamide peroxide was used. Furthermore, significant changes in the elastic modulus or surface roughness occurred only after treatment with 10% carbamide peroxide. Conclusion All six bleaching gels effectively bleached the enamel specimens independent of their concentration of peroxide. Gels with low peroxide concentration and longer contact time negatively affected the enamel surface.

Pendahuluan: Terdapat beberapa macam pewarnaan gigi, yaitu eksternal, internal dan gabungan keduanya. Prosedur bleaching menjadi perawatan gigi yang paling digemari untuk mengatasi perubahan warna gigi. Terdapat dua macam prosedur bleaching vital, yaitu home bleaching dan in office bleaching. Bahan yang sering digunakan untuk metode home bleaching adalah carbamide peroxide 10% yang aman serta efektif memutihkan gigi, namun peroksida cenderung bersifat tidak stabil dan mutagenik dalam konsentrasi tinggi, karena itu dikembangkan bahan bleaching non peroxide.Tujuan penelitian untuk membandingkan efektifitas home bleaching carbamide peroxide 10% dan non peroxide terhadap gigi premolar rahang atas. Metode: Penelitian dilakukan dengan cara merendam gigi dalam bahan carbamide peroxide 10% dan non-peroxide hingga batas CEJ selama 14 hari dengan durasi 7 jam per hari. Sampel disimpan dalam inkubator bersuhu 37˚C. Pengukuran warna dilakukan pada hari ke-1, ke-7, dan ke-14 menggunakan spektofotometer Premiere Colorscan SS6200 yang menghasilkan pengelompokan warna CIELAB. Metode analisis data menggunakan t-test independent. Hasil: Terdapat perbedaan yang signifikan pada nilai perubahan warna 17.672 pada kelompok perlakuan carbamide peroxide 10% dan 8.863 pada non peroxide di hari ke-14. Nilai p=0.000 (<0.005) pada kedua perbandingan hari ke-7 dan ke-14. Simpulan: Penggunaan bahan carbamide peroxide 10% lebih efektif memutihkan gigi dibandingkan bahan non peroxide.Kata kunci: Home bleaching, carbamide peroxide, non peroxide, teeth discoloration

ABSTRACT Objective: Considering that different sources of carbamide peroxide bleaching agent may cause greater or lesser damage to the enamel and may have reduced effectiveness in dental whitening, the aim of this study was to compare the effects on the structure of enamel of two bleaching agents, drugstore-compounded and commercial carbamide peroxide bleaching agents. Methods: The specimens in the first group (drugstore-compounded carbamide peroxide) and second group (commercial carbamide peroxide) were treated with to 16% carbamide peroxide for 4 h per day for 20 days. The third group served as a control and was kept in artificial saliva during the test period. After the treatments, all specimens were examined via scanning electron microscopy. Results: Changes in the enamel morphology were similar in both experimental groups, but these changes were greater than those observed in the control group. The changes were mild and included only pores. Conclusion: There were no differences regarding damage to the enamel between drugstore-compounded and commercial carbamide peroxide bleaching agents.

Objective: This study evaluated the effect of internal bleaching agents on the bond strength of glass fiber posts to root dentine.Methods: Seventy bovine teeth were divided into 7 experimental groups (n=10) according to the bleaching agent used: SpH – sodium perborate + 20% hydrogen peroxide; SpW – sodium perborate + distilled water; Cp37 – 37% carbamide peroxide; Cp16 – 16% carbamide peroxide; Cp10 – 10% carbamide peroxide; H – 35% hydrogen peroxide; C – no bleaching agent (control). After bleaching, posts were cemented with a self-adhesive resin cement (RelyX U100) and the roots were crosssectioned to obtain two discs from each third. The posts underwent micropush-out testing, and bond strength values (MPa) were analyzed using ANOVA in a split-plot arrangement and the Tukey test (p<0.05). Failure mode was evaluated under confocal microscopy.Results: There were no significant differences between the control and bleaching agent groups. Bond strength was greater in the cervical third of the 16% carbamide peroxide (Cp16) group than in the sodium perborate + 20% hydrogen peroxide (SpH) group. The cervical third had a higher bond strength than the apical third in the 10% carbamide peroxide (Cp10), 16% carbamide peroxide (Cp16) and sodium perborate + distilled water (SpW) groups, and no significant differences in the other groups. Adhesive cement-dentine failure was prevalent in all groups.Conclusion: The use of internal bleaching agents did not decrease the bond strength of glass fiber posts to root dentin.

Objective: Carbamide peroxide 10% is commonly used in home bleaching procedure. Effectiveness of carbamide peroxide bleaching process as a home bleaching has no successor yet, but its use is still being debated due to the effects on oral cavity. Strawberries are one of natural ingredients that currently used to whiten decolorized teeth because it contains ellagic acid and malic acid. On contrary, malic acid is said to be involved in the process of erosion. The aim of this study was to compare tooth enamel hardness after application of dental bleaching agent carbamide peroxide 10% and strawberry gel.Material and Methods: Sample consists of 30 maxillary incisors were divided into 3 groups. The first group as control soaked in aquades. The second treatment group were applied with carbamide peroxide 10% and a third group applied with strawberry gel. Before and after the sample application, tests were performed to determine the hardness of tooth enamel as measured using Universal Hardness Tester.Results: Based on Friedman test, p-value = 0,000 (p <0,05; significant). This means that there was a significant difference in tooth enamel surface hardness of each group and treatment group using bleaching carbamide peroxide 10% and strawberry gel.Conclusion: There was a decrease on tooth enamel hardness after application of carbamide peroxide 10% compared strawberry gel.

Present tooth-bleaching techniques are based upon hydrogen peroxide as the active agent. It is applied directly, or produced in a chemical reaction from sodium perborate or carbamide peroxide. More than 90% immediate success has been reported for intracoronal bleaching of non-vital teeth, and in the period of 1–8 years’ observation time, from 10 to 40% of the initially successfully treated teeth needed re-treatment. Cervical root resorption is a possible consequence of internal bleaching and is more frequently observed in teeth treated with the thermo-catalytic procedure. When the external tooth-bleaching technique is used, the first subjective change in tooth color may be observed after 2–4 nights of tooth bleaching, and more than 90% satisfactory results have been reported. Tooth sensitivity is a common side-effect of external tooth bleaching observed in 15%-78% of the patients, but clinical studies addressing the risk of other adverse effects are lacking. Direct contact with hydrogen peroxide induced genotoxic effects in bacteria and cultured cells, whereas the effect was reduced or abolished in the presence of metabolizing enzymes. Several tumor-promoting studies, including the hamster cheek pouch model, indicated that hydrogen peroxide might act as a promoter. Multiple exposures of hydrogen peroxide have resulted in localized effects on the gastric mucosa, decreased food consumption, reduced weight gain, and blood chemistry changes in mice and rats. Our risk assessment revealed that a sufficient safety level was not reached in certain clinical situations of external tooth bleaching, such as bleaching one tooth arch with 35% carbamide peroxide, using several applications per day of 22% carbamide peroxide, and bleaching both arches simultaneously with 22% carbamide peroxide. The recommendation is to avoid using concentrations higher than 10% carbamide peroxide when one performs external bleaching. We advocate a selective use of external tooth bleaching based on high ethical standards and professional judgment.

