Polymer composites for restoration of endodontically treated teeth

Abstract

The failure of endodontically treated teeth (ETT) restored with adhesive post restorations is related to several factors but mainly associated with the mechanical and biological properties of the materials currently available to fabricate post-core systems. This study is based on developing new post materials, using a biomimetic concept to improve the survival rate of severely damaged ETT. Furthermore, the study was hypothesised that the inclusion of a polymerisable antibacterial monomer, eugenyl methacrylate (EgMA), within the resin composite core and adhesive materials would inhibit endodontic biofilm formation and lower the risk of reinfection and secondary caries.
Two experimental post materials were fabricated and optimised based on their physical and mechanical properties: (i) polyethylene-hydroxyapatite composite exhibited good aesthetics, limited water sorption and a melting temperature of 135-136 °C that would enable easy retrieval from the root canal in case of a retreatment, but their lower flexural modulus is expected to limit their use as an endodontic post and (ii) Kevlar fibre reinforced semi-IPN matrix composites showed favourable aesthetic, mechanical strength, fatigue resistance, radiopacity and cytocompatibility to function as new fibre reinforced composite post.
EgMA monomer was incorporated at 5 and 10 wt.% to formulate dual-cure composite core, and at 20 wt.% to modify two commercial dental adhesives. The antibacterial activity of these formulations was evaluated and the influence of this monomer on curing kinetics, physical and mechanical properties, wettability, bonding ability and cytotoxicity is reported. The monomer endowed the modified adhesives with obvious cavity disinfecting effects before curing and impart an effective bacteriostatic activity against oral bacteria (S. mutans, E. faecalis and P. acnes) commonly associated with endodontic and restorative failures after being cured, without influencing the degree of monomer conversion, bonding ability to root canal dentine and cytocompatibility.
The most suited materials developed in this study are feasible as post-core systems for effective treatment of ETT, and thus influence the practice of endodontics.

Date of Award	2017
Original language	English
Awarding Institution	King's College London
Supervisor	Sanjukta Deb (Supervisor) & Francesco Mannocci (Supervisor)