Sensibilidade dentária associada ao clareamento dental em dentes vitais - uma revisão de literatura

O clareamento dental pode ser realizado através da técnica caseira ou de consultório, utilizando agentes como o peróxido de carbamida (PC) e peróxido de hidrogênio (PH). Apesar de seguro, existem alguns efeitos adversos relacionados ao clareamento dental, como a sensibilidade dentinária (SD), que pode estar presente em diferentes graus dependendo da técnica utilizada. A aplicação de agentes dessensibilizantes antes, durante ou depois do clareamento dental vem sido estudada para evitar ou reduzir a sensibilidade associada ao clareamento. O estudo visa revisar a literatura em relação a aspectos e conceitos importantes do clareamento dental, discutindo seus possíveis efeitos adversos com foco na sensibilidade dentinária. Foi realizada uma pesquisa digital da base de dados Medline, via PubMed, utilizando palavras-chave relacionadas ao tema, priorizando artigos publicados há menos de 20 anos e escritos em inglês ou português. Artigos também foram buscados manualmente e foram utilizados livros de odontologias relacionados ao tema. De um total de 48 artigos, 28 foram escolhidos para a composição do trabalho, além de 2 livros de dentística que abordam o clareamento dental. Constata-se que a sensibilidade dentinária é um efeito adverso comum relacionado ao clareamento dental, que possui causa exata desconhecida, porém sabe-se que está relacionada à difusão do peróxido de hidrogênio pelos tecidos dentários. A sensibilidade dentinária é mais frequente na técnica de clareamento de consultório do que na técnica caseira, e pode ser agravada por fatores relacionados ao indivíduo e/ou ao dente. Alguns agentes como o nitrato de potássio, fosfopeptídeos de caseína-fosfato de cálcio amorfo (CPP-ACP), vidros bioativos e partículas de hidroxiapatita, se mostraram efetivos no controle da sensibilidade dentinária.

Dental bleaching can be performed in at-home or in-office techniques, using agents such as carbamide peroxide or hydrogen peroxide. Although it's safe, there are some side effects related to dental bleaching, such as tooth sensitivity, which may be present in different degrees, depending on the chosen technique. The application of desensitizing agents before, during or after dental bleaching is being studied to avoid or reduce the bleaching related sensitivity. The study aims to review the literature over important aspects and concepts of dental bleaching, discussing its possible side effects, focusing on tooth sensitivity. Methods: an online search was done on Medline's database, through PubMed, using keywords related to the theme, prioritizing articles published less than 20 years ago, written in English or Portuguese. Articles were also researched manually, and dentistry books related to the theme were used as well. Out of 48 articles, 28 were chosen to this study's composition, in addition to 2 books that approach dental bleaching. Tooth sensitivity is a common side effect related to dental bleaching, with an unknown cause, however, it is known that it's related to hydrogen peroxide's diffusion through dental tissues. Tooth sensitivity is more frequent within in-office technique than within at-home technique, and may be worsen by individual and/or dental related factors. Agents such as potassium nitrate, CPP-ACP, bioactive glasses and hydroxyapatite particles, showed up to be effective in dental sensitivity control.

Influence of repositioning guides' color and usage on precision in tooth color measurement with a clinical spectrophotometer

Abstract Repositioning guides are commonly employed in clinical studies to ensure consistent tooth color measurements. Yet, their influence on measured color remains uncertain. Objective This study evaluated the impact of repositioning guides' color and usage on tooth color measurement using a clinical spectrophotometer. Methodology In total, 18 volunteers participated in this study, in which the color of their upper left central incisor and upper left canine was measured with or without repositioning guides (control). The guides were made from pink, blue, or translucent silicone, as well as an acetate-based bleaching tray. Tooth color was measured in triplicates using a clinical spectrophotometer based on the CIELAB system. The standard deviations of these readings were used to estimate reproducibility, and color differences (ΔE00) between the measurements with guides and the control were calculated. Results Repositioning guides had a minimal effect on L* values and no effect on b* values. The use of pink silicone increased a* values, whereas blue or translucent silicone reduced them. Irrespective of the evaluated tooth, the lowest ΔE00 values were observed for the translucent silicone and bleaching tray. The usage of guides only affected data variability for the L* color coordinate. Conclusion Using repositioning guides can significantly impact the precision of tooth color measurement with a clinical spectrophotometer.

In-office dental bleaching in adolescents using 6% hydrogen peroxide with and without gingival barrier: a randomized double-blind clinical trial

Abstract At low concentrations used for in-office bleaching gels, such as 6% HP, gingival barrier continues to be performed. If we take into account that, in the at-home bleaching technique, no barrier is indicated, it seems that the use of a gingival barrier fails to make much sense when bleaching gel in low concentration is used for in-office bleaching. Objective This double-blind, split-mouth, randomized clinical trial evaluated the gingival irritation (GI) of in-office bleaching using 6% hydrogen peroxide (HP) with and without a gingival barrier in adolescents, as well as color change and the impact of oral condition on quality of life. Methodology Overall, 60 participants were randomized into which side would or would not receive the gingival barrier. In-office bleaching was performed for 50 minutes with 6% HP in three sessions. The absolute risk and intensity of GI were assessed with a visual analogue scale. Color change was assessed using a digital spectrophotometer and color guides. The impact of oral condition on quality of life was assessed using the Brazilian version of the Oral Health Impact Profile (α=0.05). Results The proportion of patients who presented GI for the "with barrier" group was 31.6% and for the "without barrier" group, 30% (p=1.0). There is an equivalence for the evaluated groups regarding GI intensity (p<0.01). Color change was detected with no statistical differences (p>0.29). There was a significant impact of oral condition on quality of life after bleaching (p<0.001). Conclusions The use or not of the gingival barrier for in-office bleaching with 6% HP was equivalent for GI, as well as for bleaching efficacy, with improvement in the impact of oral condition on quality of life.

Desensitizing Agent Previously Applied During In-Office Bleaching: A Double-Blind Randomized Clinical Trial

Abstract Objective: To compare the clinical effect of two desensitizing agents used before the application of a bleaching gel based on 35% hydrogen peroxide (HP). Material and Methods: 30 patients were selected, and two desensitizing agents with different mechanisms of action were applied: Fluorine Neutral 2% (FN), which acts by blocking dentinal canaliculi while Potassium Nitrate 5% with 2% Sodium Fluoride (PN/SF) that acts in nerve transmission and blockade. Desensitizers were used before the application of 35% HP. For whitening, three clinical sessions were performed, with an interval of seven days, with three applications of the bleaching gel for 15 minutes, totaling 45 minutes/session. Tooth sensitivity (TS) was assessed with the numerical analog scale, and a spectrophotometer was used to obtain the color variation (ΔE). ΔE were submitted to ANOVA and Tukey test (p<0.05), and TS data were submitted to a two-way ANOVA analysis. Results: For sensitivity experience, the Tukey test indicated differences between PN/SF and the placebo I, but there was no statistically significant difference between FN and the placebo II. The TS was lower when the desensitizing gel was used during the bleaching procedure compared to after treatment, regardless of the desensitizing agents. Conclusion: PN/SF before in-office tooth bleaching can reduce TS intensity, and the use of desensitizing gel before bleaching did not affect the bleaching efficacy.

