Bioceramics: Promising New Frontier or Wild West?

Drs. Jianing (Jenny) He and Allen Ali Nasseh provide a look into their recent Endodontic Practice US webinar focused on bioactives and bioceramics

Learning Objectives

• Understand the properties of the “bioceramics” and “bioactives” used in endodontics.
• Understand the knowledge gaps regarding research and clinical outcomes for newer materials versus the established bioceramics on the market.

Dr. He: The terms bioceramics and bioactives are being used at an ever-increasing rate in endodontic circles. Let’s discuss these two terms as they relate to products used in endodontics.

Dr. Nasseh: Bioceramics are essentially any inorganic, ceramic material (refractory polycrystalline compounds) used in medicine and dentistry. There are various categories of bioceramics used for various applications. They are highly biocompatible materials that (by design or selection) should have similar physical characteristics to the tissue that they are replacing or repairing. They are chemically stable, non-corrosive, and are able to withstand interfacial interactions with surrounding organic tissue without triggering a significant immune response. In endodontics, we have a few different types of bioceramics that can be generally categorized by:

1. 1. Composition
      1. “Pure Bioceramics” contain only bioceramic components
      2. “Hybrid Bioceramics” contain bioceramics in addition to resins or metals

1. 2. Setting Mechanism
      1. Premixed hydrogels (no mixing required, set in the presence of moisture in dentin)
      2. Non-premixed powders and liquids (mixed or triturated to achieve set)

• 3. Absorbable or non-absorbable

Dr. He: There is certainly some overlap between materials that are considered “bio-ceramics” and those considered “bioactives.” While the term “bioceramics” describes the composition of the material, the term “bioactives” describes the properties of the material. If a material has the ability to release biologically active compounds and elicit a response from the tissue it is placed in, it is considered bioactive.

In the field of dentistry, this definition covers two main groups of materials. The first group includes fluoride-releasing materials such as glass ionomers and resin-modified glass ionomers. The fluoride released from these materials helps to maintain or remineralize dentin or enamel. EndoSequence^® BC Liner™ also belongs to this group of non-bioceramic bioactives. The other group of bioactive materials include those that can interact with the tissue they are placed in, mostly through the release of calcium and hydroxyl ions, such as the bioceramics used in endodontics. One good example of such materials is EndoSequence^® BC Sealer™. During the hydration process, the calcium silicates in the material interact with water in the environment to first form calcium hydroxide, which further interacts with the calcium and phosphate components in the tissue fluid to form hydroxyapatite-like precipitates on the material surface. Hydroxyapatite is highly biocompatible. As it forms at the material/pulp or material/periapical tissue interface, it helps to promote healing and induce new mineralized tissue formation. Hydroxyapatite can also form a chemical bond with dentin, which helps improve the sealing ability of the material. Therefore, there are many benefits in using a bioactive bioceramics for root filling and to induce tissue repair and regeneration.

Dr. Nasseh: Some examples of bio-ceramic materials include ProRoot MTA, Biodentine^®, EndoSequence BC Sealer, and BC RRM™ Paste and Putty. There are several new brands of MTA materials, which have recently been introduced. But the materials I mentioned first are the only ones that have been thoroughly tested and proven over time. The main difference between those three materials is that MTA and Biodentine require mixing or trituration, and MTA contains a bismuth oxide, which is staining to teeth. I personally prefer the premixed EndoSequence Bioceramics because of the extensive clinical track record coupled with their superior handling and the fact that we at Real World Endo helped develop simple clinical techniques for their surgical and non-surgical use.

Dr. He: I am very excited for the future of endodontics as it relates to the “premixed bioceramic materials,” but I am hesitant to generalize all of the various products as being more or less the same. Recently, during my lectures, I have been getting a lot of questions from students and clinicians about my opinion of one brand of premixed bioceramic sealer or root repair material versus another brand. Materials like MTA, Biodentine, BC Sealer, and RRM are considered “proven” materials because they have a long track record of clinical use and very well documented success. They have been thoroughly tested and researched. In contrast, many of the newer materials have very little independent research or data published in peer-reviewed journals to support their use. We can all think of a few examples where the latest and greatest endo sealer ended up failing after a few years. These types of unproven products can undermine the entire endo specialty, and so I tread lightly when selecting a material that will remain within the patient for possibly the rest of their life.

Dr. Nasseh: I have noticed that many of these new materials that are marketed as “bioceramics” include some components that I would not categorize as pure bioceramics. Many of these newer materials contain ingredients not found in Endo-Sequence BC sealer or RRM, such as resins, calcium aluminate, calcium sulfate, iron oxide, and even mineral oil. At this time, we don’t yet have any studies to show how these components might affect the properties of the materials. The presence of aluminum compounds has also raised some concern due to the possible association between aluminum exposure and certain neurological degenerative diseases. However, it needs to be recognized that there is no evidence that the aluminum content in these materials can leach out and cause any significant accumulation in other organs. Nevertheless, clinicians may want to be cautious while using aluminum-containing materials especially when aluminum-free alternatives are available.

