In vitro evidence that lipopolysaccharide of an oral pathogen leaks from root-end filled teeth

Aim The ability to achieve a complete apical seal of the root canal system is thought to be important in the success of non-surgical and surgical endo dontics. The aim of this study was to establish whether or not root-end fil led teeth allow leakage of lipopolysaccharide (LPS) from a known oral patho gen in vitro. Methodology Lipopolysaccharide (LPS) from a virulent strain of Porphyromona s gingivalis (P. gingivalis) (A7436 from patient with refractory periodonti tis), was isolated by the Westphall and Jann technique, dialysed extensivel y, lyophilyzed, resuspended in distilled water and analysed by sodium dodec yl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). Root canals from 10 teeth were instrumented endodontically and the apical 3 mm of resected r oots were filled with gutta-percha. The teeth were mounted in 12 mL polypro pylene vials by using sticky wax and root surfaces were covered with two la yers of nail varnish. Teeth were filled with 3.3 mg mL(-1) LPS and the vial s filled with 11 mL of Tris Buffered Saline (TBS) containing 0.05% sodium a zide. Both positive and negative controls were run in parallel with the exp erimental specimens. Aliquots were removed each day and subjected to slot b lot analysis to quantitate the amount of LPS that had leaked into the botto m of the vials. The density of slots was analyzed using a laser densitomete r and regression analysis was used to generate a standard curve, confidence intervals and experimental values. Results The data indicated that teeth obturated apically with gutta-percha leaked, whilst no LPS leakage was detected in teeth covered completely with nail varnish (P < 0.05). Conclusions In vitro teeth with gutta-percha root-end fills can permit leak age of LPS from an identified oral pathogen.