From ancient artifacts to modern marvels - A historical journey of Bioceramics in Dentistry

INTRODUCTION

Bioceramics (BCs) are inorganic, non-metallic, biocompatible materials that are applied in direct contact with living tissues in the medical and dental fields.^[1] The introduction of BC materials meant a significant advancement for this new paradigm in dentistry due to their biocompatible nature, excellent physicochemical properties and broader area of clinical applications. BCs are developed and tailored based on specific clinical needs and applications, ensuring optimal performance in targeted medical and dental procedures.

The historical perspective of BCs is a fascinating journey that spans centuries and encompasses various civilizations and scientific advancements [Table 1]. Early medical books from the Greek, Egyptian, and Hindu civilizations document man’s endeavor to use implant materials to restore the human body itself. Until the end of the 19^th century, heterogeneous grafts were the main biomaterials utilized.^[2]

Archaeological findings suggest that ceramics were used for cranial surgery and dental prostheses as early as 700 BCE. In 1972, Amadeo Bobbio discovered Mayan skulls that were more than 4000 years old and had missing teeth restored with nacre substitutes.^[3] In 1824, Portland cement (PC), derived from limestone, was patented, leading to breakthroughs in ceramic materials. It was widely used in civil engineering and had properties such as antibacterial activity, biocompatibility, non-cytotoxicity, good sealability, and favorable physical characteristics, which made it suitable for dental applications involving tissue interaction.^[4] Then in 1892, Plaster of Paris, a resorbable ceramic, was described for filling bone cavities. This early use anticipated future applications in bone defect repair, showcasing the early recognition of the potential of ceramics in orthopedics.^[5] In the 1920s, calcium phosphates were first employed to stimulate osteogenesis.^[6] Ceramic hydroxyapatite (HA) granules were reported to be used for bone defect repair in the 1950s. Tricalcium phosphate (TCP), a biodegradable BC with the chemical formula, Ca₃(PO₄)₂ gets dissolved in physiological media and was used as a replacement for bone during implantation. Mixtures of HA and TCP, known as biphasic calcium phosphate, were also investigated as bone substitutes.^[7]

The development of Cerosium in 1963 marked a significant advancement in the field of bone repair and biomaterials. Cerosium, an epoxy resin-coated porous aluminate ceramic, expanded the range of materials available for bone repair, offering new possibilities for orthopedic surgeons and patients alike.^[8]

The discovery of Bioglass in 1969 by Hench and his team at the University of Florida revolutionized biomaterials and regenerative medicine. Bioglass forms a strong bond with bone tissue through a process called bioactive bonding. When Bioglass came in contact with bodily fluids, it triggered a series of reactions that resulted in the formation of a layer of hydroxycarbonate apatite on its surface. This layer replicated the mineral structure of bone, facilitating the direct integration of Bioglass with the surrounding bone tissue. The discovery of Bioglass laid the foundation for the development of a wide range of bioactive ceramics and glass-ceramic materials that have since been used in various medical applications, including bone grafts, dental implants, and tissue engineering scaffolds.^[9]

In the 1980s, HA-coated implants were introduced to improve their biocompatibility and osseointegration. Coating implants with HA helped to promote better integration with the surrounding bone tissue, leading to improved stability and long-term success rates of the implants. In 1982, the use of calcium phosphate in restorative dental cement led to the development of BCs in dentistry.^[10] One of the most widely used synthetic calcium phosphate ceramics in those days was HA, and this was due to its chemical similarities to the inorganic component of hard tissues. The development of BCs offered various materials that can better mimic the properties of natural dental tissues and promote improved clinical outcomes.

Then, in 1984, BCs were introduced as a root canal sealer in endodontic treatments.^[11] In 1986, self-hardening calcium phosphate cements (CPCs) were created, providing new possibilities for bone defect repair.

In 1993, another BC material named mineral trioxide aggregate (MTA) was developed by Loma Linda University in California for retrograde filling and endodontic perforation healing.^[12] MTA was acknowledged as a bioactive material known for its ability to conduct and induce hard tissue formation while being biocompatible. MTA was developed in two forms: Gray MTA (GMTA) and white MTA (WMTA). MTA and PC possess similarities in both physical and chemical properties. An evaluation of GMTA and WMTA dry powders, as well as ordinary and white PC, revealed identical primary elements. Tricalcium aluminate, tricalcium silicate, and tetracalcium aluminoferrite, and calcium silicate. The primary differences between both types of MTA and PC are a lack of potassium and the presence of bismuth oxide in the former.^[13] In 1997, researchers discovered low friction between zirconia and alumina, which led to advancement in dental implant material.^[14] The introduction of THZirconia implants in 1998 improved the biocompatibility and longevity of dental implants.

