Biofilm development of Porphyromonas gingivalis on titanium surfaces in response to 1, 4-dihydroxy-2-naphthoic acid - a hybrid in vitro – in silico approach

Colonization of titanium dental implants by the oral pathogenPorphyromonas gingivaliscan lead to peri-implant diseases and, ultimately, implant failure.P. gingivalisgrowth can be stimulated by 1,4-dihydroxy-2-naphthoic acid (DHNA), a menaquinone precursor from various oral bacteria, yet its impact on biofilm formation remains unclear. The aim of the study was to evaluateP. gingivalisgrowth and metabolic activity over six days in response to DHNA on two titanium grade IV surfaces with different roughness using a hybridin vitro–in silicoapproach.P. gingivalisgrowth was modestly stimulated by DHNA and exhibited an inverse correlation with ammonia concentration in culture medium. Notably, this growth pattern transitioned from an initial linear phase to a later exponential phase, with DHNA-treated biofilms reaching this exponential shift at an earlier stage than untreated controls. Confocal microscopy revealed that DHNA-treated biofilms exhibited surface-dependent growth patterns, with larger biofilm volumes observed on rougher surfaces in later biofilm stages, compared to smoother surfaces. Regardless of surface characteristics, the area occupied by biofilms and the size of the aggregates exhibited a consistent and progressive increase over time and was larger in late DHNA-treated biofilms. The experimental data were used to calibrate a coupled finite element method (FEM)-based model that simulatedP. gingivalisbiofilm dynamics and nutrient utilization. Summarizing, DHNA moderately stimulatedP. gingivalisgrowth, accelerated its transition to ammonia-independent growth, and promoted an increase in biofilm area and aggregate size. Our coupled approach offers significant potential for advancingin vitrobiofilm research.