ABSTRACT
Context: The result of the studies concerning the bonding of self-adhesive resin cements to dentin is controversial. Aims: To assess in vitro shear bond strength (SBS) of three self-adhesive dual-cured resin cements to dentin compared to a currently used dual-cured resin cement, using SBS test. Settings and Design: The extant study is an experimental in vitro one on extracted human third molars dentin. Material and Methods: 40 intact human third molars were selected and randomly divided into 4 groups of 10. Buccal dentin surfaces were exposed perpendicular to the long axis and prepared with SiC papers. A translucent plastic ring, was placed over the dentin surfaces. Group I (Control group): After 15 s of etching and application of Excite DSC Bond (Ex), Variolink II (Var II) resin cement was injected into the plastic ring and was light cured for 40 s. Group II: RelyX Unicem (RX) was injected into the plastic ring and after 30 s, was light cured for 40 s. Group III: Maxcem (Mc) was injected into the plastic ring and after 30 s, was light cured for 40 s. Group IV: Multilink Sprint (MS) was injected into the plastic ring and after 30 s, was light cured for 40 s. After thermal cycling, SBS were measured with a universal testing machine. Statistical Analysis Used: Statistical computations were conducted according to Student's t-test. Results: The mean SBS and standard deviations (in parentheses) for groups I, II, III, and IV were 12.95 (2.64), 6.73 (0.79), 3.01 (0.90), 4.60 (0.75) MPa, respectively. Statistical analysis, revealed that: (1) the mean SBS of Var II were significantly higher than the other groups (P<0.05). (2) The mean SBS of Mc and MS were significantly lower than RX (P<0.05). (3) The mean SBS of Mc and MS did not show significant difference (P>0.05). Conclusion: Bond strength of three self-adhesive resin cements was significantly lower than the conventional total-etch resin cement. RX significantly performed better SBS than Mc and MS to dentin.
Subject(s)
Acid Etching, Dental/methods , Adolescent , Adult , Carbon Compounds, Inorganic/chemistry , Curing Lights, Dental/classification , Dental Bonding , Dental Stress Analysis/instrumentation , Dentin/ultrastructure , Humans , Light-Curing of Dental Adhesives , Materials Testing , Methacrylates/chemistry , Molar, Third , Phosphoric Acids/chemistry , Resin Cements/chemistry , Self-Curing of Dental Resins , Shear Strength , Silicon Compounds/chemistry , Stress, Mechanical , Temperature , Time Factors , Water/chemistry , Young AdultABSTRACT
Objective: Intraoral corrosion of dental alloys has biological, functional, and esthetic consequences. Since it is well known that the salivary urea concentrations undergo changes with various diseases, the present study was undertaken to determine the effect of salivary urea concentrations on the corrosion behavior of commonly used dental casting alloys. Materials and Methods: Three casting alloys were subjected to polarization scans in synthetic saliva with three different urea concentrations. Results: Cyclic polarization clearly showed that urea levels above 20 mg/100 ml decreased corrosion current densities, increased the corrosion potentials and, at much higher urea levels, the breakdown potentials. Conclusion: The data indicate that elevated urea levels reduced the corrosion susceptibility of all alloys, possibly through adsorption of organics onto the metal surface. This study indicates that corrosion testing performed in sterile saline or synthetic saliva without organic components could be misleading.
Subject(s)
Adsorption , Carbon Compounds, Inorganic/chemistry , Chromium Alloys/chemistry , Corrosion , Dental Alloys/chemistry , Dental Polishing/methods , Gold Alloys/chemistry , Humans , Materials Testing , Platinum/chemistry , Polarography , Saliva, Artificial/chemistry , Silicon Compounds/chemistry , Surface Properties , Urea/administration & dosage , Urea/chemistryABSTRACT
The objective of this study was to evaluate the effect of two bleaching agents (10% and 35% hydrogen peroxide) on the color stability and surface roughness of two composites, one nanohybrid and one nanoparticle. Specimens were polished, aged, stained, bleached and polished again. The action of the bleaching agents on the composites was analyzed using a profilometer (surface roughness) and a spectrophotometer (color stability). The effect of polishing the composites on the surface roughness and the resumption of the composite color was also evaluated. The results were analyzed statistically by ANOVA and Tukey's test at 5% significance level. The analysis indicated that the nanohybrid composite was more affected by staining. The bleaching agents were not able to promote bleaching of either composite over the evaluation period. Surface polishing returned nanohybrid composite to its original color condition, which did not occur for the nanoparticle composite. Additionally, polishing did not return the surface roughness of either composite to its original value. It may be concluded that polishing surface after bleaching should not be the treatment of choice, as it was not possible to reverse the roughness of the composites to their original values, suggesting that a more extensive and irreversible degradation might have occurred.