Since bleaching has become a popular procedure, the effect of peroxides on dental hard tissues is of great interest in research. Purpose: The aim of this in vitro study was to perform a qualitative analysis of the human enamel after the application of in-office bleaching agents, using Scanning Electron Microscopy (SEM). Materials and Methods: Twenty intact human third molars extracted for orthodontic reasons were randomly divided into four groups (n=5) treated as follows: G1- storage in artificial saliva (control group); G2- four 30-minute applications of 35% carbamide peroxide (total exposure: 2h); G3- four 2-hour exposures to 35% carbamide peroxide (total exposure: 8h); G4- two applications of 35% hydrogen peroxide, which was light-activated with halogen lamp at 700mW/cm² during 7min and remained in contact with enamel for 20min (total exposure: 40min). All bleaching treatments adopted in this study followed the application protocols advised by manufacturers. Evaluation of groups submitted to 35% carbamide peroxide was carried out after two time intervals (30 minutes and 2 hours per session), following the extreme situations recommended by the manufacturer. Specimens were prepared for SEM analysis performing gold sputter coating under vacuum and were examined using 15kV at 500x and 2000x magnification. Results: Morphological alterations on the enamel surface were similarly detected after bleaching with either 35% carbamide peroxide or 35% hydrogen peroxide. Surface porosities were characteristic of an erosive process that took place on human enamel. Depression areas, including the formation of craters, and exposure of enamel rods could also be detected. Conclusion: Bleaching effects on enamel morphology were randomly distributed throughout enamel surface and various degrees of enamel damage could be noticed. Clinical significance: In-office bleaching materials may adversely affect enamel morphology and therefore should be used with caution.

SUMMARY This study was designed to evaluate in vitro the efficacy of a novel at-home bleaching technique using 10% or 16% carbamide peroxide modified by casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) and its influence on the microhardness of bleached enamel. A total of 40 bovine incisors were divided into four groups (n=10) according to the bleaching agent used: 10% carbamide peroxide only; a blend of 10% carbamide peroxide and a CPP-ACP paste; 16% carbamide peroxide only; and a blend of 16% carbamide peroxide and a CPP-ACP paste. During the 14-day bleaching regimen, the samples were stored in artificial saliva. The Vickers microhardness and color of the teeth were assessed at baseline (T0) and immediately after the bleaching regimen (T14) using a microhardness tester and a spectrophotometer, respectively. The degree of color change was determined by the Commission Internationale de l'Eclariage (CIE) L*a*b* system (ΔE, ΔL*, Δa*, and Δb*) and Vita shade guide parameters. The data were analyzed by analysis of variance and the Tukey test (p&lt;0.05). The teeth that were bleached with a blend of peroxide (10% or 16%) and the CPP-ACP paste presented increased microhardness values at T14 compared with T0, whereas the samples that were bleached with peroxide only did not show any differences in their microhardness values. All of the bleaching agents were effective at whitening the teeth and did not show a statistically significant difference using the CIEL*a*b* system (ΔE, ΔL*, Δa*, and Δb*) or the Vita shade guide parameters. The use of a CPP-ACP paste with carbamide peroxide bleaching agents increased the bleached enamel's microhardness and did not have an influence on whitening efficacy.

Introduction. Bleaching agents can cause alteration of hard tissues of the tooth. The aim of this study was to evaluate the effect of two different concentrations of carbamide peroxide (10% and 35%) on human enamel microhardness. Material and Methods. The study was conducted on ten extracted teeth divided into two groups. The teeth were sectioned in mesiodistal direction using the diamond disc in order to obtain experimental and control samples. First group was exposed to the concentration of 10% carbamide peroxide (Opalescence gel, Ultradent. Pro, US) at the time intervals that corresponded to home night bleaching technique of vital teeth. Second group was exposed to high concentration of 35% carbamide peroxide (Opalescence Quick, Ultradent. Pro, US) at the time intervals that corresponded to the professional bleaching technique of vital teeth. Control samples were exposed to artificial saliva for the same time intervals as the samples from experimental group. Knoop?s test for enamel microhardness was performed at the beginning, after the first phase of therapy, after the therapy was completed and after three weeks of exposure to artificial saliva. The results were statistically analyzed using analysis of variance (ANOVA) and Student t-test. Results. The microhardness values of enamel samples treated with 10% carbamide peroxide decreased after 8 hours (261 khn) and three weeks of treatment (222 khn) but increased after three weeks of exposure to artificial saliva (263 khn). The decrease of enamel microhardness of the samples treated with 10% carbamide peroxide was not statistically significant. The microhardness values of enamel samples treated with 35% carbamide peroxide were reduced after 1 hour (235 khn) and 3 hours (190 khn) and increased after three weeks of exposure to artificial saliva (241 khn). Microhardness of enamel treated with 35% carbamide peroxide was significantly decreased in experimental samples compared to controls. Conclusion. Carbamide peroxide in concentration of 35% leads to the significant decrease in enamel microhardness compared to 10% carbamide peroxide.

Clinical Relevance The efficacy of vital bleaching depends on the two aspects—viz, bleaching agent and the bleaching method. Results from this in vivo study show that 10% carbamide peroxide home-bleaching and 15% hydrogen peroxide in-office bleaching were more effective than a 6% hydrogen peroxide home-bleaching over-the-counter product up to three months after completion of the bleaching treatment.

