Aims: This study evaluates the comparative effectiveness of antimicrobial 
photodynamic therapy (aPDT) versus traditional antibiotic therapy when used in 
conjunction with SRP in the treatment of Periodontitis Grade B, Stage II.. Subjects 
and Methods: Sixty participants with Stage II, Grade B periodontitis were recruited 
from Zagazig University's Faculty of Dentistry. Patients aged 20-40 received either 
antimicrobial photodynamic therapy (aPDT) or antibiotics alongside scaling and 
root planing (SRP). Clinical parameters including probing depth, clinical attachment 
level, and bleeding on probing were documented at baseline, 3 months, and 6 months 
post-intervention. Microbial analysis determined periodontopathogenic bacteria 
levels pre- and post-treatment. Treatment outcomes were analyzed using appropriate 
statistical methods. Results: Both therapies showed significant improvements in PD, 
CAL, and BOP from baseline to the 6-month follow-up. However, the aPDT group 
demonstrated statistically significant better outcomes in PD reduction and CAL gain 
at 3 and 6 months compared to the antibiotic group. Conclusion: The findings suggest 
that aPDT may be a more effective adjunct to SRP than antibiotics for the management 
of periodontitis (Stage II, Grade B). aPDT showed superior clinical and microbiological 
outcomes, indicating its potential as a non-antibiotic alternative in periodontal therapy. 
Further long-term studies are warranted to confirm these findings and to evaluate the 
sustainability of aPDT benefits