الفهرس 
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Abstract
The aim of the study was to evaluate the effect of final restoration delaying on shear bond strength (SBS) of universal adhesive applied using two different protocols to 38% silver diamine fluoride (SDF) pretreated primary dentin.
A total of sixty- six sound primary teeth extracted for orthodontic purposes were included in this study. Teeth were randomly assigned into three equal groups (n=22) according to existence or absence of 38% SDF pretreatment and time lapse between 38% SDF pretreatment and composite resin application; group I(test) dentin was pretreated with 38% SDF then final restoration was immediately applied .group II(test ) dentin was pretreated with 38% SDF then final restoration was applied one week after pretreatment. group III (control) final restoration was applied to dentin without any previous pretreatment .Each main group was subdivided into two subgroups according to the universal adhesive application technique used; Subgroup A: etch-and-rinse (ER) technique was used. Subgroup B: self-etch (SE) technique was used.
For shear bond strength test, all teeth were mounted in molds of self-cure acrylic resin with their buccal surfaces parallel to the long axis of the acrylic mold. The crowns buccal surfaces were gently mechanically ground to attain a flat dentinal surface .Dentin of teeth of the experimental groups was pretreated with 38% SDF. A standardized plastic mold was fixed on the flattened buccal surface of all teeth. group I received composite restoration directly after the 38% SDF pretreatment according to subgroup, group II teeth were kept in artificial saliva for 1 week after pretreatment then received the restoration according to the subgroup, while group III received the restoration directly on unpretreated dentin according to the subgroup. In etch-and-rinse subgroups. A 37% phosphoric acid etchant was used to etch dentin and was then rinsed, then universal bond was applied and cured. In self-etch subgroups, universal bond was rubbed directly on dentin without etching for 20 seconds, then light cured for 10 seconds.
Universal testing machine was used to asses SBS .Shear load was directed to the bonded interface with a sharp blade at a cross speed of 1 mm per minute till the restoration debonded,
Failure mode was examined after bond failure occurred using stereomicroscope ×20 magnification.
Comparison of shear bond strength (SBS) among the study groups was done using one-way ANOVA, followed by Bonferroni test. Comparisons between the sub-groups done using independent samples t-test. Comparisons of failure mode between the study groups/subgroups were done using Chi-squared test.
The results showed that there was a significant difference between mean SBS in group I (39.88 ± 27.35) and the control group (85.17 ± 40.43) P< 0.001, while there was no significant difference between group II (96.70 ± 30.28) and the control group (85.17 ± 40.43). Results also showed significance difference in mean SBS between ER and SE subgroups only when composite was applied immediately after pretreatment (78.90 ± 36.58) and (68.93 ±44.90) respectively .Regarding failure mode, no dominance of any type was found in any of the groups.
Based on the obtained results, it was concluded that SDF has a negative influence on shear bond strength of universal bond. However, this negative influence was overcame by delaying restoration bonding for one week .Using self-etch can be safely used when bonding is delayed without deterioration in bond strength.