Ana Marques*1; Mariana da Cruz1; Neusa Silva1; Beatriz Ferreira1; Joana Marques1; Antonio Mata2,3

1Oral Biology and Biochemistry Research group - UICOB, Faculdade de Medicina Dentária da Universidade de Lisboa; 2CEMDBE - Cochrane Portugal, Faculdade de Medicina da Universidade de Lisboa; 3GIBBO -LIBPhys-FCT UID/FIS/04559/2013, Faculdade de Medicina Dentária da Universidade de Lisboa, Lisbon, Portugal

Background: Chitosan is a cationic polysaccharide that has shown effect on the bacterial membrane, has a good bioadhesion capacity and the ability to form a film. Based on these properties, this agent has been incorporated in post-surgery oral hygiene products (Bexident® Post). However, there are still few studies on the cellular effects of this product in comparison to chlorhexidine-containing gels, the reference anti-bacterial agent.

Aim/Hypothesis: To evaluate the cytotoxic effects on osteoblasts of chlorhexidine gels containing chitosan used in post-operative care.

Material and Methods: Human fetal osteoblasts (hFOB 1.19) were seeded in 48-well plates and grown for 24 hours according to previously described and tested procedures. A gel containing 0.2% Chlorhexidine alone (Bexident® Gums - BG) and a gel containing 0.2% Chlorhexidine and 0.1% Chitosan (Bexident® Post - BP), were tested. Eight different gel/culture medium concentrations of each gel were incubated with cells for 15 minutes or 4 hours (n = 8). Negative (medium) and positive (DMSO) controls were used. Cell viability was evaluated at 1 and 2 days after exposure, using a resazurin-based assay and results were converted to % of the negative control. Cell morphology was assessed through phase-contrast microscopy (PCM) and fluorescence microscopy (Propidium Iodide and Phalloidin); alterations were graded according to ISO10993-5:2009(E). Comparisons between groups were made through multiple T-tests, statistical significance was defined at P < 0.05.

Results: For 15-minutes exposure BP presented a slightly higher viability (approximately 10%) than BG (P < 0.05) with a reduced cytotoxic effect for the lowest gel concentrations evaluated (3.13%, 0.78% and 0.20%). At 2 days after exposure the 0.781% and 0.195% concentrations exposed to BP showed a higher recovery of viability relative to control.

When exposed for 4h, all gels were cytotoxic for all concentrations, with overall viability decreasing from 1 to 2 days of culture.

Fluorescence and PCM images confirmed the metabolic viability assay results, demonstrating cytotoxic effects on the highest concentrations for all times and lower cytotoxicity for lower concentrations, 15 minutes of exposure time and for samples exposed to BP instead of BG.

Conclusion and Clinical implications: Chlorhexidine gels present a considerable in vitro cell toxicity but, at low concentrations and low exposure time, the addition of Chitosan to Chlorhexidine (Bexident® Post) seems to slightly improve cell viability in vitro.

Disclosure of Interest: None Declared.

Keywords: biocompatibility, osteoblast