Quantitative real-time PCR detection of Porphyromonas gingivalis and Filifactor alocis in peri-implantitis

<b>Introduction.</b> Peri-implantitis is a prevalent and challenging complication in implant dentistry, primarily induced by biofilm-associated pathogens. Among these, <i>Porphyromonas gingivalis</i> and <i>Filifactor alocis</i> have emerged as key contributors, with evidence suggesting their potential synergistic role in exacerbating peri-implant inflammation and tissue destruction.<b>Hypothesis/Gap Statement.</b> While <i>P. gingivalis</i> is a well-characterized periopathogen, the specific role of <i>F. alocis</i>, alone or in combination with <i>P. gingivalis</i>, in peri-implantitis remains underexplored. This study addresses the gap in quantifying their presence in diseased versus healthy peri-implant sites.<b>Aim.</b> To assess the prevalence and microbial load of <i>P. gingivalis</i> and <i>F. alocis</i> in peri-implantitis and healthy peri-implant sites using quantitative real-time PCR (qPCR) and to investigate their correlation with clinical parameters.<b>Methodology.</b> This cross-sectional study included 110 participants: 52 diagnosed with peri-implantitis and 58 with healthy peri-implant tissues. Clinical examination recorded probing depth (PD), clinical attachment level (CAL) and bleeding on probing (BOP). Submucosal biofilm samples were collected and analysed using species-specific qPCR. Statistical analysis employed the Mann-Whitney <i>U</i> test for intergroup comparisons and Spearman's rank correlation for associations between microbial levels and clinical indices.<b>Results.</b> Both <i>P. gingivalis</i> and <i>F. alocis</i> were significantly elevated in peri-implantitis sites compared to healthy controls. Mean <i>P. gingivalis</i> levels were 4.80×10⁶ ± 4.78×10⁶ copies µl^-1 in peri-implantitis and 2.09×10³ ± 1.26×10³ copies µl^-1 in healthy sites (<i>P</i><0.001). <i>F. alocis</i> levels averaged 4.58×10⁵ ± 3.40×10⁵ copies µl^-1 in peri-implantitis and 2.45×10³ ± 1.64×10³ copies µl^-1 in healthy sites (<i>P</i><0.001). <i>P. gingivalis</i> showed strong positive correlations with PD, CAL and BOP, while <i>F. alocis</i> correlated moderately with PD and CAL but not significantly with BOP.<b>Conclusion.</b> The significant elevation of <i>P. gingivalis</i> and <i>F. alocis</i> in peri-implantitis supports their potential synergistic involvement in disease pathogenesis. These findings underscore the need for antimicrobial strategies that target both organisms and disrupt their cooperative biofilm behaviour. Further research should clarify their pathogenic interplay and inform the development of precise therapeutic interventions.