Color stability of enamel treated with different antioxidant agents following at-home bleaching with 10% hydrogen peroxide

Abstract Objective This study evaluated the color stability of enamel submitted to 10% hydrogen peroxide (HP) followed by antioxidants agents, and the pH and antioxidant activity (AA%) of these agents. Methodology Bovine enamel-dentin blocks were randomly distributed into groups (n=10/group): GNC (negative control: no treatment); GPC (positive control: bleaching only); TOC_10% (HP+10% α-tocopherol); GT_10% (HP+10% green tea extract); GS_5% (HP+5% grape seed extract); SA_10% (HP+10% sodium ascorbate); QUI_10% (HP+10% quinoa extract); and QC_1% (HP+1% quercetin). Color (ΔE00) and whiteness index (ΔWID) changes were analyzed using a digital spectrophotometer. The pH and AA% were determined using a pH meter and the DPPH method, respectively. Data were analyzed by ANOVA/Tukey's and Dunnett's tests (α=0.05). Results At 14 days post-bleaching, GNC promoted the lowest ΔWID and ΔE00 (p<0.05), and no differences were found between GPC and the remaining groups submitted to the antioxidant agents (p>0.05). QC_1% and QUI_10% exhibited acidic pH levels (3.64 and 4.75, respectively), whereas TOC_10% and GS_5% exhibited alkaline pH (7.07 and 7.64, respectively). No differences in AA% were found between the agents (p>0.05), ranging from 92.6 to 97.6%. Conclusion The antioxidant agents did not interfere in bleached enamel color stability, showing satisfactory antioxidant activity. However, QUI and QC gels displayed acidic pH. Clinical significance: The antioxidants evaluated showed high AA% and no impact on post-bleaching color stability, suggesting that their capacity to recover bond strength demonstrated elsewhere would not compromise the esthetic efficacy of tooth bleaching. However, those with acidic pH should be used with caution due to potential enamel damage.

Effects of dentifrices containing activated charcoal on dental enamel: a review of the literature / Efeitos de dentifrícios contendo carvão ativado no esmalte dental: uma revisão da literatura

ABSTRACT The increased demand for white teeth has intensified the commercialization of new bleaching products, particularly those that can be accessed easily, do not require the direct supervision of a dentist, and are affordable. Among these new products, several dentifrices publicized as bleaching products have been developed, most recent of them being the activated charcoal toothpaste, which entered the market promising to whiten teeth. While it is portrayed as a healthy and ecological product, there is a paucity of scientific evidence supporting its alleged benefits. Therefore, this literature review aimed to evaluate activated charcoal containing oral hygiene products on their bleaching ability and effects on enamel. After analyzing several in vitro studies on the subject, it can be concluded that these products do not have a bleaching effect per se, but act by removing the extrinsic pigments from the teeth. However, most of the products containing activated charcoal could have abrasive effects on the surface of the enamel. Therefore, it is suggested caution about the indication of these dentifrices, especially for individuals predisposed to dental wear, such as gingival recession, reduced salivary flow, and high risk of caries or dental erosion.

RESUMO A maior procura por dentes brancos tem impulsionado a comercialização de novos produtos clareadores, especialmente aqueles que possam ser de fácil acesso, que não precisem supervisão direta do dentista, e que tenham um custo acessível para o consumidor. Entre esses novos produtos diversos dentifrícios, denominados como branqueadores, têm sido comercializados. Destes o mais recente é o dentifrício a base de carvão ativado, que entrou no mercado prometendo clarear os dentes, enquanto que se apresenta como um produto saudável e ecológico, porém sem grande respaldo científico. Portanto, esta revisão da literatura teve o objetivo de avaliar a capacidade branqueadora e os efeitos no esmalte após o uso de produtos de higiene oral contendo carvão ativado. Após avaliar diversos artigos in vitro sobre o tema, pode-se concluir que estes produtos não tem um efeito clareador propriamente dito e sim agem como removedores de pigmentos extrínsecos. Porém, grande parte dos produtos contendo carvão ativado poderiam apresentar um efeito abrasivo sobre a superfície do esmalte, pelo que se sugere cautela sobre a indicação destes dentifrícios, especialmente para os pacientes sujeitos a maiores riscos de desgaste dental, como recessão gengival, fluxo salivar reduzido, alto risco de cárie ou erosão dentária.

Color and surface roughness alterations of bulk-fill resin composites submitted to simulated toothbrushing with whitening dentifrices

Aim: To evaluate the surface roughness and color stability of bulk-fill resin composites after simulated toothbrushing with whitening dentifrices. The radioactive/relative dentin abrasion (RDA) and radioactive/relative enamel abrasion (REA) of dentifrices were also assessed. Methods: Specimens (n=10) of Tetric N Ceram Bulk Fill (TNCB), Filtek One Bulk Fill (FOB) resin composites, and Z100(Control) were prepared using a cylindrical Teflon matrix. Surface roughness (Ra, µm) was assessed by a roughness meter and the color evaluations (ΔEab , ΔE00 , WID ) were performed using a digital spectrophotometer based on the CIELAB system. Three measurements were performed per sample, before and after simulated toothbrushing with 3D Oral-B White Perfection (3DW) and Black is White (BW) dentifrices. The abrasivity (REA and RDA values) of the used dentifrices was also determined by the Hefferren abrasivity test. Results: The Ra values increased significantly in all resin composites after 3DW and BW toothbrushing. The acceptable threshold color varied among resin composites, and TNCB and Z100 presented the highest ΔEab and ΔE00 for BW dentifrice. The 3DW dentifrice was significantly more abrasive than BW dentifrice on enamel and dentin. Conclusions: simulated toothbrushing with tested whitening dentifrices increased the surface roughness at acceptable levels. The Tetric N Ceram Bulk-fill and Z100 composite showed the highest color alteration in BW. 3D White Perfection dentifrice was more abrasive on dentin and enamel than Black is White.