O objetivo deste estudo foi avaliar o efeito de dois agentes clareadores (peróxido de hidrogênio a 10% e 35%) sobre a estabilidade de cor e rugosidade superficial de dois compósitos, um nanohíbrido e um nanoparticulado. Os espécimes foram polidos, envelhecidos, manchados, clareados e polidos novamente. A ação dos agentes clareadores sobre os compósitos foi analisada em perfilômetro (rugosidade) e um espectrofotômetro (estabilidade de cor). A ação de polimento dos compósitos sobre a rugosidade superficial e a retomada da cor dos compósitos também foi avaliada. Os resultados foram analisados estatisticamente por ANOVA e teste de Tukey (5% de significância). A análise indicou que o compósito nanohíbrido foi mais afetado pelo manchamento. Os agentes clareadores não foram capazes de promover o clareamento dos compósitos ao longo do período de avaliação. O polimento da superfície retornou o compósito nanohíbrido à sua condição de cor original, o que não foi observado para o nanoparticulado. Além disso, o polimento não retornou a rugosidade de superfície dos compósitos para os valores originais. Os autores concluíram que o polimento da superfície após o clareamento não deve ser a opção de tratamento, uma vez que não foi possível inverter a rugosidade dos compósitos à sua rugosidade original, sugerindo que uma degradação mais extensa e irreversível pode ter ocorrido.
Subject(s)
Humans , Composite Resins/chemistry , Dental Materials/chemistry , Hydrogen Peroxide/chemistry , Tooth Bleaching Agents/chemistry , Color , Carbon Compounds, Inorganic/chemistry , Coffee/chemistry , Dental Polishing/instrumentation , Dental Polishing/methods , Light , Materials Testing , Nanocomposites/chemistry , Spectrophotometry , Surface Properties , Saliva, Artificial/chemistry , Silicon Compounds/chemistry , Temperature , Time FactorsABSTRACT
OBJECTIVE: The purpose of this study was to evaluate the effect of different filler sizes and shapes on the surface roughness of experimental resin-composite series. MATERIAL AND METHODS: Thirty-three disc-shaped specimens of the series (Spherical-RZD 102, 105, 106, 107, 114 and Irregular-RZD 103, 108, 109, 110, 111, 112) were prepared in a split Teflon mold and irradiated with an halogen light-curing unit (450 mW/cm² for 40 s) at both top and bottom surfaces. The specimens were stored for 3 months in distilled water. The surface roughness values in form of surface finish-vertical parameter (Ra), maximum roughness depth (Rmax) and horizontal roughness parameter (Sm) were recorded using a contact profilometer. The data were analyzed by one-way ANOVA and the means were compared by Scheffé post-hoc test (a=0.05). RESULTS: The lowest surface roughness (Ra) was observed in S-100 (0.079±0.013), while the roughest surface was noted in I-450/700/1000 (0.125±0.011) and I-450/1000 (0.124±0.004). The spherical-shape series showed the smoothest surface finish compared to the irregular-shape ones with higher significant difference (p>0.05). The vertical surface roughness parameter (Ra) values increased as the filler size increased yielding a linear relation (r²=0.82). On the contrary, the horizontal parameter (Sm) was not significantly affected by the filler size (r²=0.24) as well as the filler shape. CONCLUSIONS: Filler particle's size and shape have a great effect on the surface roughness parameters of these composite series.
