The effect of photodynamic therapy on pathogenic bacteria around peri‐implant sulcus and in the cavity between abutment and implant after healing phase: A prospective clinical study

OBJECTIVES: To compare levels of pathogens from peri-implant sulcus versus abutment screw cavities after photodynamic therapy. MATERIAL AND METHODS: Twenty patients were included. Photodynamic therapy (PDT) was applied both in sulcus and cavities after sampling following suprastructures loading, and repeated after 2 weeks. Two samples each containing four paper points were collected for each implant at baseline, 2 weeks, 3 months: (i) peri-implant sulcus and (ii) abutment screw cavities. Seventy-five percent ethanol was applied in another 20 patients as the control group in the same way. qPCR was used to quantify periodontal pathogens: Porphyromonas gingivalis, Fusobacterium nucleatum, Streptococcus mutans. RESULTS: PDT showed a better bacterial reduction than ethanol. P. g. and F. n. were most frequently detected, while less for S. m. P. gingivalis' proportion from both sites was significantly higher than the other two bacteria (P < 0.05), except for 2 weeks' peri-implant sulcus sample. Bacteria counts from abutment screw cavities were always less than those from peri-implant sulcus and was significantly lower for total bacteria at 3 months (P < 0.05). Total bacterial from abutment screw cavities significantly reduced at 3 months compared to baseline (P < 0.05). CONCLUSIONS: PDT appears to be effective in bacterial reduction compared to ethanol and can reduce P. gingivalis with short time intervals, as well as decreasing total bacteria counts within abutment screw cavities in the long run, suggesting PDT an effective way sterilizing inner surface of oral implant suprastrutures. Lasers Surg. Med. 50:433-439, 2018. © 2018 Wiley Periodicals, Inc.