Shelf life effects on the bond strength and microhardness of self-adhesive resin cements.

Background: Among the main advantages of self-adhesive resin cements comprise good aesthetics, strong restoration-tooth bond and biocompatibility. However, some disadvantages, such as high viscosity level, color limitation and short shelf life should be mentioned. Thus, the aim of the current study was to assess bond strength between fiberglass post and root dentin in teeth subjected to self-adhesive resin cements with expired shelf life and hardness. Material and Methods: Sixty (60) single-rooted human teeth were sectioned and divided into 2 groups of different cements: U200 3M and MaxCem Elite Kerr. Each group was divided into 3 subgroups, based on self-adhesive resin cements' shelf life, namely: Within the use-time recommended by the manufacturer or no expiration date; 6 months after opening the aluminum blister; 12 months after opening the aluminum blister. Bond strength was measured through push-out test conducted in universal testing machine; fracture pattern was analyzed, and microhardness was investigated through Knoop test, based on hardness readings. Data were subjected to Shapiro-Wilk normality test; nonparametric test was applied to hardness data, whereas parametric test was applied to bond strength data. Hardness data were subjected to Kruskal-Wallis test, whereas bond strength data were subjected to analysis of variance, which was followed by Tukey test; both tests were conducted at 5% significance level (α = 0.05). Results: There was no statistically significant difference in knoop hardness values recorded for the material / time / root thirds combination (p=0.483). There was no statistically significant difference in bond strength values recorded for the Material / Time / Thirds combination (p=0.237). Conclusions: It was possible concluding that shelf life did not influence material's hardness and bond strength. Key words:Dental cements, Resin Cements, Shelf Life of Products.

Comparative study of physical-chemical properties of bioactive glass ionomer cement.

This study analyzed the physical-chemical properties of bioactive ionomer materials. Cention N bioactive materials were evaluated chemically activated (CN) and light-cured (CN-LC), Equia Forte Fill (EQUI); conventional resin composite Filtek Z350 XT (Z350); resin glass ionomer cement Riva light Cure (RIVA) and flowable resin composite Filtek Bulk Fill Flow (BULK-F) were evaluated. Sixty specimens (n=10) were prepared for sorption (SR), solubility (SL), flexural strength (FS), shrinkage stress (SS), conversion degree (CD), microhardness (MI), and surface roughness (SR) tests. Non-cured and light-cured materials were assessed on FTIR. 30 human molar teeth were used in the bond strength test (BS). Data were subjected to ANOVA and post-hoc Tukey's test (5% of significance). EQUI showed more sorption in SR and no statistical difference from RIVA and CN-LC. CN group showed more solubility and EQUI presented less (p<0.05). BULK-F showed higher FS (MPa), without differences from CN and Z350, whereas EQUI presented the lowest FS not differing from RIVA. BULK-F and CN-LC showed more shrinkage stress differing from EQUI. CN-LC and CN showed higher CD differing from the other which showed no differences (p>0.05) between them. EQUI showed the highest hardness (p<0.05) in MI. There were no differences (p>0.05) in SR (µm). Z350 and BULK-F presented higher BS, whereas CN-LC showed the lowest, although not differing from EQUI and RIVA. Equia Forte's solubility and microhardness make it a good alternative as a restorative material. Cention N degree of conversion and flexural strength making it an esthetic option to amalgam.

Whitening efficacy of activated charcoal-based products: A single-blind randomized controlled clinical trial.

OBJECTIVE: This randomized controlled clinical trial evaluated the whitening efficacy, tooth sensitivity (TS), and volunteers' satisfaction following the use of activated charcoal powder and toothpaste. METHODS: Fifty-six volunteers were randomly allocated into 4 groups (n = 14) according to a 14-day toothbrushing or whitening treatment with activated charcoal powder (ACPW), activated charcoal toothpaste (ACT), regular fluoridated toothpaste (RT), and 10 % carbamide peroxide (CP). Objective (ΔE00) and subjective (ΔSGU) color and whiteness index (ΔWID) changes were calculated. Patients self-reported the risk and intensity of TS using a visual analogue scale and the volunteer's satisfaction was determined by a questionnaire. Color assessments were analyzed by Kruskal-Wallis followed by Dwas-Steel-Crithlow-Fligner, and absolute TS risk and volunteer's satisfaction by Fisher exact test (p < 0.05). RESULTS: ACPW and ACT promoted similar effects in ΔE00, ΔSGU, and ΔWID to that observed for RT. No significant difference was found in terms of TS risk intensity. TS risk became high after 7 and 14 days, with higher TS prevalence in CP. Volunteers reported that ACPW exhibited the lowest ease-of-use, comfort, and whitening satisfaction among groups (p < 0.05). CONCLUSION: Activated charcoal-based products presented a minor and unsatisfactory whitening effect while CP resulted in optimal tooth whitening and the highest level of satisfaction among volunteers. Risk was higher from 7 days onwards and was more pronounced in the CP. CLINICAL RELEVANCE: Based on the whitening effect and patient satisfaction, this controlled-randomized clinical evidence supports that the use of activated charcoal-based products should be discouraged.

