Effect of Nisin-based pretreatment solution on dentin bond strength, antibacterial property, and MMP activity of the adhesive interface.

OBJECTIVE: To evaluate the effect of a Nisin-based dentin pretreatment solution on microtensile bond strength, antibacterial activity, and matrix metalloproteinase (MMP) activity of the adhesive interface. MATERIALS AND METHODS: 100 human molars were sectioned to expose dentin. The teeth were assigned to five groups (n = 20), according to the dentin pretreatment: 0.5%, 1.0%, or 1.5% Nisin; 0.12% chlorhexidine (positive control), and no solution (negative control), and divided into 2 subgroups: no aging, and thermomechanical aging. Specimens were etched with 37% H3PO4 for 15 s and submitted to the dentin pretreatment. Then, they were bonded with an adhesive (Adper Single Bond 2) and a resin composite for microtensile bond strength (µTBS) evaluation. Antibacterial activity against Streptococcus mutans was qualitatively examined using an agar diffusion test. Anti-MMP activity within hybrid layers was examined using in-situ zymography. Data were analyzed with two-factor ANOVA and post-hoc Tukey's test (α = 0.050). RESULTS: For µTBS, significant differences were identified for the factors "solutions" (p = 0.002), "aging" (p = 0.017), and interaction of the two factors (p = 0.002). In the absence of aging, higher µTBS was observed for the group 0.5% Nisin. In the presence of aging, all groups showed similar µTBS values. All Nisin concentrations were effective in inhibiting the growth of S. mutans. Endogenous MMP activity was more significantly inhibited using 0.5% and 1.0% Nisin (p < 0.050). CONCLUSION: 0.5% and 1.0% Nisin solutions do not adversely affect resin-dentin bond strength and exhibit a potential bactericidal effect against S. mutans. Both concentrations effectively reduce endogenous gelatinolytic activity within the hybrid layer. CLINICAL RELEVANCE: The use of 0.5% and 1.0% Nisin solutions for dentin pretreatment potentially contributes to preserving the adhesive interface, increasing the longevity of composite restorations.

Is the whitening effect of charcoal-based dentifrices related to their abrasive potential or the ability of charcoal to adsorb dyes?

OBJECTIVES: To evaluate if tooth color alteration of activated charcoal-based dentifrices may be attributed to the dye adsorption potential of charcoal (chemical action - C - slurry only) or to the association of dye adsorption with abrasion (chemo-mechanical action - CM- slurry/toothbrushing). Potential adverse effects in surface roughness, gloss, and wear were also assessed. METHODS: Bovine enamel/dentin specimens were randomly allocated into the groups according to treatments and test model (n = 15): deionized water (negative control- NC); Colgate Maximum Anticaries Protection (conventional toothpaste- positive control- PC); Colgate Luminous White Activated Charcoal (LW); Oral-B 3D White Therapy Charcoal (WT); Curaprox Black is White (BW); Dermavita Whitemax (Activated charcoal powder- WP). Specimens were exposed to the C or CM models, in 28-day staining-treatment cycling. Color change (ΔE00), whiteness index (ΔWID), percentage of alteration of surface roughness (%Raalt), and gloss (%GUalt) were calculated. Additional specimens (n = 9) were indented with a Knoop diamond and subjected to 100,000 abrasion cycles. Enamel wear was determined by calculating the decrease in indentations geometry. Data were analyzed by ANOVA/Tukey tests (α = 0.05). RESULTS: The CM-model produced lower color change (staining) than C (p = 0.0001). PC, LW, WT, BW, and WP showed similar color results for both models, differing from NC (p < 0.05).%Ra and%GU did not differ among the C-model groups (p > 0.05) and WP exhibited the highest variation (%Ra and%GU) under CM-model. Enamel wear values were lowest in the NC and PC groups, intermediate for LW, WT, BW, and highest for the WP (p < 0.05). CONCLUSION: Activated charcoal-based dentifrices have a similar ability to minimize tooth staining as the conventional toothpaste, with increased enamel wear potential in the long term (after 100,000 cycles). The activated charcoal powder damaged the enamel surface, showing a higher deleterious effect on enamel roughness, gloss, and wear. CLINICAL SIGNIFICANCE: Dentifrices containing activated charcoal do not provide superior results to minimize tooth staining compared to conventional toothpaste. Charcoal powder should be used with caution because it promotes higher superficial alterations on the enamel surface.

