Avaliação dos preparos da superfície cerâmica para a colagem de acessórios ortodônticos

The purpose of this study was to evaluate the effects of two conditioning methods used to enhance the shear strength of orthodontic brackets bonded to porcelain surfaces. A total of 18 feldspathic specimens were used. The specimens were divided randomly into two groups (n = 9): group free silane, the porcelain specimens were etched with hidrofuoric acid 10% (Acid Gel-Maquira) for 4 minutes followed by adhesive-primer (Transbond XT) and the metallic brackets (Morelli Roth Light .022" x .030") were bonded with a light-cured microfilled resin (Transbond XT Light Cure Orthodontic Adhesive); group silane, the porcelain specimens were etched with hidrofuoric acid 10% (Acid Gel-Maquira) for 4 minutes followed by silane (Silano Ângelus) for 1 minute, adhesive-primer (Transbond XT) and the metallic brackets (Morelli Roth Light .022" x .030") were bonded with a light-cured microfilled resin (Transbond XT Light Cure Orthodontic Adhesive). All specimens were stored in solution of artificial saliva at ambient temperature for 24 hours. The debonding was done with shear strength through a universal testing machine (DL 500-Emic) calibrated with a fixed speed of 1mm/minute. Statical analysis was performed using the Student t test. The results indicated that in the free silane group the mean bond strength was 9,97 MPA, significantly lower than the silane group, that was 12,38 MPa (p < 0,05). The both groups were effective for bonding, although the silane group had the highest bond strength values.

Avaliação da resistência adesiva de diferentes sistemas resinosos de colagem ortodôntica

Recent orthodontic bonding materials have aimed to reduce the working time of the clinician, by simplifying the acid etching procedure by applying self-etching primer adhesive systems. However, the adhesion quality of these materials still demands investigation. Thus, the present study aimed to evaluate the bond strengths of three different adhesive systems. A hundred and eighty bovine lower incisors were cut and embebbed in acrylic resin matrices, in which orthodontic brackets were bonded with Transbond XT (2n = 60), Transbond XT Self Etching Primer (2n = 60) e Tyrian (2n = 60). For each composite, bond strength tests were executed immediately (n = 30) and 24 hours (n = 30) after the bonding, in the assay machine Versat 2000 (Pantec), by applying 500 Kgf of load at 1mm/min of velocity. Transbond XT, Transbond XT Self Etching Primer and Tyrian presented, respectively, average values of bond strength of 7.43, 7.09 and 3.41 MPa at the time immediately, and 7.42, 8.81 and 5.35 MPa at 24 hours after the bonding, where differences were statistically significant at 5% between Tyrian and Transbond groups at both observation times. It was concluded that Tyrian was the material that presented significant lower bond strength with regard to Transbond groups that were similar.

Uso de 2-octil-cianoacrilato na reconstrução da cavidade anoftálmica de coelhos

OBJETIVO: Avaliar a ligação entre músculos oculares extrínsecos e esferas de polietileno poroso usando um bioadesivo. MÉTODOS: Estudo experimental envolvendo 8 coelhos albinos submetidos a enucleação do olho direto com colocação de implante esférico de polietileno poroso de 12 mm de diâmetro unido aos músculos oculares extrínsecos por meio do bioadesivo 2-octil-cianoacrilato. Noventa dias após a cirurgia os animais foram sacrificados e o conteúdo orbitário removido. em 4 animais foi realizado estudo biomecânico, avaliando-se a força de ruptura entre a musculatura e a esfera (grupo implante) e entre a musculatura e a esclera nos olhos contralaterais (grupo controle). Nos outros 4 animais foi realizada análise histológica. RESULTADO: A avaliação biomecânica revelou que a força de ruptura entre esfera-músculo e esclera-músculo foram semelhantes quando se usa o adesivo de cianoacrilato. O exame histológico mostrou reação fibrovascular no local da adesão entre a musculatura e a esfera, sem efeitos deletérios aos tecidos. Ao redor dos implantes foi possível observar pseudocápsula e no interior, neovasos e tecido fibrovascular preenchendo os espaços entre os grânulos do polietileno. CONCLUSÃO: O adesivo 2-octil-cianoacrilato mantém boa força de adesão na união entre os músculos e as esferas de polietileno poroso, com redução do tempo cirúrgico e sem efeitos deletérios aos tecidos orbitais. Desta forma, deve-se considerar o uso do bioadesivo na reconstrução da cavidade anoftálmica.

