O objetivo deste estudo clínico randomizado duplo cego boca-dividida foi avaliar, in vivo, a efetividade do condicionamento ácido prévio do esmalte e de géis clareadores a base de peróxido de hidrogênio (PH) de baixa concentração, associados a fontes de luz híbrida (LH), tendo como variáveis de reposta: sensibilidade dental, fluxo sanguíneo pulpar, grau de mudança e estabilidade de cor ao longo de 6 meses. Trinta e seis voluntários que se encaixaram nos critérios de inclusão e exclusão foram selecionados e randomizados em 3 grupos (n=12), de acordo com o protocolo clareador a ser utilizado. Dentro de cada grupo, um dos hemiarcos foi aleatoriamente selecionado para a realização do condicionamento ácido do esmalte, previamente a aplicação do gel clareador. Os géis que compunham os três protocolos clareadores foram: PH a 10% (experimental) associado a LH a base de LED violeta + laser de diodo (experimental); PH a 15% associado a LH a base de LED azul + laser de diodo; e PH a 35% sem ativação com fonte de luz. A sensibilidade foi avaliada com a escala VAS; a fluxometria pulpar, com o sistema Laser Doppler; e a cor pelo cálculo do ?E via espectrofotômetro. Os dados foram tratados pela análise de variância de medidas repetidas (ANOVA), Tukey e teste de Friedman (p<0,05). Com relação à sensibilidade, foram encontradas diferenças significativas na interação tempo e grupo, mas não com relação ao ácido. Quanto à vascularização pulpar, o efeito de grupo não foi rejeitado, sendo o grupo de PH a 35% o que apresentou as menores medianas para as variações percentuais, porém os efeitos de ácido e tempo não foram significativos. Quanto à cor, diferenças significantes foram encontradas entre os grupos, mas não com relação ao uso do ácido, sendo o PH a 35% o que promoveu maior aumento do ?E. Conclui-se assim que o condicionamento ácido não foi capaz de favorecer a efetividade do clareamento em função do grau de mudança e estabilidade de cor, bem como não aumentou a sensibilidade e o fluxo sanguíneo da polpa dental. A concentração dos agentes clareadores foi determinante para o grau de mudança de cor e demonstrou influenciar a sensibilidade e o fluxo sanguíneo pulpar. / The aim of this double blind split-mouth randomized clinical study was to evaluate, in vivo, the effectiveness of prior acid etching on enamel and low concentration bleaching gels based on hydrogen peroxide (HP) associated with hybrid light (HL) sources, having as response variables: dental sensitivity, dental pulp vascularization and degree of color change and stability over 6 months. Thirty-six volunteers in agreement with the inclusion and exclusion criteria were selected and randomly divided into 3 groups (n = 12) according to the bleaching protocol to be used. Within each group, one of the sides was randomly selected for the execution of acid etching prior to the gel application. The three bleaching gels were: 10% HP (experimental) associated with HL-based violet LED/laser (experimental); 15% HP associated with HL-based blue LED/laser; and 35% HP without light activation. Sensitivity was evaluated with the VAS scale; pulp flowmetry by the use of the Laser Doppler system; and efficacy was evaluated by calculating the ?E via a spectrophotometer. Data were analyzed by analysis of variance for repeated measures (ANOVA), Tukeys and Friedman tests (p<0.05). Regarding sensitivity, significant differences were found in the interaction between the application time and group but not regarding etching. For dental pulp flowmetry, the group effect was not rejected, where the 35% HP showed the lowest medians for the percentile variations, but the effects of etching and time were not significant. For color, significant differences were found between the groups, but not between the sides with and without acid etching, where the 35% HP gel promoted the highest increase in ?E. It is therefore concluded that the etching was not able to favor the effectiveness of whitening due to color variation and stability, as well as not increasing sensitivity or pulp blood flow. The concentration of bleaching agents determined the degree of color change and influenced the sensitivity and blood flow of the dental pulp.