Chemical behavior of 20%-22% carbamide peroxide gels in at-home bleaching: Randomized crossover in situ trial.

OBJECTIVE: To evaluate if distinct 20%-22% carbamide peroxide bleaching gels present similar decomposition pattern and pH during the clinical use in both arches, as well as gels viscosity. METHODS: Participants randomly received treatments with carbamide peroxide gels (n = 10): OPF (OpalescencePF-20%); PNT (Polanight-22%); and WPC (Whiteness Perfect-22%) in three different days, with 2-day washout. Decomposition pattern was assessed by peroxide concentration. Both PC and pH of bleaching gels were measured in different time points in upper and lower trays during a total of 120 min of clinical use. Viscosity of bleaching gels was measured in triplicate. ANOVA and Tukey's test were applied (α = 0.05). RESULTS: Regarding decomposition pattern, no significant differences were observed for the interaction between gel, time, and tray position factors. The peroxide concentration progressively reduced until 120 min of trays use (p < 0.001), being overall more notable in lower trays (p < 0.001). Regarding pH, the lowest values were verified in WPC within time. At 120 min, an increase of pH was observed for both WPC and OPF (p < 0.001) compared to baseline means. PNT exhibited constant pH values over time. The values of viscosity were: OPF (1.682.000 ± 19 cP)a, WPC (1.388.667 ± 172.63 cP)ab, PNT (579.567 ± 0.98 cP)b. CONCLUSIONS: The bleaching gels presented overall decomposition pattern clinically equivalent, being more notable in lower trays over time. Nevertheless, distinct pH and viscosities were observed among the products. CLINICAL SIGNIFICANCE: Although the manufacturers recommend different times of use for bleaching gels with similar peroxide concentrations, the commercial products tested did not exhibit clinically relevant difference in the decomposition pattern during the 120 min of clinical procedure.

Pellicle modification with natural bioproducts: Influence on tooth color under erosive conditions.

Salivary pellicle was modified with bioproducts and we assessed the change in tooth color and the protection of enamel to erosion. Human enamel specimens were assigned to one of three solutions: grape seed extract or black tea (bioproducts), or deionized water (negative control); after which one half the specimens underwent erosive challenges. The specimens underwent 15 cycles involving salivary pellicle formation (10 min, 37°C), incubation in solution (2 min, 25°C), subsequent pellicle formation (90 min, 37°C). Half of the specimens was kept in a humid chamber and the other half was submitted to erosion (2 min, 1% citric acid). After 15 such cycles, the pellicle was removed. Tooth color and the surface reflection intensity were assessed after every five cycles and after pellicle removal. For non-eroded specimens, the exposure to bioproducts promoted significantly greater color change than the deionized water, with increases in yellow appearance. After pellicle removal, the color was similar in all non-eroded specimens. The bioproducts increased the surface reflection intensity over cycles. For the erosion-exposed specimens, erosion itself resulted in color change. Black tea and deionized water resulted in increased yellow appearance. Exposure to the bioproducts resulted in higher relative surface reflection intensity values over time, but only grape seed extract resulted in higher relative surface reflection intensity value at the time of pellicle removal. The bioproducts caused transient staining effect, which was reduced after pellicle removal. For enamel submitted to erosion, grape seed extract resulted in less color change and better protection of enamel against erosion than black tea or water.

Eficácia e segurança do enxaguatório clareador sobre o esmalte dental: estudo clínico controlado randomizado e estudo in vitro / Efficacy and safety of whitening mouthrinse on enamel: randomized clinical trial and in vitro study