I do think there is a place for hybrid bio-ceramics because pure bioceramics have the inherent drawbacks of not being light curable and not having enough strength and wear characteristics for certain applications. An example of a hybrid composition “bioactive” material that shows beneficial bioactive properties while interacting with pure bioceramics is EndoSequence BC Liner. I use this product as a liner, an orifice barrier over the furcation floor, as a long-term provisional during vital pulp therapy, and in cervical resorption and transgingival reparative defects. I would encourage the reader to watch the Endodontic Practice US Webinar under this same title, to learn more about the clinical applications of this product.

Dr. He: I would strongly recommend that clinicians review the SDS documents as well as the third-party research for any materials that they are considering to incorporate into their armamentarium. The guiding principles of evidence-based dentistry ask us to consider our professional judgment, clinical circumstance, scientific evidence, and patient preference when we make clinical decisions. I have been actively following research in the field of bioceramic materials and have participated in some studies as well. I would like to review some of what I consider the most relevant research that supports the efficacy of the EndoSequence Bioceramics, which are the materials that I use clinically and are most familiar with. There have been over 150 independent studies on EndoSequence Bioceramics since these materials came to the market over 14 years ago. Due to space limitations, I am only able to review a few of the most important studies. Therefore, I would encourage the reader to search PubMed for additional literature support.

In vitro studies (Figures 1-3)

For an endodontic material that is intended to be used for root canal obturation, tissue repair, and regeneration, the properties most relevant to their functions include biocompatibility, antibacterial properties, and sealing abilities. Regarding biocompatibility, although these materials may have some initial cytotoxicity due to their high pH, overall, they support and encourage cell attachment and growth (Chen, et al., 2016), and promote osteogenic and odontogenic differentiation (Zhang, et al., 2010; Rifaey, et al., 2016; Giocomino, et al., 2019).

The antibacterial properties of a root filling material are beneficial as they enable the material to inhibit the growth of any remaining bacteria that are present in the canal at the time of obturation. Studies have shown that both EndoSequence BC Sealer and BC RRM are effective against Enterococcus faecalis and Enterococcus faecalis biofilms (Lovato, et al., 2011; Wang, et al., 2014; Bukari, et al., 2019). MTA and EndoSequence BC RRM have also been shown to have antifungal properties (Alsalleeh, et al., 2014).

Results from in vitro studies on the sealing ability are less consistent, mainly due to the limitations of the in vitro models and the variations in methodology used in different studies. Many of these studies show the materials to have less leakage (Ballullaya, et al., 2017), higher bond strength (DeLong, et al., 2014) and better dentin tubule penetration (Wang, et al., 2018) compared to traditional materials like AH Plus^®. However, we do need to be aware of the limitations of the in vitro models and not to over-interpret the in vitro data.

Clinical studies on obturation (Figure 6)

Evidence from clinical studies is considered more important because it is more relevant to our clinical practice. However, clinical studies on obturation with a meaningful sample size are difficult to do. As a result, not many of them are available. We published the first outcome study on BC-based obturation technique in 2018 (Chybowski, et al., 2018). This study was a retrospective case series, which included over 300 cases treated in our private practice. Both initial treatment and retreatment cases were included. The majority of the cases were posterior teeth (92.2%); about half of the cases had pre-op periapical lesions, and the average follow-up time was around 30 months. All the included cases were treated in a single-visit and obturated with the hydraulic condensation technique using BC sealer. We found an overall success rate of close to 91%, which is well within the range of success rates reported in the literature. Dr. Nasseh also has some preliminary data on the cases treated at his office that shows a survival rate of greater than 97%.

Clinical studies on root-end surgery (Figure 7)

There have been at least five studies published in the past 6 years on the clinical success of EndoSequence BC RRM as a root-end filling material in endodontic microsurgery. The first of these studies reports a success rate of 92% in a series of more than 100 cases treated at our office with a minimum 1-year follow-up (Shinbori, et al., 2015). This data was later confirmed by another study that retrospectively compared the outcome between MTA and BC RRM used in surgery cases treated by our postgraduate endodontic residents (Chan, et al., 2020). No significant difference was found between the two materials (MTA-92.1%, BC RRM-92.4%). Two randomized controlled trials have been published that corroborate our findings and show no difference between MTA and BC RRM with both materials showing a success rate above 92% (Zhou, et al., 2017; Safi, et al., 2019). Dr. Thomas von Arx recently published another case series that reports an overall success rate of 94.1% at 1-year follow-up (von Arx, et al., 2020). Based on these studies, it appears EndoSequence BC RRM offers consistent, predictable success similar to that achieved with MTA, which has been considered the “gold standard” for apical surgery.

Dr. Nasseh and Dr. He: It is clear that bioceramics and bioactive materials have positively impacted clinical endodontics. While bioceramics have excellent clinical properties, clinicians must be diligent to research and select clinically proven materials, backed by research, to help improve the efficacy and safety of their care. We also want to encourage you to watch the Endodontic Practice US Webinar on this topic as it includes more clinically relevant information that was omitted in this article due to space limitations.