O objetivo deste estudo clínico randomizado duplo cego boca-dividida foi avaliar, in vivo, a efetividade do condicionamento ácido prévio do esmalte e de géis clareadores a base de peróxido de hidrogênio (PH) de baixa concentração, associados a fontes de luz híbrida (LH), tendo como variáveis de reposta: sensibilidade dental, fluxo sanguíneo pulpar, grau de mudança e estabilidade de cor ao longo de 6 meses. Trinta e seis voluntários que se encaixaram nos critérios de inclusão e exclusão foram selecionados e randomizados em 3 grupos (n=12), de acordo com o protocolo clareador a ser utilizado. Dentro de cada grupo, um dos hemiarcos foi aleatoriamente selecionado para a realização do condicionamento ácido do esmalte, previamente a aplicação do gel clareador. Os géis que compunham os três protocolos clareadores foram: PH a 10% (experimental) associado a LH a base de LED violeta + laser de diodo (experimental); PH a 15% associado a LH a base de LED azul + laser de diodo; e PH a 35% sem ativação com fonte de luz. A sensibilidade foi avaliada com a escala VAS; a fluxometria pulpar, com o sistema Laser Doppler; e a cor pelo cálculo do ?E via espectrofotômetro. Os dados foram tratados pela análise de variância de medidas repetidas (ANOVA), Tukey e teste de Friedman (p<0,05). Com relação à sensibilidade, foram encontradas diferenças significativas na interação tempo e grupo, mas não com relação ao ácido. Quanto à vascularização pulpar, o efeito de grupo não foi rejeitado, sendo o grupo de PH a 35% o que apresentou as menores medianas para as variações percentuais, porém os efeitos de ácido e tempo não foram significativos. Quanto à cor, diferenças significantes foram encontradas entre os grupos, mas não com relação ao uso do ácido, sendo o PH a 35% o que promoveu maior aumento do ?E. Conclui-se assim que o condicionamento ácido não foi capaz de favorecer a efetividade do clareamento em função do grau de mudança e estabilidade de cor, bem como não aumentou a sensibilidade e o fluxo sanguíneo da polpa dental. A concentração dos agentes clareadores foi determinante para o grau de mudança de cor e demonstrou influenciar a sensibilidade e o fluxo sanguíneo pulpar. / The aim of this double blind split-mouth randomized clinical study was to evaluate, in vivo, the effectiveness of prior acid etching on enamel and low concentration bleaching gels based on hydrogen peroxide (HP) associated with hybrid light (HL) sources, having as response variables: dental sensitivity, dental pulp vascularization and degree of color change and stability over 6 months. Thirty-six volunteers in agreement with the inclusion and exclusion criteria were selected and randomly divided into 3 groups (n = 12) according to the bleaching protocol to be used. Within each group, one of the sides was randomly selected for the execution of acid etching prior to the gel application. The three bleaching gels were: 10% HP (experimental) associated with HL-based violet LED/laser (experimental); 15% HP associated with HL-based blue LED/laser; and 35% HP without light activation. Sensitivity was evaluated with the VAS scale; pulp flowmetry by the use of the Laser Doppler system; and efficacy was evaluated by calculating the ?E via a spectrophotometer. Data were analyzed by analysis of variance for repeated measures (ANOVA), Tukeys and Friedman tests (p<0.05). Regarding sensitivity, significant differences were found in the interaction between the application time and group but not regarding etching. For dental pulp flowmetry, the group effect was not rejected, where the 35% HP showed the lowest medians for the percentile variations, but the effects of etching and time were not significant. For color, significant differences were found between the groups, but not between the sides with and without acid etching, where the 35% HP gel promoted the highest increase in ?E. It is therefore concluded that the etching was not able to favor the effectiveness of whitening due to color variation and stability, as well as not increasing sensitivity or pulp blood flow. The concentration of bleaching agents determined the degree of color change and influenced the sensitivity and blood flow of the dental pulp.