Enxaguatórios clareadores tornaram-se muito populares devido ao seu fácil uso e disponibilidade. Contudo, não há evidência dos efeitos e segurança desses produtos sobre o esmalte sadio e desmineralizado. Esta proposta foi dividida em duas partes. A primeira foi um estudo clínico randomizado que avaliou a eficácia e segurança do enxaguatório clareador. Participantes (n=45) foram alocados aleatoriamente em três grupos de tratamento: LWE (Listerine Whitening Extreme­peróxido de hidrogênio a 2,5%); PL (Enxaguatório placebo); e OPF (Opalescence PF­peróxido de carbamida a 10%). O tratamento foi realizado 1x/dia por 14 dias durante 2h para OPF, e 2x/dia por 90 dias durante 30s para LWE e PL. A cor dos dentes foi avaliada com escalas de cor (DUEC) e por espectrofotometria. Foram avaliados sensibilidade dental, condição gengival, potencial de desmineralização do esmalte, e a satisfação do participante. As avaliações foram realizadas em diferentes tempos. Para as escalas de cor, KruskalWallis mostrou diferença significante entre os tratamentos nos tempos avaliados (p<0,05). LWE apresentou maiores valores de DUEC comparado ao PL a partir de 60 dias. PL e OPF exibiram valores constantes, sendo significativamente maiores para OPF. Para o espectrofotômetro, RM-ANOVA mostrou diferença significante para os grupos e interação (p<0,05). LWE apresentou maiores valores de alteração de cor do que PL a partir de T14. OPF exibiu os maiores valores de alteração de cor durante todo o período de estudo. Após 2 anos, houve manutenção da cor dos dentes para todos os grupos. Houve baixa intensidade de sensibilidade para LWE e OPF. Nenhum participante apresentou inflamação gengival. LWE e OPF promoveram uma diminuição significativa na concentração de cálcio, mas após 1 semana, os valores foram intermediários. A concentração de fosforo não apresentou alteração nos tempos avaliados. Todos os participantes ficaram satisfeitos com o tratamento com OPF e 67% dos participantes do grupo LWE apresentaram satisfação. A segunda parte consistiu em um estudo in vitro que comparou o efeito do enxaguatório clareador na desmineralização do esmalte e em lesões incipientes de cárie durante ciclagem de pH. Espécimes de esmalte/dentina bovino (n=120) com a superfície dividida em três áreas [esmalte sadio controle, esmalte tratado (ET); e lesão incipiente de carie tratada (LICT)] foram distribuídos aleatoriamente nos grupos experimentais: LWE; PL; OPF e água deionizada (AD). Os tratamentos (2min para LWE, PL e AD; e 2h para OPF) foram realizados durante uma ciclagem de pH de 28 dias (6´60min desmineralização). Intensidade de reflexão superficial (rSRI), perda mineral e concentração de flúor (espécimes adicionais) foram avaliados. Para ET, foi observado maior valor de rSRI em LWE (89,99%±6,94) e maior diminuição de rSRI foi observada para OPF e AD. Não houve perda mineral nos grupos (p>0,05). Para LICT, rSRI diminuiu significativamente após a ciclagem para todos os grupos sem diferença entre eles (p>0,05). Maior concentração de flúor foi encontrada em OPF. LWE e OPF exibiram efeitos semelhantes na perda mineral com valores intermediários. Houve eficácia clareadora tanto para LWE quanto para OPF e manutenção da cor após 2 anos. Houve efeito protetor do enxaguatório durante a ciclagem. (AU)

Whitening mouthrinses have become very popular because they are easy to use and are accessible. However, there is no evidence of the effects and safety of this product on sound and demineralized enamel. The proposal comprised in two parts. The first one was a randomized clinical trial that evaluated the efficacy and safety of the whitening mouthrinse. Participants (n=45) were randomly allocated to three treatment groups: LWE (Listerine Whitening Extreme­2.5% hydrogen peroxide); PL (placebo mouthrinse); and OPF (Opalescence PF­10% carbamide peroxide). The treatment was performed 1x/day for 14 days during 2h for OPF, and 2x/day for 90 days during 30s for LWE and PL. Tooth color was measured using shade guides (DUEC) and spectrophotometer. Tooth sensitivity, gingival condition, enamel demineralization potential, and participant satisfaction were analyzed. The analyses were performed in different times. For shade guides, Kruskal-Wallis showed a significant difference between treatments in the evaluated times (p<0.05). LWE showed higher DUEC values compared to PL after 60 days. PL and OPF exhibit constant values, being significantly higher for OPF. For spectrophotometer, RM-ANOVA showed significance for the groups and interaction (p<0.05). LWE showed higher color difference values than PL from T14. OPF exhibited the highest values throughout the study. After 2 years, there was maintenance of tooth color for all groups. There was lower intensity of sensitivity for LWE and OPF. No participant exhibited gingival inflammation. LWE and OPF promote a significant decrease in calcium concentration, but after 1 week the values were intermediate. Phosphorus concentration did not alter over time. All participants of OPF group were satisfied with the treatment and 67% of the participants of LWE group showed satisfaction. The second part of the study consisted of an in vitro study that compared the effect of whitening mouthrinse on enamel demineralization and on initial caries lesions. Bovine enamel/dentin specimens (n=120) had their surface divided into three areas [control sound enamel, enamel treated (ET); and initial caries lesion treated (ICLT)] and were randomly assigned to the experimental groups: LWE; PL; OPF; and deionized water (DW). The treatments (2min for LWE, PL and DW; and 2h for OPF) were performed during a 28-day pH cycle (6x60min demineralization). Surface reflection intensity (rSRI), mineral loss, and fluoride concentration (additional specimens) were performed. For ET, a higher value of rSRI was observed in LWE (89.99%±6.94) and a greater decrease in rSRI was observed for OPF and DW. There was no mineral loss in the groups (p>0.05). For ICLT, rSRI was significantly significant after cycling for all groups with no difference between them (p>0.05). Higher fluoride concentration was found in OPF. LWE and OPF exhibited similar effects on the mineral loss with intermediate values. There was whitening efficacy for both LWE and OPF and color maintenance after 2 years. There was a protective effect of the mouthrinse during cycling (AU)