Comparative study of physical-chemical properties of bioactive glass ionomer cement

Abstract This study analyzed the physical-chemical properties of bioactive ionomer materials. Cention N bioactive materials were evaluated chemically activated (CN) and light-cured (CN-LC), Equia Forte Fill (EQUI); conventional resin composite Filtek Z350 XT (Z350); resin glass ionomer cement Riva light Cure (RIVA) and flowable resin composite Filtek Bulk Fill Flow (BULK-F) were evaluated. Sixty specimens (n=10) were prepared for sorption (SR), solubility (SL), flexural strength (FS), shrinkage stress (SS), conversion degree (CD), microhardness (MI), and surface roughness (SR) tests. Non-cured and light-cured materials were assessed on FTIR. 30 human molar teeth were used in the bond strength test (BS). Data were subjected to ANOVA and post-hoc Tukey's test (5% of significance). EQUI showed more sorption in SR and no statistical difference from RIVA and CN-LC. CN group showed more solubility and EQUI presented less (p<0.05). BULK-F showed higher FS (MPa), without differences from CN and Z350, whereas EQUI presented the lowest FS not differing from RIVA. BULK-F and CN-LC showed more shrinkage stress differing from EQUI. CN-LC and CN showed higher CD differing from the other which showed no differences (p>0.05) between them. EQUI showed the highest hardness (p<0.05) in MI. There were no differences (p>0.05) in SR (µm). Z350 and BULK-F presented higher BS, whereas CN-LC showed the lowest, although not differing from EQUI and RIVA. Equia Forte's solubility and microhardness make it a good alternative as a restorative material. Cention N degree of conversion and flexural strength making it an esthetic option to amalgam.

Resumo Este estudo analisou as propriedades físico-químicas dos materiais de ionômero bioativo. Os materiais bioativos Cention N quimicamente ativados (CN) e fotopolimerizados (CN-LC), Equia Forte Fill (EQUI); resina composta convencional Filtek Z350 XT (Z350); resina de ionômero de vidro Riva light Cure (RIVA) e resina composta fluida Filtek Bulk Fill Flow (BULK-F) foram avaliados. Sessenta espécimes (n=10) foram preparados para testes de sorção (SR), solubilidade (SL), resistência à flexão (FS), tensão de contração (SS), grau de conversão (CD), microdureza (MI) e rugosidade da superfície (SR). Os materiais não curados e curados com luz foram avaliados por FTIR. 30 dentes molares humanos foram usados no teste de resistência de união (BS). Os dados foram submetidos a ANOVA e teste de post-hoc Tukey (5% de significância). O EQUI apresentou maior sorção no SR e não mostrou diferença estatística em relação aos grupos RIVA e CN-LC. O grupo CN apresentou maior solubilidade e o EQUI apresentou menor (p<0,05). O BULK-F apresentou maior FS (MPa), sem diferir do CN e do Z350, enquanto o EQUI apresentou o menor FS, não diferindo do RIVA. O BULK-F e o CN-LC apresentaram maior estresse de contração, diferindo do EQUI. O CN-LC e o CN apresentaram maior CD (%), diferindo dos demais, que não apresentaram diferenças (p>0,05) entre si. A EQUI apresentou a maior dureza (p<0,05) no MI. Não houve diferenças (p>0,05) na SR (µm). Z350 and BULK-F apresentaram BS, enquanto a CN-LC apresentou a menor, embora não diferindo da EQUI e da RIVA. A solubilidade e a microdureza do Equia Forte o tornam uma boa alternativa como material restaurador. O grau de conversão e a resistência à flexão do Cention N o tornam uma opção estética ao amálgama.

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.

Dental aesthetic perception of patients submitted to activated charcoal-based bleaching agents: A randomized clinical trial.

