The effect of different surface treatments on repair with composite resin of ceramic.

OBJECTIVES: This study evaluated the effect of Er, Cr: YSGG laser irradiation at different powers on repair bond strength (RBS) between ceramic restoration and composite resin (CR). MATERIALS AND METHODS: Sixty ceramic samples were prepared and thermocycled for 2,500 cycles between 5°C and 55°C. Samples randomly divided into six groups (n = 10) according to the different surface treatment: control group (no surface treatment), 9.6% hydrofluoric acid etching, 37% phosphoric acid etching, and irradiations with Er, Cr: YSGG lasers (1 to 3W). The Cimara System was applied to all samples surface according to the manufacturer's instructions. CR resin was built-up on each ceramic surface using a tygon tube. The RBS test was performed at a crosshead speed of 1 mm/min, and one sample of each group was also observed under SEM and EDS was used to measure the elemental profiles of each specimen. Data was analyzed with one-way ANOVA and Tukey HSD test. RESULTS: The lowest RBS was recorded in Group OF, and the highest RBS was recorded in Group HF, followed by Group 3W. There was no statistical difference between Group Control, 1W and 2W. Furthermore, differences in RBSs between Group 3W and the other groups except Group 2W were significant (P < 0.05). In EDS analysis, there are evident differences between surface treated samples and controls. CONCLUSIONS: 3W laser irradiation may be an alternative method to acid etching for enhancing the RBS of CR to ceramic.

Shear Bond Strength of Orthodontic Brackets Bonded to Zirconium Crowns.

BACKGROUND: An increasing demand for esthetic restorations has resulted in an increased use of all-ceramic restorations, such as zirconium. However, one of the challenges the orthodontist must be willing to face is how to increase bond strength between the brackets and various ceramic restorations.Bond strength can beaffected bybracket type, by the material that bracketsaremade of, and their base surface design or retention mode. ​: Aim: of this study was to perform a comparative analysis of the shear bond strength (SBS) of metallic and ceramic orthodontic brackets bonded to all-zirconium ceramic surfaces used for prosthetic restorations, and also to evaluate the fracture mode of these two types of orthodontic brackets. MATERIAL AND METHODS: Twenty samples/semi-crowns of all-zirconium ceramic, on which orthodontic brackets were bonded, 10 metallic and 10 ceramic polycrystalline brackets, were prepared for this research. SBS has been testedby Universal Testing Machine, with a load applied using a knife edged rod moving at a fixed rate of 1 mm/min, until failure occurred. The force required to debond the brackets was recorded in Newton, then SBS was calculated to MPa. In addition, the samples were analyzed using a digital camera magnifier to determine Adhesive Remnant Index (ARI). Statistical data were processed using t-test, and the level of significance was set at α = 0.05. RESULTS: Higher shear bond strength values were observed in metallic brackets bonded to zirconium crowns compared tothoseof ceramic brackets, with a significant difference. During the test, two of the ceramic brackets were partially or totally damaged. CONCLUSION: Metallic brackets, compared to ceramic polycrystalline brackets, seemed tocreate stronger adhesion with all-zirconium surfaces due to their better retention mode. Also, ceramic brackets showed higher fragility during debonding.

Avaliação in vitro de materiais utilizados para colagem ortodôntica: potencial cariostático, resistência ao cisalhamento e padrão de descolagem / In vitro evaluation of orthodontic bonding materials: cariostatic effect, shear bond strength and debonding pattern