Effect of whitening mouthrinses on color change of stained resin composites / Efeito de enxaguatórios clareadores na alteração de cor de resinas compostas previamente manchadas

Objective: The present study compared the effect of whitening mouthrinses (WM) on the color change of stained resin composites (RC). Material and Methods: Cylindrical specimens (6mm-diameter and 1mm-thickness) were prepared with the following RC (n=60/group): Filtek Z350XT (Z350- methacrylate-based), Admira Fusion (AD- ormocer-based), TPH3 (TPH- methacrylate-based), and Beautifil II (BII- giomer/methacrylate-based). The initial color was assessed with reflectance spectrophotometer using CIE L*a*b* system. The specimens were immersed in staining broth during 14 days, submitted to color evaluation (ΔE1) and randomly allocated in 4 subgroups (n=15), according to WM adopted: Listerine Whitening (LW-2% hydrogen peroxide), Plax Whitening (PW-1.5% hydrogen peroxide), Bromelain/papain (BP-experimental solution), and Deionized water (DW-negative control). The whitening cycle consisted of RC immersion in WM for 1 min and in artificial saliva for 30 min, simulating 12 weeks, and final color assessment was performed (ΔE2). Color change data were analysed by ANOVA and Tukey's tests (α=5%). Results: After staining, TPH showed the lowest ΔE1 values and Z350 showed the highest color change (p=0.001). The whitening effect promoted by LW was significantly higher than color alteration obtained with PW (ΔE2), and BII showed the highest color change values (ΔE2) after whitening cycle. Conclusion: LW exhibited the greatest whitening potential on stained RC, mainly with the Giomer (Beautifill II) and the Ormocer-based (Admira Fusion) materials. Bromelain/papain solution showed no whitening effect on stained RC. (AU)

Objetivo: O presente estudo comparou o efeito de enxaguatórios clareadores (EC) na alteração de cor de resinas compostas (RC) previamente manchadas. Material e Métodos: Espécimes cilíndricos (6mm de diâmetro e 1mm de espessura) foram preparados com as seguintes RC (n=60/grupo): Filtek Z350XT (Z350- metacrilato), Admira Fusion (AD- ormocer), TPH3 (TPH- metacrilato), e Beautifil II (BII- giomer/metacrilato). A cor inicial foi mensurada com espectrofotômetro de reflectância utilizando o sistema CIE L*a*b*. Os espécimes foram imersos em um caldo de manchamento durante 14 dias, submetidos a avaliação de cor (ΔE1) e alocados aleatoriamente em 4 subgrupos (n=15), de acordo com EC adotado: Listerine Whitening (LW-peróxido de hidrogênio a 2%), Plax Whitening (PW- peróxido de hidrogênio a 1,5%), Bromelina/papaína (BP-solução experimental), e Água deionizada (AD- controle negativo). O ciclo clareador consistiu na imersão da RC no EC por 1 min e na saliva artificial por 30 min, simulando 12 semanas, e a cor final foi mensurada (ΔE2). Os dados de alteração de cor foram analisados pelos testes ANOVA e Tukey (α=5%). Resultados: Após o manchamento, TPH apresentou o menor valor de ΔE1 e Z350 apresentou a maior alteração de cor (p=0,001). O efeito clareador promovido pelo LW foi significativamente maior que o obtido com o PW (ΔE2) e BII teve a maior alteração de cor (ΔE2) após o ciclo clareador. Conclusão: LW exibiu maior potencial clareador nas RC manchadas. BII apresentou maior alteração de cor em resposta à ação clareadora de ambos enxaguatórios à base de peróxido de hidrogênio testados.(AU)

The influence of a liner on deep bulk-fill restorations: Randomized clinical trial.

