# Enhanced Efficacy of Laser‐Activated Irrigation (Er,Cr:YSGG) in Eradicating Enterococcus faecalis Biofilm in 3D‐Printed Molar Replicas: A Pilot Study

## TL;DR

This study shows that laser-activated irrigation is more effective than sonic activation in killing a stubborn bacterial biofilm in 3D-printed molar replicas.

## Contribution

The study introduces Er,Cr:YSGG laser activation as a promising method for disinfecting complex root canal structures.

## Key findings

- Laser activation significantly reduced bacterial load compared to the control group.
- Both sonic and laser activation reduced bacteria to near-undetectable levels.
- Laser activation showed superior performance in the challenging apical isthmus region.

## Abstract

This study compared the efficacy of Sonic (EDDY) and Er,Cr:YSGG (2780 nm) laser activation in eradicating Enterococcus faecalis biofilm formed in 3D‐printed molar replicas with two mesial canals and one distal canal.

An in vitro design was implemented using 20 3D‐printed mandibular molar replicas mimicking the natural canal morphology. Root canals were inoculated with E. faecalis and incubated for 21 days to allow the development of a mature biofilm. Three irrigation protocols were tested: Conventional needle irrigation (CNI), EDDY sonic activation (SA), and Er,Cr:YSGG (2780 nm) laser activation (LA). The control group was irrigated with phosphate‐buffered saline (PBS) without activation. Residual bacterial load was quantified through colony‐forming unit (CFU) counts and quantitative PCR (qPCR). Bacterial viability in the apical isthmus was assessed using fluorescence microscopy. A Student's t‐test was performed to identify significant differences between CFU/mL values in groups, with significance set at 5% (p < 0.05).

CFU counts of E. faecalis were significantly lower in the CNI, SA, and LA groups compared to the control (p < 0.05). In the SA and LA groups, bacterial counts were reduced to the lower detection limit (< log10 CFU/mL of 1.00), suggesting near‐total bacterial elimination. qPCR and fluorescence microscopy corroborated these results, providing greater differentiation between the outcomes of sonic and laser activations.

Er,Cr:YSGG (2780 nm) laser activation showed superior efficacy in endodontic disinfection by effectively eradicating E. faecalis biofilm, including in the challenging isthmus region, representing a promising method for complex root canal anatomies.