A systematic review finds a possible reinforcing effect, but no clear winner among sealer categories
A common concern after root canal treatment is whether the tooth has become more vulnerable to fracture. The removal of dentin during access preparation and canal instrumentation can alter the mechanical behaviour of the tooth. This has led to growing interest in whether obturation materials can do more than seal the canal space—whether they can also help reinforce the remaining tooth structure.
Calcium silicate-based and bioceramic sealers are often discussed in this context because of their proposed bioactivity, dentinal interaction and ability to form mineral deposits at the sealer–dentin interface. But does the available evidence show that these materials strengthen endodontically treated teeth more effectively than conventional resin-based sealers?
A systematic review published in Frontiers in Dental Medicine evaluated this question by examining studies on the fracture resistance of endodontically treated teeth obturated with different root canal sealers and materials. The review included 24 studies in its qualitative synthesis. However, the evidence was predominantly laboratory-based: 22 studies were in vitro, one was an animal study and one was ex vivo.
What did the review find?
The review found that teeth obturated with root canal sealers generally showed greater fracture resistance than instrumented but unobturated teeth. This suggests that filling the prepared canal space may provide a degree of mechanical support.
However, the authors did not identify a specific sealer that could be considered clearly superior. Epoxy resin-based and calcium silicate-based sealers demonstrated broadly comparable performance overall. Zinc oxide eugenol-based sealers generally showed less reinforcing ability in the included studies.
The findings should not be interpreted as proof that obturation restores the original strength of a tooth. Endodontic treatment involves the removal of tooth structure, and the remaining dentin thickness, root morphology and extent of coronal destruction continue to influence fracture resistance.
The review also noted that the reported results varied considerably between studies. Some investigations found higher fracture resistance with calcium silicate-based or bioceramic sealers, while others reported comparable results between calcium silicate-based and epoxy resin-based materials.
Why are bioceramic sealers attracting attention?
Calcium silicate-based sealers have been proposed to reinforce dentin through several mechanisms. Their calcium ion release and potential to form hydroxyapatite-like deposits may improve the interaction between the sealer and the canal wall. These materials have also been investigated for their sealing ability and possible contribution to intratubular mineralisation.
Several studies included in the review reported higher fracture resistance values with bioceramic sealers compared with resin-based materials. In some comparisons, materials such as BioRoot RCS and other calcium silicate-based sealers performed better than epoxy resin-based sealers.
Nevertheless, the findings were not consistent across the entire evidence base. The review’s overall conclusion was that calcium silicate-based and resin-based sealers demonstrated generally comparable performance, and that the available evidence did not establish clear clinical superiority for any particular sealer category.
The review also observed that zinc oxide eugenol-based sealers generally showed limited reinforcement. The authors suggested that this may be related to their relatively higher solubility and limited adhesive interaction with dentin.
The sealer may not be the only important variable
One of the most important findings of the review was the considerable variation in the methods used by the included studies.
The investigations differed in:
Tooth type and root anatomy Canal preparation size Irrigation protocols Obturation technique Sealer thickness Loading direction Crosshead speed Periodontal ligament simulation Method of embedding the specimens
The studies used cold lateral compaction, single-cone obturation and warm vertical compaction. These techniques may influence the stresses placed on the root and the extent to which the sealer contributes to the final obturation mass.
For example, single-cone obturation relies more heavily on the sealer to occupy the space between the gutta-percha cone and the canal wall. In contrast, cold lateral compaction introduces condensation forces, while warm vertical compaction involves heat and compaction-related variables.
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