OBJECTIVE: The aim of this study was to evaluate the influence of a liner on the clinical performance of deep posterior restorations performed with bulk-fill composite. METHODS: 30 subjects received two restorations on deep preparations in posterior teeth, without pulpal exposure, after selective carious-tissue removal in one-stage. The internal walls reached the inner quarter of dentin, but with a radiographically detectable zone of firm dentin remaining. The pulpal protection using a layer of glass ionomer composite liner (Ionoseal, Voco) was applied in just one preparation. The adhesive system Futurabond U (Voco) was applied in all preparations, which were restored with the bulk-fill pure Ormocer nanohybrid composite (Admira Fusion Xtra - Voco), in up to 4 mm thick increments. All restorations were evaluated using the FDI criteria after 7 days, 6, 12 and 24 months postoperatively. RESULTS: After 24-months, 25 patients attended the recall and 50 restorations were evaluated. The Fisher's statistical analysis (5%) showed no difference between the techniques for the esthetic, functional and biological properties. No postoperative sensitivity was reported for both groups. CONCLUSION: The application of a liner did not influence the clinical performance of deep restorations with bulk-fill Ormocer composite. CLINICAL RELEVANCE: The application of a liner with a GIC-based material did not have a significant effect on the clinical performance of bulk-fill restorations and seems to be unnecessary for the material tested.

A randomized clinical trial of class II composite restorations using direct and semidirect techniques.

OBJECTIVE: This prospective study evaluated the clinical performance of large class II restorations made with different techniques over 24 months. MATERIALS AND METHODS: Thirty patients received two class II restorations (n = 60) using a nanohybrid composite and different restorative techniques (direct (DT), semidirect (SDT)), in a split-mouth randomized design. The same adhesive system was applied for all restorations. For DT, the restorative material was applied directly inside the tooth preparation. For SDT, a tooth preparation impression was obtained using alginate and a silicone flexible die was prepared. The restoration was made chairside on the model and additionally light cured. After that, it was cemented in preparation using resinous cement. All restorations were evaluated using the FDI criteria after 7 days, 6, 12, and 24 months postoperatively. RESULTS: After 24 months, 24 patients attended the recall and 48 restorations were evaluated. Fisher's statistical analysis (5%) showed no difference between the techniques. Nevertheless, Friedman's test showed significant differences for some criteria after 12 months of evaluation for both techniques. Postoperative sensitivity was reported in one DT restoration. Also, after 24 months, one SDT restoration presented marginal fracture, which was deemed unsatisfactory. CONCLUSIONS: After a 24-month follow-up, no significant difference between the tested techniques was detected. The restorations performed with both techniques produced clinically acceptable restorations. CLINICAL RELEVANCE: This study demonstrated the viability of applying two different operatory techniques (direct and semidirect) for class II resin composite restorations.

Protocols to control contamination and strategies to optimize the clinical practice in Restorative Dentistry during the COVID-19 pandemic / Protocolos para controle de contaminação e estratégias para otimizar a prática clínica em Odontologia Restauradora durante a pandemia de COVID-19

The current outbreak of coronavirus 2019 (COVID-19) challenges how professional standards have been defined so far. In Dentistry, biosafety measures already taken by professionals have been intensified, aiming to offer the patient urgent and emergency treatment with safety for both. In this context, Restorative Dentistry is responsible for the care of patients with caries injuries, with or without symptoms and, fractures of teeth and existing restorations. This article guides professionals, during the pandemic period, on the risks involved in adult and pediatric dental care for patients with restorative needs. It also discusses strategies to optimize clinical practice, reducing risks of contamination and virus transmission. (AU)

O atual surto de coronavírus 2019 (COVID-19), fez com que muitos profissionais repensassem sua postura de trabalho. Na Odontologia, medidas de biossegurança já realizadas pelos profissionais, foram intensificadas, com o objetivo de oferecer ao paciente um tratamento de urgência e emergência com segurança para ambos. Neste contexto, a Odontologia Restauradora é responsável pelo atendimento de pacientes com lesões de cárie, com ou sem sintomatologia, e fraturas de dentes e restaurações já existentes. Este trabalho orienta os profissionais quanto aos riscos envolvidos no atendimento odontológico, adulto e pediátrico, de paciente com necessidades restauradoras durante o período de pandemia. O artigo também discute estratégias para otimizar o atendimento, diminuindo riscos de contaminação e transmissão do vírus. (AU)

Effects of artificial staining on bulk-filled resin composites.

