Abrasion resistance of direct and indirect resins as a function of a sealant veneer.

BACKGROUND: Abrasive wear is one of the most common type of wear that not only affect teeth, as also dental restorations. Thus to investigate one of the etiological factors as tooth brushing procedure is clinical relevant in order to select the best material combination that may prevent damage of resin dental restoration's abrasion. AIMS: This study evaluated the influence of tooth brushing on mass loss and surface roughness of direct Venus (Vs) and indirect Signum (Sg) resin composites, with and without a surface sealant, Fortify (F). MATERIALS AND METHODS: Twenty-four specimens were prepared with each resin composite, using their proprietary curing units, according to manufacturer's instructions. All the specimens were polished and ultrasonically cleaned in distilled water for 5 minutes. Half of the specimens of each resin (n = 12) were covered with F (Vs F and Sg F ), except for the control (C) specimens (Vs C and Sg C ), which were not sealed. Mass loss (ML) as well as surface roughness (Ra ) was measured for all the specimens. Then, the specimens were subjected to toothbrush-dentifrice abrasion, using a testing machine for 67.000 brushing strokes, in an abrasive slurry. After brushing simulation, the specimens were removed from the holder, rinsed thoroughly and blot dried with soft absorbent paper. The abrasion of the material was quantitatively determined with final measurements of ML and surface roughness, using the method described above. RESULTS: ML data were analyzed by two-way analysis of variance (ANOVA) and the analysis indicated that resin composites were not statistically different; however, the specimens sealed with F showed higher ML. Ra mean values of the groups Vs F and Sg F significantly increased. CONCLUSION: Tooth brushing affects mainly the roughness of the direct and indirect resin composites veneered with a sealant.

Carbon film coating of abutment surfaces: effect on the abutment screw removal torque.

PURPOSE: To evaluate the effect of diamond-like carbon (DLC) coating of prefabricated implant abutment on screw removal torque (RT) before and after mechanical cycling (MC). MATERIALS AND METHODS: Fifty-four abutments for external-hex implants were divided among 6 groups (n = 9): S, straight abutment (control); SC, straight coated abutment; SCy, straight abutment and MC; SCCy, straight coated abutment and MC; ACy, angled abutment and MC; and ACCy, angled coated abutment and MC. The abutments were attached to the implants by a titanium screw. RT values were measured and registered. Data (in Newton centimeter) were analyzed with analysis of variance and Dunnet test (α = 0.05). RESULTS: RT values were significantly affected by MC (P = 0.001) and the interaction between DLC coating and MC (P = 0.038). SCy and ACy showed the lowest RT values, statistically different from the control. The abutment coated groups had no statistical difference compared with the control. Scanning electron microscopy analysis showed DLC film with a thickness of 3 µm uniformly coating the hexagonal abutment. CONCLUSION: DLC film deposited on the abutment can be used as an alternative procedure to reduce abutment screw loosening.

Strength of a feldspar ceramic according to the thickness and polymerization mode of the resin cement coating.

The aim of this study was to evaluate, in vitro, the biaxial flexural strength (ISO 6872) of a feldspathic ceramic (VM7, Vita Zahnfabrik) coated with a resin cement with different thicknesses and polymerization mode. Control groups consisted in VM7 with and without acid etching with 10% hydrofluoric acid for 1 min. Experimental groups comprised VM7 etched, silanated and coated with Variolink II (Ivoclar Vivadent) cement, that was polymerized through the porcelain in light-cure and dual-cure modes, with thickness ≤150 µm or >150 µm. The specimens (n=15) were subjected to the biaxial flexural strength essay and analyzed fractographically. Parametric (Dunnet, Anova 2-way, Tukey) and non-parametric tests (Weibull) were used to evaluate results. Ceramic disks coated with resin cements of either activation modes and thicknesses exhibited higher flexural strength while the Weibull moduli did not present significant differences for a confidence interval of 95%.

