Cold atmospheric pressure plasma treatment to assist the restoration of the apical region of a root canal in endodontic procedures

Purpose In Endodontics, in order to complete a root canal treatment, the use of guttapercha to completely seal the root apex must be coupled with endodontic cements known as sealers to improve the adhesion with dentine, despite their cytotoxicity and solubility. The present study investigates the effect of enhancement of adhesion between these materials and Cold Atmospheric Plasma (CAP)-treated dentine of the apical region of ex-vivo teeth as a first step towards the reduction on the use of cytotoxic materials and the use of CAP in-vivo at a clinical stage. Methods A dielectric barrier discharge (DBD) helium plasma jet was used to treat for 180 sec the shaped root canal dentin. Pushout tests and confocal microscopy analysis have been performed to evaluate the effect of cold plasma treatment in terms of adhesion performances and interaction between filling materials and dentin respectively. Results The pushout test results highlight how a 180 seconds CAP treatment of dentin promotes an enhancement of bonding strength between filling materials and dentine in all investigated cases. In particular, when the dentine is CAP-treated in the apical region, the adhesion performances of guttapercha achieved a relevant increase (~ +200%), revealing how it was able to “self-bond” with the substrate with results comparable with the conventional procedure but without any sealer application, while the conventional (guttapercha+sealer) apical sealing procedure shows an improvement around +50%. Moreover, confocal images qualitatively confirmed the higher spreading and penetration of both guttapercha and sealer into dentinal tubules. The ergonomics of the prototype has been also improved to comply with the dimensions of devices commonly used in the dental field, with a plasma source diameter of 21.5 mm and with a choice of materials to minimise its weight. Conclusion CAP treatment of dentin increases the adhesion performances and paves the way for a sealer-free and safer procedure for apical restoration.