OBJECTIVE: To evaluate the effects of activated charcoal-based products used in two presentation forms (powder or toothpaste), compared to 10 % carbamide peroxide and conventional toothpaste on aesthetic perception and psychosocial impact before and after treatment. METHODS: Fifty-six participants were divided into 4 experimental groups (n = 14). Activated charcoal-based powder (PW); Activated charcoal-based dentifrice (AC); Conventional fluoride toothpaste (CD) and 10 % carbamide peroxide (CP). All products were used for 14 days. Psychosocial impact on dental esthetics (PIDAQ), oral health impact profile (OHIP- Esthetics) and orofacial esthetics scale (OES) questionnaires were applied before and after treatment. Descriptive and exploratory data analyses were performed and analyzed using linear mixed models for repeated measures over time considering significance level of α = 0.05. RESULTS: For PIDAQ, the CP group showed significant decrease in psychological impact, aesthetic perception domains and overall score, while in the PW group, there was only a significant decrease in the psychological impact domain. Decrease in OHIP was observed for the functional limitation domain scores for treatments with CP and PW, in the psychological discomfort domain, decrease was observed for all groups, while for the OES questionnaire, significant increase in the color domain was observed for the CP group. CONCLUSION: Activated charcoal-based products showed lower scores in all questionnaires when compared with carbamide peroxide; thus, charcoal-based products promoted lower impact on quality of life and aesthetic perception. CLINICAL RELEVANCE: In this randomized clinical trial, charcoal-based OTC products had inferior quality of life and aesthetic perception results compared to conventional carbamide peroxide bleaching.

Effect of silver nanoparticles associated with fluoride on the progression of root dentin caries in vitro.

OBJECTIVES: To assess the anti-proteolytic effect and potential to inhibit dentin root caries progression of a silver nanoparticle and fluoride solution (CNanoF) in comparison to silver diamine fluoride (SDF). METHODS: 48 specimens of root dentin artificial caries lesion were treated with 38% SDF, CNanoF, CNano or F (n = 6 per group). Ph cycling with demineralization and remineralization solutions simulated caries lesion progression. In addition, specimens were incubated with or without bacterial collagenase in the remineralization solution to induce dentin proteolytic degradation. Dentin degradation was assessed by weight loss rate and hydroxyproline (Hyp) release. Changes in cross-sectional microhardness, and lesion permeability and collagen integrity as determined by confocal laser scanning microscopy indicated potential for further demineralization inhibition. The effect of the solutions on the activity of metalloproteinases (MMP) -2 and -9 was also investigated. Statistical analysis consisted of ANOVA, Kruskal-Wallis, and linear mixed models with post-hoc pairwise Tukey, Dunn, and t-tests (α = 0.05). RESULTS: Treatment with SDF resulted in lower weight loss rate than did other solutions, but all groups showed similar Hyp release (p = 0.183). SDF resulted in greater microhardness at superficial layers of the caries lesions (p<0.05), while there were no differences among CNanoF, CNano, and F. Lesion permeability was similar among all groups after pH cycling (p>0.05), with or without the use of collagenase (p = 0.58). No statistically significant difference was noted among solutions regarding collagen integrity after pH cycling; however, SDF-treated dentin had a significant decrease in collagen integrity when collagenase was used (p = 0.003). Interestingly, only SDF was able to completely inactivate MMP-2 and -9. CONCLUSIONS: CNanoF and SDF both potentially prevent dentin degradation during caries lesion progression in vitro; however, SDF was more effective at inhibiting further tissue demineralization.

In vitro assessment of activated charcoal-based dental products.

OBJECTIVE: Assess the effects of activated charcoal-based products on whitening and changes on dental enamel surface. MATERIAL AND METHODS: Fifty-two blocks of bovine dental enamel were randomly distributed in four groups (n = 13): brushing with activated charcoal-based powder (PW); brushing with activated charcoal-based dentifrice (AC); brushing with a conventional dentifrice containing 1450 ppm of fluoride (CD); and whitening with 10% carbamide peroxide (CP). Color, microhardness, and surface alteration were analyzed at baseline and after 14 days of treatment. Three samples per group were randomly selected and examined using scanning electron microscopy (SEM) to analyze the morphology. RESULTS: PW exhibited greater color change for the ΔE00 , ΔWID, Δb* and ΔL* parameters than other groups (p < 0.05). After treatment, microhardness decreased in AC and CP groups (p < 0.05). Also, PW and AC groups showed more surface alteration than CD and CP (p < 0.001). Changes in the morphology of dental enamel were observed by SEM in PW and AC groups. CONCLUSION: Activated charcoal-based products showed a lower whitening effect than 10% carbamide peroxide. These products also influenced dental enamel microhardness, resulting in greater surface alteration. CLINICAL SIGNIFICANCE: Activated charcoal-based products promoted minimum whitening effects with significant enamel surface alteration. The 10% carbamide peroxide was more effective for whitening and caused slight enamel surface alteration.

