Effect of Argon Plasma Surface Treatment on Bond Strength of Resin Composite Repair.

OBJECTIVES:: This study evaluated the effect of argon plasma treatment (PLA) and its combination with sandblasting (SAN), silanization (SIL), and hydrophobic bonding resin (HBR) application on the micro-shear bond strength of water-aged restorative resin composite to a newly placed composite, simulating restoration repair. METHODS AND MATERIALS:: Forty-five light-cured composite plates (20-mm long × 20-mm wide × 4-mm thick) were fabricated using a hybrid composite and stored at 37°C in distilled water for six months. The aged composite surfaces were treated according to the following experimental groups, varying both treatment and order of application: 1) SAN + SIL + HBR (control), 2) SAN + PLA for 30 seconds + SIL + HBR, 3) SAN + SIL + PLA + HBR, 4) PLA + SIL + HBR, 5) PLA + SIL, 6) PLA + HBR, 7) SIL + PLA + HBR, 8) SIL + PLA, and 9) PLA. After the surface treatments, four fresh resin composite cylinders (1.5-mm high × 1.5-mm diameter) of the same composite were built on each aged composite surface using a silicone mold. After water storage for 24 hours or one year, the specimens were submitted to shear bond strength testing. Data were statistically analyzed by two-way analysis of variance and Tukey's test (5%). RESULTS:: Groups 1, 2, and 4 presented significantly higher bond strength means at 24 hours, although group 4 did not differ from group 7. Groups 5, 8, and 9 demonstrated significantly lower means than the other groups. Even though groups 1 and 2 had a significant bond strength reduction after 1 year, they still demonstrated higher bond strength at one year of storage. CONCLUSIONS:: While PLA application combined with surface treatment methods demonstrated high bond strength results, this treatment alone was not as beneficial as other methods that included SAN, SIL and HBR.

Effect of Mouth Rinse Treatments on Bleached Enamel Properties, Surface Morphology, and Tooth Color.

OBJECTIVE:: To evaluate, in vitro, the effect of mouth rinse exposure on bleached enamel. METHODS:: Enamel/dentin bovine blocks (4×4×2 mm) were bleached with 35% hydrogen peroxide (HP) and were submitted to immersion twice daily for 14 days with different rinses (n=10), including those involving: distilled water (C [control]), 225-ppm NaF (FM, Colgate Plax Classic), essential oil (EM, Listerine Tartar Control), 1.5% hydrogen peroxide (HPM, Colgate Plax Whitening), and 2% hydrogen peroxide, pyrophosphates, and 225-ppm NaF (HPM+P, Colgate® Luminous White). The specimens were stored in a remineralizing solution during all experiments. Analyses of color (ΔE, L*, a*, b*) and roughness (Ra) were performed at the baseline, after HP, and after exposure to the rinse. The cross-sectional microhardness (CSMH) and images by scanning electron microscopy (SEM) were assessed at the end. The data were subjected to analysis of variance (ANOVA) (ΔE), repeated measures ANOVA (Ra), and split-plot ANOVA (CSMH), followed by the Tukey test. The L*, a*, and b* values were analyzed by generalized linear models (α=0.05). RESULTS:: Color changes were not statistically different in the groups. Ra increased in all groups after bleaching; however, it was reestablished in C, FM, and HPM+F and increased in EM after 14 days of the rinse. EM and HPM reduced the CSMH values differing from C and promoted alterations on the enamel surface visualized by SEM. CONCLUSION:: The mouth rinses did not affect the whitening efficacy or promote benefits on bleached enamel properties. Moreover, the 1.5% hydrogen peroxide- or essential oil-based mouth rinses affected the bleached enamel properties, promoting an alteration in morphologic surface and mineral loss in depth.

Effect of Toothpaste Use Against Mineral Loss Promoted by Dental Bleaching.

