الفهرس 
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Abstract
The aim of this work was to evaluate the bond strength (shear and tensile) of Versacrylic soft lining material (either self-cured or heat-cured) to the acrylic resin denture base. Material and method. For this study eighty acrylic resin specimens were prepared (heat-cure acrylic resin*). Each one consists of two similar pieces. Fourty cylindrical specimens of them for tensile test (31 mm long and 16 mm diameter) where preparation according to manufactures, twenty specimens where joined to anther twenty specimens by 3 mm thickness of (ten specimens self-cured and ten specimens heat-cured) of Versacrylic** soft lining material. The other fourty block specimens for shear test (46 mm X 13 mm X 3 mm) were prepared twenty specimens where joined to anther twenty specimens by 3 mm thickness of(ten specimens self-cured and ten specimens heat-cured) of Versacrylic soft lining material. The prepared cylindrical and block specimens, were subdivided into two groups. Each group sub divided also into two sub groups as follow Group (I): consists of twenty testing specimens to evaluate the bond strength of self-cure Versacryl soft lining materials, then they we are divided into two equal sub-groups as follows: Sub-group (A): Ten testing specimens were prepared for shear bond strength test. Sub-group (B): Another ten testing specimens were prepared for tensile bond strength test. Group (II): consist of twenty testing specimens to evaluate the bond strength of heat-cure Versacryl soft lining material, then they were subdivided into two equal sub-groups as follows, Sub-Group (A): Ten testing specimens were prepared for shear bond strength test. Sub-group (B): Another ten testing specimens were prepared for tensile bond strength test. Pearson correlation test was used to determine the correlation between shear and bond strength for each group. The data was analyzed using SPSS (statistical package for social science). P value is significant if it was less than .05.
-Results: The highest mean Tensile bond strength value was obtained for Versacryl soft lining material heat-cure(3.85±0.66 MPa) self-cure (2.29±0.523 MPa. ) Shear bond strength value was obtained for Versacryl soft lining material) heat-cure(1.22±0.45) self-cure(1.167±.399Tensile bond strength (MPa) was significant higher than shear bond strength (MPa) in both groups, There was no significant difference in shear bond strength (MPa) between both group There was no significant correlation between tensile bond strength (MPa) and shear bond strength (MPa) for each group. Conclusion: The use versacrylic resin material to reline the acrylic resin denture base, appear in this study to be satisfactory. As the bond strength of this material (shear and tensile) was suitable to be used clinically.
Recommendation :
With the limitation of this study this type of resin meets established success of its bond strength to acrylic resin. Despite this finding it is important to mention that further long term evaluation of the bond strength is needed.