Indiana University-Purdue University Indianapolis (IUPUI) / This study was conducted in order to determine if there is any change in the active ingredient of tooth-whitening agents when the products are received from the manufacturer (Baseline), two months, four months, and six months after they are received, under two different storage conditions. Thirty-six products were received from multiple manufacturers: eight with hydrogen peroxide and 28 carbamide with peroxide products. All the bleaching syringes for a specific product were from the same lot. Once the products were received, one sample of each product was stored at room temperature and the other sample was stored in a refrigerator. Assays to determine the baseline concentration were performed within the first two weeks of their arrival and again 2 months, 4 months, and 6 months after receiving the products. All samples were analyzed for peroxide content by using the United States Pharmacopeia recommended method. The results obtained from this study show the following: 1. Bleaching products have different concentrations than what are indicated on the label. 2. Storage of bleaching products for an extended time at room temperature can cause bleaching products to lose some of their potency. 3. The preferable storage condition verified in this study is under refrigeration.

Submitted by Kamila Costa (kamilavasconceloscosta@gmail.com) on 2015-06-24T20:51:58Z No. of bitstreams: 1 Dissertação-Cristiano P e Silva.pdf: 2768387 bytes, checksum: 2918349c69f33356b77eef93c4a83a6b (MD5) / Approved for entry into archive by Divisão de Documentação/BC Biblioteca Central (ddbc@ufam.edu.br) on 2015-07-08T18:16:12Z (GMT) No. of bitstreams: 1 Dissertação-Cristiano P e Silva.pdf: 2768387 bytes, checksum: 2918349c69f33356b77eef93c4a83a6b (MD5) / Approved for entry into archive by Divisão de Documentação/BC Biblioteca Central (ddbc@ufam.edu.br) on 2015-07-08T18:19:19Z (GMT) No. of bitstreams: 1 Dissertação-Cristiano P e Silva.pdf: 2768387 bytes, checksum: 2918349c69f33356b77eef93c4a83a6b (MD5) / Made available in DSpace on 2015-07-08T18:19:19Z (GMT). No. of bitstreams: 1 Dissertação-Cristiano P e Silva.pdf: 2768387 bytes, checksum: 2918349c69f33356b77eef93c4a83a6b (MD5) Previous issue date: 2015-02-06 / Não Informada / After completing the tooth bleaching, reaction products remain in the tooth structure not allowing the correct polymerization of adesives restorations. The purpose of this study was to investigate the antioxidants effects of sodium ascorbate hydrogel on the residual oxygen in the bovine enamel structure bleached with hydrogen peroxide and after restorated with composite resin. One hundred and twenty bovines teeth were divided into twelve groups (n: 10), the groups G1;G2;G3;G4;G5;G6 were subjected to a test of shear strength after one week, the groups G7;G8;G9;G10;G11;G12 were tested after six months (aged), being G1; G7 - restored without bleaching ; G2; G8 - bleached and restored after fourteen days; G3; G9 - bleached and restored at the same day; G4; G10 - bleached, treated with sodium ascorbate hydrogel of 10% and restored; G5; G11 - bleached, treated with sodium ascorbate hydrogel of 20% and restored and G6; G12 - bleached, treated with sodium ascorbate hydrogel of 40% and restored. The results of the shear test were subjected to two ANOVA’s criteria and Tukey's analysis to compare the scores (p≤ 0,05). The groups G1: 152,6N +- 21,2; G2: 183,2N +- 31,4; G5: 171,53N +- 20,6; G6: 179,9N +- 33,1 showed similar resistance to shear and the groups G3: 99,3N +- 33,9; G4: 101,3N +- 29,3 were statistically significant lower resistance. The second group had lower shear resistance, however maintained the same pattern of statistical difference between the groups. The aged groups G7: 98,1 +- 22,6; G8: 111,9 +- 34,0; G11: 91,9 +- 24,0; G12: 90,0 +- 13,1 showed lower shear resistance when compared to the non-aged. However, when compared between the aged, as well as between no-aged, the groups G9: 59,3 +- 19,9; G10: 59,7 +- 10,9 also showed lower resistance when compared to the others groups. We can conclude that the tooth bleaching with 35% hydrogen peroxide promoted reduction of the bond strength. In addition, treatment of the bleached enamel with 20% and 40% sodium ascorbate hydrogel allowed to reach values of bond strength similar of the enamel not bleached. / Após finalizar o tratamento de clareamento dentário os subprodutos