Efeito da adição de partículas bioativas ao gel clareador dental / Efeito da adição de partículas bioativas ao gel clareador dental

O estudo avaliou o efeito da adição de partículas bioativas ao gel clareador (peróxido de hidrogênio 35%, técnica de consultório), quanto ao clareamento e sobre a estrutura dental, além da resistência à desmineralização. O objetivo da primeira parte do estudo foi avaliar géis, com diferentes partículas bioativas e concentrações, para o potencial clareador e às alterações da estrutura dental. O objetivo da segunda parte foi avaliar géis, com diferentes partículas bioativas e concentrações, perante a suscetibilidade do esmalte ao protocolo cariogênico e ao desgaste dental erosivo. Espécimes de incisivos bovinos foram avaliados na primeira parte por análise da cor, microdureza Knoop e rugosidade. Os grupos foram controle negativo (CN), controle comercial (CCWhiteness HP), controle experimental (CE-gel sem partícula), controle positivo (CPsolução de peróxido), e os grupos experimentais onde as partículas bioativas S-PRG e 45S5 foram utilizadas nas concentrações de 5, 10, 15 e 20 %. Na segunda parte foram avaliados por microradiografia para a alteração da densidade mineral e profundidade da lesão perante o protocolo cariogênico e pela perfilometria para o desgaste dental erosivo. Os grupos foram CN, CC, CE, controle fluoreto (CF), e os grupos experimentais onde as partículas bioativas S-PRG e 45S5 foram utilizados nas concentrações de 15 e 20 % apenas. Os dados foram analisados estatisticamente para verificar a diferença entre os grupos (α=5%). Para a mudança de cor (∆E*00) foi observada diferença apenas para o fator partícula, S-PRG-3,37(0,48)a e 45S5-3,67(0,76)b. Todos os grupos experimentais foram estatisticamente iguais o CP e diferentes do CN. Para a microdureza (KNH%) foi observada diferença para a interação dos fatores, sendo o S-PRG 20% o grupo com maior aumento da microdureza. Todos os grupos experimentais foram diferentes e maiores que CP, CC e CE. Não foram observadas diferenças de rugosidade entre os grupos. Para a alteração da densidade mineral foi observada diferença para a interação dos fatores e tempo. Os grupos S-PRG 15% e 20% foram os grupos que apresentaram a menor alteração da densidade mineral em todos os tempos testados. Aos 14 e 21 dias o SPRG 20% foi diferente do CN e semelhante ao CF. Para a profundidade da lesão foram observadas diferenças estatísticas para o fator partícula e tempo, S-PRG206,8(59,2)a e 45S5 230,0(63,7)b, 7 dias-148,9(19,7)a, 14 dias-217,7(22,5)b e 21 dias288,7(30,7)c. Aos 14 e 21 dias o S-PRG 20% foi diferente do CN e semelhante ao CF. Para o desgaste foi observada diferença apenas para o tempo, 5 dias-1,2(0,2)a e 10 dias-2,3(0,3)b. Conclui-se que: a adição de partículas bioativas não reduziu a efetividade clareadora, contribuiu para o aumento da microdureza e não alterou a rugosidade. Além disso, o grupo S-PRG com 20% teve suscetibilidade à desmineralização por cárie semelhante ao grupo controle fluoreto e nenhum grupo alterou a suscetibilidade ao desgaste dental erosivo (AU)

The study evaluated the consequences of bioparticle addition on tooth bleaching gel (hydrogen peroxide 35%, in-office technique), for its bleaching effect and changes on tooth structure, also for resistance against demineralization. The aim of the first part of the study was to evaluate bleaching gels containing different bioactive particles and concentrations over the bleaching potential and possible dental structural changes. The objective of the second part was to evaluate bleaching gels containing different bioactive particles and concentrations to assess enamel susceptibility to cariogenic and erosive tooth wear protocols after bleaching treatments. Bovine incisors specimens were used in the first part for analysis of color, Knoop microhardness and roughness. The groups were negative control (NC), commercial control (CCWhiteness HP), experimental control (EC-gel without particles), positive control (PCperoxide solution), and experimental groups were the bioactive particles S-PRG and 45S5 used in concentrations of 5, 10, 15, and 20 %. In the second part, specimens were evaluated using advanced transverse microradiography to assess the change in mineral density and lesion depth in response to the cariogenic protocol, and profilometry to measure wear in response to the erosive tooth wear protocol. The groups were NC, CC, EC, fluoride control (FC), and experimental groups were the bioactive particles S-PRG and 45S5 used only in concentrations of 15 and 20 %. The data were statistically analyzed to verify the differences between the groups (α=5%). For the color change (∆E*00), a difference was observed only for particle, S-PRG3,37(0,48)a and 45S5-3,67(0,76)b. All experimental groups were statistically similar to PC and different from NC. For the microhardness (KNH%), difference was observed for factors interaction, S-PRG 20% was the group with higher hardness increase. All experimental groups were different and higher than PC, CC, and EC. No roughness differences were observed between groups. For the mineral density alteration differences were observed for factors interaction and time. S-PRG 15% and 20% presented the lower mineral density change for all measurements times. On 14 and 21 days S-PRG 20% was different from NC and similar to FC. For lesion depth differences were observed for factor particle and time, S-PRG-206,8(59,2)a and 45S5- 230,0(63,7)b, 7 days-148,9(19,7)a, 14 days-217,7(22,5)b and 21 days-288,7(30,7)c. On 14 and 21 days S-PRG 20% was different from NC and similar to FC. For wear the only difference was for time, 5 days-1,2(0,2)a and 10 days-2,3(0,3)b. It was concluded that the addition of bioactive particles did not reduce the bleaching effectiveness, it contributed to microhardness increase and did not change roughness. Furthermore, the S-PRG group with 20% susceptibility to cariogenic demineralization was similar to the fluoride control group, and no group showed a change in susceptibility to erosive tooth wear (AU)

Does the combination of whitening toothpaste and hydrogen peroxide bleaching increase the surface roughness and change the morphology of a nanofilled composite?

Aim: To evaluate changes in the surface roughness and morphology of a nanofilled composite following toothbrushing with a whitening (WT) or regular toothpaste (RT), alone or combined with 35% hydrogen peroxide bleaching (HP). Methods: Seventy disc-shaped nanofilled composite (Filtek Z350XT) specimens were randomly divided into groups (n=10): WT, RT, TB (without toothpaste ­ control) or the combinations WT/ HP, RT/HP, TB/HP and HP. All groups underwent toothbrushing simulation (60,000 cycles) and bleaching treatment (4 sessions). Mean surface roughness (Ra, µm) was measured before (T0) and after treatments (TB). Surface morphology was assessed by scanning electron microscopy (SEM) at TB. Mean Ra was analyzed using general mixed models and multiple comparisons by the Tukey-Kramer test (α=5%). Results: HP caused no surface roughness changes on the nanofilled composite after treatment (p>0.05). RT toothbrushing, combined or not with HP, increased the surface roughness (p<0.05). WT and WT/ HP protocols had no effect on the surface roughness of the composite (p>0.05). The nanofilled composite submitted to RT toothbrushing combined with HP (RT/HP) presented substantial surface alterations under SEM, showing deep depressions and round-shaped defects. Toothbrushing with RT combined with the bleaching agent increased exposure of the inorganic fillers. Conclusion: WT toothbrushing, regardless of HP combination, or the single HP protocol had no effect on the surface roughness of the nanofilled composite. However, RT combined with HP negatively affected surface roughness and presented the most noticeable surface changes among groups