Reforzamiento oclusal estético en protésis totales / Strengthening Total Denture aesthetic occlusal

Este trabajo tuvo como objetivo presentar una técnica de recubrimiento oclusal en prótesis totales utilizando uan resina compuesta de uso en laboratorio, con el propósito de optimizar la relación oclusal, prolongar la vida útil de las prótesis y ofrecer mejor estética comparado al recubrimiento metálico con eficiencia masticatoria similar

The aim of this research was to describe a method of oclusal recovery in complete dentures with an indirect resin composite in order to improve occlusion, to prolong clinical longevity and offer a better esthetic compared to metallic recovery but with similar function

Dental fluorosis: Exposure, prevention and managementJenny

Dental fluorosis is a developmental disturbance of dental enamel, caused by successive exposures to high concentrationsof fluoride during tooth development, leading to enamel with lower mineral content and increasedporosity. The severity of dental fluorosis depends on when and for how long the overexposure to fluoride occurs,the individual response, weight, degree of physical activity, nutritional factors and bone growth. The risk periodfor esthetic changes in permanent teeth is between 20 and 30 months of age. The recommended level for dailyfluoride intake is 0.05 - 0.07 mg F/Kg/day, which is considered of great help in preventing dental caries, actingin remineralization. A daily intake above this safe level leads to an increased risk of dental fluorosis. Currentlyrecommended procedures for diagnosis of fluorosis should discriminate between symmetrical and asymmetricaland/or discrete patterns of opaque defects. Fluorosis can be prevented by having an adequate knowledge of thefluoride sources, knowing how to manage this issue and therefore, avoid overexposure (AU)

Altura de los tallados coronales en la retención de prótesis parcial fija / Height of crown carved on the retention of fixed partial denture

La altura y convergencia de las paredes axiales, el diámetro de los tallados, la presencia de surcos para mejorar la retención y el tipo de cemento son algunas de las condiciones que influencian el ajuste y la retención de las restauraciones fundidas. El objetivo de este trabajo fue verificar larelación de la cantidad de retención con el aumento gradual de la altura de los tallados coronales. Usando 11 troqueles y 11 cápsulas metálicas, fresados y perfectamente adaptados, con alturas desde 3mm hasta 8mm, con el aumento gradual de 0,5mm. Todas las capsuladas fueron cementadas de forma estandarizada y luego de 24 horas fueron sometidas a la prueba de tracción (EMIC - 1000). Los resultados mostraron que incrementos de 0,5mm en la altura del tallado aumentaron en promedio de 7N la resistencia a tracción de los cuerpos de prueba, por tal motivo se puede concluir que existe una influencia de la altura del tallado en la capacidad retentiva de los troqueles.

The height and convergence of axial walls, the diameter of the coronal preparation, the presence of grooves to improve retention and the type of cement are some of the conditionsthat influence the adjustment and retention of cast restorations. The aim of this study was to verify the relationship between the amount of retention with the gradual increase in the heightof the coronal preparation. Using 11 die and 11 metal capsules milled and perfectly adapted, with heights from 3mm to 8mm, with the gradual increase of 0.5 mm. All capsules were cementsin a standardized way, and after 24 hours were tested for tensile strength (EMIC-1000). The results showed increases of 0.5 mm in height of coronal preparations, rose 7N on average thetraction resistance of all tested bodies, therefore we can conclude that there is an influence of the height of the coronal preparation on the retention capacity of dies.

Influência da ciclagem térmica na resistência à flexão de resinas laboratoriais / The effect of thermo-cycling on flexural strength of laboratorial resins

