## 4 Discussion  
Analyzing the findings from our in vivo study within the context of pediatric dentistry, we underscored the potential of 5-aminolevulinic acid (ALA)-based photodynamic therapy (PDT) as an innovative adjunctive approach for managing endodontic infections in primary teeth. Our results confirmed the tested hypothesis, reinforcing this therapy's effectiveness. While the literature has extensively explored PDT in permanent dentition--particularly its capacity to reduce _Enterococcus faecalis_ counts [35; 36]--our study provides novel insights into its application in primary teeth. Given its non-invasive nature and pediatric suitability, ALA-based PDT emerges as a promising tool for bacterial reduction and improved clinical outcomes in endodontics. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**15 Patients** & **T0-A** & **T1-A** & **T2-A** \\
**Sample** & **(pre-ALAD)** & **(45 min ALAD Gel)** & **(+7 min Red Light)** \\ \hline CFU/mL & 5.473 \(\times\) 10\({}^{6}\) * & 1.7411 \(\times\) 10\({}^{4}\) * & 78 * \\ \hline SD & 9.3322 \(\times\) 10\({}^{4}\) * & 2.02 \(\times\) 10\({}^{2}\) * & 8.6 * \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Total microbial count (colony-forming units/mL) for Group A (protocol performed in a single session). T0-A: pre-ALAD. T1-A: sample collection after 45 min of ALAD gel application. T2-A: sample collection after photoactivation using a red LED light with a dedicated optical fiber for 7 min. *\(p<0.05\). \begin{table}
\begin{tabular}{c c c c} \hline \hline
**15 Patients** & **T0-B** & **T1-B** & **T2-B** \\
**Sample** & **(pre-ALAD)** & **(1-Week ALAD Gel)** & **(+7 min Red Light)** \\ \hline CFU/mL & 4.65 \(\times\) 10\({}^{6}\) * & 1.2 \(\times\) 10\({}^{4}\) * & 3 * \\ \hline SD & 5.868 \(\times\) 10\({}^{4}\) * & 1.41 \(\times\) 10\({}^{2}\) * & 2.2 * \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Total microbial count (colony-forming units/mL) for Group B (protocol completed after one week). T0-B: sample collection after pulp chamber opening. T1-B: sample collection one week after ALAD gel application. T2-B: sample collection after photoactivation using a red LED light with a dedicated optical fiber for 7 min. *\(p<0.05\). [PERSON] et al. 2014 [37] showed that higher ALAD concentrations incubated for 1 h significantly reduced CFUs, even without LED irradiation, due to ALA's \"dark toxicity\". This effect, coupled with preservatives like potassium sorbate and sodium benzoate [38; 39], may enhance its bactericidal action. Meanwhile, in vivo studies by [PERSON] [32] and [PERSON] [40] demonstrated that 7 min LED exposure after ALA incubation (50% concentration) nearly eliminated E. faecalis. LED's sustained antimicrobial effect contrasts with chemical agents that pathogens may resist over time [32; 40]. Photosensitizing agents such as methylene blue [41], methylene blue with nanoparticles [42], toluidine blue [41], and 5-aminolevulinic acid (ALA) [33; 36]--each paired with various light sources have shown efficacy against _E. faecalis_. Some studies have compared their effects with sodium hypochlorite and conventional chemo-mechanical methods, with PDT showing comparable results [36; 43; 44]. In a clinical trial on primary teeth, standard treatment was compared to one combining PDT with 0.005% methylene blue, also showing similar efficacy [45]. Our findings support these results, reinforcing ALAD's antimicrobial potential when combined with light irradiation. The substantial reduction in bacterial load following ALA-based PDT highlights the potential of this treatment to eradicate pathogens within infected root canals [27]. ALA-based PDT uses light-activated photosensizers to deliver targeted antimicrobial action, reducing the likelihood of failure and contributing to positive clinical outcomes. A key advantage lies in its selective targeting of pathogenic bacteria, preserving healthy host tissue.