Shear bond strength of different lingual buttons bonded to wet and dry enamel surfaces with resin modified glass ionomer cement (in vitro comparative study)


Background: This study was aimed to investigate the effect of three lingual button (Nickel free / rectangular base,Nickel free / round base and Composite) and bonding environment, wet and dry enamel surface, on: the shearbond strength (SBS) of light and self-cured Resin Modified Glass Ionomer Cements, and the debonding failure sites.Materials and method: One hundred twenty no-carious, free of cracks maxillary first premolar teeth were selected.Three types of orthodontic lingual buttons were used in this study: Nickel free / rectangular base, Nickel free / roundbase and Composite buttons. The teeth were divided into two groups of sixty teeth each. One group was used fortesting the chemically cured GC Fuji Ortho Resin modified Glass Ionomer (RMGIC), while the other was used fortesting the light cured GC Fuji Ortho LC RMGIC. Each was further subdivided into two subgroup; thirty teeth werebonded to wet enamel surface while the other was bonded after drying the enamel surface. Then each ten teethfrom each subgroup were bonded with only one type of buttons. The sample was tested for bond strength using theuniversal testing machine and the Adhesive Remnant Index (ARI) was inspected under the stereomicroscope.Results:The highest (SBS) values were obtained in the Nickel free / round base button with both types of RMGIC in wetand dry environment as revealed by ANOVA test. While t-test revealed that both systems of RMGIC yield relativelylower values of (SBS).Conclusions:The GC Fuji Ortho RMGICs resist shear force in dry better that in wet environment.Nickel free / roundbase buttons give the greatest shear bond strength among the three types of button.The composite buttons givegreater bond strength in dry than in wet environment with both GC Fuji Ortho and GC Fuji Ortho LC RMGICs