Subject(s)
Humans , Composite Resins/chemistry , Dental Materials/chemistry , Aluminum Oxide/chemistry , Barium Compounds/chemistry , Bisphenol A-Glycidyl Methacrylate/chemistry , Carbon Compounds, Inorganic/chemistry , Composite Resins/radiation effects , Curing Lights, Dental/classification , Dental Materials/radiation effects , Dental Polishing/methods , Glass/chemistry , Materials Testing , Methacrylates/chemistry , Nanocomposites/chemistry , Particle Size , Polyethylene Glycols/chemistry , Polymethacrylic Acids/chemistry , Polyurethanes/chemistry , Surface Properties , Silanes/chemistry , Silicon Compounds/chemistry , Silicon Dioxide/chemistry , Time Factors , Water/chemistryABSTRACT
Cell culture system has been used to evaluate alloy cytotoxicity under different environments, testing the extracts, but the effect of temperature variation on the cytotoxicity of dental alloys has not been analyzed. OBJECTIVE: The aim of the present study was to investigate if temperature variation could affect dental alloy cytotoxicity, testing alloy extracts in an epithelial cell culture system. MATERIAL AND METHODS: Discs of Ni-Cr, Co-Cr-Mo, Ni-Cr-Ti, Ti-6Al-4V and commercially pure titanium (cp Ti) were cast by arc melting, under argon atmosphere, injected by vacuum-pressure. Discs were immersed in artificial saliva and subjected to different temperatures: 37ºC and thermocycling (37ºC/5ºC/37ºC/55ºC/37ºC). After thermocycling, extracts were put in a subconfluent culture during 6 h, and the number of cells and their viability were used to evaluate cytotoxicity in these temperatures. For each alloy, data from temperature conditions were compared by Student's t-test (α=0.05). RESULTS: The cytotoxicity tests with alloy/metal extracts showed that Ni-Cr, Co-Cr-Mo, Ti-6Al-4V and cp Ti extracts (p>0.05) did not affect cell number or cell viability, while Ni-Cr-Ti (p<0.05) extract decreased cell number and viability when the alloy was subjected to thermocycling. CONCLUSION: Within the limitations of the present study, the Ni-Cr-Ti alloy had cell number and viability decreased when subjected to temperature variation, while the other alloys/metal extracts did not show these results.
Subject(s)
Humans , Dental Alloys/toxicity , Dental Casting Investment/toxicity , Dental Materials/toxicity , Titanium/toxicity , Alloys/chemistry , Alloys/toxicity , Aluminum Oxide/chemistry , Biocompatible Materials/chemistry , Biocompatible Materials/toxicity , Cell Count , Cell Line, Tumor , Carbon Compounds, Inorganic/chemistry , Cell Survival/drug effects , Chromium Alloys/chemistry , Chromium Alloys/toxicity , Dental Casting Technique , Dental Etching , Dental Alloys/chemistry , Dental Casting Investment/chemistry , Dental Materials/chemistry , Dental Polishing/methods , Diamond/chemistry , Materials Testing , Saliva, Artificial/chemistry , Silicon Compounds/chemistry , Silicon Dioxide/chemistry , Temperature , Titanium/chemistryABSTRACT
This study evaluated the bond strength (push-out method) and Knoop hardness of Z250 composite resin, photoactivated with XL 2500 curing unit, using different protocols: continuous mode (700mW/cm² for 20s) (CO); soft-start (50 mW/cm² for 5 s, followed by 700 mW/cm² for 15 s) (SS1); soft-start (100 mW/cm² for 5 s, followed by 700 mW/cm² for 15 s) (SS2); soft-start (150 mW/cm² for 5 s, followed by 700mW/cm² for 15s) (SS3); soft-start (200mW/cm² for 5s, followed by 700mW/cm² for 15s) (SS4); soft-start (250mW/cm² for 5 s, followed by 700 mW/cm² for 15 s) (SS5); soft-start (300 mW/cm² for 5 s, followed by 700 mW/cm² for 15 s) (SS6). For the push-out test, the specimens were tested in a universal testing machine at a crosshead speed of 0.5 mm/min. For the hardness test, the specimens were polished for the hardness measurements, using a 50 g load for 15 s. Data were submitted to ANOVA and Tukey's test (alpha=5 percent). The results of bond strength showed that the SS3 group obtained the highest bond strength when compared to the CO group. There were no significant differences among the other modes in relation to the other groups. Regarding the other results in hardness, there were no significant differences among the groups in the surface region and up to 4 mm depth.
