Composite bond strength of one and two - step adhesive systems used for restorations on primary teeth using varying acid etch application times
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The objective of this study was to determine whether the composite bond strength acquired using a single step self-etching bonding system is as or more effective when compared to the two step etch-rinse-bond system at clinically relevant in-vitro standards. A total of 80 extracted human deciduous with at least one intact smooth surface were collected with parental consent. Collected teeth were randomly assigned to one of four treatment protocols (n=20): single step self-etch (Adper Prompt L-Pop, 3M ESPE), two step etch (15s)-rinse-bond (Optibond Solo Plus, Kerr), single step self etch (Adper L Pop, 3M ESPE) with 30s pre-etch, and two step etch (30s)-rinse-bond (Optibond Solo Plus, Kerr). A composite cylinder of uniform shape was bonded to each tooth using the designated adhesive system and specimens were tested with a universal testing machine. Descriptive statistics and statistical analysis was performed. Median shear bond strengths for all specimens, regardless of treatment group, ranged from 3.25 MPa to 43.13 MPa. These values are above suggested minimum clinical required values of 3MPa. A Kruskal-Wallis analysis between treatment groups found statistical significance (p<0.05) for shear bond strength between the groups and both one step system protocols, had higher mean and median shear bond strength values than the two step systems. An adhesive remnant index (ARI) was analyzed to confirm uniform adhesive fracture between all four treatment groups. Both a Fisher’s exact test, and a Hantel-Haenszel statistic found no significant difference (p<0.05) between the samples. Based on these findings we concluded that: 1. The ARI score for all treatment groups was not statistically significant, suggesting that the type of bond breakage was consistent regardless of adhesive system used. 2. Both Optibond Solo Plus and Adper Prompt L-Pop systems achieve adequate shear bond strengths as described by current literature. 3. The use of a one-step system to save chair time and aid in patient behavior management may be clinically useful.