PURPOSE: To evaluate the color stability of bulk-fill resin composites (RC) in comparison to conventional RC submitted to artificial staining. METHODS: 15 specimens of each RC were prepared. Five bulk-fill RC [X-tra Base (XB), Filtek Bulk-Fill Flowable (FBF), Admira Fusion X-tra (AD), Tetric N-Ceram Bulk-Fill (TB), and Filtek Bulk-Fill (FB) ], and two conventional RC [GrandioSO (GO) and Filtek Z350XT (FXT) ] were used. After preparation of the samples, the specimens were immersed in a staining broth for 5 weeks and repolished. The color change was assessed using a spectrophotometer. Data were analyzed using one-way ANOVA, Tukey's tests, and paired t-test. RESULTS: The bulk-fill flowable (XB and FBF) presented color change clinically acceptable (ΔE< 2.7) after staining. Among the bulk-fill regular resins, only AD presented clinically acceptable values (ΔE= 1.99). Regarding the conventional resins, GO presented a significantly lower color change than the other resins, but was not significantly different from AD. For all the resins, except AD, the repolishing procedures resulted in a significant decrease of color change. Tested resins did not present the same behavior under staining, despite their similarities. All the resins stained above the perceptibility threshold (ΔE> 1.2). After repolishing, the color change was reduced overall. CLINICAL SIGNIFICANCE: Color stability of resin composites was related to the properties of the resin material. The staining degree was related to the replacement of the restorations and repolishing contributes to the maintenance and longevity of these composites.

Effect of whitening mouthrinses on enamel toothbrush abrasion.

PURPOSE: To evaluate the effect of whitening mouthrinses used before toothbrushing on enamel microhardness and wear. METHODS: 80 polished bovine enamel specimens were randomly assigned into four groups according to the mouthrinses tested (n=20): PW: Plax Whitening - 1.5% hydrogen peroxide (HP); LW: Listerine Whitening Pre-Brush Rinse - 2% HP; U: Ultradex - Chlorine dioxide; C: Control - Artificial saliva. The specimens were immersed in the mouthrinses for 1 minute and brushed with 10 strokes, using a dentifrice containing sodium fluoride. After treatments, they were immersed in artificial saliva for 30 minutes. A total of 540 cycles were performed simulating 9 months of use. Enamel surface was assessed with a Knoop microhardness tester and by a contact profilometer before and after treatments to obtain the surface microhardness (KHN) and enamel loss (µm) values. The specimens were immersed in artificial saliva for an additional 30 days and microhardness was measured again. Data were analyzed by ANOVA and Tukey's tests (5%). RESULTS: Significant differences were observed in KHN (P= 0.0001) and wear (P= 0.0001). Results of Tukey's for KHN: U-320.08±13.86a, PW-323.58±32.75a, LW-331.66±24.74a, C-354.24±16.40b. Wear (µm) : PW-10.03±0.94a, LW-9.92±0.81a, U-8.88±1.02b, C-6.56±0.91c. Groups followed by the same letters do not present significant differences. After 30 days in saliva, there was no significant difference for SMH among the groups. CLINICAL SIGNIFICANCE: The continuous use of whitening mouthrinses can increase the enamel abrasion potential promoted by daily toothbrushing; therefore, they should be used with caution.

Effect of whitening toothpastes on wear and roughness of ormocer and methacrylate-based composites.