da reação permanecem na estrutura dentária impedindo a correta polimerização das restaurações adesivas. O objetivo deste trabalho foi investigar os efeitos antioxidantes do hidrogel de ascorbato de sódio sobre o oxigênio residual na estrutura de esmalte bovino clareado com peróxido de hidrogênio e posteriormente restaurado com resina composta. Cento e vinte dentes bovinos foram divididos em 12 grupos (n=10), os grupos G1;G2;G3;G4;G5;G6 foram submetidos ao teste de cisalhamento após uma semana, os grupos G7;G8;G9;G10;G11;G12 foram testados após seis meses (envelhecimento), sendo G1;G7 - restaurado sem clareamento; G2;G8 - clareado e restaurado após 14 dias; G3;G9 - clareado e restaurado no mesmo dia; G4;G10 - clareado, tratado com hidrogel de ascorbato de sódio 10% e restaurado; G5;G11 - clareado, tratado com hidrogel de ascorbato de sódio a 20% e restaurado e G6;G12 - clareado, tratado com hidrogel de ascorbato de sódio a 40% e restaurado. Os resultados do teste de cisalhamento foram submetidos a ANOVA a 2 critérios e teste de Tukey para comparação das medias (p≤ 0,05). Os grupos G1: 152,6N +-­‐ 21,2; G2: 183,2N +-­‐ 31,4; G5: 171,53N +-­‐ 20,6; G6: 179,9N +-­‐ 33,1 apresentaram resistência ao cisalhamento semelhante e os grupos G3: 99,3N +-­‐ 33,9; G4: 101,3N +-­‐ 29,3 apresentaram resistência inferior estatisticamente significativa. O segundo grupo apresentou menor resistência ao cisalhamento porém, mantive o mesmo padrão de diferença estatística entre os grupos. Os grupos envelhecidos G7: 98,1N +- 22,6; G8: 111,9N +- 34,0; G11: 91,9N +- 24,0; G12: 90,0N +- 13,1 apresentaram menor resistência ao cisalhamento quando comparados aos não envelhecidos. No entanto, quando comparado entre os envelhecidos, assim como nos não envelhecidos, os grupos G9: 59,3N +- 19,9; G10: 59,7N +- 10,9 também apresentaram resistência inferior comparado aos demais grupos. Podemos concluir que o clareamento dental com o peróxido de hidrogênio a 35% promoveu redução da resistência adesiva. Além disso, o tratamento do esmalte clareado com hidrogel de ascorbato de sódio a 20% e a 40% permitiu alcançar valores de resistência de união similar ao esmalte não clareado.

Objectives: To measure the level of hydrogen peroxide penetration into the pulp chamber and to evaluate its whitening efficacy when the tooth is treated with an innovative double layer of potassium nitrate desensitizing agent and hydrogen peroxide whitening gel. Methods: Extracted human molar teeth (n=160) were collected. Roots were trimmed 3 mm apical to the cemento-enamel junction, the pulp was removed and a cavity prepared, leaving a standardized wall of 2 mm thickness, which retained 100 µL of acetate buffer solution. A standardized whitening area of 6 mm in diameter was established buccally by painting the rest of the tooth with gray nail varnish. The teeth were randomly assigned into four groups. Group 1: no treatment (glycerin gel, negative control); Group 2: double layer of 20 L 5% potassium nitrate (Relief ACP, Philips Oral Healthcare) and 100 L 25% hydrogen peroxide (Zoom Chairside Whitening Gel, Philips Oral Healthcare); Group 3: double layer of 40 L 5% potassium nitrate and 100 L 25% hydrogen peroxide; and Group 4: 100 L 25% hydrogen peroxide (positive control). All groups received three 45-minute sessions of in-office whitening with light activation at 3-day intervals. Hydrogen peroxide penetration was assessed spectrophotometrically using leucocrystal violet and horseradish peroxidase. Color measurements were assessed with VITA Easyshade at baseline, 1-day, and 1-month post-whitening. Tooth color change was measured per Commission Internationale de l'Eclairage methodology. One-way ANOVA with Tukey multiple comparisons adjustment was performed to compare group differences in overall tooth color change (Delta E*) and hydrogen peroxide penetration (type I error = 0.05). Results: Hydrogen peroxide penetration levels were not significantly different between Group 2 and Group 4; however, the levels were significantly higher than Group 1 and Group 3 (p< 0.0001). Groups 2, 3 and 4 showed no differences for overall tooth color change but differed significantly from the negative control group (Group 1) at 1-day and 1-month post-whitening. Conclusions: Hydrogen peroxide penetration was affected when pretreated by potassium nitrate desensitizer; however, the double layer technique did not adversely affect the whitening efficacy.

