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Endodontic treatment in dentistry is a delicate procedure and many treatment attempts fail. Despite constant development of new root canal filling techniques, the clinician is confronted with both a complex root canal system and the use of filling materials that are harmful for periapical tissues. This paper evaluates reported studies on biomaterials used in endodontics, including calcium hydroxide, mineral trioxide aggregate, calcium phosphate ceramics and calcium phosphate cements. Special emphasis is made on promising new biomaterials, such as injectable bone substitute and injectable calcium phosphate cements. These materials, which combine biocompatibility, bioactivity and rheological properties, could be good alternatives in endodontics as root canal fillers. They could also be used as drug-delivery vehicles (e.g., for antibiotics and growth factors) or as scaffolds in pulp tissue engineering.

An injectable bone substitute (IBS) made of a suspension of calcium phosphate ceramic was used to filled dental root canal after removing of canal pulp. Compared with current filling materials, which are toxic to periapical tissues, calcium phosphate materials, due to their biocompatibility and bioactive properties, may be viewed as possible alternatives. The aim of this study was first to determine if an injectable bone substitute could be used to obtain further healing of apical tissue by the neoformation of a mineralized barrier. In the next step, the paper will focus on rheological measurements as a tool for physical characterisation and on the improvement of the injection technique. Rheology concerns the flow and deformation of the suspension and, in particular, its behaviour in the transient area between solids and fluids. The results showed that injection is possible with a good level of BCP granules at the end of the root dental canal with extracted tooth. Other experiments with other animal models closer to a Human model have to be performed before human trials.

An injectable bone substitute (IBS) made of a suspension of Calcium phosphate ceramic was used to filled dental root canal after removing of canal pulp. The aim of this study was to verify the ability of calcium phosphate ceramic suspension to fill the apical zone of teeth ex vivo (n=40) and in vivo in a sheep model (n=8). The results showed that injection is possible with a good level of BCP granules at the end of the root dental canal with extracted tooth. In vivo, the presence of blood pressure due to the pulpectomy is a negative parameter to allow a good filling. The scanning electron microscopy revealed mineral formation at the apex level with mineral tissue conduction between the BCP granules but only one tooth showed a good apical filling with a good sealing. The sealing of the apex seems to depend of the amount of BCP granules. Other experiments with other animal models closer to a Human model have to be performed before human trials.

Although initial results were promising for an injectable bone substitute (IBS) associating a hydroxypropyl methylcellulose (HPMC) polymer vector (Benecel®, 2 w/w %) with biphasic calcium phosphate (BCP), a sensitization reaction occurred probably related to the degree of polymer purity. In this context, Benecel® and another HPMC, E4M® were investigated in the present study. The expected composition of the polymers was confirmed by gas–liquid chromatography. Studies in the guinea pig showed that Benecel® has strong sensitization capacity and E4M® none. Benecel® manifests impurities (30 times more than E4M®) in individual fibers or rounded clumps that are apparently responsible for extreme sensitization. Purification by ultracentrifugation associated with 0.2 μm filtration can decrease sensitization capacity considerably, though with a slight loss of polymer concentration. Fourier transform infrared (FTIR) analysis showed that the impurities were largely cellulose derivatives. However, extraction by organic solvent, followed by FTIR studies and micro-X analysis, detected an oily substance containing carbon and silicon associated with the cellulose derivatives. E4M®, a polymer with no sensitization capacity, could replace Benecel® and improve results with IBS.