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O uso do perÃxido de carbamida a 10% em moldeiras para o clareamento caseiro por 2 a 8 horas diÃrias, de 2 a 6 semanas pode resultar em grande satisfaÃÃo do paciente. A associaÃÃo de dentes brancos a um aumento da autoestima do indivÃduo promoveu o aparecimento de agentes clareadores disponÃveis para a compra sem, necessariamente, passar pela supervisÃo do dentista. Como consequÃncia, podem surgir efeitos adversos na estrutura dental. Baseado nesse contexto, o presente estudo avaliou a microdureza do esmalte apÃs a utilizaÃÃo de agentes clareadores. 70 amostras de esmalte humano, com 4x4mm, foram divididas em sete grupos (G1 a G7). Cada grupo recebeu trÃs tratamentos por 28 dias: G1: pasta nÃo clareadora, Ãgua destilada e gel placebo; G2: pasta clareadora, Ãgua destilada e gel placebo; G3: pasta nÃo clareadora, enxaguatÃrio clareador e gel placebo; G4: pasta nÃo clareadora, Ãgua destilada e gel perÃxido de carbamida a 10%; G5: pasta clareadora, Ãgua destilada e gel de perÃxido de carbamida a 10%; G6: pasta nÃo clareadora, enxaguatÃrio clareador e gel de perÃxido de carbamida a 10%; G7: pasta clareadora, enxaguatÃrio clareador e gel de perÃxido de carbamida a 10%. A microdureza foi aferida antes dos tratamentos, com 14 dias e no 28Âdia. AtravÃs da anÃlise de variÃncia ANOVA verificou-se diferenÃa entre os tipos de tratamento. Para os nÃveis de tempo, o teste de Tukey mostrou diferenÃas significativas nas medidas antes, apÃs 14 e 28 dias. O G2 se comportou estatisticamente semelhante ao G1. O G3 e G6 se mostraram estÃveis durante todo o tratamento. O G4 e G5 nÃo mostraram diferenÃa significativa entre si. O Ãnico grupo que desmineralizou significativamente entre os trÃs nÃveis de tempo foi o G7. Logo, demonstra-se que a reduÃÃo da microdureza ocorreu de forma mais intensa pelo uso coletivo de agentes clareadores durante o tratamento.

Existem muitas metodologias utilizadas para tentar analisar a permeação de peróxido de hidrogênio através das estruturas dentárias, porém não conseguem determinar o momento exato em que o peróxido começa a alcançar concentrações detectáveis dentro da câmara pulpar. OBJETIVO: Investigar a viabilidade de um modelo experimental de análise eletroquímica para detecção e mensuração da concentração de peróxido de hidrogênio proveniente de produtos utilizados em tratamento clareador e avaliar a cinética da difusão destes peróxidos através dos tecidos duros dentários. MATERIAIS E MÉTODOS: Foram utilizados 45 dentes incisivos bovinos permanentes mandibulares, cujo preparo envolveu a remoção da face lingual coronária, mantendo-se o esmalte e a dentina vestibulares intactos. Todos os dentes foram fixados em resina acrílica com auxílio de matriz elastomérica quadrangular e organizados segundo os testes: 1: análise eletroquímica e 2: análise espectrofotométrica. Para os testes foram utilizados clareadores à base de peróxido de hidrogênio (HP) e de peróxido de carbamida (CP) e seus respectivos placebos (PHP e PCP). Foram realizados três cronoamperogramas e três voltamogramas para cada uma das amostras. Utilizou-se a mesma cela no experimento eletroquímico e no teste espectrofotométrico, permitindo assim a comparação das metodologias. RESULTADOS: A análise eletroquímica mostrou na 1ª permeação de HP média de 1688,50 segundos quando comparada a 857,70s e a 457,70s da 2ª e da 3ª permeações, respectivamente. Desta forma observa-se que a 1ª permeação representa aproximadamente o dobro e o quadruplo dos valores sequenciais da 2ª e da 3ª permeações. Não foi detectado início de permeação para CP, PHP e PCP. Para o grupo HP há uma relação crescente nas concentrações de moléculas de peróxido de hidrogênio detectadas nas três permeações respectivamente. Entretanto, o crescimento entre a 1ª e 2ª permeação é discreto, quando comparado à 3ª permeação, onde foi detectada maior concentração de moléculas do peróxido de hidrogênio. No grupo CP observam-se médias de 2,96E-02 A na 1ª permeação, 3,11E-05 A na 2ª permeação e 1,37E-04 A na 3ª permeação, havendo diferença entre a 1ª e 3ª permeação (p = 0,00472). Todavia, não ocorreram diferenças entre os demais grupos (p > 0,05). Quando comparado o método eletroquímico e o método espectrofotométrico, o peróxido de hidrogênio (HP) não demonstrou diferença significativa entre as análises (p =0,0826); todavia o peróxido de carbamida mostrou diferenças entre as duas análises (p=0,0093). CONCLUSÕES: A metodologia eletroquímica é tão eficaz quanto à metodologia consolidada na literatura para a detecção da presença de peróxido de hidrogênio na câmara pulpar, nos testes com peróxido de hidrogênio 35%. O tempo necessário para que o peróxido de hidrogênio chegasse à câmara pulpar diminuiu a cada aplicação e a penetração do peróxido de hidrogênio aumentou a permeabilidade dos tecidos duros dentais.
There are many methods used to analyze the permeation of hydrogen peroxide through the tooth structure, but they cannot determine the exact moment when the peroxide begins to reach detectable concentrations within the pulp chamber. OBJECTIVE: To investigate the feasibility of an experimental model of electrochemical analysis for detection and measurement of the concentration of hydrogen peroxide from products used in bleaching and evaluate the kinetics of diffusion of these peroxides through dental hard tissues. MATERIALS AND METHODS: We used 45 bovine permanent mandibular incisors, whose preparation involved removing the lingual coronary hard tissues keeping intact the vestibular enamel and dentin. All teeth were fixed in acrylic resin with the aid of elastomeric matrix square and organized according to the tests: 1: electrochemical analysis and 2: spectrophotometric analysis. For tests were used based bleaching hydrogen peroxide (HP) and carbamide peroxide (CP) and their respective placebos (PHP and PCP). Three cronoamperograms and three voltammograms were performed for each sample. We used the same cell to the spectrophotometric test, thus allowing comparison of methodologies. RESULTS: The analysis showed the 1st electrochemical permeation HP average of 1688.50 seconds when compared to 857.70s and 457.70s of the 2nd and 3rd permeations respectively. Thus we observe that the 1st permeation is approximately double and quadruple sequential values of the 2nd and the 3rd permeations. Not detected early permeation for CP, PHP and PCP. For Group HP there is a ratio of molecules increasing concentrations of hydrogen peroxide detected in three permeations respectively. However, the growth between the 1st and 2nd permeation is understated when compared to 3rd permeation, where there has been a greater concentration of molecules of hydrogen peroxide. In the CP group were observed averages of 2.96 E-02A in the 1st permeation, 3.11 E-05 A in the 2nd permeation and 1.37 E-04 A in 3rd permeation, no difference between 1st and 3rd permeation (p = 0.00472) . However, there were no differences between the other groups (p> 0.05). When compared the electrochemical and spectrophotometric methods, hydrogen peroxide (HP) showed no significant difference between the analysis (p = 0.0826), yet the carbamide peroxide showed differences between the two analyzes (p = 0.0093). CONCLUSIONS: The electrochemical method is as effective as the consolidated methodology in the literature to detect the presence of hydrogen peroxide in the pulp chamber, in the tests with hydrogen peroxide 35%. The time required for the hydrogen peroxide to reach the pulp chamber decreased to each application and the penetration of hydrogen peroxide increased the permeability of dental hard tissues.