The first commercially available MTA that has revolutionized the endodontic treatments was the ProRoot MTA, which was launched in the United States in 1999. GMTA presented with the limitation of tooth discoloration, so WMTA, with lower quantities of iron, aluminum, and magnesium oxides, was introduced in 2002. MTA Angelus was introduced in 2001 and approved by the Food and Drug Administration in 2011. MTA Angelus offers a reduced setting time and enhanced ease of use, while still maintaining the excellent performance of traditional MTA.^[14]

Around the early 2000s, BC gutta-percha (GP) was introduced into endodontics as an alternative to traditional GP for root canal therapy. The EndoSequence BC GP points were impregnated and coated with BC nanoparticles. This formulation aimed to enhance the sealing ability and potentially provide bioactive properties that traditional GP lacks. EndoSequence BC GP points and BC Sealer represented a modern approach to root canal obturation, leveraging BC technology for potentially enhanced sealing and biocompatibility. The promising features provided by BC-coated GP were standardized manufacturing, unique stiffening processes, and monobloc formation but their efficacy and long-term performance require validation through robust scientific studies and clinical trials.^[15]

In 2007, Innovative BioCeramix, Inc., based in Vancouver, Canada, developed iRoot SP, which was a premixed, ready-to-use calcium silicate-based root canal sealer. This material is known as iRoot SP injectable root canal sealer.^[16] Improvements in the handling properties of ceramic granulates, particularly in dental and biomedical applications, have been significant. The endodontic pre-mixed BC products such as EndoSequence BC Sealer, EndoSequence BC root repair material (RRM), and EndoSequence BC RRM-Fast Set Putty were initially available in North America from Brasseler USA starting from 2008.^[17]

Then, more advancements in the calcium silicate-based products were advocated with the introduction of Biodentine in 2009. Biodentine is a calcium-silicate based material that was specifically designed as a “dentine replacement” material.^[18] In 2010, Angelus introduced MTA-Fillapex, a paste/paste BC root canal sealer. TheraCal LC was introduced to the market in 2011 as a light-curing resin-modified calcium silicate liner for use in direct and indirect pulp capping procedures.^[14] ApaCal Art, launched in 2014 by Prevest DenPro was photo-cure, resin-modified, TCP pulp protectant used in direct and indirect pulp capping, as a protective base/liner under composites, amalgam, and other restorative materials.

MicroMega MTA (France), another formulation of MTA, was developed in 2011 to overcome the drawbacks of the original MTA products. It is an injectable osteoconductive, osteoinductive, and biocompatible tricalcium silicate-based cement and also contains calcium carbonate, which helps in reducing the setting time. Biner LC, a light cure, fluoride releasing, radiopaque cavity liner and base material contains hydroxy calcium phosphate, which was specially formulated for use with adhesives and composites and with conventional restorative materials. Biner LC was introduced in the year 2019.

Angelus developed Bio-C Temp, a ready-to-use BC paste for intracanal dressing that reduced the microbial contamination and promotes the peri-radicular healing in the year 2019. BioActive Root Canal Sealer (RCS), launched by SafeEndo in the year 2022, was a bioactive mineral root canal sealer based on innovative mineral micro-aggregate chemistry “Active Biosilicate Technology” that offers biocompatibility, bioactive properties, alkaline pH, sealing properties, and retreatable.

Despite the existing limitations of current BC materials – such as brittleness, handling difficulties, or slow setting times – ongoing research is focused on enhancing their biological and mechanical properties to expand their clinical applications.

Recent advancements in BCs are revolutionizing dental tissue engineering and regenerative dentistry. Research is advancing with the use of 3D-printed calcium silicate scaffolds for odontogenesis and dentin regeneration. Combining nanostructured BCs with dental stem cells and growth factors aims to regenerate enamel, dentin, and periodontal tissues, offering breakthroughs in restorative dentistry. Incorporating bioactive agents such as fibronectin-like proteins into CPCs enhances interaction with human umbilical cord-derived mesenchymal stem cells, promoting osteogenic differentiation and bone regeneration in dental and craniofacial applications.^[19]

CONCLUSION

The evolution of BCs has been driven by the quest to develop materials that are compatible with living tissues and capable of promoting healing and regeneration. Today, BCs play a key role in various medical and dental applications, ranging from orthopedic implants to dental restorations. The advancements in BC materials aim to improve the outcomes of root canal therapy by providing enhanced sealing, biocompatibility, and antimicrobial properties.