At-home bleaching versus whitening toothpastes for treatment of tooth discoloration: a cost-effectiveness analysis

Abstract Objectives This study aimed to analyze the cost-effectiveness of whitening toothpastes and at-home bleaching for the treatment of tooth discoloration. Methodology A cost-effectiveness economic analysis was conducted, and eight randomized clinical trials were selected based on the whitening agent product used: blue covarine dentifrices (BCD), hydrogen peroxide dentifrices (HPD), dentifrices without bleaching agents (CD, negative control), and 10% carbamide peroxide (CP10, positive control) for at-home bleaching. The consumer/patient perspective was adopted, macro-costing techniques were used and a decision tree model was performed considering the costs in the American and Brazilian markets. The color change evaluation (ΔE*ab) was used to calculate the effectiveness of tooth bleaching. A probabilistic analysis was performed using a Monte Carlo simulation and incremental cost-effectiveness ratios were obtained. Results CP10 resulted in the highest cost-effectiveness compared to the use of dentifrices in both markets. In Brazil, HPD was more cost-effective than BCD and CD. In the US, the increased costs of HPD and BCD did not generate any whitening benefit compared to CD. Conclusions CP10 was more cost-effective than BCD and HPD for tooth bleaching from the perspectives of the Brazilian and American markets. Decision-making should consider the use of CP10 for treating tooth discoloration.

Efeito do pH do gel clareador de consultório na cor e na sensibilidade dentária / Effect of the pHof the in-office tooth bleaching gelon color and tooth sensitivity / Efecto del pH del gel blanqueador dental de consultorio sobre el color y la sensibilidad dental

Introdução:Sabe-se que a busca pela estética é algo cada vez mais crescente. Dentre os procedimentos mais procurados na odontologia estética, destaca-se o clareamento dental de consultório. Diante disso, ainda são poucos os estudos que avaliam os efeitos dos agentes clareadores de diferentes pHs na efetividade clareadora e na sensibilidade dentária.Objetivo:Avaliar a sensibilidade dentária e a eficácia clareadora de géis clareadores à base de peróxido de hidrogênio a 35% com diferentes pHs.Metodologia:Trata-se de um relato de três casos, descritivo e observacional, do tipo boca dividida (split-mouth) para cada estratégia clareadora (gel clareador com pH básico e gel clareador com pH ácido). Foram avaliados três pacientes de25, 26e 27anos de idade.Realizou-se registro de cor por meio da escala VITAClassical e avaliação da sensibilidade dentária pela escala visual analógica. Resultados:Todos os pacientes avaliados apresentaram cor A3 no registro de cor inicial e, após o clareamento dental,atingiram a cor A1. Todos relataram uma maior sensibilidade no hemiarco direito (local onde foi aplicada o gel clareador Whiteness HP que possui pH ácido. Dois pacientes relataram sensibilidade dentária no hemiarco esquerdo em que foi aplicado o gel clareador de pH básico. Conclusões:Observa-se a eficácia clínica dos géis clareadores de consultório à base de peróxido de hidrogênio a 35% na estabilidade de cor após o tratamento clareador, independente do seu pH. Ademais, nota-se que o gel clareador de pH básico promoveu menor sensibilidade pós-operatória (AU).

Introduction:It is known that the search for aesthetics is something increasingly growing. Among the most sought-after procedures in cosmetic dentistry, in-office tooth bleaching stands out. Therefore, there are still few studies that evaluate the effects of bleaching agents ofdifferent pHs on bleaching effectiveness and tooth sensitivity.Objective:To evaluate tooth sensitivity and bleaching efficacy of 35% hydrogen peroxide-based tooth bleaching gels with different pHs.Methodology:This is a report of three cases, descriptive and observational, of the split-mouth type for each bleaching strategy (bleaching gel with basic pH and bleaching gel with acidic pH). Three patients aged 25, 26 and 27 years were evaluated. Color registration was performed using the VITA Classical scale and tooth sensitivity was evaluated using the visual analogue scale.Results:All evaluated patients presented color A3 in the initial color registration and, after tooth bleaching, reached color A1. All reported greater sensitivity in the right hemi-arch (place where the Whiteness HP bleaching gel with an acid pH was applied. Two patients reported tooth sensitivity in the left hemi-arch where the basic pH bleaching gel was applied.Conclusions:The clinical efficacy of in-office tooth bleaching gels based on 35% hydrogen peroxide in terms of color stability after bleaching treatment is observed, regardless of its pH. In addition, it is noted that the basic pH bleaching gel promoted less postoperative sensitivity (AU).

Introducción: Se sabe que la búsqueda de la estética es algo cada vez más creciente. Entre los procedimientos más populares en odontología estética, se destaca el blanqueamiento dental en consultorio. Ante esto, aún existen pocos estudios que evalúen los efectos de agentes blanqueadores de diferentes pHs sobre la efectividad del blanqueamiento y la sensibilidad dental.Objetivo: Evaluar la sensibilidad dental y la eficacia blanqueadora de geles blanqueadores a base de peróxido de hidrógeno al 35 % con diferentes pH. Metodología: Este es un reporte de tres casos, descriptivo y observacional, del tipo boca partida para cada estrategia de blanqueamiento (gel blanqueador con pH básico y gel blanqueador con pH ácido). Se evaluaron tres pacientes de 25, 26 y 27 años. El registro de color se realizó con la escala clásica VITA y la sensibilidad dental se evaluó con la escala analógica visual.Resultados: Todos los pacientes evaluados presentaron color A3 en el registro de color inicial y, después del blanqueamiento dental, alcanzaron el color A1. Todos refirieron mayor sensibilidad en la hemiarcada derecha (lugar donde se aplicó el gel blanqueador de pH ácido Whiteness HP). Dos pacientes refirieron sensibilidad dental en la hemiarcadaizquierda donde se aplicó el gel blanqueador de pH básico.Conclusiones: Se observala eficacia clínica de los geles blanqueadores de consultorio a base de peróxido de hidrógeno al 35% en cuanto a la estabilidad del color tras el tratamiento blanqueador, independientemente de su pH. Además, se observa que el gel blanqueador de pH básico promovió una menor sensibilidad postoperatoria (AU).