Projeto de Pós-Graduação/Dissertação apresentado à Universidade Fernando Pessoa como parte dos requisitos para obtenção do grau de Mestre em Medicina Dentária
Cada vez mais nos dia de hoje os pacientes recorrem a tratamentos estéticos em medicina dentária, em busca de se enquadrarem no padrão de beleza imposto pela sociedade, procurando ter dentes mais brancos, dentes alinhados e bem contornados. No entanto, muitos pacientes apresentam frequentemente dentes com cor alterada, comprometendo desta forma a estética do sorriso. O branqueamento dentário é uma técnica não invasiva, conservadora que não altera a forma natural do dente, e que permite alterações estéticas consideráveis. Para se atingir sucesso num tratamento branquedor é da maior importância o diagnóstico preciso da etiologia da alteração de cor, por isso uma anamnese detalhada e um exame clínico e dentário são da maior importância para se poder aconselhar o paciente pelo melhor tratamento a adoptar, podendo este não passar por uma terapêutica branqueadora. É importante que o médico dentista saiba discernir o que tem validade científica do que é marketing comercial, para que desta forma possa fazer as melhores opções clínicas. O objetivo deste trabalho foi avaliar a informação científica disponível que comprove a eficácia das técnicas disponíveis para realizar branqueamento dentário, vantagens e desvantagens de cada técnica, bem com da sua utilização combinada. Para tal foi efetuada uma pesquisa nas bases de dados PubMed e B-On de artigos publicados entre 1990-2013 com as seguintes palavras-chave: “Tooth Whitening”OR “Tooth Bleaching”AND “Carbamide Peroxide” OR “Hydrogen Peroxide”AND ”Lights”OR “Laser” OR “LED”. Os estudos existentes são cientificamente insuficientes para que se possa comprovar a eficácia e a segurança da utilização clínica das luzes no branqueamento dentário em consultório. A opção da técnica em ambulatório vs consultório depende de fatores relacionados com o paciente (impaciente, perfecionista, expectativas …) e de fatores relacionados com as vantagens inerentes a cada técnica. Os estudos não são consensuais, mas a maioria indica que ambas as técnicas têm resultados de eficácia semelhantes. Each and every day patients are resorting to cosmetic treatments in dentistry, looking to fit the beauty standard imposed by society, seeking to have whiter, straighter and well contoured teeth. However, many patients often present discolored teeth, thus compromising the smile aesthetics. The tooth whitening is a noninvasive and conservative technique does not alter the natural shape of the tooth, and allows considerable aesthetics changes. To achieve a successful whitening treatment it is of utmost importance an accurate diagnosis of the cause of color change, so a detailed anamnesis and a clinical and dental examination are of great importance to be able to advise the most suitable treatment for the patient, which may or may not be a whitening treatment. It is important that the dentist is able to differentiate what has scientific validity and what is commercial marketing, so that he can make the best clinical options. The aim of this study was to evaluate the available scientific information that proves the efficiency of the available techniques to perform tooth whitening, advantages and disadvantages of each technique, as well as their combined use. For such a research has been made in the databases of PubMed and B -On for articles published between 1990-2013 with the following keywords : "Tooth Whitening " OR "Tooth Bleaching " AND " Carbamide Peroxide " OR "Hydrogen Peroxide " AND " Lights " OR " Laser " OR " LED " Existing studies are scientifically insufficient to prove the efficiency and safety of clinical use of lights on tooth whitening. The choice of the at-home bleaching vs. in-office bleaching depends on factors related to the patient (impatient, perfectionist, expectations ...) and factors related to the inherent advantages of each technique. The studies are not a consensus but the majority indicates that both techniques have similar efficiency results.

In recent years bleaching of vital teeth has become popular among both dentist and patients. Different bleaching agents were used for this purpose. They are either applied professionally at high dose (office bleaching) or by patient at lower dose (home bleaching). In the present work we studied the effects of a high concentration bleaching agent (35% hydrogen peroxide), and a low concentration bleaching agent (17% carbamide peroxide) on human enamel and dentin using Fourier Transform Infrared (FTIR) Spectroscopic Technique. The OH stretching band of hydroxyapatite at 3567 cm-1 appeared in the spectra of enamel tissue which was absent in dentin. Carbamide peroxide and hydrogen peroxide treatment induced some differences in enamel and dentin spectra according to control group spectra. While the treatment of hydrogen peroxide leaded to significant decrease in mineral to matrix ratio, carbamide peroxide treatment did not cause decrease in this level. In addition, organic components of the teeth were changed after the treatment of bleaching agents. The frequency of the Amide A and Amide I bands were significantly changed for enamel tissue after the treatment of high concentration bleaching agent. However, it is observed that these changes result from two different bleaching methods are negligible in dentin tissue. In conclusion it can be stated that hydrogen peroxide treatment caused dramatic changes in enamel structure according to carbamide peroxide treatment, but two methods did not cause significant changes in dentin tissue.