Evaluating changes in the color and luminosity of dental enamel after orthodontic treatment: A clinical study.

The aims of this clinical study were to evaluate the Color change - ΔE (based on spectrophotometry and visual analysis) and luminosity - L* (based on spectrophotometry) of dental enamel surface (after orthodontic treatment) around the area where orthodontic brackets were fixed, based on different cementing materials such as a resin (R group) and resin-modified glass ionomer cement (RMGIC group). The split-mouth study initially comprised 14 patients. Orthodontic brackets were fixed to the upper central incisors with resin or RMGIC. The color of the buccal surface of each tooth was measured through spectrophotometry and visual examination before the bracket-fixation process. Four individuals were excluded during the follow-up; thus 10 patients were evaluated (n=10). Brackets were removed after 12 months of orthodontic treatment, tooth color measurement and visual examination were performed again, and Adhesive Remaining Index (ARI) was also measured. ΔE and L* results were subjected to Student's t-test and by repeated-measures analysis of variance, respectively (α=0.05). ARI data were analyzed in percentages. There was statistically significant difference in ΔE between groups; the R group showed statistically higher values of L* after orthodontic treatment. ARI of 2 and 3 prevailed in the RMGIC group, whereas the R group presented 0 and 1. After orthodontic treatment, the RMGIC group presented smaller changes in ΔE, and the increase in the white scale was observed on the enamel surface around the area where brackets were fixed in the R group. The visual analysis did not show color change on the evaluated teeth.

Evaluating changes in the color and luminosity of dental enamel after orthodontic treatment: A clinical study

Abstract The aims of this clinical study were to evaluate the Color change - ΔE (based on spectrophotometry and visual analysis) and luminosity - L* (based on spectrophotometry) of dental enamel surface (after orthodontic treatment) around the area where orthodontic brackets were fixed, based on different cementing materials such as a resin (R group) and resin-modified glass ionomer cement (RMGIC group). The split-mouth study initially comprised 14 patients. Orthodontic brackets were fixed to the upper central incisors with resin or RMGIC. The color of the buccal surface of each tooth was measured through spectrophotometry and visual examination before the bracket-fixation process. Four individuals were excluded during the follow-up; thus 10 patients were evaluated (n=10). Brackets were removed after 12 months of orthodontic treatment, tooth color measurement and visual examination were performed again, and Adhesive Remaining Index (ARI) was also measured. ΔE and L* results were subjected to Student's t-test and by repeated-measures analysis of variance, respectively (α=0.05). ARI data were analyzed in percentages. There was statistically significant difference in ΔE between groups; the R group showed statistically higher values of L* after orthodontic treatment. ARI of 2 and 3 prevailed in the RMGIC group, whereas the R group presented 0 and 1. After orthodontic treatment, the RMGIC group presented smaller changes in ΔE, and the increase in the white scale was observed on the enamel surface around the area where brackets were fixed in the R group. The visual analysis did not show color change on the evaluated teeth.

Resumo Os objetivos deste estudo clínico foram avaliar a alteração de cor - ΔE (baseada em espectrofotometria e análise visual) e luminosidade - L* (baseada em espectrofotometria) da superfície do esmalte dentário (após tratamento ortodôntico) ao redor da área onde os braquetes ortodônticos foram fixados, com base em diferentes materiais de cimentação, como resina (grupo R) e cimento de ionômero de vidro modificado por resina (grupo RMGIC). Estudo boca dividida foi inicialmente composto por 14 pacientes. Os braquetes ortodônticos foram fixados nos incisivos centrais superiores com resina ou RMGIC. A cor da superfície vestibular de cada dente foi mensurada por espectrofotometria e avaliada por exame visual antes do processo de fixação dos braquetes. Quatro indivíduos foram excluídos durante o acompanhamento; assim, 10 pacientes foram avaliados (n=10). Os braquetes foram removidos após 12 meses de tratamento ortodôntico, a mensuração da cor do dente e o exame visual foram realizados novamente, e o Índice de Remanescente do Adesivo (IRA) também foi mensurado. Os resultados ΔE e L* foram submetidos ao teste t de Student e à análise de variância para medidas repetidas, respectivamente (α=0.05). Os dados do ARI foram analisados em porcentagens. Houve diferença estatisticamente significativa no ΔE entre os grupos; o grupo R apresentou valores estatisticamente maiores de L* após o tratamento ortodôntico. O IRA 2 e 3 prevaleceu no grupo RMGIC, enquanto o grupo R apresentou 0 e 1. Após o tratamento ortodôntico, o grupo RMGIC apresentou menores alterações no ΔE e o aumento da escala branca foi observado na superfície do esmalte ao redor da área onde os braquetes foram fixados no grupo R. A análise visual não mostrou mudança de cor nos dentes avaliados.

