Root canal therapy aims to clean the internal chamber of a tooth and then seal the space completely to prevent bacterial re-entry. The long-term success of this procedure depends heavily on the endodontic sealer, which fills any voids between the root canal wall and the core filling material. Dental materials science continually refines these sealers, moving toward materials with improved physical and biological interactions to enhance seal integrity and support natural healing.
Defining Modern Endodontic Sealers
Modern endodontic sealers are primarily categorized into resin-based materials and the newer calcium silicate-based formulations, which have fundamentally different chemical structures. AH Plus is the prime example of a paste-paste, epoxy-amine resin-based sealer, representing the long-standing standard in the field. This sealer achieves its solid state through a polymerization reaction between its epoxy resin and amine components. Its composition also includes fillers like zirconium oxide and calcium tungstate to ensure it is visible on X-rays.
In contrast, modern bioceramic sealers are based on calcium silicate compounds, such as tricalcium and dicalcium silicate, often combined with a radiopacifier like zirconium oxide. These materials are hydraulic, meaning they require the presence of water to initiate their setting process. Bioceramics represent a high-technology approach, moving away from inert materials toward compositions that actively interact with the surrounding biological environment. This fundamental difference in chemical composition dictates how each material behaves once placed inside the tooth.
Key Physical Performance Characteristics
The physical characteristics of an endodontic sealer determine its ability to establish a tight, durable seal within the complex network of the root canal system. Flow is a measure of how well the material can penetrate fine lateral canals and accessory anatomy. Both AH Plus and bioceramics typically meet or exceed standard requirements. AH Plus, for instance, exhibits excellent flow behavior and a minimal film thickness, ensuring it can spread thinly to fill microscopic irregularities.
A significant difference lies in dimensional stability, which describes the material’s volume change upon setting. The polymerization reaction of AH Plus results in a slight shrinkage. Bioceramic sealers, conversely, are designed to remain dimensionally stable and may even undergo a slight expansion upon hydration during the setting process. This expansion is advantageous because it counteracts the potential formation of microscopic gaps between the material and the dentin wall.
Solubility, or the material’s resistance to breaking down in tissue fluids, is another distinguishing factor. AH Plus is known for its very low solubility, which is desirable for maintaining a long-term seal. Bioceramic sealers tend to exhibit higher solubility compared to resin-based alternatives, though most modern formulations still meet international standards. This controlled, partial dissolution in bioceramics is intrinsically linked to their biological activity, facilitating the release of therapeutic ions.
Biocompatibility and Bioactive Capabilities
The material’s interaction with living tissue is the most significant difference between the two sealer types. Biocompatibility means the material does not provoke an inflammatory or toxic reaction in the surrounding periapical tissues. AH Plus is considered biologically inert once fully set, but some studies indicate it may exhibit temporary toxicity immediately after placement compared to bioceramics.
Bioceramic sealers are highly favored for their excellent biocompatibility and bioactive capabilities. The hydration reaction of calcium silicate releases calcium ions and hydroxyl ions, which drives the material’s bioactivity. The high concentration of hydroxyl ions creates a highly alkaline environment, with a pH often exceeding 11, which provides an intrinsic antimicrobial effect against residual bacteria.
This bioactivity is characterized by the material’s ability to promote biomineralization when in contact with tissue fluids. The released calcium and hydroxyl ions encourage the formation of a layer of hydroxyapatite, which is the natural mineral component of teeth and bone. This process allows the bioceramic sealer to form a chemical bond with the dentin, creating a continuous, gap-free interface that enhances the seal. This active tissue response is fundamentally different from the passive, physical seal achieved by the inert resin-based AH Plus.
Translating Properties into Patient Benefits
The superior properties of bioceramic sealers translate directly into tangible benefits for the patient undergoing root canal treatment. The combination of slight expansion upon setting and the chemical bond formation results in a seal that is highly resistant to bacterial leakage. Studies have shown that this enhanced seal integrity in bioceramics can significantly reduce microbial infiltration compared to resin-based sealers.
The bioactive nature of the calcium silicate materials actively supports the body’s natural recovery. By promoting hydroxyapatite formation, bioceramics encourage tissue healing and can facilitate the repair of bone and periodontal ligament tissues surrounding the root end. This biological integration is particularly beneficial when the sealer is inadvertently extruded slightly past the end of the root.
The high biocompatibility and alkaline nature of bioceramic sealers may also contribute to a reduction in post-treatment discomfort. Patients receiving bioceramic sealers have been reported to experience less postoperative pain compared to those treated with resin-based sealers. Furthermore, the hydrophilic nature of bioceramics and their use in simpler single-cone obturation techniques can lead to a less technique-sensitive procedure, which may contribute to more consistent clinical outcomes.