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

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 endodontics. The aim of this study was to establish whether or not root-end filled teeth allow leakage of lipopolysaccharide (LPS) from a known oral pathogen in vitro.

Lipopolysaccharide (LPS) from a virulent strain of Prophyromonas gingivalis (P. gingivalis) (A7436 from patient with refractory periodontitis), was isolated by the Westphall and Jann technique, dialysed extensively, lyophilyzed, resuspended in distilled water and analysed by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). Root canals from 10 teeth were instrumented endodontically and the apical 3 mm of resected roots were filled with gutta-percha. The teeth were mounted in 12 mL polypropylene vials by using sticky wax and root surfaces were covered with two layers of nail varnish. Teeth were filled with 3.3 mg mL-1 LPS and the vials filled with 11 mL of Tris Buffered Saline (TBS) containing 0.05% sodium azide. Both positive and negative controls were run in parallel with the experimental specimens. Aliquots were removed each day and subjected to slot blot analysis to quantitate the amount of LPS that had leaked into the bottom of the vials. The density of slots was analyzed using a laser densitometer and regression analysis was used to generate a standard curve, confidence intervals and experimental values.

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).

In vitro teeth with gutta-percha root-end fills can permit leakage of LPS from an identified oral pathogen.