Assessing the bleaching effect of an experimental stabilized chlorine dioxide agent used for internal bleaching purposes

Aim Assessing the intracoronal bleaching effectiveness of an experimental chlorine dioxide product, based on the walking bleach technique. Methods Extracted bovine incisors were artificially stained with bovine blood and filled with zinc phosphate cement at cementoenamel junction level. Teeth were divided into 3 groups (n=10): (SP) sodium perborate added with distilled water, (CD) chlorine dioxide and (C) control - dry cotton inserted into the pulp chamber. Bleaching agents were used at 0, 7 and 14 days. VITA Easyshadetm (∆Eab) was used to analyze tooth color at the 7th, 14th and 21st days, based on the CIE2000 system. Data were analyzed through ANOVA and Tukey's test. Results There were no statistically significant differences in Δb, ΔE, ΔE00 and ΔWID between CD and the control group. These parameters have shown significant differences between CD and SP, which differed from the control. However, they did not show significant differences either in the control group or in CD at the 7th, 14th and 21st days. Values recorded for SP at the 7th day differed from those recorded at the 14th and 21st days. Δa has shown differences within the same group at the 7th, 14th and 21st days. There was no difference between groups, when they were compared at the same day (7th and 14th). The control group differed from SP at the 21st day. CD did not differ from the other two groups. ΔL did not show differences between groups and times. Conclusion Stabilized chlorine dioxide (0.07%, at pH 3.5) should not be used as intracoronal bleaching agent along with the walking bleach technique.

Evaluation of Removal Force in Prosthetic Components of Morse Taper Dental Implants.

The longevity of prosthetic rehabilitation is determined by the stability of the implant and abutment interfaces. True morse taper connections on dental restorations have been effective, however activation force still empirical. This work compared the activation strength and internal contact of Morse taper system according to the removal force. Eighty sets, composed of implants and prosthetic abutments, were evaluated with different internal contact areas; 15.12mm2 (G3.3) and 21.25mm2 (G4.3). The specimens were activated at 0° and 30°, with loads of 10, 20, 40 and 60N. The specimens were submitted to tensile test and the data to ANOVA and Tukey's tests (α=0.05). Representative specimens were examined under SEM. Removal force of G3.3 (2.15±1.33MPa) did not differed to G4.3 (1.99±1.03MPa). The activation at 0º (2.95±0.98MPa) statistically differed to 30º (1.19±0.54MPa). The 60N load was statistically superior for G3.3 and there was no statistical difference between 20N to 60N in G4.3. The values of 10N at 30o and 20N at the long axis of the morse taper implant, independent of the frictional contact area showed the best settlement.

Evaluation of Removal Force in Prosthetic Components of Morse Taper Dental Implants

Abstract The longevity of prosthetic rehabilitation is determined by the stability of the implant and abutment interfaces. True morse taper connections on dental restorations have been effective, however activation force still empirical. This work compared the activation strength and internal contact of Morse taper system according to the removal force. Eighty sets, composed of implants and prosthetic abutments, were evaluated with different internal contact areas; 15.12mm2 (G3.3) and 21.25mm2 (G4.3). The specimens were activated at 0° and 30°, with loads of 10, 20, 40 and 60N. The specimens were submitted to tensile test and the data to ANOVA and Tukey's tests (α=0.05). Representative specimens were examined under SEM. Removal force of G3.3 (2.15±1.33MPa) did not differed to G4.3 (1.99±1.03MPa). The activation at 0º (2.95±0.98MPa) statistically differed to 30º (1.19±0.54MPa). The 60N load was statistically superior for G3.3 and there was no statistical difference between 20N to 60N in G4.3. The values of 10N at 30o and 20N at the long axis of the morse taper implant, independent of the frictional contact area showed the best settlement.

Resumo A longevidade da reabilitação protética é determinada pela estabilidade das interfaces implante e pilar. Conexões de cone Morse em restaurações dentárias têm se mostrado eficazes, porém a força de ativação ainda é empírica. Este trabalho comparou a força de ativação e contato interno do sistema cone Morse de acordo com a força de remoção. Oitenta conjuntos, compostos por implantes e pilares protéticos, foram avaliados com diferentes áreas de contato interno; 15,12mm2 (G3.3) e 21,25mm2 (G4.3). Os corpos-de-prova foram ativados a 0° e 30°, com cargas de 10, 20, 40 e 60N. Os corpos de prova foram submetidos ao ensaio de tração e os dados aos testes ANOVA e Tukey (α=0,05). Espécimes representativos foram examinados em MEV. A força de deslocamento do G3.3 (2,15±1,33MPa) não diferiu do G4.3 (1,99±1,03MPa). A ativação a 0º (2,95±0,98MPa) diferiu estatisticamente para 30º (1,19±0,54MPa). A carga de 60N foi estatisticamente superior para G3.3 e não houve diferença estatística entre 20N a 60N no G4.3. Os valores de 10N em 30o e 20N no longo eixo do implante cone morse, independente da área de contato friccional apresentaram o melhor assentamento.

