4.3.1. Photodynamic Therapy Group (PDT)

The contaminated PICN discs were sprayed with 150 µL of MB (Sigma Aldrich, St. Louis, MO, USA) and left undisturbed for 60 s. The discs were washed thoroughly with PBS solution and later irradiated with 630 ± 10 nm diode laser (FotoSan, CMS Dental APS, Copenhagen, Denmark) with power output 100 mW and density of 2000–4000 mW/cm<sup>2</sup> for 60 s. The power fluence was set at 90 J/cm<sup>2</sup> . The distance between the diode laser tip and the specimen was maintained at 1 mm and spot area of 0.502 cm<sup>2</sup> .

### 4.3.2. Diode Laser Group (DL)

In this group, the contaminated PICN were treated using an 808 nm diode laser (Lasercat 500, Medsolution, Radolfzell, Germany) in contact mode. The laser tip was positioned at 1 mm and sequentially, until the irradiation time reached 1 min per surface of the PICN section.

### 4.3.3. Methylene Blue Group (MB)

The PICN discs in this group were immersed in 3 mL of MB dye solution (Sigma Aldrich) of concentration 1 mg/mL for 60 s. Later on, the discs were taken out and rinsed thoroughly with PBS solution.
