Application Of Adhesive System Research Articles

Bonding Properties of Heat-polymerized Denture Base Resin to Ti-6Al-7Nb Alloy

The purpose of this study was to evaluate the shear bonding strength and leakage of heat-polymerized denture base resin to titanium-aluminum-niobium (Ti-6Al-7Nb) and cobalt-chromium (Co-Cr) castings using four adhesive systems; three adhesive primers (Metal Primer II, Metal Link, MR. Bond) and one heat-polymerized adhesive resin containing 4-META (Metadent). The resin tab was heat-polymerized directly with or without the primer. Shear bonding strengths and dye penetration distances were determined before and after 10,000 times of thermocycling. The results were analyzed with three-way ANOVA and Tukey's comparison (p<0.05). Thermocycling significantly decreased bonding strength and promoted dye penetration. However, with the application of adhesive systems, post-thermocycling bond strength was significantly improved and dye penetration was inhibited. The bonding strength of Ti-6Al-7Nb was significantly smaller than that of Co-Cr, but the difference was marginal. These results suggested that the examined adhesive systems significantly improved the bonding efficiency of heat-polymerized resin to Ti-6Al-7Nb and Co-Cr alloys.

Effect of cyclic compressive loading on the bond strength of an adhesive system to dentin after collagen removal.

The objective of this study was to verify the effect of cyclic compressive loading on the shear bond strength of an adhesive system following collagen removal. Sixty bovine teeth were divided into 4 groups based on the adhesive procedure used: groups 1 and 2--etching with 35% phosphoric acid and application of the Single Bond adhesive system; groups 3 and 4--after etching, a 10% sodium hypochlorite solution was applied for 1 min before the application of the adhesive. In all the specimens, a Z100 resin cylinder was built up over the bond area. Groups 2 and 4 were submitted to 500,000 cycles with a load of 100 N. The mean values for the shear bond test (MPa) were: group 1: 7.37 +/- 1.15; group 2: 5.72 +/- 1.66; group 3: 5.95 +/- 1.21; group 4: 3.66 +/- 1.12. There was no difference between groups 1 and 2 (p > 0.01). Between groups 1 and 3, 2 and 4, and 3 and 4 there was a significant difference (p < 0.01). The majority of the specimens demonstrated an adhesive failure. The application of sodium hypochlorite on dentin decreased the values of shear bond strength, as did the load cycling in the group treated with sodium hypochlorite.

Morphology and thickness of the diffusion of resin through demineralized or unconditioned dentinal matrix.

The formation of a hybrid layer is the main bonding mechanism of current dentin-bonding systems. This study evaluated the morphology and thickness of the resin-infiltrated dentinal layer after the application of adhesive systems. The dentin-bonding agents were evaluated on flat dentinal preparations confected on the occlusal surfaces of human teeth. The test specimens were prepared and inspected under scanning electron microscopy at a magnification of X 2,000. The adhesive systems were responsible for different hybrid layer thicknesses (p < 0.05), and the mean values were: for Scotchbond MP Plus (SM), 7.41 +/- 1.24 micrometer for Single Bond (SB), 5.55 +/- 0.82 micrometer for Etch & Prime 3.0 (EP), 3.86 +/- 1.17 micrometer and for Clearfil SE Bond (CB), 1.22 +/- 0.45 micrometer. The results suggest that the conventional three-step adhesive system (SM) was responsible for the thickest hybrid layer, followed by the one-bottle adhesive (SB). The self-etching adhesives, EP and CB, produced the formation of the thinnest hybrid layers.