Introdução: Uma nova geração de resinas laboratoriais contendo micro-partículas cerâmicas em sua composição tem sido introduzida no mercado com a finalidade de melhorar suas propriedades mecânicas. Objetivo: O objetivo deste estudo foi avaliar o efeito da termociclagem na resistência à flexão de três resinas laboratoriais. Materiais e método: Foram confeccionadas 48 barras com medidas de 2 mm × 2 mm × 25 mm, utilizando as resinas laboratoriais: G1 - RESILAB MASTER (Wilcos, Brasil), G2 - VITA VM LC (Vita Zanhfabrik, Germany), G3 - VITA ZETA LC (Vita Zanhfabrik, Germany). A metade das barras de cada grupo foi submetida a 3000 ciclos térmicos (5ºC/55ºC ± 1, com banhos de 30 s). Os ensaios mecânicos foram efetuados em máquina de ensaio universal EMIC com capacidade de carga de 100 kg e velocidade de 0,5 mm/min. Resultados: Os dados obtidos foram analisados estatisticamente pelo teste de ANOVA (two-way) e Tukey (p < 0,05). As médias (± DP) observadas para os grupos sem ciclagem foram: G1(112,6 ± 25,39), G2(116,5 ± 18,51) e G3(136,1 ± 24,34); e para os grupos com ciclagem: G1(91,8 ± 18,86), G2(101,9 ± 20,61) e G3(89,9 ± 23,05). Conclusão: Concluiu-se que a diminuição da resistência à flexão em MPa está diretamente dependente da ciclagem térmica nos grupos testados, sendo que os maiores valores foram obtidos pela resina VITA VM LC. Entretanto, na condição sem ciclagem térmica a VITA ZETA apresentou os maiores valores.

Introduction: A new laboratorial resin generation that content ceramic microparticles in its composition has been introduced in the market with the purpose to improve its mechanical properties. Objective: The objective of this study was to evaluate the effect of the thermocycling in the flexural strength of three laboratorial resins. Method: Forty-eight specimens with measures of 2 mm × 2 mm × 25 mm were made using laboratorial resins: G1 - RESILAB MASTER (Wilcos, Brazil), G2 - VITA VM LC (Vita Zanhfabrik, Germany) and G3 - VITA ZETA (Vita Zanhfabrik, Germany). After their confection, half of each group was submitted to 3000 thermal-cycles (5ºC/55ºC ± 1, with rinse bath of 30 s). The mechanical essays were done in Universal essay machine EMIC with the loading capacity of 100 kg and the equispeed of 0,5 mm/min. Results: The obtained data was analyzed statistically by the ANOVA test (two-way) and Turkey?s test (p < 0,05). The averages (± DP) observed for the groups without cycles were: G1(112,6 ± 25,39), G2(116,5 ± 18,51) and G3(136,1 ± 24,34); and for the groups with cycles: G1(91,8 ± 18,86), G2(101,9 ± 20,61) and G3 89,9 ± 23,05). Conclusion: It was concluded that the decrease in the flexural strength in MPa is directly dependent on the thermo-cycling in the tested groups, being that the highest values were obtained by VM LC resin. However, in the group without thermo-cycling the VITA ZETA showed the highest values.UNITERMS: three point bending; thermo-cycling; composite resin.

Thermocycling effect on microhardness of laboratory composite resins

The aim of this study was to evaluate the thermocycling effect on microhardness of laboratory composite resins. 30 disks were fabricated, 5 mm of diameter and 2mm of width, using 3 laboratory resins: G1 (n=10) - RESILAB MASTER (Wilcos-Brasil), G2 (n=10) - Vita VMLC (VITA Zahnfabrik-Germany), and G3 (n=10) û Vita Zeta (VITA Zahnfabrik-Germany). Vickers microhardness (HV) of all specimens was evaluated using a microhardness tester FM-700 (Future Tech- 50 g/10s). The specimens were measured before and after the thermocycling (3.000 times and 12.000 times - 5º /55ºC±1). The microhardness values before cycling were (mean±SD): G1: 55.50±4.6; G2: 35.54±2.5; G3: 27.97±1.6.; after 3.000 thermocycles: G1: 55.54±3,9; G2: 29.92±2,73; G3:21.01±1.4 and after 12.000 cycles G1:54.27±3.2; G2: 30.91±1.6. G3: 23.81±0.9. Variance analysis (ANOVA) and TukeyÆs test was accomplished (p<0,05), the highest microhardness values were observed in G1; G2 and G3 showed reduction of microhardness values. It was concluded that, after thermocycling, the tested laboratory composites resins are susceptible to the decrease of surface microhardness.The aim of this study was to evaluate the thermocycling effect on microhardness of laboratory composite resins. 30 disks were fabricated, 5 mm of diameter and 2mm of width, using 3 laboratory resins: G1 (n=10) - RESILAB MASTER (Wilcos-Brasil), G2 (n=10) - Vita VMLC (VITA Zahnfabrik-Germany), and G3 (n=10) û Vita Zeta (VITA Zahnfabrik-Germany). Vickers microhardness (HV) of all specimens was evaluated using a microhardness tester FM-700 (Future Tech- 50 g/10s). The specimens were measured before and after the thermocycling (3.000 times and 12.000 times - 5º /55ºC±1). The microhardness values before cycling were (mean±SD): G1: 55.50±4.6; G2: 35.54±2.5; G3: 27.97±1.6.; after 3.000 thermocycles: G1: 55.54±3,9; G2: 29.92±2,73; G3:21.01±1.4 and after 12.000 cycles G1:54.27±3.2; G2: 30.91±1.6. G3: 23.81±0.9.