Anticaries Agent Based on Silver Nanoparticles and Fluoride: Characterization and Biological and Remineralizing Effects-An In Vitro Study.

Objective: The aim of the study was to characterize and evaluate the stability, antimicrobial activity, cytotoxicity, and remineralizing effects of silver nanoparticles and fluoride anticaries agent (AgF) on staining dental enamel. Materials and Methods: An experimental AgF solution was prepared and compared to silver diamine fluoride (SDF). First, the AgF was characterized and the stability was evaluated by transmission electron microscopy (TEM). Streptococcus mutans, Enterococcus faecalis, and Escherichia coli strains were used to evaluate the minimum inhibitory and bactericidal concentration and cytotoxicity performed using L929 fibroblastic cells by MTT test. Caries-like lesions induced by pH-cycling in human enamel were obtained, and then, the superficial microhardness, cross-sectional microhardness (CSMH), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS) were performed. Photographic images were taken to analyze the enamel staining. Results: The AgF showed stableness in long term with bacteriostatic and bactericidal actions without cytotoxicity. Enamel remineralization, in surface and in depth (CSMH), was observed when the AgF was used, and it was similar to SDF. SEM showed enamel precipitation, and EDS observed the presence of P, Ca, Au, Ag, and Cl elements. Contrary to SDF, AgF did not stain the enamel. Conclusion: The nano silver fluoride anticaries agent tested presented long-term stability, superficial and in-depth remineralizing capacity with antimicrobial potential and biocompatibility and did not stain the enamel.

Effect of Chemical Challenges on the Properties of Composite Resins.

OBJECTIVE: To evaluate the chemical degradation effect on microhardness and roughness of composite resins after aging. MATERIALS AND METHODS: Specimens (n = 10) were used for Filtek Z350 XT (Z350), Filtek Bulk Fill (BULK), Micerium HRI (HRI), Micerium BIOFUNCION (BIO), and Vittra APS (VITTRA). Microhardness and roughness were performed before and after degradation with the followed solutions: citric acid, phosphoric acid, 75% alcohol, and distilled water. Samples were to a 180-day chemical cycling protocol. After degradation, one sample of each group was selected for scanning electron microscope evaluation. The data were analyzed with normal distribution (Kolmogorov-Smirnov) and similarities of variations for the Bartlett test. ANOVA (two-way) followed by Tukey's test was performed considering treatment and composite resin (P < 0.05). RESULTS: For microhardness and roughness, variations were noted to different solution and resin formulations. Z350 and HRI showed higher microhardness percentage loss, and it was more evident after storage in alcohol (-48.49 ± 20.16 and -25.02 ± 14.04, respectively) and citric acid (-65.05 ± 28.97 and 16.12 ± 8.35, respectively). For roughness, Z350 and VITTRA showed less delta values after alcohol storage (-0.047 ± 0.007 and -0.022 ± 0.009, respectively). HRI had the worst roughness for citric acid (-0.090 ± 0.025). All resins were not statistically different between each other in water and phosphoric acid. CONCLUSION: The formulations of restorative resin materials influenced in degree of surface degradation after 180 days of chemical degradation. Water was considered the solution that causes less degradation for microhardness and roughness evaluations. For microhardness, alcohol was considered the worst solution for Z350 and HRI. For superficial roughness, Z350 and VITTRA showed less degradation in alcohol and citric and phosphoric acid solutions.

Evaluation of enamel roughness after the removal of brackets bonded with different materials: In vivo study.