PURPOSE: To investigate the effects of whitening toothpastes over the wear and surface roughness of ormocer and methacrylate composites. METHODS: Cylindrical specimens (n=120) were prepared using methacrylate-based composites (Filtek Z350 XT, TPH3 and GrandioSO) and a pure-ormocer composite (Admira Fusion). Brushing abrasion (100,000 strokes) was performed using whitening toothpastes containing different abrasives: alumina (Colgate Ultrawhite), perlite (CloseUp Whitening) and sodium bicarbonate (Kin Progressive Whitening). Wear and roughness alteration were evaluated. Additional analyses of microhardness, degree of conversion and scanning electron microscopy were also performed. RESULTS: Data were separately analyzed with Kruskal-Wallis and ANOVA tests. Statistically significant differences were found for the composites and whitening toothpastes (P<0.05). For all toothpastes, GrandioSO showed lower wear than Z350 XT and Admira Fusion, although non-significant differences in relation to TPH3 were observed. For perlite and bicarbonate-based toothpastes, Z350 XT, Admira Fusion and TPH3 did not present significant differences among them for wear. For alumina-based toothpaste, Z350 XT showed higher wear than TPH3, while Admira Fusion showed intermediate values. Higher wear and roughness alteration were observed after using alumina-containing toothpaste. All composites tested showed increased roughness after brushing. Z350 XT presented the lowest roughness alteration, while Admira Fusion the highest. CLINICAL SIGNIFICANCE: The alumina-containing whitening toothpaste significantly increased the wear and roughness of composites in relation to the other abrasives tested. However, using the ADA standards, the wear promoted by all whitening toothpastes tested would be considered clinically acceptable for all materials. The type of organic matrix in a composite is not the main factor that determines the wear rate, but also its interaction with the inorganic fillers and the filler content. The composite GrandioSO showed the lowest overall wear values, while Z350 XT resulted in the smoothest surfaces.

Determination of chemical elements and cross-section hardness of sclerotic darkened human dentin / Determinação de elementos químicos e da microdureza transversal da dentina esclerótica humana

Objetivo: O objetivo deste estudo foi avaliar a quantidade de elementos químicos (Ca, O, C, P, Fe e Mg) e a microdureza superficial da dentina esclerótica escurecida em dentes humanos. Material e Métodos: O estudo foi aprovado pelo Comitê de Ética local e dez dentes extraídos (cinco hígidos e cinco apresentando dentina esclerosada) foram utilizados. Os dentes foram seccionados no sentido mésiodistal e cada metade foi utilizada para cada teste. A quantidade de elementos químicos (%w) foi determinada pela espectroscopia de raio-x por dispersão em energia (EDS) em três áreas dentinárias diferentes (superficial, média ou profunda). Estas mesmas áreas tiveram a microdureza superficial Knoop determinada. Os dados foram analisados por ANOVA dois fatores e teste de comparações múltiplas, com nível de significância de 5%. Resultados: Nenhuma diferença quanto à microdureza foi detectada entre a dentina hígida e esclerótica (p = 0,743) e nem em relação às profundidades (p = 0,837). Menor quantidade de Ca (p = 0,024) e maior quantidade de C (p = 0,015) foram encontradas na dentina esclerótica superficial. O aumento do conteúdo de Mg (p < 0,001) foi detectado na dentina hígida. Conclusão: Pode-se concluir que a dentina esclerótica apresenta microdureza superficial similar à dentina hígida. Os elementos químicos estudados apresentaram-se igualmente para os dois tipos de dentina, exceto para o Mg, o qual estava em maior quantidade na dentina hígida. O cálcio e o fósforo apresentaram quantidades reduzidas na dentina esclerótica superficial.(AU)

Objective: The aim of this study was to assess the amount of chemical elements (Ca, O, C, P, Fe, and Mg) and the cross-section hardness of sclerotic darkened dentin in human teeth. Material and Methods: The study was approved by the local IRB and ten extracted teeth (five sound and five presenting sclerotic darkened dentin) were used. Tooth was sectioned mesiodistally and each half was used for each test. Amount of chemical elements (%w) was determined by energy dispersive X-ray spectroscopy (EDS) in three different dentin areas (shallow, medium, or deep sound or sclerotic dentin). Knoop microhardness was determined at the same EDS areas. Data were analyzed by two-way ANOVA and multiple comparison tests, with significance level at 5%. Results: No difference on microhardness was detected between sound and sclerotic dentin (p = 0.743) and also among dentin depths (p = 0.837). Lower Ca (p = 0.024) and higher C (p = 0.015) amounts were found at superficial sclerotic dentin. Increased Mg content (p < 0.001) was detected in sound dentin. Conclusion: It was concluded darkened sclerotic dentin presents similar cross-section microhardness to sound dentin. The assessed chemical elements were similarly present in sound or sclerotic dentin, except for Mg, which was present higher concentration in sound dentin. Ca and P were lower in superficial sclerotic dentin (AU)