Effectiveness of Methylene Blue Photosensitizer-Loaded Chitosan and Sepiolite Nanoparticles and Er,Cr: YSGG Laser on the Smear Layer and Push-out Bond Strength of Glass Fiber Post to Canal Dentin: An In Vitro SEM Evaluation

Abstract

Aim:

To investigate the impact of different post space sterilants, namely methylene blue (MB) photosensitizer (PS)-loaded chitosan nanoparticles (CHNPs), sepiolite nanoparticles (SepNPs), and Er, Cr: YSGG laser (ECL), on the smear layer (SL) removal and push-out bond strength (PBS) of glass fiber posts (GFPs) to canal dentin.

Methods:

A total of 52 single-rooted premolars were carefully selected, crowns were decoronated, and endodontic therapy was performed; subsequently, the samples were prepared for post space utilizing Gates-Glidden instruments. The specimens were categorized into four cohorts based on the disinfection regime (n = 13): Group 1: 2.5% NaOCl + ethylenediamine tetraacetic acid (EDTA), Group 2: MB-CHNPs-PDT + EDTA, Group 3: MB-SepNPs-PDT + EDTA, and Group 4: ECL + EDTA. SL removal analysis and PS-loaded nanoparticle characterization were executed using scanning electron microscopy. Self-cure resin cement was used for bonding GFP, followed by thermocycling. The evaluation of bond strength and the analysis of the fracture mode were conducted utilizing a universal testing machine and stereomicroscope, respectively. Data analysis was conducted using Analysis of Variance (ANOVA) and a post hoc test (p < 0.05).

Result:

The cervical section of Group 2 (MB-CHNPs-PDT + EDTA) test specimens displayed the maximum cleaning of SL (1.22 ± 0.23) and the highest PBS (11.23 ± 0.12 MPa). However, the apical third of Group 1 (MB-SepNPs-PDT + EDTA) reported minimum SL removal (4.53 ± 0.17) and the lowest bond strength (6.65 ± 0.13 MP). Group 1 (2.5% NaOCl + EDTA) and Group 4 (ECL + EDTA) presented no significant variation in SL elimination and PBS of GFP.

Conclusion:

Using EDTA co-application, the MB-loaded CHNP protocol was associated with lower smear layer scores and higher PBS compared with the other tested groups.