Abstract
Purpose: Resin composites are commonly used in pediatric dentistry, but there is limited evidence on adhesion to primary teeth, especially primary enamel. In this study, three bonding strategies were assessed - one-step self-etch (1-SE), two-step self-etch (2-SE), and three-step etch-and-rinse (3-ER) - by measuring the immediate and aged micro-shear bond strength (µSBS) to sound primary enamel.
Materials and Methods: 120 extracted human primary molars with sound buccal surfaces were used for µSBS testing. Six adhesive protocols (two per bonding strategy) were selected and µSBS was measured either after 24 hours or 10,000 thermal cycles (n=10).
Confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM) were used to determine failure modes. Furthermore, 18 primary molars were etched using the different adhesive protocols (n=3) for the measurement of surface roughness (Sa) using CLSM and morphological analysis using SEM.
Results: After 24 hours, there was no significant difference in µSBS between 1-SE and 2-SE strategies (p=0.96), but the 2-SE strategy yielded significantly higher µSBS after thermocycling (p0.95). Conclusion: The 3-ER strategy is optimal for bonding to primary enamel.
The etching effect of SE strategies is weaker, resulting in lower µSBS. Thermocycling revealed that the bonding durability of the 1-SE strategy is inferior compared to multi-step strategies.