Avaliação da resistencia a fratura de raizes bovinas com sistemas de retenção intra-radicular submetidas a ciclagem mecanica

Orientadores : Giselle Maria Marchi Baron, Luiz Andre Freire PimentaDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Odontologia de PiracicabaMestrad

Dentin Bonding On Different Walls Of A Class Ii Preparation.

To evaluate the bond strength on different cavity walls of Class II preparations. Different bonding systems and the effect of thermomechanical cycling were investigated. Human third molars received MOD preparations with dentin margins. Teeth were randomly assigned to 18 groups (n=5) according to the combination of cavity wall (axial, occlusal, and gingival), bonding system (Single Bond Plus, Clearfil SE Bond, and Adper Prompt) and the occurrence of thermomechanical cycling. Restorations were concluded with Filtek Z250 composite. Specimens were sectioned according to the respective cavity wall (4 slabs/restoration), and the adhesive interface was trimmed to an hourglass shape (1 mm2). Slabs were tested under tension, and failure mode was observed. Bond strength data were analyzed with three-way ANOVA/Tukey's test. Single Bond Plus and Clearfil SE Bond performed similarly under most experimental conditions. Single Bond Plus presented similar bond strength on the three cavity walls, regardless of the aging condition. Clearfil SE Bond exhibited significant differences among cavity walls: the occlusal wall showed higher means in both aging conditions. Non-aged gingival walls and aged axial and gingival walls yielded lower means. Non-aged Adper Prompt produced similar bond strengths on the three cavity walls. After thermomechanical cycling, the gingival wall showed lower means. The effect of cavity walls was dependent on the bonding system and thermomechanical cycling. Adper Prompt demonstrated bond strengths lower than Single Bond Plus or Clearfil SE Bond under most experimental conditions.1017-2

Influence of load cycling on marginal microleakage with two self-etching and two one-bottle dentin adhesive systems in dentin

PURPOSE: To evaluate the influence of occlusal load cycling on cervical microleakage of proximal slot restorations located in dentin, using two self-etching and two one-bottle dentin adhesive systems. MATERIALS AND METHODS: 240 proximal slot cavities were prepared in 120 bovine teeth and divided into two groups, one with load cycling and one without. The groups were then subdivided into four subgroups according to the adhesive system used (Experimental EXL 547 Self-etching 3M, Clearfil SE Bond, Single Bond, and Optibond Solo Plus) and restored following the manufacturers' instructions. The teeth were then submitted to mechanical load cycling with a force of 80 N and a frequency of 5 Hz, simultaneously over both restorations of each tooth, for a total of 50,000 cycles per specimen. All specimens were subsequently immersed in a 2% methylene blue solution (pH 7.0), and sectioned to examine the extent of dye penetration under a stereomicroscope (40X). RESULTS: There was no statistically significant difference (p = 0.00002) between the loaded and unloaded teeth. However, a statistically significant difference was observed between the adhesive systems used. The experimental self-etching EXL 547 presented the lowest mean microleakage, but was only statistically significantly different from the Single Bond loaded and unloaded groups and the Clearfil SE Bond unloaded group. CONCLUSION: The application of 50,000 loading cycles did not affect the microleakage of the two self-etching and the two one-bottle adhesive systems evaluated. In vitro mechanical load cycling is an important factor to consider when evaluating the performance of adhesive systems under simulated masticatory conditions

Influence of thermal and mechanical load cycling on bond strength of Class II composite resin restorations using three adhesive systems

