Effect of whitening toothpaste on superficial roughness of composite resin.

This study sought to evaluate the effect of different toothpastes with whitening action on the average surface roughness (Ra) of a microhybrid composite resin. Twenty-five specimens of composite resin were prepared and distributed randomly among 5 experimental groups (n = 5). Groups 1-3 were treated with whitening toothpastes: Close-up Extra Whitening, Colgate Ultra White, and Colgate Total 12 Whitening. Group 4 was a negative control group (with samples brushed with deionized water), and Group 5 was a positive control group (with samples brushed using a non-whitening toothpaste). A profilometer was used to determine Ra before and after brushing. A simulated brushing machine was used for all groups, providing horizontal back and forth movement with an amplitude of 3.8 cm applying an axial load of 200 g and a speed of 356 rpm, totaling 20,000 cycles. To determine the Ra in each specimen, 6 readings were taken at various positions before and after brushing. The results were submitted to variance analyses and Tukey's test. (P < 0.05). Groups 1, 2, 3, and 5 demonstrated statistically significant differences between initial and final averages. Based on these results, it was determined that brushing with toothpaste, regardless of formulation, significantly increased the Ra of the resin composite evaluated in this study.

Intensidade de fluorescência em resina composta: influência do polimento superficial e dos meios de armazenagem / Fluorescence intensity in composite resin: influence of superficial polishing and storage means

Introdução: A resina composta é um material versátil em Odontologia Estética, principalmente por suas propriedades ópticas, dentre as quais a fluorescência. Poucos são os estudos que avaliaram esta propriedade e a comparação dos resultados encontrados torna-se difícil em função da inexistência de padronização nas metodologias na confecção e na armazenagem dos corpos de prova. Objetivo: Verificar a influência do polimento superficial e do meio de armazenagem, em estudos in vitro, em que se avalia a propriedade óptica de fluorescência em resinas compostas. Material e Método: Foram preparados 70 corpos de prova circulares (10 mm × 2 mm ) com resina composta microhíbrida (Opallis,- A2E - FGM.) Os meios de armazenagem foram: água deionizada, água da torneira e saliva artificial. Os protocolos de polimento superficial, realizados em politriz após a obtenção dos corpos de prova, utilizaram lixas de granulações 600, 1200 e 2500. Os valores de intensidade de fluorescência foram avaliados através do espectrofotômetro Cary Eclipse, após 1, 7 e 21 dias. Resultado: Não houve diferença estatisticamente significativa na Intensidade de Fluorescência entre os grupos submetidos aos diferentes protocolos de polimento. Quanto aos meios de armazenagem, a partir do sétimo dia, a variação de fluorescência foi significativamente maior em água da torneira e deionizada, quando comparada à variação observada em saliva artificial, resultado que se manteve após 21 dias. Conclusão: O protocolo de polimento superficial não promoveu alterações significativas na fluorescência da resina composta avaliada. Quanto ao meio de armazenagem, a intensidade de fluorescência foi menos afetada quando em saliva artificial.

Introduction: Resin composite is a versatile material in cosmetic dentistry due mainly to its optical properties, fluorescence among them. There are a few studies which assessed such property and a comparison of results becomes difficult due to the lack of a pattern in the specimens storage and confection methodologies. Objective: Verify the influence of superficial polishing and means of storage in in vitro studies that assess the optical property of fluorescence in dental resin composites. Material and Method: 70 circular specimens (10 mm × 2 mm) were prepared with microhybrid composite resin (Opallis, - A2E - FGM). The means of storage were: deionized water, tap water and artificial saliva. The superficial polishing protocols used 600, 1200 and 2500 sandpaper grit sizes, accomplished with polisher after specimens were obtained. The fluorescence intensity values were assessed using Cary Eclipse Fluorescence Spectrophotometer after 1, 7 and 21 days. Result: There was not a statistically significant difference in Fluorescence Intensity among the groups submitted to the different polishing protocols. Concerning the means of storage, from the seventh day on the fluorescence variation was significantly bigger in tap and deionized water, compared to artificial saliva, such result kept on after 21 days. Conclusion: the superficial polishing protocol did not promote significant changes in the assessed resin composite fluorescence. Regarding the means of storage, the fluorescence intensity was less affected when in artificial saliva.

Assessment of the release of mercury from silver amalgam alloys exposed to different 10% carbamide peroxide bleaching agents.