Objetivo: avaliar os efeitos do peróxido de carbamida a 16% aplicado na mucosa oral de ratos diabéticos e não diabéticos. Métodos:foram utilizados trinta ratos albinos sendo 15 diabéticos induzidos por estreptozotocina e 15 normais, machos, adultos jovens, variedade Wistar. Os animais foram dividos em 6 grupos: NDC(não diabético controle), NDIP(não diabético imediato peróxido), ND7DP(não diabético 7 dias peróxido), DC(diabético controle), DIP(diabético imediato peróxido), D7DP(diabético 7 dias peróxido). Os grupos NDC e DC não receberam qualquer tratamento. Nos grupos NDIP e DIP foi aplicado o gel de peróxido de carbamida a 16% por 7dias (2 horas/dia) e os animais foram sacrificados no sétimo dia do experimento. Nos grupos ND7DP e D7DP foi aplicado o gel de peróxido de carbamida a 16% por 7 dias (2 horas dia) e os animais foram sacrificados 7 dias após (reparo). Após o sacrifício dos animais, a região mentual foi retirada cirurgicamente e preparada para estudo ao microscópio de luz com estereologia e imunohistoquímica para α-actina de músculo liso (ACML, detecção de vasos). Resultados: todos os animais tratados com estreptozotocina tornaram-se diabéticos. A determinação da densidade de volume de tecido conjuntivo (Vv[tc]), da densidade de volume de vasos (Vv[vasos]) e da densidade de mastócitos na área-teste (QA[mast]) foram realizadas através do programa Image Pro Plus Version 5.0.5 2004 Media Cybernetics Inc. O Vv[tc] se apresentou 23% maior no grupo DC, em relação ao grupo NDC. A Vv[vasos] foi 125% maior no grupo DC em relação ao grupo NDC, e 108% maior no grupo DP7D em relação ao grupo NDP7D, todos com diferença estatística significante. A (QA[mast]) se apresentou maior nos grupos diabéticos, porém sem diferença estatística significante. Conclusão: O peróxido de carbamida a 16% induz a formação de fibrose, migração de mastócitos e proliferação de vasos, como reação tecidual no tecido celular subcutâneo, na região vestíbulo-mentual inferior de ratos diabéticos e não diabéticos.
Purpose: to evaluate the effects of the application of 16% carbamide peroxide in the oral mucosa of diabetic and non diabetic rats. Methods: we studied 30 young, male and adult Wistar albino rats, 15 diabetics induced by streptozotocin, and 15 non diabetics. The animals were divided in 6 groups: NDC(non diabetic control), NDIP(non diabetic immediately peroxide), ND7DP(non diabetic 7 days peroxide), DC(diabetic control), DIP(diabetic immediately peroxide), D7DP(diabetic 7 days peroxide). Groups NDC and DC had no treatment. In groups NDIP e DIP were applied the 16% carbamide peroxide gel (for 2 hours a day) and the animals were sacrificed in the seventh day of the experimentation. In groups ND7DP e D7DP were applied the 16% carbamide peroxide gel (for 2 hours a day) and the animals were sacrificed 7 days after (repair). After the sacrifice, the material from the jugal mucosa of the animals was removed for study with light microscope, stereology and immunohistochemistry for smooth muscle alfa-actin (SMAA, vessel detection). Results: all the specimens treated with streptozotocin became diabetics. For determination of the density of connective tissue (Vv[tc]), of the density of vessel volume (Vv[vasos]) and the density of mast cells (QA[mast]) was used the program Image Pro Plus Version 5.0.5 2004 Media Cybernetics Inc. The Vv[tc] were 23% higher in group DC than the group NDC . The Vv[vasos] was 125% higher in group DC than the group NDC, and 108% higher in group DP7D than the group NDP7D, all data with statistically significant difference. The (QA[mast]) was higher in diabetic groups but without statistically significant difference. Conclusion: The 16% of carbamide peroxide induces the formation of fibrosis, migration of mast cells and vessel proliferation as a tissue reaction in the cellular subcutaneous tissue of the oral mucosa of diabetics and non diabetics rats.

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O objetivo deste estudo é comparar a eficácia do peróxido de carbamida a 37%, do perborato de sódio e da associação do perborato de sódio com o peróxido de hidrogênio a 35% sobre o clareamento interno de dentes bovinos, tratados endodonticamente, escurecidos e não escurecidos, in vitro. Unidades dentais bovinas hígidas originaram os corpos-de-prova empregados nas experimentações. Realizado o escurecimento experimental com sangue, durante 14 dias ininterruptos, e o tratamento endodôntico em todas as amostras, seguiram-se os procedimentos de clareamento endógeno através da técnica walking bleach, durante três semanas consecutivas. A avaliação da eficácia clareadora dos agentes utilizados, nos três terços dentários, foi determinada pela comparação da resposta dos fatores L*, a* e b* dos grupos estudados, através de leituras realizadas em espectrofotômetro Easyshade-Vita, com base no sistema CIE Lab. Concluiu-se que os três agentes clareadores estudados apresentaram o mesmo efeito clareador para o terço cervical de dentes pigmentados e terço médio de dentes não pigmentados; o peróxido de carbamida apresentou efeito clareador inferior nos terços incisal e médio de dentes escurecidos e nos terços incisal e cervical de dentes sem pigmentação por sangue, principalmente no que se refere ao efeito residual da ação de agentes clareadores internos. Contudo, o perborato de sódio, administrado com água destilada, e a associação entre perborato de sódio e peróxido de hidrogênio a 35% apresentaram o mesmo comportamento clareador para os três terços dentários, independentemente da presença ou ausência de pigmentação da câmara pulpar por sangue.
Salvador

