Effect of Incorporation of Bioactive Hydroxyapatite Nano-rods in Self-Etch Adhesive on Microleakage, Nanoleakage Pattern and Elemental analysis of Resin/Dentin Interface

Objective: To compare the effect of four types of adhesives immediately and after 6 months storage in artificial saliva followed by thermocycling (2000 cycle) on microleakage patterns, the nanoleakage pattern, and elemental analysis of adhesive interface. Materials and Methods:  A total of 120 extracted sound human permanent molars were selected. And assigned into 4 groups according to adhesive types (one step-self-etch (1S-SE) adhesive, modified self-etch adhesive with hydroxyapatite nanorods (HA-NR), universal adhesive, resin-modified glass ionomer-based adhesive). Each group was further subdivided into two subgroups according to time of testing, (a) immediately evaluated, (b) was subjected to the 6 months storage in artificial saliva followed by thermocycling. For each adhesive group, teeth divided into three groups according to test types: (I) for microleakage (ML) test (n =80), (II) for nanoleakage (NL) test (n =24), and (III) for elemental analysis test (n = 16). For the (ML) test, all collected data were tabulated and statistically analyzed using a statistical package with IBM SPSS. A Chi-squared test was used to compare microleakage scores among different adhesive groups. Results: The microleakage was significantly affected by the “type of adhesive material” (P ≤ 0.05) and the “time”. Another Chi-squared test showed that there was no significant difference in microleakage between occlusal and gingival margins among tested groups. Calcium and phosphate levels increased in, the modified self-etch adhesive group. Conclusion: Incorporation of bioactive hydroxyapatite nano-rods (HA-NR) into self-etch adhesives decreases microleakage and nanoleakage pattern of resin/dentin interface.  It improves Calcium and Phosphate levels at the resin- dentin interface.