AIM: To investigate the effect of different toothpaste formulations used prior to dental bleaching with 35% hydrogen peroxide (HP) on the mineral content and surface morphology of enamel. METHODS: Seventy bovine enamel blocks (4×4×2 mm) were submitted to in vitro treatment protocols using a toothbrushing machine prior to dental bleaching or a placebo procedure (n=10) as proposed in the following groups: unbleached control (PLA), bleached control (HP), and brushing with differing toothpastes prior to HP bleaching, including: potassium nitrate toothpaste containing sodium fluoride (PN), sodium monofluorophosphate/MFP toothpaste (FT), arginine-carbonate (8% arginine) (PA) or arginine-carbonate (1.5% arginine) toothpaste (SAN), and toothpaste containing bioactive glass (NM). Phosphorus concentration in gel ([P]) was evaluated (µg of P/mg of gel), and the elemental levels (wt%) of Ca, P, and Na as well as the proportion between Ca and P and spectra graphics were determined using an energy-dispersive X-ray spectrometer (EDS). The surface morphology was assessed using scanning electron microscopy (SEM). The data were subjected to analysis of variance and the Tukey test (α=0.05). RESULTS: HP demonstrated the greatest [P] values in gel, being statistically different from PLA. The [P] of NM was statistically similar to PLA. HP showed a significant decrease in the Ca% and Ca/P values when compared to PLA in EDS analysis. PA showed Ca/P values statistically different from HP. In accordance with SEM analysis, the PA, SAN, and NM groups presented a smooth and uniform enamel surface, while HP and FT demonstrated some alterations in morphology. CONCLUSION: The toothpastes containing bioactive glass or arginine carbonate used prior to dental bleaching were effective in protecting enamel against mineral loss promoted by the whitening procedure.

Light-curing time and aging effects on the nanomechanical properties of methacrylate- and silorane-based restorations.

SUMMARY The aim of this study was to assess the influence of light-curing time on the nanohardness (H) and reduced elastic modulus (Er) of components (underlying dentin, hybrid layer, adhesive, and composite) of methacrylate- and silorane-based restorations after 24 hours and six months of storage. Class II slot preparations were carried out in human molars (n=3) and restored with methacrylate (Clearfil SE Bond [Kuraray] + Filtek Z250 [3M ESPE]) or silorane (LS restorative system [3M ESPE]) restorative systems and light-cured using light-emitting diode at 1390 mW/cm(2) for the recommended manufacturers' time or double time. Restorations were sectioned, and bonded dentin-resin interfaces were embedded in epoxy resin and polished for evaluation with a Berkovich fluid cell tip (TI 700 Ubi-1 nanoindenter, Hysitron). Data were statistically analyzed by analysis of variance and Tukey's test (alpha=0.05). Overall, the H and Er values were higher for methacrylate-based restorations than for silorane materials (p≤0.05), an increase in curing time did not improve the H and Er of the bonded interface components of either material (p>0.05), and aging significantly decreased the mechanical properties of interface components of both resin-based restorative systems (p≤0.05). In general, nanomechanical properties decreased after six months of storage, the methacrylate restorative system exhibited higher H and Er than silorane, and light-curing time did not influence the properties tested.

In situ surface biodegradation of restorative materials.

SUMMARY This study aimed to evaluate the surface characteristics of restorative materials (roughness, hardness, chemical changes by energy-dispersive spectroscopy [EDX], and scanning electron microscopy [SEM]) submitted to in situ biodegradation. Fifteen discs of each material (IPS e.max [EM], Filtek Supreme [FS], Vitremer [VI], Ketac Molar Easymix [KM], and Amalgam GS-80 [AM]) were fabricated in a metallic mold (4.0 mm × 1.5 mm). Roughness, hardness, SEM, and EDX were then evaluated. Fifteen healthy volunteers used a palatal device containing one disc of each restorative material for seven days. After the biodegradation, the roughness, hardness, SEM, and EDX were once again evaluated. Data obtained from the roughness and hardness evaluations were submitted to Kolmogorov-Smirnov and Tukey-Kramer tests (p<0.05). All esthetic restorative materials showed a significant increase in the roughness after biodegradation. Before biodegradation, significant differences in the hardness among the materials were seen: EM>AM>FS>KM>VI. After biodegradation, the hardness was significantly altered among the materials studied: EM>AM>FS=KM>VI, along with a significant increase in the hardness for AM, KM, and VI. SEM images indicated degradation on the surface of all materials, showing porosities, cracks, and roughness. Furthermore, after biodegradation, FS showed the presence of Cl, K, and Ca on the surface, while F was not present on the VI and KM surfaces. EM and AM did not have alterations in their chemical composition after biodegradation. It was concluded that the dental biofilm accumulation in situ on different restorative materials is a material-dependent parameter. Overall, all materials changed after biodegradation: esthetic restorative materials showed increased roughness, confirmed by SEM, and the ionomer materials and silver amalgam showed a significantly higher hardness. Finally, the initial chemical composition of the composite resin and ionomer materials evaluated was significantly altered by the action of the biofilm in situ.