Orientador : Giselle Maria Marchi BaronTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Odontologia de PiracicabaResumo: O objetivo deste estudo foi avaliar a influência da aplicação de ciclos térmicos e de carga mecânica na resistência de união à microtração, em restaurações de resina composta em cavidades Classe II do tipo ¿slot¿ vertical, com margem em dentina, confeccionadas com três sistemas adesivos. Cento e sessenta e oito cavidades foram preparadas nas superfícies proximais de dentes bovinos e distribuídas, aleatoriamente, de acordo com o sistema adesivo a ser aplicado (Single Bond, OptiBond Solo Plus e Clearfil SE Bond). Após a restauração das cavidades, utilizando o compósito resinoso Filtek Z250, foi realizada nova distribuição dos dentes, de acordo com o tipo de tratamento (térmico / mecânico) aos quais os dentes foram submetidos, formando dessa maneira 21 grupos experimentais no total (n=8): I - sem tratamento (controle), II - 100.000 ciclos mecânicos (CM), III - 200.000 CM, IV - 500.000 CM, V - 100.000 CM + 1000 ciclos térmicos (CT), VI - 200.000 CM + 1000 CT, VII - 500.000 CM + 1000 CT. A ciclagem térmica submeteu os espécimes a banhos de 60 segundos, a temperaturas de 5 e 55oC. Já o teste de ciclagem mecânica foi realizado mediante aplicação de força axial de 80N e freqüência de 2Hz. Após os ensaios de ciclagem, as restaurações sofreram três cortes seriados, perpendicularmente à parede cervical das restaurações, de forma a obter-se duas fatias no centro da restauração com espessuras de 0,8 a 1mm cada. As fatias obtidas foram desgastadas precisamente em lados opostos da interface adesiva, determinando-se uma área de secção transversal de 0,8 a 1mm2. Todos os espécimes obtidos foram submetidos ao teste de microtração a uma velocidade de 0,5 mm/min até a fratura. Após o ensaio, as duas porções fraturadas de cada espécime foram avaliadas em MEV para análise dos padrões de fratura. Os valores de resistência de união (MPa) foram submetidos à análise de variância 3 fatores e teste Tukey, com nível de significância de 5%. Para a análise dos protocolos de envelhecimento em relação aos grupos controles de cada adesivo, foi aplicado o teste de Dunnett ao mesmo nível de significância de 5%. O sistema adesivo autocondicionante apresentou médias de resistência de união significativamente menores em relação aos adesivos que preconizam o condicionamento total (p<0,0001) e, além disso, os espécimes restaurados com esse adesivo não resistiram à aplicação de 200.000 e 500.000 CM associados à CT. A efetividade dos protocolos de envelhecimento realizadas no estudo variou de acordo com o sistema adesivo avaliado, sendo que a aplicação de 100.000 ciclos de carga isoladamente não acarretou em uma diminuição significativa das médias de resistência de união. O padrão de fratura variou de acordo com o grupo analisado, tendo sido verificado todos os tipos de fratura nos espécimes avaliados. Na medida em que se aumentavam as tensões (ciclagens térmica e mecânica) a que os espécimes foram submetidos, diminuiu o número de fratura na interface e aumentou o percentual das fraturas mistasAbstract: The aim of this study was to evaluate the influence of thermal and mechanical loading cycling on microtensile bond strength of Class II composite restorations in dentin, with three adhesive systems. One hundred and sixty eight slot vertical cavities were prepared on proximal surfaces of bovine teeth, and divided according to the adhesive system used (Single Bond, OptiBond Solo Plus, and Clearfil SE Bond). All cavities were filled with Filtek Z250 composite resin. Following restorative procedures, the teeth were once again allocated into different groups according to the thermal / mechanical treatment, thus obtaining 21 experimental groups (n=8): I - control, II - 100,000 mechanical cycles, III - 200,000 mechanical cycles, IV - 500,000 mechanical cycles, V - 100,000 mechanical cycles + 1,000 thermal cycles, VI - 200,000 mechanical cycles + 1,000 thermal cycles, VII - 500,000 mechanical cycles + 1,000 thermal cycles. Thermal cycling was performed by submitting the specimens to alternating 5o and 55oC baths, with a dwell time of 60 seconds in each bath. The teeth were then submitted to mechanical load cycling with an occlusal force of 80N at a frequency of 2Hz. The restorations were sectioned perpendicular to the cervical bonded interface into two 0.8-1mm thick slabs. The slabs were trimmed at the interface with a fine diamond bur in order to obtain a cross-sectional surface area of 0.8-1mm2. All specimens were then subjected to microtensile testing, at a cross-head speed of 0.5 mm/min, until failure of the specimens. The fractured surfaces were observed with a scanning electron microscope (SEM) to evaluate the fracture mode. Microtensile bond strength mean values (MPa) were subjected to ANOVA 3-way and Tukey¿s test, at significance level of 5%. The Dunnett¿s test was used in order to compare the groups that were submitted to load and thermal cycling with the control groups of each adhesive system (p<0.05). The self-etching primer presented lower bond strength mean values when compared to the total-etch systems (p<0.0001). In addition, the specimens restored with the self-etching primer did not resist to 200,000 e 500,000 load cycles associated with thermal cycling. The effectiveness of the aging protocols performed in this study showed different behavior according to the adhesive system evaluated. The application of only 100,000 load cycles did not present significant lower bond strength mean values. Failure modes varied according to the analyzed group, and all failures modes were verified in the fractured specimens. The number of mixed failures increased and the percentage of interphase failures decreased when the amount of thermal/mechanical cycles applied was higherDoutoradoDentísticaDoutor em Clínica Odontológic

Influence Of Adhesive Systems And Flowable Composite Lining On Bond Strength Of Class Ii Restorations Submitted To Thermal And Mechanical Stresses.

The purpose of this study was to evaluate the effect of adhesive systems and flowable composite lining on bond strength to gingival margins of Class II restorations after thermal/mechanical stresses. Proximal cavities were prepared in 90 bovine incisors. Teeth were assigned into nine groups (n = 10), according to the combination of bonding agent [Single Bond (SB), Optibond Solo Plus (OP), Prime & Bond NT (NT)] and layer (1 mm) of flowable composite Filtek Flow (FF) [absent, one layer, two layers]. Materials were applied according to manufacturers' instructions, and FF layers were photoactivated separately. Restorations were concluded with composite resin and were submitted to thermal (1000x, 5-55 degrees C) and mechanical stresses (100,000x, 80 N). For microtensile evaluation, slabs from the gingival bonded interface were obtained, tested under tension, and their failure mode was observed by scanning electron microscopy. Bond strength data were analyzed using two-way ANOVA/Tukey's test. No interaction was observed between adhesive systems and FF lining (p = 0.89). Also, no significant difference was found between bond strength values, whether or not FF layers were used (p = 0.33). However, bonding systems demonstrated significant differences (p = 0.01). SB and NT presented means higher than those observed with OP. Fracture modes varied considerably between experimental groups, and a greater frequency of cohesive failures was noted when FF layers were used.8052-

Effect Of Different Mouthrinses On Knoop Hardness Of A Restorative Composite.

To evaluate the effect of mouthrinses on Knoop hardness number (KHN) of a restorative composite, at different exposure times. 50 composite specimens (TPH Spectrum) were randomly allocated into five groups (n=10): distilled water; Listerine; Reach; Plax and Periogard. The samples were immersed daily for 14 days in 20 ml of the respective solution for 2 minutes twice a day (with a 12-hour interval between exposures). Measurements were carried out at four different times: 1 hour after sample preparation, 1, 7 and 14 days after the first immersion in the solutions. Statistical analyses (Repeated Measures ANOVA and Tukey test at 0.05 significance level) showed significant differences among KHN of t wo experimental groups (mean values): Listerine (49.17) and Plax (51.14). There was n ointeraction between products and time, although the highest means were registered 24 hours after the first immersion for all tested groups.18338-4