Long-term effect of carbodiimide on dentin matrix and resin-dentin bonds

Objectives: To characterize the interaction of 1-Ethyl-3-[3-dimethylaminopropyl] carbodiimide Hydrochloride (EDC) with dentin matrix and its effect on the resin-dentin bond. Methods: Changes to the stiffness of demineralized dentin fragments treated with EDC/N-hydroxysuccinimide (NHS) in different solutions were evaluated at different time points. The resistance against enzymatic degradation was indirectly evaluated by ultimate tensile strength (UTS) test of demineralized dentin treated or not with EDC/NHS and subjected to collagenase digestion. Short- and long-term evaluations of the strength of resin-dentin interfaces treated with EDC/NHS for 1 h were performed using microtensile bond strength (mu TBS) test. All data (MPa) were individually analyzed using ANOVA and Tukey HSD tests (alpha = 0.05). Results: The different exposure times significantly increased the stiffness of dentin (p < 0.0001, control-5.15 and EDC/NHS-29.50), while no differences were observed among the different solutions of EDC/NHS (p = 0.063). Collagenase challenge did not affect the UTS values of EDC/NHS group (6.08) (p > 0.05), while complete degradation was observed for the control group (p = 0.0008, control-20.84 and EDC/NHS-43.15). EDC/NHS treatment did not significantly increase resin-dentin mu TBS, but the values remained stable after 12 months water storage (p < 0.05). Conclusions: Biomimetic use of EDC/NHS to induce exogenous collagen cross-links resulted in increased mechanical properties and stability of dentin matrix and dentin-resin interfaces. (C) 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 94B: 250-255, 2010.

The volumetric fraction of inorganic particles and the flexural strength of composites for posterior teeth

Objective. To evaluate the content of inorganic particles and the flexural strength of new condensable composites for posterior teeth in comparison to hybrid conventional composites.Method. The determination of the content of inorganic particles was performed by mass weighing of a polymerized composite before and after the elimination of the organic phase. The volumetric particle content was determined by a practical method based on Archimedes' principle, which calculates the volume of the composite and their particles by differential mass measured in the air and in water. The flexural. strength of three points was evaluated according to the norm ISO 4049:1988.Results. The results showed the following filter content: Alert, 67.26%; Z-100, 65.27%; Filtek P 60, 62.34%; Ariston pHc, 64.07%; Tetric Ceram, 57.22%; Definite, 54.42%; Solitaire, 47.76%. In the flexural strength test, the materials presented the following decreasing order of resistance: Filtek P 60 (170.02 MPa) > Z-100 (151.34 MPa) > Tetric Ceram (126.14 MPa) = Alert (124.89 MPa) > Ariston pHc (102.00 MPa) = Definite (93.63 MPa) > Solitaire (56.71 MPa).Conclusion. New condensable composites for posterior teeth present a concentration of inorganic particles similar to those of hybrid composites but do not necessarily present higher flexural strength. (C) 2003 Elsevier B.V. Ltd. Alt rights reserved.