Objectives: Evaluate and assess the effect of an innovative double layer, single application desensitizing/whitening technique on Nitrate penetration and total color change. Methods: Specimens were prepared from extracted caries free human molars (n=160). Teeth were randomly assigned into four groups: 100μl 25% hydrogen peroxide “Philips Zoom chairside” as control group (CTRL), double layer treatment of 20μl 5% potassium nitrate “Relief ACP, Philips oral care” and 100μl 25% hydrogen peroxide (DL20), double layer treatment of 40μl 5% potassium nitrate and 100μl 25% hydrogen peroxide (DL40), and one layer treatment of 40 μl 5% potassium nitrate (PN40). Spectrophotometric color measurements (Vita EasyShade) were done at base line (T0), one day (T1), and one month (T2) following the treatment. Nitrate penetration was measured using a nitrate/nitrite assay kit. Group comparisons of tooth color difference measurements, and nitrate penetration readings were made using the Kruskal-Wallis test. Adjustment was made for pairwise treatment comparisons using the Tukey method in conjunction with an overall 0.05 level of significance. Results: 160 teeth were used. Color difference (ΔE) results at (T1) and (T2) showed no significant difference among the CTRL, DL20, DL40 groups. But there was a statistical significant difference between those groups and the single layer (PN40) group (p

Chlorhexidine mouth rinses remove dental plaque from teeth, preventing dental caries, dental decay, and more serious systemic infections. Tooth discoloration due to extrinsic staining is the most prominent side effect of regular chlorhexidine use. Decreasing the concentration of chlorhexidine reduces staining area and severity. Staining can also be prevented and treated by tooth bleaching, a common cosmetic dental procedure that diminishes extrinsic staining by oxidizing chromagens adsorbed onto the tooth surface. In the proposed trial, common bleaching agents will be investigated for their efficacies in preventing chlorhexidine staining. Results of the trial could further the development of a chlorhexidine mouth rinse that is suitable for long term use.