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The aim of this double-blind randomized clinical study was to evaluate whether the use of a desensitizing agent (5% potassium nitrate and 2% sodium fluoride [Desensibilize KF 2%, FGM]) before at-home bleaching would prevention/decrease tooth sensitivity when compared to a placebo. Sixty caries-free patients, over 18 years were divided into desensitizer and placebo groups. Before at-home bleaching with 16% carbamide peroxide gel (Whiteness Standard, FGM) under night, a placebo or desensitizer gel was applied in the tray and using by patients for 10 min. The same bleaching protocol was repeated for 4 weeks for both groups. The patients recorded their perception of tooth sensitivity on a 0-4 scale. For color changes at each two-week recall for both groups was evaluated for a repeated measures two-way ANOVA and Tukey´s test (α=0.05). The percentage of patients with tooth sensitivity were analyzed using the Fisher's exact test. The different levels of sensitivity were analyzed using the Fisher's exact test or Chi-square test, and the intensity of sensitivity were analyzed using the Student's t-test (α=0.05). The use of desensitizing gel did not affect the bleaching efficacy of the carbamide peroxide agent (p>0.05). The tooth sensitivity frequency was similar for both groups (66,6% for placebo and 63,3% for desensitizer group; p=0.93). The number of days without sensitivity was more frequency in the desensitizer group, despite no significant difference was found (p>0.05). However, the intensity of sensitivity was higher for the placebo (1.51 ± 0.51) compared to the desensitizer group (1.16 ± 0.52) (p=0.009). The use of the desensitizing gel based on 5% nitrate potassium and 2% sodium fluoride before the at-home bleaching regimen with 16% carbamide peroxide does not affect the bleaching efficacy and reduce the tooth sensitivity intensity.
O objetivo deste estudo clínico duplo-cego randomizado foi avaliar o efeito de um agente dessensibilizante (nitrato de potássio 5% e fluoreto de sódio 2% [Desensibilize KF 2%, FGM]) antes do clareamento dental na técnica caseira na prevenção/diminuição da sensibilidade dental. Foram selecionados 60 pacientes livres de lesões de cárie, com mais de 18 anos divididos em grupos dessensibilizante e placebo. Antes do clareamento com peróxido de carbamida 16% (Whiteness Standart, FGM), em regime noturno, um gel placebo ou com agente dessensibilizante foi aplicado na moldeira e usado pelos pacientes de cada um dos grupos durante 10 min. O mesmo procedimento foi repetido durante 4 semanas para os dois grupos. Os pacientes registraram sua percepção de sensibilidade dentária em uma escala 0-4. Para a análise da cor foi realizada uma análise de variância de medidas repetidas de dois fatores (tempo de tratamento) e teste de Tukey (α=0,05). Os diferentes graus de sensibilidade dentária foram comparados pelo teste exato de Fisher ou Teste de Qui-Quadrado (α=0,05). A porcentagem de pacientes com sensibilidade dentária foi analisada através do teste exato de Fisher (α=0,05) e a intensidade média da sensibilidade através do teste t de Student (α=0,05). O uso de gel dessensibilizante não afetou a eficácia do clareamento com peróxido de carbamida (p>0,05). A freqüência da sensibilidade foi semelhante entre os grupos placebo (66,6%) e com dessensibilizante (63,3%) (p=0,93). O número de dias sem sensibilidade foi mais freqüente no grupo dessensibilizante, mas não houve diferenças entre os grupos (p>0,05). Porém a intensidade de sensibilidade foi significativamente maior no placebo (1,51±0,51) do que com o dessensibilizante (1,16±0,52) (p=0,001). Conclui-se que o uso de um agente dessensibilizante à base de nitrato de potássio e flúor antes do tratamento clareador com peróxido de carbamida 16% pode diminuir a intensidade da sensibilidade causada pelo clareamento dental caseiro.

Este estudo teve como objetivos: 01.Avaliar ex vivo o efeito de diferentes sistemas clareadores na microdureza dentinária em dentes bovinos submetidos ao clareamento dental interno. 02.Avaliar ex vivo o efeito de diferentes sistemas clareadores na morfologia superficial da dentina bovina. Fragmentos de 4 x 4mm, contendo esmalte e dentina, foram obtidos de coroas de incisivos bovinos extraídos. Os espécimes foram submetidos ao clareamento dental interno com peróxido de hidrogênio a 35% e peróxido de carbamida a 37% utilizando sistemas convencionais (Opalescence Endo® and Whiteness Super Endo®) e fotoativados (Opalescence Xtra® and Whiteness HP Maxx®). Os controles foram tratados com perborato de sódio misturado com peróxido de hidrogênio a 10% ou nenhum tratamento foi realizado. A microdureza dentinária foi mensurada antes e após os tratamentos clareadores, e os valores de dureza Knoop (KHN) foram submetidos à análise estatística (two-way ANOVA, Tukey\'s port-test). Os espécimes foram observados e fotografados sob microscópio eletrônico de varredura e avaliados com relação às alterações morfológicas da superfície da dentina. Houve uma redução significante na microdureza dentinária para todos os grupos testados quando comparados aos grupos controles. Opalescence Xtra® (-11.36 ± 8.14 KHN), Opalescence Endo® (-13.71 ± 8.02 KHN), Whiteness HP Maxx® (-15.18 ± 9.58 KHN) e Whiteness Super Endo® (-16.97 ± 6.55 KHN) foram semelhantes estatisticamente. O grupo do perborato de sódio misturado com peróxido de hidrogênio 10% (2.10 ± 8.58 KHN) e o grupo sem tratamento clareador (-2.71 ± 2.40 KHN) também foram estatisticamente semelhantes entre si. Ocorreu uma grande variação no padrão de alterações da morfologia superficial da dentina com os sistemas clareadores utilizados. Todos os produtos testados apresentaram redução significativa da microdureza dentinária, exceto o grupo de perborato de sódio misturado com peróxido de hidrogênio a 10%. Ambos, pH e oxidação do peróxido de hidrogênio apresentam o papel de alterar a estrutura da dentina durante o clareamento interno. A utilização de produtos alcalinos com um tempo reduzido de aplicação (técnicas fotoativadas) pode diminuir as alterações morfológicas na dentina.
The aim of this study was: 01. To evaluate in vitro the effect of different in-office bleaching systems on the surface morphology of bovine dentin. 02. To evaluate ex vivo the effect of different bleaching systems on the microhardness of bovine dentine. Tooth fragments measuring 4 x 4mm, containing enamel and dentin, were obtained from the crowns of extracted bovine incisors. Samples were submitted to simulated intracoronal bleaching techniques with 35% hydrogen peroxide and 37% carbamide peroxide using conventional (Opalescence Endo® and Whiteness Super Endo®) and light activated systems (Opalescence Xtra® and Whiteness HP Maxx®). Controls were treated either with sodium perborate mixed with 10% hydrogen peroxide or no bleaching agent. Dentine microhardness values were measured before and after bleaching procedures, recorded as KHN (Knoop Hardness Number), and the differences between them analyzed (two-way ANOVA, Tukey\'s port-test). The samples were observed under SEM and the recorded images were evaluated for topographic alterations. Significant reductions of dentine microhardness were observed for all treatments when compared to the control groups. Opalescence Xtra® (-11.36 ± 8.14 KHN), Opalescence Endo® (-13.71 ± 8.02 KHN), Whiteness HP Maxx® (-15.18 ± 9.58 KHN) and Whiteness Super Endo® (- 16.97 ± 6.55 KHN) presented similar differences. The walking bleach technique (2.10 ± 8.58 KHN) and the untreated groups (-2.71 ± 2.40 KHN) were statistically alike.The ultrastructural alterations of dentin observed in this study varied greatly between groups, according to the products used. Apparently, higher pH products associated to in-office techniques yielded to better maintenance of dentin ultrastructure. The in-office products tested in the present study caused a significant reduction in dentine microhardness. The walking bleach technique did not affect dentine microhardness. Both low pH and hydrogen peroxide oxidation play a role in altering the ultrastructure of dentin during internal dental bleaching. The use of alkaline products with reduced time of application (in-office techniques) may decrease such morphological alterations.