The aims of this in vivo study were to evaluate the effect of bonding with resin-modified glass ionomer cement (RMGIC) and to assess enamel surface roughness before and after the removal of brackets bonded with composite or RMGIC from the maxillary central incisors. Fifteen orthodontic patients were selected for the study. For each patient, the teeth were rinsed and dried, and brackets were bonded with composite (Transbond XT) and RMGIC (Vitremer Core Buildup/Restorative). At the conclusion of orthodontic treatment, their brackets were removed. Dental replicas were made of epoxy resin in initial conditions (before bonded) and after polishing with an aluminum oxide disc system. Adhesive remnant index (ARI) and surface roughness was measured on the dental replicas and data were evaluated statistically by Mann-Whitney and paired t-test, respectively. No bracket debonding occurred during patients' treatment periods. It was verified that the ARI values of the two maxillary central incisors were similar (p = 0.665). For both bonding materials, the ARI value of 3 was predominant. After polishing, surface roughness was similar in the composite and RMGIC groups (0.245 µm and 0.248 µm, respectively; p = 0.07). In both groups, enamel surface roughness values were significantly lower after polishing compared with the initial condition (p < 0.001). RMGIC promoted efficiency in cementing brackets without fail during treatment; the choice of composite or RMGIC materials was not a factor that influenced the roughness of the enamel surface, however, polishing led to smoother surfaces than those found at the beginning of the treatment.

Effect of Amelogenin Solution in the Microhardness of Remineralized Enamel and Shear Bond Strength of Orthodontic Brackets.

OBJECTIVES: To evaluate the microhardness of tooth enamel remineralized with enamel matrix protein solution as well as the shear bond strength of orthodontic brackets bonded to this surface. MATERIALS AND METHODS: In total, 24 human premolars were selected and divided into 3 experimental groups (n = 8): SE-sound enamel, DE-demineralized enamel, and TE-demineralized enamel treated with amelogenin solution. Samples from DE and TE groups were subjected to pH cycling to induce initial artificial caries lesion. TE group was treated with amelogenin solution. Samples were placed in artificial saliva for 7 days. Knoop microhardness was measured before any intervention (T0), after pH cycling (T1) and after amelogenin solution treatment application (T2). Twenty-four hours after ceramic orthodontic brackets were bonded, samples were subjected to shear test in a universal testing machine. Microhardness and shear measurement distributions were subjected to Kolmogorov-Smirnov normality test, which was followed by parametric tests (α = 0.05): 2-way analysis of variance (factors: enamel condition × treatment) and Tukey posttest for all three groups (SE, DE, and TE) in T0 and T2 for microhardness; analysis of variance and Tukey's test, for shear bond strength test. RESULTS: Means recorded for Knoop microhardness in T2, for the SE (366.7 KHN) and TE (342.8 KHN) groups, were significantly higher than those recorded for the DE group (263.5 KHN). The shear bond strength of the SE (15.44 MPa) and TE (14.84 MPa) groups statistically differed from that of the DE group (11.95 MPa). CONCLUSION: In vitro demineralized enamel treatment with amelogenin solution was capable of taking samples' hardness back to levels similar to those observed for sound enamel. The shear bond strength on the enamel subjected to this treatment was similar to that observed for healthy enamel and higher than that observed for demineralized enamel.

Evaluation of enamel roughness after the removal of brackets bonded with different materials: In vivo study

Abstract The aims of this in vivo study were to evaluate the effect of bonding with resin-modified glass ionomer cement (RMGIC) and to assess enamel surface roughness before and after the removal of brackets bonded with composite or RMGIC from the maxillary central incisors. Fifteen orthodontic patients were selected for the study. For each patient, the teeth were rinsed and dried, and brackets were bonded with composite (Transbond XT) and RMGIC (Vitremer Core Buildup/Restorative). At the conclusion of orthodontic treatment, their brackets were removed. Dental replicas were made of epoxy resin in initial conditions (before bonded) and after polishing with an aluminum oxide disc system. Adhesive remnant index (ARI) and surface roughness was measured on the dental replicas and data were evaluated statistically by Mann-Whitney and paired t-test, respectively. No bracket debonding occurred during patients' treatment periods. It was verified that the ARI values of the two maxillary central incisors were similar (p = 0.665). For both bonding materials, the ARI value of 3 was predominant. After polishing, surface roughness was similar in the composite and RMGIC groups (0.245 μm and 0.248 μm, respectively; p = 0.07). In both groups, enamel surface roughness values were significantly lower after polishing compared with the initial condition (p < 0.001). RMGIC promoted efficiency in cementing brackets without fail during treatment; the choice of composite or RMGIC materials was not a factor that influenced the roughness of the enamel surface, however, polishing led to smoother surfaces than those found at the beginning of the treatment.