O objetivo deste estudo foi avaliar, comparativamente, um cimento de ionômero de vidro modificado por resina (Fuji Ortho LC - GC) e duas resinas compostas com flúor, uma fotoativada (Sequence/Fluorobond VCL - Ormco) e outra pasta única (Rely-a-Bond - Reliance), tendo como controle uma resina convencional (Concise - 3M). Para a avaliação do potencial cariostático desses materiais, foram colados bráquetes em fragmentos de terceiros molares humanos extraídos (n=20) e realizadas ciclagens de pH (Des/Re) durante 14 dias. Utilizando-se um eletrodo íon específico, foram realizadas dosagens de flúor nas soluções empregadas nas ciclagens. Concluídas as ciclagens, foram realizadas análises de dureza Knoop (KHN) do esmalte adjacente aos bráquetes, em secção longitudinal. Para a avaliação da resistência ao cisalhamento, foram colados bráquetes em premolares humanos, extraídos por indicação ortodôntica. Foram formados seis grupos (n=20) representando os materiais, tendo o CIVMR três grupos, nos quais variou-se o tratamento do esmalte (sem condicionamento, condicionamento com ácido poliacrílico, condicionamento com ácido fosfórico). Após os ensaios mecânicos de cisalhamento, realizados decorridas 48 horas das colagens, foi avaliado o índice de adesivo remanescente (IAR), além da presença de fraturas de esmalte, por meio de microscopia ótica. Os resultados demonstraram que: (a) o CIVMR foi capaz de liberar flúor e reduzir a extensão e a profundidade de lesões de cárie adjacentes aos acessórios ortodônticos; (b) as resinas com flúor analisadas apresentaram liberação de flúor mínima e não demonstraram efetividade na inibição de desmineralização; (c) o CIVMR, quando utilizado sem condicionamento ácido do esmalte, apresentou força de adesão significativamente menor que os demais materiais e/ou tratamentos avaliados; (d) quando associado ao condicionamento do esmalte (com ácido fosfórico ou poliacrílico) o CIVMR equiparou-se às resinas compostas fotoativada e pasta única; (e) quando utilizado sem condicionamento ácido do esmalte, o CIVMR apresentou padrão de descolagem sem adesivo remanescente no esmalte; (f) já, quando associado ao condicionamento do esmalte, comportou-se de forma variada, semelhante às resinas compostas e (g) casos de fratura extensa de esmalte, após a descolagem, foram observados nos grupos que apresentaram maiores valores de força de adesão (resinas compostas convencional e fotoativada). Portanto, o CIVMR avaliado demonstrou possuir propriedades que indicam seu uso clínico, principalmente em pacientes que já apresentem indícios de risco à cárie

The aim of this in vitro study was to comparatively evaluate a resin-modified glass ionomer cement (Fuji Ortho LC - GC) and two composite resins with fluoride, one light-cured (Sequence/Fluorobond VLC - Ormco) and other no-mix (Rely-a-Bond - Reliance), with a conventional control resin (Concise - 3M). In order to evaluate the cariostatic effect of these materials, brackets were bonded in human extracted third molars fragments (n=20) and then subjected to a demineralization and remineralization cycling model during two weeks. The fluoride ion concentration in the cycling solutions was measured using a fluoride ion electrode. After cycling, hardness (Knoop) analysis was performed in enamel adjacent to brackets in longitudinal section. To evaluate the shear bond strengt, brackets were bonded in human extracted premolars divided into six groups (n=20) representing the materials, with three groups of the GICRM, varyng the enamel treatment (without etching, etching with polyacrylic acid and etching with phosphoric acid). After the shear bond strength tests, done 48 hours after bonding, the Adhesive Remnant Index (ARI) and the presence of enamel cracks were evaluated by optical microscopy. The results indicated that: (a) GICRM released significantly more fluoride and reduced enamel demineralization adjacent to orthodontic bracktes; (b) composite resins with fluoride demonstrated minimal carostatic effect and fluoride release; (c) GICRM when used without enamel etching presented the lowerst shear bond strenght; (d) however when the enamel was etching (phosphoric or polyacrylic acid) the GICRM was equivalent to composites, light-cured or no-mix; (e) when used without etching, the GICRM after debonding showed no adhesive remains in enamel; (f) when associated with acid etching, the ARI varied lie composite resins and (g) extensive enamel cracks, after debonding, were observed in groups that presented higher shear bond strenght (composite resins conventional and light cured). Finally, the GICRM demonstred to have properties that indicate its use for orthodontic bonding, specially for patients with caries risk