Tooth bleaching is an aesthetic procedure that is usually carried out with products containing carbamide peroxide, which has a potential deleterious effect mediated by hydrogen peroxide formation. Dental amalgam has still been widely used for posterior teeth restorations, despite its mercury content. There is concern that hydrogen peroxide generated from bleaching agents can cause enhanced metal ion release from dental amalgam restorations when in contact, but there are few studies about the synergistic systemic toxic effects of these products. The aim of the present study was to investigate the possible toxic effects of carbamide peroxide in vivo after oral administration, and in vitro, as dental amalgam metals toxicity. The parameters studied for characterization of toxicity were hepatic δ-aminolevulinate dehydratase (δ - ALA-D) activity, 2-thiobarbituric acid reactive substance (TBARS) levels in liver, brain, kidney and dental pulp of rats, and in addition the topic effect over palatal mucosa, which was investigated by histological study. In vivo, exposure to carbamide peroxide did not change TBARS levels in liver and dental pulps, or liver δ - ALA-D activity. However, only the 35% carbamide peroxide treatment provoked an increase in the epithelium thickness, which was associated with an elevation in the number of epithelium cell layers, and an elevation in epithelium basal cell layer dimension. Carbamide peroxide produced a significant increase in TBARS production in vitro when tested at extremely high concentrations in liver, brain and dental pulp. CuSO4 and SnCl2 produced a significant decrease in liver TBARS levels when tested at concentrations of 100 and 200 μM. Otherwise in brain, 100 μM CuSO4 caused an increase in TBARS production. In dental pulp, 100 and 200 μM HgCl2 caused an increase in TBARS levels production. When amalgam metals constituents and carbamide peroxide dissolved in carbopol were incubated together, carbopol and 200 μM SnCl2 significantly decreased brain TBARS production. Carbopol, the gel vehicle, caused a decreased TBARS production in all tissues. In conclusion, carbamide peroxide, CuSO4 and HgCl2 were found to have some pro-oxidant activity over tissues. Therefore, care is needed when bleaching treatment is performed in amalgam restored teeth, because pulp tissue may be overwhelmed by the concomitant toxic activity of these substances.
O clareamento dental é um procedimento estético que usualmente é realizado através de produtos contendo o peróxido de carbamida, que possui potencial efeito deletério mediado pela formação do peróxido de hidrogênio. O amálgama dental ainda tem sido amplamente utilizado para restaurações em dentes posteriores, apesar das controvérsias devido ao seu conteúdo de mercúrio. O peróxido de hidrogênio gerado através dos agentes clareadores tem sido considerado por aumentar a liberação de íons metálicos quando em contato com as restaurações de amálgama, porém existem poucos estudos a respeito dos efeitos tóxicos sinergísticos destes produtos. O objetivo do presente estudo foi investigar os possíveis efeitos do peróxido de carbamida in vivo após a administração oral, e in vitro, assim como dos metais presentes no amálgama dental. Os parâmetros estudados para a caracterização da toxicidade foram a atividade da δ-aminolevulinato desidratase (δ - ALA-D) hepática, os níveis de substâncias reativas com o ácido 2-tiobarbitúrico (TBARS) no fígado, cérebro, rim e na polpa dental de ratos, além do efeito tópico sobre a mucosa do palato, a qual foi investigada por estudo histológico. In vivo, a exposição ao peróxido de carbamida não modificou os níveis de TBARS no fígado ou na polpa dental, e também não alterou a atividade da δ - ALA-D hepática. Entretanto, apenas o peróxido de carbamida a 35% provocou um aumento na espessura do epitélio, o qual foi associado com um aumento no número de camadas celulares epiteliais, e um aumento na dimensão da camada celular epitelial basal. O peróxido de carbamida produziu um aumento significativo na produção de TBARS in vitro quando testado em concentrações extremamente altas no fígado, no cérebro e polpa dental. CuSO4 e SnCl2 produziram um decréscimo significativo nos níveis de TBARS no fígado quando testados em concentrações de 100 and 200 μM. Por outro lado no cérebro, 100 μM CuSO4 causou um aumento na produção de TBARS. Na polpa dental, 100 and 200 μM HgCl2 causaram um aumento na produção dos níveis TBARS. Quando os metais constituintes do amálgama e o peróxido de carbamida dissolvido em carbopol foram incubados concomitantemente, carbopol e 200 μM SnCl2 diminuíram significativamente a produção de TBARS no cérebro. Carbopol, o veículo em gel, causou um decréscimo na produção de TBARS em todos os tecidos. Concluindo, o peróxido de carbamida, o CuSO4 e o HgCl2 demonstraram capacidade pró-oxidativa sobre os tecidos. Portanto, é necessária uma atenção especial quando o clareamento é realizado em dentes com restaurações de amálgama, pois o tecido pulpar pode ser subjugado pela atividade tóxica concomitante destas substâncias.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
The aim of this study was to obtain and investigate the in vitro effect of bioglass (Bv) and hydroxyapatite (HaP) nanoparticles loaded into a gel of 37.5% carbamide peroxide on mechanical properties of enamel, hydrogen peroxide permeability and tooth bleaching. The hypothesis of this study is that Bv and HaP nanoparticles can reinforce the enamel and avoid the diffusion of hydrogen peroxide to the pulp chamber, without affecting bleaching potential. Bovine teeth were obtained from Matadouro Municipal de Ponta Grossa, Paraná, Brazil, and stored into distilled water until the preparation of specimens. The specimens were randomly distributed into the experimental groups: positive control: CarbopolTM EDT2020 gel containing 37.5% carbamide peroxide without nanoparticles (37.5%PC), CarbopolTM EDT2020 gel containing 37.5% carbamide peroxide and 5% bioglass nanoparticles (37.5%+5%BvPC),CarbopolTM EDT2020 gel containing 37.5% carbamide peroxide and 5% hydroxyapatite nanoparticles (37.5% PC+5%HaP), CarbopolTM EDT2020 gel containing 5% bioglass nanoparticles (5%Bv), CarbopolTM EDT2020 gel containing 5% hydroxyapatite nanoparticles (5%HaP), negative control: CarbopolTM EDT2020 gel (CAR), a non-treated group (D). These formulations were applied in 3 sessions after 5 days from each one, during 45 min per session, divided into 3 applications of 15 min. The specimens were evaluated using morphological and chemical analyses (scanning electron microscopy, energy-dispersive Xray spectroscopy and atomic force microscopy), roughness and hardness. The permeability of peroxide hydrogen was investigated for 37.5%PC, 37.5%PC+5%Bv and 37.5%PC+5%HaP and compared to group D. An artificial pigmentation process based on red wine and black tea was used to evaluate the whitening effect of 37.5%PC, 37.5%PC+5%Bv and 37.5%PC+5%HaP. Morphological analyses confirmed the presence of particle aggregates on enamel surface for 37.5%PC+5%Bv, 5%Bv, 37.5%PC+%5HaP and 5%HaP. Only 37.5%PC showed a statistically significant reduction (p < 0.05) of hardness and roughness when the initial and final results for each group were evaluated. The bleaching effect of 37.5%PC, 37.5%PC+5%Bv and 37.5%PC+5%HaP was successfully confirmed by the use of a portable spectrophotometer. Bioglass and hydroxyapatite nanoparticles avoid enamel demineralization caused by a 37.5% carbamide peroxide gel, prevent the diffusion of hydrogen peroxide to the pulp chamber and did not affect/reduce the whitening effect of carbamide peroxide 37.5%.
O objetivo deste estudo foi desenvolver e avaliar formulações inovadoras de gel de peróxido de carbamida contendo nanopartículas de biovidro (Bv) ou de hidroxiapatita (HaP) para o clareamento dental em consultório (PC) 37,5%, nas propriedades mecânicas do esmalte dental, na permeabilidade dentinária e efetividade do clareamento dental. A hipótese estabelecida para este trabalho é que as nanopartículas de Bv e de HaP podem mineralizar o esmalte e reduzir a difusão do peróxido de hidrogênio (PH) para a câmera pulpar, sem comprometer o potencial clareador. Foram selecionados dentes bovinos obtidos do Matadouro Municipal de Ponta Grossa, Paraná, Brasil, que foram armazenados em água destilada até a confecção dos corpos de prova (CPs). Os CPs ou coroas foram distribuídos aleatoriamente e tratados com os seguintes grupos experimentais: controle positivo: gel de Carbopol® EDT2020 contendo PC 37,5%, sem a presença de nanopartículas de Bv e de HaP (37,5%PC), gel de Carbopol® EDT2020 contendo PC 37,5% e adicionado 5% de nanopartículas de Bv (37,5%PC+5%Bv), gel de Carbopol® EDT2020 contendo PC 37,5% e adicionado 5% de nanopartículas de HaP (37,5%PC+5%HaP), gel de Carbopol® EDT2020 contendo 5% de nanopartículas de Bv (5%Bv), gel de Carbopol® EDT2020 contendo 5% de nanopartículas de HaP (5%HaP), controle negativo: gel de Carbopol® EDT2020 (CAR) e grupo sem nenhum tratamento (D). As formulações foram aplicadas em 3 sessões, a cada 5 dias, sendo que o gel permaneceu em contato com o dente por um período total de 45 min por sessão, dividido em 3 aplicações de 15 min. Os CPs foram submetidos às análises morfológicas e químicas de superfície (microscopia eletrônica de varredura, energia dispersiva de raios X e microscopia de força atômica), à rugosidade superficial e à dureza superficial. Os dentes foram tratados com os grupos 37,5%PC, 37,5%PC+5%Bv e 37,5%PC+5%HaP, para avaliar à permeabilidade do PH frente ao grupo D. O efeito clareador dessas formulações contendo PC foi investigado por meio do processo de pigmentação artificial, empregando vinho tinto e chá-preto. As análises morfológicas confirmaram a presença de agregados de partículas na superfície do esmalte, tanto para os grupos contendo biovidro (37,5%PC+5%Bv e 5%Bv), quanto para os grupos com hidroxiapatita (37,5%PC+5%HaP e 5%HaP). Com relação à rugosidade superficial e microdureza superficial, apenas o grupo 37,5%PC apresentou uma redução estatisticamente significativa (p<0,05), comparando-se os resultados iniciais e finais para cada grupo. A efetividade clareadora dos grupos 37,5%PC, 37,5%PC+5%Bv e 37,5%PC+5%HaP foi avaliado com o auxílio de um espectrofotômetro portátil, comprovando a eficácia dos três tratamentos. As nanopartículas de Bv e HaP reduziram a desmineralização do esmalte causada pelo gel PC 37,5%, impediram a difusão do PH para a câmara pulpar e não afetaram/ reduziram a efetividade do clareamento com PC 37,5%.

