Injectable dental implants for controlled release of drugs

INTRODUCTION

Enterococcus faecalis is the most commonly recovered species from the root canals after failed root canal therapy. Ideally, an intracanal medicament should eliminate any remaining bacteria, reduce inflammation of periapical tissues, render canal contents inert and neutralize debris, act as a barrier against leakage from temporary filling and help to dry persistently wet canals. Good antibacterial effects of a drug alone however, are not sufficient when combating endodontic biofilms since its penetration into the deepest layers of the biofilm is limited by extracellular polysaccharides. A sustained release injectable implant containing cetylpyridinium chloride (SRII-CPC) was tested in this study. Our main goal was to analyze the antibacterial effects of SRII-CPC against E. faecalis biofilm.

METHODS

Eudragit®-based injectable implants were produced by dissolution in organic injectable solvents with CPC and additives. Handlable specimens were prepared by solidification of a measured amount of the solution in a plastic tube placed on an agar plate and applying access of PBS. Biofilm was grown in individual wells in the presence of either SRII-CPC or SRII-placebo. Each day during a 9-week test period, the supernatant-fluid was removed and replaced by fresh bacterial suspension for biofilm growth. Formula penetration into root canals and dentin adhesion were evaluated in transparent acrylic models, and by SEM on ex-vivo tissues.

RESULTS

SRII-CPC penetrated easily root canals and adhered well to dentin. Zones of inhibition around the SRII specimens were measured every 24 h for 9 days in agar test. The inhibitory effect of SRII-CPC against E. faecalis was highest after one day, with a significant reduction on the second day and a slow continuous decrease in activity during the following days. The SRII-Placebo sample didn’t exhibit any bacterial inhibition. SRII-CPC inhibited biofilm formation for 7 weeks and during following two weeks a significant reduction of biofilm activity was observed when compared to the placebo and control samples. E. faecalis biofilms grown for either 1, 3 or 7 days, exposed to the SRIIs for 24 hours, were destructed regardless of their maturity stage, whereas SRII-Placebo did not reduce biofilm viability.

CONTRIBUTION

BF&DK have equally contributed to this work.