Effect of microwave disinfection on the hardness and adhesion of two resilient liners

Statement of problem. Microwave irradiation has been suggested for denture disinfection. However, the effect of this procedure on the hardness and bond strength between resilient liners and denture base acrylic resin is not known.Purpose. This study evaluated the effect of water storage time and microwave disinfection on the hardness and peel bond strength of 2 silicone resilient lining materials to a heat-polymerized acrylic resin.Material and methods. Acrylic resin (Lucitone 199) specimens (75 X 10 X 3 mm) were stored in water at 37 degrees C (2 or 30 days) before bonding (n = 160). The resilient lining materials (GC Reline Extra Soft and Dentusil) were bonded to the denture base and divided into the following 4 groups (n = 10): Tests performed immediately after bonding (control); specimens immersed in water (200 mL) and irradiated twice, with 650 W for 6 minutes; specimens irradiated daily for 7 total cycles of disinfection; specimens immersed in water (37 degrees C) for 7 days. Specimens were submitted to a 180-degree peel test (at a crosshead speed of 10 mm/min) and the failure values (MPa) and mode of failure were recorded. Pretreatment and posttreatment hardness measurements (Shore A) of the resilient materials were also performed. Three-way analysis of variance, followed by the Tukey HSD test, was performed (alpha=.05).Results. The analysis revealed that, for all conditions, the mean failure strengths of GC Reline Extra Soft (0.95-1.19 MPa) were significantly higher (P<.001) than those of Dentusil (0.45-0.50 MPa). The adhesion of the liners was not adversely affected by water storage time of Lucitone 199 or microwave disinfection. All peel test failures were cohesive. There was a small but significant difference (P<.001) between the pretreatment (34.33 Shore A) and posttreatment (38.69 Shore A) hardness measurements.Conclusion. Microwave disinfection did not compromise the hardness of either resilient liners or their adhesion to the denture base resin Lucitone 199.

Effect of Conventional and Resin-modified Glass-Ionomer Liner on Dentin Adhesive Interface of Class I Cavity Walls After Thermocycling

Objective: The aim of this in vitro study was to analyze the effect of glass-ionomer cement as a liner on the dentin/resin adhesive interface of lateral walls of occlusal restorations after thermocycling.Materials and Methods: Occlusal cavities were prepared in 60 human molars, divided into six groups: no liner (1 and 4); glass-ionomer cement (GIC, Ketac Molar Easymix, 3M ESPE) (2 and 5); and resin-modified glass-ionomer cement (RMGIC, Vitrebond, 3M ESPE) (3 and 6). Resin composite (Filtek Z250, 3M ESPE) was placed after application of an adhesive system (Adper Single Bond 2, 3M ESPE) that was mixed with a fluorescent reagent (Rhodamine B) to allow confocal microscopy analysis. Specimens of groups 4, 5 and 6 were thermocycled (5 degrees C-55 degrees C) with a dwell time of 30 seconds for 5000 cycles. After this period, teeth were sectioned in approximately 0.8-mm slices. One slice of each tooth was randomly selected for confocal microscopy analysis. The other slices were sectioned into 0.8 nun x 0.8 mm beams, which were submitted to microtensile testing (MPa). Data were analyzed using two-way ANOVA and Tukey test (p < 0.05).Results: There was no detectedstatistical difference on bond strength among groups (alpha < 0.05). Confocal microscopy analysis showed a higher mean gap size in group 4(12.5 mu m) and a higher percentage of marginal gaps in the thermocycled groups. The RNIGIC liner groups showed the lowest percentage of marginal gaps.Conclusions: Lining with RMGIC resulted in less gap formation at the dentin/resin adhesive interface after artificial aging. RMGIC or GIC liners did not alter the microtensile bond strength of adhesive system/resin composite to dentin on the lateral walls of Class I restorations.

