The Effect of Different Implant Surfaces and Photodynamic Therapy on Periodontopathic Bacteria Using TaqMan PCR Assay following Peri-Implantitis Treatment in Dog Model

INTRODUCTION: Peri-implantitis is one of the late complications that leads to implant failure and is associated with specific microorganisms identified as periodontopathic bacteria. The objective of this study was to evaluate the relationship between the different implant surfaces and number of Porphyromonas gingivalis, Tannerella forsythia, and Treponema denticola using TaqMan PCR assay after peri-implantitis treatment using photodynamic therapy. METHOD: Forty-eight dental implants with four different surface treatments (M: machined; SA: sandblasted acid-etched; S: 1 µm sputter HA-coated; and P: plasma spraying HA-coated) were inserted in six beagle dogs. After nine months of peri-implantitis induction, a split mouth design was used; on control side decontamination was performed using open flap mechanical debridement OFD with plastic curette, while photodynamic therapy PDT using diode laser (Ga Al As 830-nm) was used in the test side. For the following 2 weeks low-level laser therapy LLLT (10mW) was applied for the test side on alternative days for 6 sec on each implant side. Peri-implant microbial samples were collected using paper points and analyzed using TaqMan PCR before peri-implantitis treatment, immediately after treatment and 5 months posttreatment. RESULTS: Both treatment modalities showed significant decrease in all bacterial count from baseline to immediately after treatment (P< 0.0001). The count increased between immediately after treatment to 5 months after treatment (P< 0.0001); however, the count after 5 months was significantly lower than at baseline. PDT had a stronger effect on reducing P. gingivalis count than T. denticola and T. forsythia compared to OFD. For T. forsythia, implant surface treatment had the greatest effect which was also statistically significant (P= 0.02) with considerably lower effect of PDT or their interaction. CONCLUSION: The results suggest that PDT and OFD have significant benefits in peri-implantitis treatment by reducing bacterial count. The presence of bacterial complex with different response to therapeutic modality suggests the use of combined decontamination methods for peri-implantitis treatment.