Magister Scientiae - MSc / The main hypothesis in this study is the development of a nanocomposite mediated amperometric biosensor for detection of hydrogen peroxide. The aim is to combine the electrochemical properties of both polyaniline and ferrocenium hexafluorophosphate into highly conductive nano composites capable of exhibiting electrochemistry in non acidic media; shuttling electrons between HRP and GCE for biosensor applications. / South Africa

Made available in DSpace on 2014-12-17T14:13:27Z (GMT). No. of bitstreams: 1 MariaCSM_Capa_ate_cap4.pdf: 6011904 bytes, checksum: 63effbb0509556702ce462b8f08c7651 (MD5) Previous issue date: 2008-04-11 / The aim of the present study was to assess the effectiveness and adverse effects on dental enamel caused by nightguard vital bleaching with 10% carbamide peroxide. This was accomplished through the interaction of researchers from different areas such as dentistry, materials engineering and physics. Fifty volunteers took part in the doubleblind randomized controlled clinical trial. They were allocated to an experimental group that used Opalescence PF 10% (OPA) and a control group that used a placebo gel (PLA). Fragments of human dental enamel from the vestibular surface of healthy premolars, extracted for orthodontic reasons, were fixed to the vestibular surface of the first upper molars of the volunteers for in situ observation. Bleaching was performed at night for 21 days. The observation periods included Baseline (BL), T0 (21 days), T30 (30 days after treatment) and T180 (180 days after treatment, only for the OPA group). Tooth color was assessed by comparing it with the Vita? scale and by the degree of satisfaction expressed by the volunteer. We also assessed adverse clinical effects, dental sensitivity and gingival bleeding. The study of adverse effects on enamel was conducted in vivo and in situ, using the DIAGNOdent? laser fluorescence device to detect mineral loss. Scanning electron microscopy (SEM) was used to check for superficial morphological alterations, energy dispersive spectrophotometry (EDS) to semiquantitatively assess chemical composition using the Ca/P ratio, and the x-ray diffraction (XRD) technique to observe alterations in enamel microstructure. The results showed that nightguard vital bleaching with 10% carbamide peroxide was effective in 96% of the cases, versus 8% for the PLA group. Dental sensitivity was present in 36% (9/25) of the cases. There was no significant association between gingival bleeding and the type of gel used (p = 1.00). In vivo laser fluorescence analysis showed no difference in values for the control group, whereas in the OPA group there was a statistically significant difference between baseline values in relation to the subsequent periods (p<0.01), with lower mean values for post-bleaching times. There was a significant difference between the groups for times T0 and T30. Micrographic analysis showed no enamel surface alterations related to the treatment performed. No significant alteration in Ca/P ratio was observed in the OPA group (p = 0.624) or in the PLA group (p = 0.462) for each of the observation periods, nor between the groups studied (p=0.102). The XRD pattern for both groups showed the presence of three-phase Hydroxyapatite according to JCPDS files (9-0432[Ca5(PO4)3(OH)], 18-0303[Ca3(PO4)2.xH2O] and 25-0166[Ca5(PO4)3(OH, Cl, F)]). No other peak associated to other phases was found, independent of the group analyzed, which reveals there was no disappearance, nucleation or phase transformation. Neither was there any alteration in peak pattern location. With the methodology and protocol used in this study, nightguard vital bleaching with 10% carbamide peroxide proved to be an effective and safe procedure for dental enamel / O presente estudo objetivou avaliar a efetividade e os efeitos adversos sobre o esmalte dent?rio promovidos pelo clareamento caseiro supervisionado pelo dentista com per?xido de carbamida a 10% e s? foi poss?vel mediante a intera??o de alguns pesquisadores das mais variadas ?reas do conhecimento como a Odontologia, a Engenharia de Materiais e a F?sica. Cinq?enta volunt?rios participaram de um ensaio cl?nico controlado e randomizado duplo-cego e foram alocados em um grupo experimental, que utilizou Opalescence PF 10% (OPA) e um grupo controle que usou um gel placebo (PLA). Fragmentos de esmalte dent?rio humano provenientes da face vestibular de pr?