La importancia del peritaje en el estudio comparativo histomorfológico del esmalte, dentina y cemento de dientes humanos y de otros animales

Los patólogos Médicos y Odontólogos reciben fragmentos mineralizados para que los mismos establezcan su origen, si se trata de dientes humanos o de animales. Estos materiales no permiten la clasificación de la especie cuando los caracteres anatómicos diferenciales se encuentran fragmentados o deteriorados por agentes físicos o químicos. Situación ésta donde se tornan necesarios exámenes histomorfológicos para tal clasificación. El objetivo del presente trabajo es proporcionar soporte científico al estudio de los fragmentos mineralizados, cuando es necesario establecer el origen e individualidad de los mismos. Para el siguiente estudio fueron utilizados cortes histológicos, longitudinales y transversales, por desgaste del esmalte, dentina y cemento dentario de cada mamífero estudiado, y analizados por medio de microscopía de luz. Los resultados demuestran con claridad y precisión que el análisis histomorfológico de las estructuras citadas posibilita la identificación y diferenciación de los géneros estudiados o excluyen la posibilidad de fragmentos dentarios examinados pertenecer al género Homo sapiens.

Pathologist and forensic odontologist receive mineralized fragments to identify their origin, if human or animal teeth. These structures don’t permit the classification of the species when the differential anatomical characters are fragmented or deteriorated by physical or chemical agents, where histomorphological studies are needed for such classification. The purpose of this study is to provide scientifical support to study the mineralized fragments, when it comes to the necessity of the establishment of the origin and individuality of them. For the present study longitudinal and transversal histological cuts by abrasion of the enamel, dentin and cement were utilized and analyzed by means of microscopy. The results have clearly and accurately shown that the histomorphologic analysis of the above-mentioned structures makes either possible to identify and differentiate the gender studied or to exclude the possibility that the dental fragment may belong to the gender Homo sapiens.

Influência de variáveis socioeconômicas, clínicas e demográfica na experiência de cárie dentária em pré-escolares de Piracicaba, SP

OBJETIVO: Avaliar a influência de variáveis socioeconômicas, clínicas e demográfica na experiência de cárie em pré-escolares de 5 anos de idade da cidade de Piracicaba.METODOLOGIA: A amostra consistiu de 728 crianças matriculadas em 22 pré-escolas públicas (n = 428) e 18 pré-escolas privadas (n = 300). A cárie dentária foi avaliada pelos índices ceo-d e ceo-s e pela detecção de lesão inicial (LI). Outras variáveis clínicas como gengivite, apinhamento, espaçamento, fluorose e respiração bucal também foram coletadas. As variáveis socioeconômicas (renda familiar mensal, número de residentes na mesma casa, escolaridade do pai e da mãe, habitação e posse de automóvel) foram obtidas por meio de um questionário semi-estruturado enviado aos pais.RESULTADOS: As médias (desvio-padrão) do ceo-d e ceo-s foram de 1,30 (2,47) e 3,08 (7,55), respectivamente, sendo que 62,2% da amostra estava livre de cárie. As médias (desvio-padrão) do ceo-d+LI e ceo-s+LI foram 1,72 (3,36) e 3,45 (7,94), respectivamente e 59,7% estavam livres de cáries. Por meio da análise de regressão logística múltipla, as crianças com fluorose (Odds Ratio-OR=0,40) ou de famílias com renda superior a 4 salários mínimos (OR = 0,49) apresentaram menor probabilidade de ter experiência de cárie. Aquelas com gengivite (OR = 1,87) tiveram maior chance de ter a doença. Para o critério de diagnóstico de cárie com a inclusão de LI, as crianças com fluorose (OR = 0,39) ou de famílias com renda superior a 4 salários mínimos (OR = 0,52) tiveram menor chance de ter cárie. Aquelas com gengivite (OR=1,80), apinhamento (OR = 2,63 e OR = 1,01) ou respiração bucal (OR = 1,37) apresentaram maior probabilidade de ter a doença.CONCLUSÃO: Os pré-escolares que apresentaram gengivite, apinhamento, respiração bucal ou renda familiar mensal inferior a 4 salários mínimos tiveram maior probabilidade de ter experiência de cárie. Assim, o planejamento de ações de prevenção e intervenção direcionadas a este público seria essencial para o controle da doença.(AU)