Resumo Os objetivos deste estudo in vivo foram avaliar o efeito da colagem com cimento de ionômero de vidro modificado por resina (CIVMR) e a rugosidade da superfície do esmalte antes e após a remoção dos braquetes colados com compósito ou CIVMR em incisivos centrais superiores. Quinze pacientes ortodônticos foram selecionados para o estudo. Para cada paciente, os dentes foram lavados e secos, e os braquetes colados com compósito (Transbond XT) e CIVMR (Vitremer Core Buildup / Restorative). Ao término do tratamento ortodôntico, os braquetes foram removidos. As réplicas dentais foram confeccionadas em resina epóxica nas condições iniciais (antes da colagem) e após o polimento com sistema de discos de óxido de alumínio. O índice de remanescente adesivo (IRA) e a rugosidade da superfície foram mensurados nas réplicas dentais e os dados foram avaliados estatisticamente por Mann-Whitney e teste t pareado, respectivamente. Não ocorreu descolagem de braquetes durante os períodos de tratamento dos pacientes. Verificou-se que os valores do IRA dos dois incisivos centrais superiores foram semelhantes (p = 0,665). Para ambos os materiais de colagem, o valor de IRA predominante foi 3. Após o polimento, a rugosidade da superfície do esmalte foi semelhante nos grupos compósito (0,245 μm) e CIVMR (0,248 μm) (p = 0,07). Em ambos os grupos, os valores de rugosidade da superfície do esmalte foram significativamente menores após o polimento em comparação com a condição inicial (p <0,001). CIVMR promoveu eficiência na colagem de braquetes sem falhas durante o tratamento; a escolha dos materiais compósito ou CIVMR não foi um fator que influenciou na rugosidade da superfície do esmalte, porém, o polimento levou a superfícies mais lisas do que as encontradas no início do tratamento.

Effect of application time and concentration of silver diamine fluoride on the enamel remineralization.

BACKGROUND: Silver diamine fluoride has attracted attention because of its clinical success in arresting dental caries. Thus, the aim of this study was to evaluate the effect of different application times and concentrations of silver diamine fluoride (SDF) on deciduous tooth enamel remineralization. MATERIAL AND METHODS: Blocks of deciduous tooth enamel were categorized into six groups of 11 each: 2 control groups: intact enamel, and demineralized enamel; 38% SDF and 30% SDF which were subdivided according to application times (1 and 3 min). The microhardness of samples was determined, and all groups except the intact enamel group were subjected to pH cycling to produce initial carious lesions. The 38% and 30% SDF solutions were applied to the enamel for 1 or 3 min. After pH cycling and SDF treatments, the microhardness was again determined. Samples were sectioned to evaluate the cross-sectional microhardness. Furthermore, internal porosity of the samples was examined using micro-CT. Data were statistically analyzed by analysis of variance followed by Tukey's test, and linear regression analyses were performed. RESULTS: There was no difference in enamel remineralization based on surface and cross-sectional microhardness. The 30% SDF solution applied for 3 min promoted significantly less pores than the other groups. CONCLUSIONS: The 1-min application time promoted enamel remineralization regardless of the SDF concentration (30% or 38%). Key words:Cariostatic agents, dental caries, primary tooth, tooth remineralization.

The impact of different surface treatments on the shear bond strength of orthodontic metal brackets applied to different CAD/CAM composites.

BACKGROUND: To investigate the shear bond strength (SBS) of orthodontic metal brackets applied to different CAD/CAM composites treated with different surface treatments. MATERIAL AND METHODS: Specimens of two CAD/CAM composites were obtained of Lava Ultimate (LU; n=60) and Brilliant Crios (BC; n=60) which were randomly separated into six subgroups (n=10) according to the surface treatment: control (CTL); sandblasting (SB); sandblasting and silane (SBSL); hydrofluoric acid (HF); hydrofluoric acid and silane (HFSL); and Monobond Etch&Prime (MEP). The mandibular central incisor metal brackets were bonded with a light-cure adhesive. The SBS data were analyzed using the two-way analysis of variance and Turkey's test, while the adhesive remnant index (ARI) by the Kruskal-Wallis, all the significance was set at 5%. RESULTS: A higher SBS was found for BC in comparison with LU (p< 0.05). All the surface treatments increased the SBS in comparison with CTL (p< 0.0001). Treatment with HF, SBSL and HFSL (p> 0.05) showed a higher SBS, which was followed by MEP and SB (p> 0.05), all in comparison with CTL (p< 0.0001). For ARI, a significant effect was detected only for the surface treatment (p< 0.01), and not for CAD/CAM resin (p> 0.05). Significant differences were detected between CTL to HF, and HF to MEP, as well. CONCLUSIONS: The SBS is highly affected by the surface treatment and also by the CAD/CAM composite. The surface treatment improves the SBS and should be encouraged when orthodontic brackets are bonded to CAD/CAM composites. Key words:CAD/CAM composite resin, brackets, shear bond strength, surface treatment, bonding.