-molares h?gidos, extra?dos por motivos ortod?nticos, foram fixados ? superf?cie vestibular dos primeiros molares superiores dos volunt?rios objetivando uma observa??o in situ. O tempo do clareamento foi de 21 dias em regime noturno. Os per?odos de observa??o compreenderam a Linha Base (LB), T0 (21 dias), T30 (30 dias ap?s o tratamento) e T180 (180 dias ap?s o tratamento) sendo este ?ltimo apenas para o grupo OPA. A avalia??o da cor dos dentes foi feita pela compara??o com a escala Vita? e atrav?s do grau de satisfa??o do volunt?rio em rela??o ao tratamento. Adicionalmente, avaliaram-se os efeitos cl?nicos adversos, sensibilidade dent?ria e sangramento gengival. O estudo dos efeitos adversos ao esmalte dent?rio foi realizado in vivo e in situ, atrav?s da fluoresc?ncia a laser com o uso do DIAGNOdent?, objetivando detectar perdas de mineral. Foram empregadas ainda, a Microscopia Eletr?nica de Varredura (MEV), para verificar altera??es morfol?gicas superficiais, a Espectrometria de Energia Dispersiva (EDS), para avaliar semiquantitativamente a composi??o qu?mica atrav?s do ratio Ca/P, e a t?cnica de Difra??o de Raio-X (DRX) com a finalidade de observar altera??es na microestrutura do esmalte. Os resultados revelaram ser a t?cnica de clareamento caseiro com per?xido de carbamida a 10% efetiva em 96% dos casos, contra 8% do grupo PLA, apresentando 36% (9/25) de sensibilidade dent?ria. N?o houve associa??o significativa entre a presen?a de sangramento gengival e o tipo de gel utilizado (p=1,00). A an?lise da fluoresc?ncia a laser in vivo n?o revelou diferen?a nos valores para o grupo controle, enquanto no grupo OPA houve diferen?a estatisticamente significativa entre os valores da linha base em rela??o aos per?odos subseq?entes (p<0,01), com valores m?dios menores nos tempos p?s-clareamento. Entre os grupos, houve diferen?a significativa nos per?odos T0 e T30. A avalia??o das micrografias n?o revelou altera??es na superf?cie do esmalte que possam ser relacionadas ao tratamento realizado. Nenhuma altera??o significativa na propor??o Ca/P foi observada no grupo OPA (p=0,624) nem no grupo PLA (p=0,462) para cada um dos per?odos de observa??o, nem entre os grupos estudados (p=0,102). O padr?o da DRX para todos os grupos evidenciou a presen?a de tr?s fases relativas ? hidroxiapatita de acordo com os arquivos JCPDS (9-0432[Ca5(PO4)3(OH)], 18- 0303[Ca3(PO4)2.xH2O] e 25-0166[Ca5(PO4)3(OH,Cl,F)]). Nenhum outro pico associado a outras fases foi encontrado, independente do grupo analisado, o que revela n?o ter havido desaparecimento, nuclea??o ou transforma??o de fases. Pode-se constatar ainda que n?o houve altera??o no padr?o dos picos em rela??o ? localiza??o dos mesmos. Atrav?s da metodologia empregada neste estudo, pode-se concluir que o clareamento caseiro supervisionado pelo dentista com per?xido de carbamida a 10%, dentro do protocolo aqui utilizado, se mostrou um procedimento efetivo e seguro para o esmalte dent?rio

Indiana University-Purdue University Indianapolis (IUPUI) / Whitening dentifrices use different mechanisms for stain removal and prevention. These approaches are abrasives, oxidizing agents, and chemical cleaning agents. The objectives of this in-vitro study were: 1) To compare the whitening effect of commercial whitening and non-whitening dentifrices; 2) To verify the mechanism of action of whitening dentifrices by contrasting two experimental models: chemical model (toothpaste exposure only) and chemo-mechanical (toothpaste exposure with tooth-brushing abrasion). The 256 bovine enamel specimens (10 mm x10 mm) were prepared and partially stained. They were assigned to 8 groups: 6 whitening dentifrices, 1 non-whitening reference dentifrice and deionized water (control); and they were further divided in 2 subgroups (n = 16), chemical and chemo-mechanical. Specimens were exposed to dentifrice slurries 2X/day for 1 min and brushed or not, according to each model. In between dentifrice treatments, specimens were exposed to the staining solution for 5 h. This protocol was repeated for 5 consecutive days and enamel color changes (∆E, ∆L) were measured by spectrophotometry after each day. The abrasivity of the toothpastes was determined using a standard test (ISO 11609). Significantly higher ∆E values (whitening effect) were observed for all groups (p < 0.05), except for the control, when tested in the chemo-mechanical model. In this model, the whitening ability of the toothpastes was mainly determined by their abrasive levels. For the chemical model, no significant differences were observed among groups (p > 0.05). Whitening dentifrices can be effective in preventing and removing enamel surface staining, when associated with tooth-brushing abrasion. This was modulated by the abrasive level of the tested toothpastes, with no chemical action attributed to the chemical agents. / indefinitely