Human pulp response after an adhesive system application in deep cavities

Objectives: To evaluate the pulpo-dentin complex response to a dentin adhesive application in deep cavities performed in human teeth. Methods: Deep class V cavities were prepared on the buccal surface of 46 premolars. The remaining dentin of the axial wall received 10% phosphoric acid and dentin adhesive (group DA), or was protected before the acid and dentin adhesive application with calcium hydroxide cement (group CH). Half of the teeth, which received the acid application directly over the axial wall, were contaminated prior to the procedures with dental plaque collected from the patient's own teeth (group DAC). The plaque was placed on the dentin for 5 min and then the cavity was washed. All teeth were restored with a light-cured composite resin. The teeth were extracted after 7, 30 or 60 days and prepared according to normal histologic techniques. Serial sections were stained with H/E, Masson's trichrome and Brown & Brenn technique for demonstration of bacteria. Results: The histopathologic evaluation showed that in groups DA and DAC, the inflammatory response was more evident than in group CH. Also, the intensity of the pulp reaction increased as the remaining dentin thickness decreased. There was no statistical difference in the inflammatory response between the groups DA and DAC. Conclusion: Based on the experimental conditions, we concluded that the All Bond 2 adhesive system, when applied on dentin in deep cavities, showed an acceptable biocompatibility. However, the intensity of the pulpo-dentin complex response depends on the remaining dentin thickness.

Avaliação da citotoxicidade de dois sistemas adesivos

Avaliamos a citotoxicidade in vitro de dois sistemas adesivos (Scotchbond Multipurpose Plus e Clearfil Liner Bond 2) utilizando fibroblastos NIH-3T3. Culturas celulares confluentes entraram em contato com os sistemas adesivos completos e com seus componentes individuais ("primer" e adesivo). As substâncias foram aplicadas sobre lamínulas de vidro e, a seguir, introduzidas nos cultivos celulares. Adicionalmente, testamos a citotoxicidade da resina composta (Z100); do cimento de hidróxido de cálcio (Hidro C) e do ácido fosfórico. Como controle utilizamos culturas que receberam lamínulas de vidro sem substâncias. Com exceção do ácido fosfórico, que permaneceu por 20 segundos, todos os materiais foram deixados por 24 horas, período após o qual determinamos a porcentagem de viabilidade celular pelo método da exclusão de células coradas pelo azul de trypan. Os dados dos diferentes grupos foram submetidos a análise estatística (ANOVA e teste de Tukey). Foi possível observar que todas as culturas tratadas apresentaram menor porcentagem de viabilidade celular em relação ao grupo controle, com exceção das culturas tratadas pelo Ca(OH)2, que apresentaram valores similares de viabilidade celular. A aplicação da resina composta, do ácido fosfórico, do "primer" e do adesivo do sistema adesivo Scotchbond Multipurpose Plus empregados individualmente levaram as culturas a apresentar viabilidade celular similar àquela do grupo do Ca(OH)2. Os dois sistemas adesivos, bem como o "primer" e o adesivo do sistema Clearfil Liner Bond 2, quando aplicados individualmente, causaram citotoxicidades similares, levando a porcentagens de viabilidade celular menores do que aquela encontrada com o Ca(OH)2. Não foram encontradas diferenças estatisticamente significantes nos efeitos citotóxicos causados pelos diversos componentes dos dois sistemas adesivos testados.

Morphological aspects of the resin-dentin interdiffusion zone with different dentin adhesive systems.

Cross-sections of resin-dentin interfaces were etched with an argon-ion beam to make their substructure detectable by scanning electron microscopy. The dentin adhesive systems were categorized morphologically into three groups, and an attempt was made to clarify their adhesive mechanism. The first group of products removed the smear layer. The argon-ion bombardment clearly disclosed a hybrid or resin-impregnated dentin layer. It is hypothesized that conditioning with acidic or chelating agents demineralized the dentin surface-layer to a certain depth, leaving behind a collagen-rich mesh-work. Hydrophilic monomers are then believed to alter this collagen-fiber arrangement in a way that facilitates penetration of the adhesive resin, resulting in a mechanical, intermingled link between collagen and the adhesive resin. The second group preserved the smear layer. In this case, the dentinal tubules were obliterated with globular particles at their orifices and remained patent underneath these smear plugs. This type of adhesive system aims at the incorporation of the smear layer into the hydrophilic monomers, which have an affinity for the organic and/or inorganic components of the underlying dentin. Finally, a third, small group only partly dissolved the smear layer, creating a thin resin-impregnated dentin layer and a resin-impregnated smear plug. This study clearly showed that the application of recent adhesive systems induced structural changes in the dentin surface morphology, creating a retentive interface, called the inter-diffusion zone, between the deep, untouched dentin layers and the composite filling material. This resin-dentin interdiffusion zone offers bonding sites for copolymerization with the resin composite and, concurrently, might have protective potential for the pulp tissues.