Effects of the application of sodium ascorbate after in-office bleaching on the penetration of hydrogen peroxide, color change, and microtensile bond strength

Abstract This study aimed to evaluate the effects of the application of 10% sodium ascorbate (SA) after in-office bleaching on the penetration of hydrogen peroxide (HP) into the pulp chamber, color change, and microtensile bond strength (µTBS) to the resin-enamel interface. Thirty premolars and thirty molars were randomly divided into three groups (n = 20 each). One group was exposed to deionized water (negative control). The other two groups were bleached with 35% HP in a single session for 3x15 minutes for each application. However, in only one of them, SA was applied for 10 minutes after bleaching. After, the concentration (µg/mL) of HP in each pulp chamber was evaluated by UV-Vis spectrophotometry. Color changes (ΔEab, ΔE00, and ΔWID) were evaluated with a digital spectrophotometer before and in the first week after bleaching. After treatment, molars were restored and sectioned to obtain resin-enamel interface sticks for µTBS at a crosshead speed of 1 mm/min until failure. The HP concentration and µTBS data were analyzed using one-way ANOVA and Tukey tests, and color changes were analyzed by t-tests (α = 0.05). SA application significantly improved the µTBS values and reduced the HP concentrations within the pulp chambers (p < 0.0001). The application of SA significantly interfered with the color changes after bleaching when compared to the control group (p < 0.05). Application of 10% SA after in-office bleaching successfully reduced the penetration of HP into the pulp chamber; however, it decreased color change.

Resumo Este estudo teve como objetivo avaliar os efeitos da aplicação do ascorbato de sódio a 10% (AS) depois do clareamento em consultório na penetração do peróxido do hidrogênio (PH) na câmara pulpar, mudança de cor e resistência de união (RU) da interface resina-esmalte. Trinta pré-molares e trinta molares foram divididos aleatoriamente em três grupos (n = 20). Um grupo foi exposto em água deionizada (controle negativo). Os outros dois grupos foram clareados com 35% PH numa única sessão de 3x15 minutos para cada aplicação. Porém, só um grupo recebeu AS durante 10 minutos depois do clareamento. Depois, a concentração (µg/mL) do PH no interior de cada câmara pulpar foi avaliado com espectrofotometria UV-Vis. A mudança de cor (ΔEab, ΔE00 and ΔWID) foi avaliada como espectrofotômetro digital antes e depois de uma semana do clareamento. Após de cada tratamento, os molares foram restaurados e seccionados em espécimes com interface resina-esmalte para o teste de RU por microtração a uma velocidade de 1 mm/min até a fratura. Os dados da concentração de PH e RU foram analisados usando ANOVA de uma via e teste de Tukey, e a mudança de cor com o teste t (α = 0.05). A aplicação de AS melhorou significativamente a RU e reduziu a concentração de PH na câmara pulpar (p < 0.0001). A aplicação de AS interferiu significativamente na mudança de cor depois do clareamento comprado com o grupo controle (p < 0.05). A aplicação de SA a 10% depois do clareamento em consultório reduziu significativamente a penetração do PH na câmara pulpar e interferiu na mudança de cor.

Fracture resistance and bonding performance after antioxidants pre-treatment in non-vital and bleached teeth

Abstract This study aimed to evaluate the effect of antioxidant solutions on fracture strength and bonding performance in non-vital and bleached (38% hydrogen peroxide) teeth. One hundred and eighty dentin specimens were obtained, 60 for each test: fracture strength, hybrid layer thickness, and bond strength. The groups (n=10) were randomly composed according to post-bleaching protocol: REST - restoration, without bleaching; BL - bleaching + restoration; SA - bleaching, 10% sodium ascorbate solution, and restoration; AT - bleaching, 10% α-tocopherol solution, and restoration; CRAN - bleaching, 5% cranberry solution, and restoration; CAP - bleaching, 0.0025% capsaicin solution, and restoration. Data were analyzed with ANOVA, Kruskal-Wallis, Dunn, and Qui-Square tests (α=0.05). The highest fracture strength values were observed in REST (1508.96 ±148.15 N), without significant difference for the bleached groups (p>0.05), regardless of the antioxidant use. The hybrid layer thickness in the group that was not subjected to bleaching (REST) was significantly higher than in any other group. The bond strength in the bleached and antioxidants-treated groups (SA, AT, CRAN, CAP) has no differences with the bleached group without antioxidants (BL). Adhesive failures were predominant in the groups that did not receive the antioxidant application. In conclusion, the evaluated antioxidants did not show an effect on the fracture strength, hybrid layer thickness, or bond strength of dentin bleached after endodontic treatment. The application of 10% sodium ascorbate, 10% alpha-tocopherol, 5% cranberry, or 0.0025% capsaicin solutions is not an effective step and should not be considered for the restorative protocols after non-vital bleaching.

Resumo Este estudo teve como objetivo avaliar o efeito de soluções antioxidantes na resistência à fratura e resistência de união em dentes tratados endodonticamente e clareados (38% de peróxido de hidrogênio). Cento e oitenta espécimes de dentina foram obtidos, 60 para cada teste: resistência à fratura, espessura da camada híbrida e resistência de união. Os grupos (n=10) foram compostos aleatoriamente de acordo com o protocolo pós-clareamento: REST - restauração, sem clareamento; BL - clareamento + restauração; SA - clareamento, solução de ascorbato de sódio a 10% e restauração; AT - clareamento, solução de α-tocoferol a 10% e restauração; CRAN - clareamento, solução de cranberry a 5% e restauração; CAP - clareamento, solução de capsaicina 0,0025% e restauração. Os dados foram analisados ​​com os testes ANOVA, Kruskal-Wallis, Dunn e Qui-Quadrado (α=0,05). Os maiores valores de resistência à fratura foram observados em REST (1508,96 ±148,15 N), sem diferença significativa para os grupos clareados (p>0,05), independente do uso de antioxidantes. A espessura da camada híbrida no grupo que não foi submetido ao clareamento (REST) foi significativamente maior do que em qualquer outro grupo. A resistência de união nos grupos clareado e tratado com antioxidantes (SA, AT, CRAN, CAP) não apresentou diferenças com o grupo branqueado sem antioxidantes (BL). As falhas adesivas foram predominantes nos grupos que não receberam a aplicação do antioxidante. Em conclusão, os antioxidantes avaliados não mostraram efeito sobre a resistência à fratura, espessura da camada híbrida ou resistência de união à dentina clareada após tratamento endodôntico. A aplicação de soluções de ascorbato de sódio 10%, alfa-tocoferol 10%, cranberry 5% ou capsaicina 0,0025% não é uma etapa eficaz e não deve ser considerada para os protocolos restauradores após clareamento não vital.