Effects of mechanical cycling on the bonding of zirconia and fiber posts to human root dentin

Purpose: To evaluate the effect of cyclical mechanical loading on the bond strength of a fiber and a zirconia post bonded to root dentin.Materials and Methods: Forty single-rooted human teeth (maxillary incisors and canines) were sectioned, and the root canals were prepared at 12 mm. Twenty randomly seleced specimens received a quartz fiber post (FRC) (D.T. Light-Post) and 20 others received a zirconia post (ZR) (Cosmopost). The posts were resin luted (All Bond 2 + resin cement Duo-link) and each specimen was embedded in epoxy resin inside a PVC cylinder. Ten specimens with FRC post and 10 specimens with ZR post were submitted to fatigue testing (2,000,000 cycles; load: 50 N; angle of 45 degrees; frequency: 8 Hz), while the other 20 specimens were not fatigued. Thus, 4 groups were formed: G1: FRC+O cycles; G2: FRC+2,000,000 cycles; G3: ZR+O cycles; G4: ZR+2,000,000 cycles. Later, the specimens were cut perpendicular to their long axis to form 2-mm-thick disk-shaped samples (4 sections/specimen), which were submitted to the push-out test (1 mm/min). The mean bond strength values (MPa) were calculated for each tooth (n = 10) and data were submitted to statistical analysis (alpha = 0.05).Results: Two-way ANOVA revealed that the bond strength was significantly affected by mechanical cycling (p = 0.0014) and root post (p = 0.0325). The interaction was also statistically significant (p = 0.0010). Tukey's test showed that the mechanical cycling did not affect the bonding of FRC to root dentin, while fatigue impaired the bonding of zirconium to root dentin.Conclusion: (1) the bond strength of the FRC post to root dentin was not reduced after fatigue testing, whereas the bonding of the zirconia post was significantly affected by the fatigue. (2) Cyclical mechanical loading appears to damage the bond strength of the rigid post only.

The adhesive system and root canal region do not influence the degree of conversion of dual resin cement

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Mechanical and thermal cycling effects on the flexural strength of glass ceramics fused to titanium

This study evaluated the effects of mechanical and thermal cycling on the flexural strength (ISO 9693) of three brands of ceramics fused to commercially pure titanium (cpTi). Metallic frameworks of 25 x 3 x 0.5 mm dimensions (N = 84) were cast in cpTi, followed by 150-mu m aluminum oxide airborne particle abrasion at a designated area of the frameworks (8 x 3 mm). Bonder and opaque ceramic were applied on the frameworks, and then the corresponding ceramic (Triceram, Super Porcelain Ti-22, Vita Titankeramik) was fired onto them (thickness: 1 mm). Half of the specimens from each ceramic-metal combination were randomly tested without aging (only water storage at 37 degrees C for 24 hours), while the other half were mechanically loaded (20,000 cycles under 10 N load, immersion in distilled water at 37 degrees C) and thermocycled (3,000 cycles, between 5-55 degrees C, dwell time of 13 seconds). After the flexural strength test, failure types were noted. Mechanical and thermal cycling decreased the mean flexural strength values significantly (p<0.05) for all the three ceramic-cpTi combinations tested when compared to the control group. In all the three groups, failure type was exclusively adhesive at the opaque ceramic-cpTi interfacial zone with no presence of ceramic on the substrate surface except for a visible oxide layer.

Deposition of SiOx Thin Films on Y-TZP by Reactive Magnetron Sputtering: Influence of Plasma Parameters on the Adhesion Properties Between Y-TZP and Resin Cement for Application in Dental Prosthesis

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Bond strengths, degree of conversion of the cement and molecular structure of the adhesive-dentine joint in fibre post restorations

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Avaliação da resistência de união metalocerâmica em função de diferentes tempos de oxidação prévia

Avaliou-se a resistência de união metal/porcelana utilizando-se uma liga de Ni-Cr, submetida a diferentes tempos de oxidação prévia com o sistema cerâmico Vita-VMK, através do teste preconizado por CHIODI NETTO3. A análise dos resultados permitiu as seguintes conclusões: a ausência da oxidação prévia possibilitou os melhores resultados, sendo que a diferença foi estatisticamente significante; diferentes tempos de oxidação prévia provocaram redução acentuada nos valores obtidos e foram semelhantes entre si; o grupo submetido ao processo de jateamento após a oxidação prévia por cinco minutos mostrou resultados similares aos grupos que também passaram pelo processo de oxidação e não sofreram jateamento posterior.

