Sequential Application of Calcium Phosphate and ε-Polylysine Show Antibacterial and Dentin Tubule Occluding Effects In Vitro

In this study, epsilon-polylysine and calcium phosphate precipitation (CPP) methods were employed to induce antibacterial effects and dentin tubule occlusion. Antibacterial effects of epsilon-polylysine were evaluated with broth dilution assay against P. gingivalis. CPP solution from MCPM, DCPD, and TTCP was prepared. Four concentrations of epsilon-polylysine(epsilon-PL) solutions (0.125%, 0.25%, 0.5%, 1%) were prepared. Dentin discs were prepared from recently extracted human third molars. Dentin discs were incubated with P. gingivalis (ATCC 33277) bacterial suspension (ca. 10(5) bacteria) containing Brain Heart Infusion medium supplemented with 0.1 g/mL Vitamin K, 0.5 mg/mL hemin, 0.4 g/mL L-cysteine in anaerobic jars (37 & DEG;C) for 7 days to allow for biofilm formation. P. g-infected dentin specimens were randomly divided into four groups: CPP + 0.125% epsilon-PL, CPP + 0.25% epsilon-PL, CPP + 0.5% epsilon-PL, CPP + 1% epsilon-PL. On each dentin specimen, CPP solution was applied followed by polylysine solution with microbrush and immersed in artificial saliva. Precipitate formation, antibacterial effects, and occlusion of dentinal tubules were characterized in vitro over up to 72 h using scanning electron microscopy. epsilon-PL showed 34.97% to 61.19% growth inhibition levels against P. gingivalis (P. g) after 24 h of incubation. On P. g-infected dentin specimens, DCPD + 0.25% epsilon-PL, and DCPD + 0.5% epsilon-PL groups showed complete bacterial inhibition and 78.6% and 98.1% dentin tubule occlusion, respectively (p < 0.001). The longitudinal analysis on fractured dentin samples in DCPD and TTCP groups revealed deeply penetrated hydroxyapatite-like crystal formations in dentinal tubules after 72 h of incubation in artificial saliva.

Automated summary

The study utilized epsilon-polylysine and calcium phosphate precipitation methods to induce antibacterial effects and dentin tubule occlusion. Epsilon-polylysine demonstrated significant inhibition levels against P. gingivalis, with certain concentrations achieving complete bacterial inhibition and high dentin tubule occlusion. Longitudinal analysis revealed deep hydroxyapatite-like crystal formations in dentinal tubules after incubation in artificial saliva.