Ozone gas therapy for tooth bleaching preserves enamel microhardness, roughness and surface micromorphology / Ozonioterapia gasosa para clareamento dental preserva a microdureza, rugosidade e micromorfologia superficial do esmalte

ABSTRACT After ozone therapy for bleaching, it is important to evalúate enamel surface properties, to ensure that bleaching provides adequate conditions for sound dental substrate. Aim: The aim of this in vitro study was to evaluate the effects of a bleaching treatment with 10% carbamide peroxide (CP), with or without ozone (O), on the microhardness, roughness and micromorphology of the enamel surface. Materials and Method: Bovine enamel blocks were planed and distributed among the following three bleaching treatment groups (n=10): CP - 1 hour per day/14 days (Opalescence PF 10%/ Ultradent); O - 1 hour per day every 3 days/3 sessions (Medplus VPhilozon, 60 mcg/mL and oxygen flow rate of 1 L/min); and OCP - CP with O, 1 hour per day every 3 days/3 sessions. Enamel surface microhardness (Knoop), roughness (Ra), and micromorphology by scanning electron microscopy (5,000x magnificaron) were determined before and after the treatments. Results: ANOVA and Tukey-Kramer's test showed that enamel microhardness remained unchanged by treatment with O and OCP (p=0.0087), but decreased by treatment with CP. Treatment with O promoted higher enamel microhardness than the other groups (p=0.0169). Generalized linear mixed models for repeated measures over time indicated treatment with CP increased enamel roughness more than OCP or O (p=0.0003). CP produced slight irregularities in enamel micromorphology after the whitening treatment. O, with or without CP, maintained the mechanical and physical properties of microhardness and enamel surface micromorphology, and either maintained or reduced surface roughness, compared to the conventional tray-delivered CP bleaching treatment. Conclusions: Treatment with 10% carbamide peroxide in trays promoted greater changes in enamel surface properties than treatments with ozone and with 10% ozonized carbamide peroxide in the office.

RESUMO É importante avaliar as propriedades da superficie do esmalte após a aplicagao da ozonioterapia para clareamento, para garantir que o efeito clareadorproporcione condigoes adequadaspara um substrato dentário higido. Objetivo: O objetivo deste estudo in vitro foi avaliar os efeitos de um tratamento clareador com peróxido de carbamida (PC) a 10%, associado ou nao ao ozonio (O), na microdureza, rugosidade e micromorfologia da superficie do esmalte. Materials e Método: Blocos de esmalte bovino foram aplainados e distribuidos entre tres grupos de tratamento clareador (n=10): PC - 1 hora por dia/14 dias (Opalescence PF 10%/ Ultradent); O - 1 hora por dia a cada 3 dias/3 sessoes (Medplus VPhilozon, 60 mcg/mL e fluxo de oxigenio de 1 L/min); e PCO - CP com O, 1 hora por dia a cada 3 dias/3 sessoes. A microdureza (Knoop), a rugosidade (Ra) e a micromorfologia da superficie do esmalte avaliada por microscopia eletronica de varredura (aumento de 5.000x) foram analisadas antes e após os tratamentos. Resultados: ANOVA e teste de Tukey-Kramer mostraram que O e PCO mantiveram os valores de microdureza do esmalte ao final do tratamento (p=0,0087), enquanto PC promoveu diminuigao da microdureza. O promoveu maiores valores de microdureza do esmalte do que os outros grupos ao final do tratamento (p=0,0169). Modelos lineares generalizados mistos para medidas repetidas no tempo indicaram um aumento na rugosidade da superficie para PC, levando a maior rugosidade do esmalte ao final do tratamento, em comparagao com PCO ou O (p=0,0003). PC apresentou pequenas irregularidades na micromorfologia do esmalte após o tratamento clareador. O, com ou sem PC, manteve as propriedades mecánicas e fisicas de microdureza e micromorfologia da superficie do esmalte, e manteve ou reduziu a rugosidade da superficie, em comparagao com o tratamento clareador a base de PC aplicado em moldeira convencional. Conclusoes: O tratamento com peróxido de carbamida a 10% para uso em moldeiras promoveu maiores alteragoes nas propriedades de superficie do esmalte do que aquelas observadas nos tratamentos com ozonio e com peróxido de carbamida ozonizado a 10% para uso em consultório.

The Effect of Nicotine Lozenge Over Teeth Bleaching During Cigarette's Addiction Treatment

The aim of this study was to evaluate the effect of nicotine lozenge on teeth staining with/without bleaching in animal model study. A total of 15 Wistar rats were exposed in an acrylic container to 10 cigarettes smoke three times a day for 8 minutes per time, and sacrificed after 60 days. A total of 30 incisor teeth were treated (n=10) as the following: Group-1: in-office bleaching, at-home bleaching and immersion in artificial saliva; group-2: in-office bleaching, at - home bleaching and immersion in nicotine lozenge solution and in artificial saliva; group-3: immersion in nicotine lozenge solution and in artificial. The specimens of all groups were photographed using a stereomicroscope at T1) immediately after the extraction and before any treatment; T2) after one month of the treatment; and T3) after two months of the treatment. Four equidistant points of each specimen were analyzed using CMYK shade guide. The data were analyzed one-way ANOVA test followed by Tukey test for multiple comparisons with (a ≤ 0.05). In group-1, there was a significant difference of the color saturation of specimens between T1 and T2, and between T1 and T3 readings (P<0.0001). In group-2, there was a significant difference of the color saturation of specimens between T1 and T2, between T2 and T3 readings (P<0.0001). In group-3, there was a significant difference of the color saturation of specimens between T1 and T2, and between T1 and T3 readings (P<0.0001). The usage of nicotine lozenge promotes teeth lighting with/without bleaching.

El objetivo de este estudio fue evaluar el efecto de comprimidos de nicotina sobre la tinción de los dientes con/sin blanqueamiento en un estudio de modelo animal. Un total de 15 ratas Wistar fueron expuestas en un recipiente acrílico al humo de 10 cigarrillos tres veces al día durante 8 minutos por vez, y sacrificadas después de 60 días. Se trataron un total de 30 dientes incisivos (n=10) de la siguiente manera: Grupo-1: blanqueamiento en consultorio, blanqueamiento en casa e inmersión en saliva artificial; grupo-2: blanqueamiento en consultorio, blanqueamiento en casa e inmersión en solución de comprimidos de nicotina y en saliva artificial; grupo-3: inmersión en solución de nicotina en comprimidos y en artificial. Los especímenes de todos los grupos fueron fotografiados utilizando un microscopio estereoscópico en T1) inmediatamente después de la extracción y antes de cualquier tratamiento; T2) después de un mes del tratamiento; y T3) a los dos meses del tratamiento. Se analizaron cuatro puntos equidistantes de cada espécimen utilizando la guía de colores CMYK. Los datos se analizaron con la prueba ANOVA unidireccional seguida de la prueba de Tukey para comparaciones múltiples con (a ≤ 0,05). En el grupo 1, hubo una diferencia significativa de la saturación de color de las muestras entre T1 y T2, y entre las lecturas T1 y T3 (P<0,0001). En el grupo 2, hubo una diferencia significativa de la saturación de color de las muestras entre T1 y T2, entre las lecturas de T2 y T3 (P<0.0001). En el grupo 3, hubo unadiferencia significativa de la saturación de color de las muestras entre T1 y T2, y entre las lecturas T1 y T3 (P<0,0001). El uso de comprimidos de nicotina promueve la iluminación de los dientes con/sin blanqueamiento.

