ボンディングシステムの歯質に対する接着強さ : 組成の異なる 2 種類のボンディングシステムの組み合わせによる影響

Abstract

Many kinds of dentin bonding systems have recently been introduced, which are reported to have significantly improved bond strengths to dentin. To enhance the dentin adhesion, the adhesion process of these dentin bonding systems include various processes such as, 1) acid etching of enamel to create a mechanical retention, 2) dentin conditioning to fully or partially remove the smear layer, 3) pretreating of dentin surfaces with primers, 4) application of a bonding agent before resin filling. All the components of these dentin bonding systems are designed in different mechanism to enhance the bonding strength, and careful observance of all the manufacturers' directions is also recommended. The effect of each component of dentin bonding systems on the tooth bonding has so far been unclear in detail. In this report, two different kinds of dentin bonding systems, Clearfil Liner Bond System (CLB) and Scotchbond Multi-Purpose (SMP), were used in various combinations to smearlayer-covered-dentin and polished-enamel surfaces of freshly extracted caries-free human molars and incisors to investigate the effects of the conditioners, primers and bonding agents on the tooth bonding. The conditioners, primers and bonding agents of the two dentin bonding systems were used in various combinations. The specimens were stored in room temperature for 48 hr, before tensile bond testing with cross-head speed of 2mm/min. The results were analyzed using ANOVA (p<0.05). The scanning electron microscope (SEM) was also used to observe the conditioner and/or primer treated dentin surfaces and the fracture surface after tensile bond test. The bonding aspect of bonding agent and synthetic hydroxyapatite (HAP) with SEM were also performed by using the method described by Hsiao et al. (1987). In the cases of smear-layer-covered-dentin surfaces, the tensile bond strengths of the original combination of LBS show a higher bond strength than any other combination. There were no statistically significant differences in the combination use of different conditioners or dentin primers. The tensile bond strength shows a significant decrease in the case of dentin surfaces without dentin conditioning. SEM micrographs showed an opening tubule appearance in the condition and/or primer treated dentin surfaces. Cohesive failures of dentin were observed in the case of dentin surface treated with conditioner. The adhesion failures of bonding were noted in the specimens without conditioner treating. In the cases of polished-enamel surfaces, the tensile bond strengths of both the original combination and non-primer treatment of LBS and SMP show a higher bond strength than any other combination. The tensile bond strength shows a significant decrease in the case of enamel surfaces without conditioning, especially SMP. SEM micrographs showed an etched appearance in the condition and/or primer treated enamel surfaces. Cohesive failures of enamel were observed in the case of dentin surface treated with conditioner. The adhesion failures of bonding were noted in the specimens without conditioner treating. The dentin primer pretreated hydroxyapatite showed an enhanced bonding capacity with bonding agent, especially in case of those primers and bonding agents containing adhering substances. The results indicate that acidic conditioners are necessary for high bond strength with either system and that MP can substitute KP and vice versa. Using manufacturers' directions, LBS gave higher dentin tensile bond strength than did SMP. Acidic conditioners are necessary for dentin bonding system and an adhesive-containing bonding agent might contribute to a higher bond strength.