Este estudo avaliou a resistência de união (push-out) e a dureza Knoop do compósito Z250, fotoativado por luz de lâmpada halógena XL2500, com diferentes modos: Contínuo (700 mW/cm²/20 s) (CO); Soft-start (50 mW/cm²/5 s + 700 mW/cm²/15 s) (SS1), (100 mW/cm²/5 s + 700 mW/cm²/15 s) (SS2), (150 mW/cm²/5 s + 700 mW/cm²/15 s) (SS3), (200 mW/cm²/5 s + 700 mW/cm²/15 s) (SS4), (250 mW/cm²/5 s + 700 mW/cm²/15 s) (SS5), (300 mW/cm²/5 s + 700 mW/cm²/15 s) (SS6). Para o ensaio de resistência de união, os espécimes foram testados em máquina de ensaio universal com velocidade de 0,5 mm/min. Para o teste de dureza, os espécimes foram polidos para a realização das leituras de dureza, realizadas com carga de 50 g por 15 s. Os dados foram submetidos a ANOVA e ao teste de Tukey (alfa=5 por cento). Os resultados de resistência da união mostraram que o grupo SS3 apresentou maior resistência da união quando comparado ao grupo CO. Não houve diferença entre os demais grupos testados. O teste de dureza Knoop mostrou que não houve diferença entre os grupos até 4 mm de profundidade.
Subject(s)
Humans , Composite Resins/chemistry , Light-Curing of Dental Adhesives/methods , Dental Materials/chemistry , Carbon Compounds, Inorganic/chemistry , Composite Resins/radiation effects , Dental Polishing , Dental Materials/radiation effects , Hardness , Light , Materials Testing , Stress, Mechanical , Surface Properties , Silicon/chemistry , Temperature , Time FactorsABSTRACT
Scaling and root planing contribute to the recovery of periodontal health. All periodontal instruments loose their fine cutting angle after use. To maintain this angle, correct sharpening is required using specifically designed stones. The characteristics of sharpening stones can be compared to the blade of the instruments and also transported to root surface during instrumentation. Root smoothness is related to the quality of the blade. Therefore, the purpose of this study was to evaluate the characteristics of 9 sharpening stones by scanning electron microscopic and profilometric analyses. Ceramic and Neumar stones were very fine and both may be recommended to maintain the sharpness of the instruments. Arkansas, Thompson and CE stones presented greater roughness with very regular and round particles, and are suitable for maintenance of the cutting angle. In addition, these stones may be indicated for the routine sharpening of the instruments that are partly dull. Oxide Aluminum, Carborundum and JON stones were the coarsest with large irregular particles and may be indicated for initial sharpening of totally dull instruments with completion of sharpening with finer stones.
Sabe-se que a raspagem e aplainamento (RAR) radicular contribuem na obtenção da saúde periodontal tornando a raiz compatível com os tecidos gengivais. Todo instrumento perde o corte após ser utilizado, tornando-se menos eficaz. Portanto, é necessário mantê-lo corretamente afiado utilizando pedras especificas para tal objetivo. Considerando que características do ângulo de corte após a afiação podem ser transportadas para a raiz formando irregularidades semelhantes às da pedra utilizada e que a lisura da raiz está relacionada com a qualidade do ângulo de corte, o objetivo deste estudo foi avaliar sob microscopia eletrônica de varredura e análise em rugosímetro as características de 9 pedras de afiar. As pedras cerâmica e tipo Arkansas (Neumar) mostraram-se muito finas sendo indicadas para a manutenção do corte durante o tratamento; as pedras de Arkansas (Hu-Friedy), Thompson e CE (Tipo Arkansas) apresentaram abrasividade maior com partículas muito regulares e arredondadas, sendo indicadas para a manutenção do corte e afiação rotineira de instrumentos parcialmente sem corte. As pedras de óxido de alumínio, carborundum, Norton e JON (Oxido de Alumínio tipo Arkansas) mostraram-se grossas, com partículas grandes e irregulares, sendo indicadas para a afiação inicial de instrumentos sem corte, requerendo pedras mais finas para o acabamento final.