Evaluation of bond strength to root canal dentin after using different intracanal medicaments and their removal by different techniques : An in-vitro study /

Abstract

Intracanal medicament (ICM) is a crucial treatment for infected root canals. Calcium hydroxide is the most commonly used intracanal medicament and considered a gold standard in endodontics. However, several studies reported that some endodontic pathogens can resist the alkaline PH of calcium hydroxide. With the demand for new antimicrobial agents, Lately, nanotechnology in dentistry has promoted the development of excellent biomaterials with unique physical, chemical, and biological properties. The nanoparticles (NPs) have superior antibacterial effects due to their higher volume-to-surface area ratio and lesser particle dimension which results in higher effective contact and larger reaction surface. Subsequently, they penetrate the dentinal tubules and produce a prolonged antibacterial impact at the infection site at reduced doses. Nano-calcium hydroxide (NCH) has been recently introduced in the field of endodontics and gaining popularity in dentistry and medicine as antibacterial agents. Nano calcium hydroxide (NCH) exhibits a higher antibacterial efficacy, superior penetration depth into the dentinal tubules and higher alkalization capacity in a shorter time compared to the conventional calcium hydroxide. Nano Silver nanoparticles (AgNPs) over the last few years have gained immense reputation as the next-generation antibiotics owing to their broad-spectrum activity against the disease-causing microbe. AgNPs release Ag ions, producing robust bactericidal effects against Gram positive, Gram negative, and multidrug-resistant bacteria. A total of one hundred and twenty single rooted teeth with mature apices were decoronated and instrumented to size F4 master apical file. Teeth samples were divided into three main groups according to the intracanal medicament used (n=40). Group I (calcium hydroxide), group II ( Nano calcium Hydroxide), group III ( nano silver). Each group was subdivided into two subgroups according to the technique used for removal of medicaments. Subgroup A: Conventional syringe irrigation was used for removal of medicaments, while subgroup B: passive ultrasonic irrigation technique was used for removal of medicaments. Then, ten samples from each subgroup were obturated with gutta percha and Ah plus sealer and prepared for the push out test to measure the bond strength between the sealer and root canal dentin. The other ten samples of the subgroup were prepared for the scanning electron microscope to evaluate the root canal cleanliness and evaluate the amount of medicament remnants on root canal wall after each method of removal. Results showed that Nano calcium hydroxide had better bond strength than nano silver but no significant difference was found between the nano calcium hydroxide and the conventional calcium hydroxide. Also, passive ultrasonic irrigation for removal of intracanal medicaments showed better bond strength than removal using conventional syringe irrigation. There was a tendency for the medicament residues to be located in the apical third for all groups .Passive ultrasonic irrigation was more efficient in removal of intracanal medicaments residues in all root canal thirds than conventional syringe irrigation technique.