The aim of this chapter is to cover the management of more complicated clinical problems associated with children and adolescents: tooth discolouration, inherited enamel and dentine defects, hypodontia, and tooth surface loss. As there is considerable overlap in the application of the various restorative techniques, the chapter is divided into two parts. The first outlines the clinical steps involved in the various procedures, while the second covers the more general principles of management of particular dental problems. It is not the remit of this chapter to cover advanced restorative dentistry in detail, but many of the techniques and indications used in children are the same as those for adults (Boxes 11.1 and 11.2). With the aid of some clinical examples, eight of the restorative procedures will be described in simple stages. Omitted from this list are the stages involved in the provision of full crown restorations and bridgework, which are the specific remit of a restorative dentistry textbook. However, the provision of porcelain veneers, more commonly associated with adult patients, will be mentioned briefly. This technique involves the daily placement of carbamide peroxide gel into a custom-fitted tray on either the upper or the lower arch. As the name suggests, it is carried out by the patient at home and is initially done on a daily basis. • Mild fluorosis. • Moderate fluorosis as an adjunct to hydrochloric acid–pumice micro-abrasion. • Yellowing of ageing. • Single teeth with sclerosed pulp chambers and canals. • Selective bleaching for aesthetic purposes. • Upper impression and working model. • Soft mouthguard—avoiding the gingival tissues. • 10% carbamide peroxide gel. 1. Take an alginate impression of the arch to be treated and cast a working model in stone. 2. Relieve the labial surfaces of the teeth by about 0.5mm and make an acrylic pull-down vacuum-formed splint as a mouthguard with or without reservoirs for bleaching agent on the teeth requiring lightening. The splint should be no more than 2mm thick and should not cover the gingival tissues. It is only a vehicle for the bleaching gel and is not intended to protect the gingivae.