| 摘要: | Numerous antimicrobial compounds have been evaluated for its local use in treatments of periodontitis, however, adverse effects such as bacterial resistance to such antimicrobial agents have been reported. Dentin hypersensitivity is the most common problem in periodontal patients after periodontal treatment. Occlusion of open dentinal tubules decreases the fluid movement in the dentinal tubules, thus, provides relief in hypersensitivity symptoms. Currently available desensitizing agents only provide dentin tubule occluding effects. Therefore, in this study, calcium phosphate precipitation (CPP) method combined with polylysine was employed to induce antibacterial effects and dentin tubule occlusion.
CPP solutions were prepared from from dicalcium phosphate dihydrate (DCPD), monocalcium phosphate monohydrate (MCPM) and tetracalcium phosphate (TTCP). Four concentrations of polylysine solutions (0.125%, 0.25%, 0.5%, 1%) were prepared. Porphyromonas gingivalis (ATCC 33277) was cultured on brain heart infusion (BHI) agar supplemented with 5% defibrinated sheep blood, 0.1g/ml Vitamin K, 0.5mg/ml hemin, 0.4g/ml L-cysteine in anaerobic jars at 37°C for 3 days. Antibacterial effect of polylysine was evaluated against P.gingivalis by broth dilution assay. Dentin discs were prepared from recently extracted human third molars. Dentin discs were incubated with P.gingivalis bacterial suspension (ca. 105 bacteria) containing BHI media supplemented with 0.1g/ml Vitamin K, 0.5mg/ml hemin, 0.4g/ml L-cysteine in anaerobic jars (37°C) for 7 days to allow for biofilm formation. P.gingivalis-infected and non-infected dentin specimens were randomly divided into five groups in each CPP solutions: DCPD, MCPM and TTCP solutions each paired with four concentrations of polylysine (0.125%, 0.25%, 0.5%, 1%) respectively and a negative control (untreated 7 days P.gingivalis-infected dentin). On each infected and non-infected dentin specimen, CPP solution was applied followed by polylysine solution with microbrush. The infected dentin specimens were proceeded for scanning electron microscope analysis after the treatment. The non-infected dentin specimens were immersed in artificial saliva and incubated at 37°C for 72 hours. The dentin discs were then proceeded for scanning electron microscope analysis for post-treatment surface evaluation. For dentin tubule longitudinal analysis, treated infected-dentin specimens were immersed in artificial saliva for 72 hours before fracturing and proceeding to SEM analysis. The mixture of different CPP and polylysine solutions were analyzed by X-ray diffractometer (XRD). The antibacterial and dentin tubule occluding effects of treatment groups have been evaluated on the dentin surface SEM images. The dentin tubule occlusion was evaluated by the change in the diameter of the tubule before and after the treatment.
Four concentrations of polylysine showed 4 to 6 log reduction in P.gingivalis growth after 24 hours of incubation. DCPD + 0.5% polylysine showed bacterial inhibition and 90.9% to 98% reduction in dentin tubule diameter in non-infected and infected dentin models, respectively. DCPD and TTCP solutions followed by 0.125%, 0.25% and 0.5% polylysine groups showed deeply penetrated hydroxyapatite-like crystal formations in dentinal tubules after 72 hours of incubation.
Calcium phosphate precipitation solutions combined with polylysine showed high antibacterial and dentin tubule occluding effects. CPP method followed by antibacterial polypeptide showed promising results for dentin hypersensitivity treatment in vitro. |