Tooth Bleaching: A bibliometric analysis of the top 100 most-cited papers

Abstract This study analyzes the characteristics of the top 100 most-cited papers related to tooth bleaching. A literature search was performed on the Web of Science up to March 2022. The number of citations was cross-matched with the citation count on Scopus and Google Scholar. The following data were collected: number and density of citations; authorship; year and journal of publication; study design and thematic; keywords; institution and country of origin. Spearman's correlation and Poisson regression were used to determine associations between the number of citations and study characteristics. The VOSviewer software was used to generate collaborative network maps for the authors and keywords. The number of citations ranged from 66 to 450. Papers were published between 1981 and 2020. The most frequent study design and topic were laboratory-based studies and 'interaction of the bleaching agent with dental tissues', respectively. Cochran M, Loguercio AD, Matis B, Reis A, and Suliman M were the authors with the highest number of papers. The countries with the most papers were the United States of America (USA) (28%) and Brazil (20%). Indiana University and State University of Ponta Grossa were the institutions with the most papers (6% each). There was a very strong correlation among the number of citations of the three databases. The 100 most-cited papers related to tooth bleaching were mainly published by the USA and Brazil, with laboratory-based studies addressing topics related to the effects of bleaching agents on tooth structure being the most prevalent.

Resumo Este estudo analisa as características dos 100 artigos mais citados relacionados ao clareamento dental. Uma pesquisa bibliográfica foi realizada na Web of Science até março de 2022. O número de citações foi cruzado com a contagem de citações na Scopus e na Google Scholar. Foram coletados os seguintes dados: número e densidade de citações; autoria; ano e periódico de publicação; desenho do estudo e temática; palavras-chave; instituição e país de origem. A correlação de Spearman e a regressão de Poisson foram usadas para determinar associações entre o número de citações e as características do estudo. O software VOSviewer foi utilizado para gerar mapas de rede colaborativa para os autores e palavras-chave. O número de citações variou de 66 a 450. Os artigos foram publicados entre 1981 e 2020. O desenho e o tópico de estudo mais frequentes foram estudos laboratoriais e interação do agente clareador com tecidos dentários, respectivamente. Cochran M, Loguercio AD, Matis B, Reis A e Suliman M foram os autores com maior número de artigos. Os países com mais artigos foram os Estados Unidos da América (EUA) (28%) e o Brasil (20%). A Universidade de Indiana e a Universidade Estadual de Ponta Grossa foram as instituições com mais artigos (6% cada). Houve uma correlação muito forte entre o número de citações das três bases de dados. Os 100 artigos mais citados relacionados ao clareamento dentário foram publicados principalmente pelos EUA e Brasil, sendo os estudos laboratoriais que abordaram tópicos relacionados aos efeitos dos agentes clareadores na estrutura dentária os mais prevalentes.

Effect of experimental bleaching gels with polymers Natrosol and Aristoflex on the enamel surface properties

Abstract Natrosol and Aristoflex® AVC polymers are widely applied in the cosmetic industry and have recently been applied as a thickener option in the composition of dental bleaching gels, with the purpose to reduce the adverse effects on enamel mineral components. The aim of this study was to evaluate the color variation (ΔE* ab, ΔE00, ∆WID), surface roughness (Ra), and mineral content quantification (Raman Spectroscopy) of dental enamel after bleaching treatment with experimental gel-based on 10% carbamide peroxide (CP), containing Carbopol, Natrosol, and Aristoflex® AVC. Sixty bovine teeth were randomly divided into 6 groups (n=10): Negative Control (NC) - no treatment; Positive Control (PC) - Whiteness Perfect 10% - FGM; CP with Carbopol (CPc); CP with Natrosol (CPn); CP with Aristoflex® AVC (CPa); NCP - no thickener. Data were analyzed, and generalized linear models (∆WID -T0 x T1) were used for repeated measurements in time for Ra and with a study factor for ΔE* ab and ΔE00. For the evaluation of the mineral content, data were submitted to one-way ANOVA and Tukey tests. For enamel topographic surface analysis the Scanning Electron Microscope (SEM) was performed. A significance level of 5% was considered. ΔE* ab and ΔE00 were significantly higher for CPc, CPn, CPa, and NCP groups. (∆WID) showed a significantly lower mean than the other groups for NC in T1. After bleaching (4-hour daily application for 14 days), Ra was higher in the CPc, CPn, and PC groups. For CPa, Ra was not altered. No significant difference was found in the quantification of mineral content. CPa preserved the surface smoothness more effectively. Aristoflex® AVC is a viable option for application as a thickener in dental bleaching gels, presenting satisfactory performance, and maintaining the whitening efficacy of the gel, with the advantage of preserving the surface roughness of tooth enamel without significant loss of mineral content.

Resumo Os polímeros Natrosol e Aristoflex® AVC são amplamente utilizados na indústria cosmética e foram recentemente aplicados como uma opção de espessante na composição de géis de clareamento dental, com o objetivo de reduzir os efeitos adversos sobre os componentes minerais do esmalte. O objetivo deste estudo foi avaliar a variação de cor (ΔE*ab, ΔE00, ∆WID), rugosidade da superfície (Ra), e quantificação do conteúdo mineral (Raman Spectroscopy) do esmalte dentário após clareamento dental com gel experimental baseado em 10% de peróxido de carbamida (CP), contendo Carbopol, Natrosol e Aristoflex® AVC. Sessenta dentes bovinos foram divididos aleatoriamente em 6 grupos (n=10): Controle Negativo (CN) - sem tratamento; Controle Positivo (CP) - Brancura Perfeita 10% - FGM; CP com Carbopol (CPc); CP com Natrosol (CPn); CP com Aristoflex® AVC (CPa); NCP - sem espessante. Os dados foram analisados e modelos lineares generalizados (∆WID -T0 x T1) foram usados para medições repetidas no tempo para Ra e com um fator de estudo para ΔE*ab e ΔE00. Para a avaliação do conteúdo mineral, os dados foram submetidos a testes unidirecionais de ANOVA e Tukey. Para a análise da superfície topográfica do esmalte, o Microscópio Eletrônico de Varredura (SEM) foi realizado. Um nível de significância de 5% foi considerado. ΔE*ab e ΔE00 foram significativamente maiores para os grupos CPc, CPn, CPa e NCP. (∆WID) mostrou uma média significativamente menor do que os outros grupos para NC em T1. Após o clareamento (aplicação diária de 4 horas por 14 dias), Ra foi maior nos grupos CPc, CPn e PC. Para CPa, Ra não foi alterado. Nenhuma diferença significativa foi encontrada na quantificação do conteúdo mineral. O CPa preservou a suavidade da superfície de forma mais eficaz. Aristoflex® AVC é uma opção viável para aplicação como espessante em géis de clareamento dental, apresentando desempenho satisfatório e mantendo a eficácia clareadora do gel, com a vantagem de preservar a rugosidade da superfície do esmalte dentário sem perda significativa de conteúdo mineral.