Muscle strength assessment among children and adolescents with growing pains and joint hypermobility

OBJETIVO: Avaliar, por meio de teste quantitativo, a força muscular em crianças e adolescentes com dores de crescimento, associada ou não com hipermobilidade articular e comparadas com controles saudáveis. MÉTODO: Quarenta e sete casos de crianças e adolescentes acompanhados por dores de crescimento, sendo 24 com hipermobilidade articular (DC-HA), 23 sem hipermobilidade articular (DC) e 47 controles saudáveis pareados por idade e gênero foram submetidos a dois testes quantitativos para a avaliação da força muscular, o Childhood Myositis Assessment Scale (CMAS) e o Manual Muscle Strength Test (MMT). Os dados antropométricos como altura, peso, índice de massa corporal, prega cutânea tricipital, circunferência média do braço e a área muscular do braço foram comparados entre os três grupos. RESULTADOS: Os três grupos não apresentaram diferença estatística entre as medidas antropométricas. Houve diferença significante entre a mediana da pontuação do CMAS, sendo menores no grupo DC (47, mínimo e máximo 39-52) e DC-HA (46, mínimo e máximo 40-51), comparados com controles (50, mínimo e máximo 45-52; p<0,0001). Dois dos exercícios cronometrados do CMAS, a elevação da cabeça e a duração da elevação das pernas, tiveram menor pontuação nos pacientes comparados aos controles (p<0.0001). A pontuação mediana do MMT no grupo DC (79, mínimo e máximo 73-80) e DC-HA (78, mínimo e máximo 32-80) também apresentou diferença significante, sendo menor nos pacientes que nos controles (80, mínimo e máximo 78-80; p<0,0001). A melhor correlação entre a pontuação do CMAS e MMT foi no grupo DC-HA (Spearman r=0,65; p=0,0007). A aplicação do CMAS e MMT em duas ocasiões apresentou boa concordância e coeficiente de correlação intraclasse de 0,87 (IC 95% 0,64-0,96; p<0,0001) e 0,92 (IC 95% 0,76-0,97; p<0,0001), respectivamente. CONCLUSÃO: Os pacientes com dores de crescimento com ou sem hipermobilidade articular apresentaram fraqueza muscular de leve a moderada quando comparados com controles saudáveis.

Avaliação da influência dos tipos de tratamento superficial da porcelana glazeada na colagem de braquetes ortodônticos

OBJETIVO: o objetivo deste trabalho foi avaliar a influência do tipo de tratamento superficial da porcelana na resistência adesiva da colagem de braquetes ortodônticos e o modo de fratura após a descolagem. METODOLOGIA:foram confeccionados 80 corpos-de-prova de porcelana, divididos em quatro grupos (n = 18) de acordo com os diferentes tratamentos de superfície: (G1) ponta diamantada; (G2) ponta diamantada e silano; (G3) ácido hidrofluorídrico e (G4) ácido hidrofluorídrico e silano. Após o preparo das superfícies, braquetes Edgewise (Morelli) foram colados com resina (Transbond XT, 3M) e submetidos ao teste de cisalhamento. Os resultados foram avaliados estatisticamente pelo teste de Kruskal-Wallis. RESULTADO: o grupo G1 apresentou uma média de resistência de 3,35, o G2 3,97, o G3 2,56 e o G4 3,10. CONCLUSÃO: constatou-se que não houve diferença estatisticamente significativa na resistência adesiva do braquete entre os tipos de tratamentos estudados (p > 0,05) e os modos de fratura ocorreram, em sua grande maioria, na interface braquete/resina. Este estudo indica que todos os tipos de tratamentos apresentados são eficientes para a colagem.