Shear Bond Strength of Resin Modified Glass Ionomer Cement Using Different Enamel Conditions

Mustafa Hamed,Zaid Tawfek,Mohammed Younis

doi:10.33899/rden.2010.8967

Abstract

Aims: In an effort to improve the shear bond strength of resin modified glass ionomer cement on orthodontic brackets, various enamel conditioning have been evaluated for use with this cement. Materials and methods: A total of 100 freshly extracted human premolars were subjected to two steps of treatment. The first step of treatment involve dividing the teeth into 5 groups each of 20 teeth: (I) treated with 20 second acid etching with 37% phosphoric acid; (II), treated with micro–etching using 50 μ aluminum oxide; (III), treated with air polisher using 45 μ sodium bicarbonate; (IV), treated with coarse finishing disk for 10 second; (V), left the enamel clean without treatment. In the second step each group then subdivided into two subgroups, ten teeth subjected to wetting with tab water and ten left dry. Following, storage for 24 hours at 37°C in distilled water, shear debonding force was measured using a Universal Testing Machine with a cross–head speed of 10 mm/minute. Results: The result indicated that the highest shear bond strength was for acid etched enamel under wet condition with lowest mean for normal dry enamel. the Mann–Whitney analysis estimated a significant difference between wet and dry condition in general with high probability of bond failure for the dry than that of wet conditions. Conclusions: The suitable enamel conditions regarding the shear bond with the mode of bond failure had been shown to be the wet and dry situation of group III and wet situation of group IV. But, it could be concluded that the most suitable enamel condition may be that treated with a coarse finishing disk under wet condition.

Highlights

Clinical improvements related to orthodontic bonding are still needed in two major areas; reduction of white spot lesions and increased tolerance to moisture contamination during bonding to reduce www.rafidaindentj.netHamed MM, Tawfek ZS, Younis MT the incidence of bond failure[1]
The introduction of resin modified glass ionomer cements (RMGICs) which are auto set by the acid–base reaction of glass ionomer cements, have a diffusion– based adhesion between the cement and the tooth surface[1], combines the advantages of conventional glass ionomer cements with the ability to form chemical bonds with enamel, dentine and metal, significant amount of fluoride release to protect against decalcification[3], absorb fluoride from other sources, such as fluoride toothpastes and mouth rinses, acting as a rechargeable, slow–release fluoride device, they possess the advantage of easier debond with less potential for damage to the enamel; their ability of adhesion even in wet condition[4]
Group III: the buccal enamel surfaces were air polished with 45 μm sodium bicarbonate for 10 second were blown with air to remove any residual contamination[11]

Summary

Introduction

Clinical improvements related to orthodontic bonding are still needed in two major areas; reduction of white spot lesions and increased tolerance to moisture contamination during bonding to reduce www.rafidaindentj.netHamed MM, Tawfek ZS, Younis MT the incidence of bond failure[1]. The introduction of resin modified glass ionomer cements (RMGICs) which are auto set by the acid–base reaction of glass ionomer cements, have a diffusion– based adhesion between the cement and the tooth surface[1], combines the advantages of conventional glass ionomer cements with the ability to form chemical bonds with enamel, dentine and metal, significant amount of fluoride release to protect against decalcification[3], absorb fluoride from other sources, such as fluoride toothpastes and mouth rinses, acting as a rechargeable, slow–release fluoride device, they possess the advantage of easier debond with less potential for damage to the enamel; their ability of adhesion even in wet condition[4]. Besides the improvement achieved by the combination of resin composites, the RMGICs still have a lower shear bond strength[8,9]. The aim of this study is to evaluate various enamel conditions trying to reach to best resin modified glass ionomer cement bond properties (shear bond and mode of bond failure)

Methods

Results

Conclusion