# Influence of different final irrigation protocols for removal of photosensitizer activated by ultrasonic device on the bond strength of gutta-percha/bioceramic sealer and fiberglass posts/self-adhesive cement

## TL;DR

This study found that using ultrasonic devices with EDTA or glycolic acid improves the bond strength of dental materials to root dentin after photodynamic therapy.

## Contribution

The study introduces a novel method combining ultrasonic activation with specific irrigants to enhance bond strength after photosensitizer removal.

## Key findings

- Groups using 17% EDTA + US and 17% GA + US showed significantly higher bond strength compared to other groups.
- Cohesive failure was the most common type of failure observed across all groups.
- The combination of ultrasonic activation with EDTA or GA improved the bond strength of both filling and restorative materials.

## Abstract

The aim of present study was to evaluate the influence of final irrigation protocols for removal of photosensitizer activated by ultrasonic device(US) on the bond strength(BS) of gutta-percha/bioceramic sealer and fiberglass posts/self-adhesive cement to root dentin. One hundred single-rooted teeth were used, being 50 roots used to assess the BS of filling material and 50 to assess the BS of restorative material. After sample preparation, photodynamic therapy with US was performed, using 0.01% methylene blue as photosensitizer and diode laser as light source. The 50 roots of each evaluation were randomly divided into five groups (n=10), according to irrigation protocol for photosensitizer removal: G1 – distilled water + US; G2 – 17% EDTA; G3–17% Glycolic acid(GA); G4 – 17% EDTA + US; G5 – 17% GA+US. Then, 50 roots were filled with gutta-percha/Bio-C bioceramic sealer and 50 roots were filled with fiber glass posts/Rely-X U200 self-adhesive cement. In both, the roots were sectioned to obtain 1 mm thick dentin/material discs, and the push-out test was performed. Failure patterns were observed under optical microscope. Specific statistical analysis was performed (α=5%). In both evaluations, BS was significantly higher in groups 4(17% EDTA + US) and 5(17% GA + US) when compared to all other groups(p < 0.05). Regarding the failure patterns, no statistically significant difference was found between groups (p > 0.05), with a predominance of cohesive failure in all groups. The association of US with EDTA and GA for photosensitizer removal improved the BS of filling/restorative material to root dentin.