This in vitro study assessed the amount of mercury (Hg) released from a silver amalgam alloy following the application of different 10% carbamide peroxide bleaching agents. A total of 30 specimens (2 mm thick x 4 mm in diameter) were stored in deionized water at 37°C for 7 days. Next, the control group (n = 10) remained in the deionized water for 15 days, while the remaining samples were exposed to 1 of 2 bleaching agents (n = 10) for 8 hours daily (total exposure = 120 hours); for the remaining 16 hours, specimens in the test groups were stored in deionized water at 37°C under relative humidity. After this period, the quantity of Hg in the deionized water was assessed (using atomic absorption spectrophotometry) and compared to the amount of Hg at baseline. The results indicate that exposing amalgam alloys to bleaching agents released greater amounts of Hg compared to exposing samples to deionized [corrected] water.

Ion release from a composite resin after exposure to different 10% carbamide peroxide bleaching agents.

OBJECTIVE: This in vitro study evaluated the influence of two 10% carbamide peroxide bleaching agents - a commercial product (Opalescence PF; Ultradent Products, Inc.) and a bleaching agent prepared in a compounding pharmacy - on the chemical degradation of a light-activated composite resin by determining its release of ions before and after exposure to the agents. MATERIAL AND METHODS: Thirty composite resin (Filtek Z250; 3M/ESPE) samples were divided into three groups: group I (exposed to Opalescence PF commercial bleaching agent), group II (exposed to a compounded bleaching agent) and group III (control - Milli-Q water). After 14 days of exposure, with a protocol of 8 h of daily exposure to the bleaching agents and 16 h of immersion in Milli-Q water, the analysis of ion release was carried out using a HP 8453 spectrophotometer. The values were analyzed statistically by ANOVA, Tukey's test and the paired t-tests. The significance level was set at 5%. RESULTS: After 14 days of the experiment, statistically significant difference was found between group II and groups I and III, with greater ion release from the composite resin in group II. CONCLUSIONS: The compounded bleaching agent had a more aggressive effect on the composite resin after 14 days of exposure than the commercial product and the control (no bleaching).

Ion release from a composite resin after exposure to different 10% carbamide peroxide bleaching agents

OBJECTIVE: This in vitro study evaluated the influence of two 10% carbamide peroxide bleaching agents - a commercial product (Opalescence PF; Ultradent Products, Inc.) and a bleaching agent prepared in a compounding pharmacy - on the chemical degradation of a light-activated composite resin by determining its release of ions before and after exposure to the agents. MATERIAL AND METHODS: Thirty composite resin (Filtek Z250; 3M/ESPE) samples were divided into three groups: group I (exposed to Opalescence PF commercial bleaching agent), group II (exposed to a compounded bleaching agent) and group III (control - Milli-Q water). After 14 days of exposure, with a protocol of 8 h of daily exposure to the bleaching agents and 16 h of immersion in Milli-Q water, the analysis of ion release was carried out using a HP 8453 spectrophotometer. The values were analyzed statistically by ANOVA, Tukey's test and the paired t-tests. The significance level was set at 5%. RESULTS: After 14 days of the experiment, statistically significant difference was found between group II and groups I and III, with greater ion release from the composite resin in group II. CONCLUSIONS: The compounded bleaching agent had a more aggressive effect on the composite resin after 14 days of exposure than the commercial product and the control (no bleaching).

Residual oxygen releasing time from dental structure after carbamide peroxide exposure: study of the effects of a neutralizer gel.

The purpose of this article was to assess in vitro the effects of a catalase-based neutralizer gel in the release of residual oxygen in permanent human teeth specimens exposed to 10% carbamide peroxide. Thirty teeth specimens (5.0 x 5.0 x 3.0 mm3) were randomly divided into three groups (n = 10): Group 1, nonbleached negative control specimens; Group 2, bleached positive control specimens; and Group 3, bleached specimens exposed to a catalase-based gel. The bleaching treatment was performed six hours per day for 14 days. At the end of the bleaching treatment, Group 3 specimens were immersed in a receptacle containing the catalase-based experimental gel for three minutes. Titrations were performed to determine the quantity of residual oxygen that each test specimen released, starting immediately after the end of the bleaching treatment and exposure (or not) to the catalase-based gel, and repeated on days 1-5, 10, and 15. The values obtained were statistically analyzed by ANOVA and a Tukey post hoc test (P < 0.05). The release values of residual O2 for Group 2 were equal to those of Group 1 after 10 days and to those of Group 3 after five days. The use of a catalase-based experimental neutralizer gel, applied for three minutes, reduced by half the time required for complete release of residual oxygen from tooth structure after exposure to a 10% carbamide peroxide bleaching agent.