Variance analysis (ANOVA) and TukeyÆs test was accomplished (p<0,05), the highest microhardness values were observed in G1; G2 and G3 showed reduction of microhardness values. It was concluded that, after thermocycling, the tested laboratory composites resins are susceptible to the decrease of surface microhardness.

A influência da osseocompressão na estabilidade de implantes: revisão de literatura / The osteocompression influence on stability of dental implants: a literature review

O uso de implantes orais para restaurar o edentulismo parcial ou total tornou-se uma modalidade consagrada e bem aceita na comunidade odontológica. A osseointegraçãotrata-se de um processo dinâmico que está sob influência qualitativa e quantitativa de tecido ósseo e pela geometria do implante. Para tanto, um dos fatores que têm maior influência nos mecanismos de reparação óssea e sua conseqüente obtenção é a estabilidade primária. A osseocompressão é um princípio fisiológico que está presente na ortopedia desde 1900. Na Odontologia, a osseocompressão funcionalmente controlada serefere a compressão criada pelo procedimento de perfuração e condensação alcançada pela inserção do implante em tecido ósseo, promovendo estimulação fisiológica e desencadeando uma série de eventos bioquímicos que culminam em uma deposição ordenadade tecido ósseo, auxiliando no suporte das forças compressivas atuantes da superfície do implante no leito cirúrgico que se mantém em constante equilíbrio. Sabe-se atualmente que a osseocompressão tornou-se condição crucial no prognóstico de implantes submetidosà carga imediata, e depende de fatores biológicos, químicos e físicos. O objetivo deste estudo foi realizar uma ampla revisão da literatura dando enfoque àimportância da estabilidade primária e osseocompressão.

Distracción osteogénica mandibular unilateral: estudio experimental en carneros / Osteogenic distraction of unilateral jaw: experimental study in young sheep

El presente trabajo de investigación tuvo como objetivo determinar la eficacia de la técnica de distracción mandibular, para lo cual se emplearon 6 carneros (3 del grupo control, 3 del grupo experimental). Al grupo experimental se le realizó el procedimiento de distracción osteogénica mandibular unilateral, realizando una corticotomia vertical a nivel de la mitad del cuerpo mandibular, fijándose los dos segmentos óseos con un distractor (HYRAX 12), el cual se activó inmediatamente después de ser instalado. Los resultados obtenidos demuestran que la técnica de distracción osteogénica mandibular es efectiva en carneros, evidenciándose la neoformación ósea en la zona de la distracción mediante el aumento en longitud del cupo mandíbula en 9 mm (fig. 3)

The objective of the investigation was to determine the effectiveness o of the mandibular distraction for which 6 sheep’s were used (3 for the experimental group, 3 for the group control). To the experimental group the procedure o unilateral osteogenic distraction was made, making a vertical corticotomy at the level of half of the mandibular body, and fixing the 2 bony fragments with a distractor (HYRAX 12), which was actived immediately after being installed. The obtained results showed that the technique o osteogenic mandibular distraction is effective in sheep’s, demonstrating itself the bony neoformation in the zone of the distraction by means of the increase in length of the mandibular body in 9 mm (fig. 3)