Effects of applying procyanidins on the bond strength of bleached dentin to composite resin / 口腔疾病防治

Objective@#To study the influence of procyanidins on the bonding strength of dentin bleached by carbamide peroxide to composite resin.@*Methods @#By applying different treatments to dentin bonding interfaces, 120 human third molars were randomly divided into 12 groups (n = 10): W group (no bleaching+deionized water), Wa group (no bleaching+deionized water+aging), WT1 group (no bleaching+5% procyanidins for 1 min), WT1a group (no bleaching+5% procyanidins for 1 min+aging), WT2 group (no bleaching+5% procyanidins for 5 min), WT2a group (no bleaching+5% procyanidins for 5 min+aging), C group (carbamide peroxide+deionized water), Ca group (carbamide peroxide+deionized water+aging), CT1 group (carbamide peroxide+5% procyanidins for 1 min), CT1a group (carbamide peroxide+5% procyanidins for 1 min+aging), CT2 group (carbamide peroxide+5% procyanidins for 5 min), and CT2a group (carbamide peroxide+5% procyanidins for 5 min+aging). The bond strength to composite resin was measured by universal mechanical testing machine, microstructure and the nanoleakages were measured by scanning electron microscope immediately or after the thermal cycling aging test.@*Results@#The immediate bond strength of the bleached groups pretreated with procyanidins for 1 min (P<0.001) and 5 min (P<0.001) was higher than that of Group C, and the difference was statistically significant. Meanwhile, there was no statistically significant difference between Group CT1 and Group CT2 (P = 1.000). After the thermal cycles, the bond strength of each group declined. The differences between Group W and Group Wa (P<0.001) and Group C and Group Ca (P<0.001) were statistically significant, but no significant differences between Group CT1 and Group CT1a (P = 0.052) or Group CT2 and Group CT2a (P = 0.053) were found. The main effects of “aging” (P<0.001), “bleaching” (P<0.001) and “procyanidins” (P<0.001) and the second-order interaction effects of “bleaching * procyanidins” (P = 0.008), “bleaching * aging” (P = 0.024), and “aging * procyanidins” (P<0.001) were statistically significant. SEM observations showed that the hybrid layers in Groups C, CT1 and CT2 were not clear, and the hybrid layers in Groups Ca, CT1a and CT2a were partially destroyed and disintegrated. Under backscattering mode, it was observed that there were a large number of silver nitrate particles in the hybrid layer of Group Ca, and the residual silver ions in the hybrid layer of Groups CT1a and CT2a were decreased. @*Conclusion@# Pretreatment with 5% procyanidins for 1 min can improve the immediate bond strength of dentin bleached by carbamide peroxide to composite resin and maintain bonding durability.

Experimental study on the therapeutic effect of different bleaching methods on white-spot lesions of the enamel using optical coherence tomography / 口腔医学

Objective@#To investigate the efficacy of different bleaching methods on white-spot lesions of the enamel using optical coherence tomography and to evaluate its feasibility for monitoring the therapeutic effects on white-spot lesions. @*Methods@#Forty-eight sound premolars extracted for orthodontic reasons were selected and cut for 4 mm×4 mm×2 mm enamel blocks in buccal surfaces of the crowns. The samples were covered with acid-resistant varnish (except for the buccal surfaces) and immersed in demineralization solution for 18 days to establish the white-spot lesion models of the enamels. Samples were randomly divided into four groups (n=12). Group A was given demineralization only. Specimens in Group B, C and D were treated with 40% hydrogen peroxide, resin infiltration and 40% hydrogen peroxide combined with resin infiltration, respectively. Eight samples in each group were randomly selected. OCT was applied to observe the optical changes of the enamel surface and according to the OCT scanning results, the demineralization depth of enamel samples in each group was calculated. Then, the enamel blocks were embedded in epoxy resins, except the buccal surfaces, and measured for the microhardness values of the enamel surface by a microindentation hardness tester. Four samples in each group were cut longitudinally, and the ultrastructural changes of enamel samples in each group were observed by scanning electron microscope. @* Results@#OCT showed that the light scattering characteristics of enamel surface changed in all groups, and the bright layer was formed, but the thickness of bright layer in Group C and D was significantly lower than that in Group A and B (P<0.05). The microhardness values (kg/mm2) of the samples in Group A-D were (214.99±31.70), (250.66±33.64), (312.42±18.01) and(286.53±26.65), respectively. The microhardness of enamel surfaces in Group C and D was significantly higher than that in Group A and B (P<0.05), and the ultrastructure of enamel surfaces in Group C and D were more flat and dense in SEM observation (P<0.05). @*Conclusion@#The methods of resin infiltration therapy or 40% hydrogen peroxide combined with resin infiltration could effectively improve white-spot lesions of the enamel and the non-invasive OCT can be used as a better evaluation method for the diagnosis and treatment of white-spot lesions of the enamel.

One-year clinical observation of the effect of internal bleaching on pulpless discolored teeth / 华西口腔医学杂志

OBJECTIVES@#This study aimed to observe the color rebound and rebound rates of non-pulp discolored teeth within 1 year after routine internal bleaching to guide clinical practice and prompt prognosis.@*METHODS@#In this work, the efficacy of bleaching was observed in 20 patients. The color of discolored teeth was measured by using a computerized colorimeter before bleaching; immediately after bleaching; and at the 1st, 3rd, 6th, 9th, and 12th months after bleaching. The L*, a*, and b* values of the color of cervical, mesial, and incisal parts of the teeth were obtained, and the color change amounts ΔE*, ΔL*, Δa*, and Δb* were calculated. The overall rebound rate (P*) and the color rebound velocity (V*) were also analyzed over time.@*RESULTS@#In 20 patients following treatment, the average ΔE* of tooth color change was 14.99. After bleaching, the neck and middle of the teeth ΔE* and ΔL* decreased in the 1st, 3rd, 6th, 9th, and 12th months, and the differences were statistically significant. Meanwhile, from the 9th month after bleaching, the rebound speed was lower than that in the 1st month, and the difference was statistically significant. The incisal end of the tooth ΔE* and ΔL* decreased in the 6th, 9th, and 12th months after bleaching, and the differences were statistically significant. No significant difference was found in the rebound speed between time points. However, this rate settled after the 9th month, with an average color rebound rate of 30.11% in 20 patients.@*CONCLUSIONS@#The results indicated that internal bleaching could cause a noticeable color change on pulpless teeth. The color rebound after bleaching was mainly caused by lightness (L*), which gradually decreased with time, and it was slightly related to a* and b*. The color of the teeth after internal bleaching rebounded to a certain extent with time, but the color rebound speed became stable from the 9th month. Clinically, secondary internal bleaching can be considered at this time according to whether the colors of the affected tooth and the adjacent tooth are coordinated and depending on the patient's needs.