The unlikely origins of dental innovation

Osseointegration: The rabbit in the machine

A shining example of cross-pollination between dentistry and biomedical research is osseointegration. It is an unlikely, though powerful, harmony of bone and metal, the marriage of two radically different substances. In relation to dentistry, this process is exemplified by the integration of titanium dental implants with the jaw bone, marking a significant advancement over earlier approaches. An essential component of modern dental implantology, this biological principle crossed into the dental world in the 1960s through the pioneering work of Swedish scientist Per-Ingvar Brånemark.

What is less well known, however, is how osseointegration—the linchpin of modern implantology—emerged through failure and accident and followed a meandering path into dentistry. It is through illuminating these contexts that the truly multifaceted character of the field reveals itself. To begin with, Brånemark was not a dentist but a physician and anatomist interested in studying bone healing and regeneration. Building on the insights generated by earlier researchers, Brånemark inserted a titanium optical chamber into the tibia and fibula of a rabbit with the intention of meticulously observing the bone marrow microcirculation. But eventual retrieval of the device proved impossible; the bone had adhered so strongly to the titanium that it was essentially a part of it.

This procedural failure was beautifully fortuitous. It was the genius of Brånemark to utilise this medical mishap in the jaw bones of human subjects. Beginning in the 1960s, Brånemark and other like-minded colleagues commenced their first experiments inserting titanium implants into dental patients. Owing to the unconventional origins and methodology of the technique, the dental community reacted tepidly, relegating the burgeoning science to the margins for many years. Accumulating long-term evidence eventually turned the tide, and by the late 1980s and early 1990s, osseointegration became established as the basis of modern implant dentistry. From a contemporary vantage point, it is both easy and understandable to focus purely on the current dental function of implants, but such a narrowing erases the serendipitous conditions of their development. What is now a dental implant was once a titanium chamber irretrievably ensconced in a rabbit’s leg.

Growing teeth: Child’s play

Unquestionably one of the most innovative areas of contemporary dentistry is regenerative dentistry. Unlike other technological developments in dentistry centred on increasing mechanical sophistication and digital workflows, such as scanners, milling machines, 3D printers and lasers, the power and beauty of regenerative dentistry is that it harnesses the cellular creativity intrinsic to dental and supporting tissue. Through the identification and subtle engineering of a variety of dental stem and progenitor cells, scientists have been able to generate some of the biological components of teeth, including the dentine–pulp complex containing blood vessels and nerves, and have regenerated periodontal ligament tissue. While the science remains in an exploratory phase, the clinical uptake of these techniques appears inevitable and immensely valuable since they stand to supersede the full suite of solutions designed to restore teeth, such as direct restorations, crowns, bridges and dentures, with living dental tissue.

The passage of this approach into dentistry was not quite as transgressive as the path followed by osseointegration, but it certainly was as serendipitous. Regenerative dentistry of the kind described here did not arise solely within dentistry but developed through the convergence of dental research, regenerative medicine, stem cell biology and tissue engineering. It borrows most directly from the field of regenerative medicine and specifically stem cell therapy, which was first established to treat blood and bone marrow disorders and later investigated for the regeneration of neural tissue, cartilage and skin.

Dental researchers had been studying reparative dentine formation since the 1950s, but it was not until the beginning of the 2000s that researchers first isolated dental pulp stem cells from adult human teeth, marking an important convergence between regenerative medicine and the dental arena. Interestingly, one of the most important discoveries which advanced this field was made when Songtao Shi, a leading researcher in the discipline, examined a primary tooth lost by his 6-year-old daughter. Isolation and culture revealed a rapidly proliferating population of stem cells and yielded a new, ethically less contentious source of these cells. As with osseointegration, regenerative dentistry draws on approaches originating elsewhere that have been repurposed for dentistry and which, in good measure, have advanced through chance as much as design.

From bacteria to biofilms: The integration of microbiology into dentistry

Ironically, given the concept’s later route into dentistry, one of the earliest recorded observations of a surface-associated microbial community was made in the seventeenth century by the Dutch microbiologist Antonie van Leeuwenhoek in material taken from his own teeth. The significance of bacteria as organised, surface-associated communities, however, was not systematically developed for centuries. Although the modern biofilm concept had important precursors in the late nineteenth and early twentieth centuries, it was not until the pioneering work of American microbiologist John William Costerton and colleagues in the 1970s that it became firmly established in scientific thinking. The modern biofilm concept describes communities of microbial cells attached to surfaces, together with their unique mixture of chemical communication, deeply collective constitution and genetic fluidity.

Like the other spheres of dental innovation under consideration in this article, the modern biofilm concept was developed largely outside dentistry. Rather, Costerton and colleagues trained their attention on the formation of biofilms on surfaces in nature and industry, such as on rocks, soil, boat hulls and water filtration systems. In due course, however, the understanding of microbial cells as biofilms entered the medical world, where chronic infections and biofilms on medical devices became important contexts for understanding the radically collective and communal nature of bacteria. This broader biofilm framework was subsequently incorporated into oral microbiology and helped reshape how plaque and caries were understood. Prior to the biofilm revolution, dental researchers tended to view plaque as the accumulation of bacterial cells on the tooth surface. Within this mass, bacteria were seen as largely autonomous and independent, and certain species were considered responsible for causing decay.

The incorporation of biofilm research from environmental microbiology into dentistry fundamentally altered this view. Instead of a series of independent cells grouped together, plaque became seen as a structured, multispecies microbial community with complex interactions and emergent properties. Disease was not simply the result of the presence of certain named pathogens; it rather ensued from the collective activity of an evolving, intelligent community of diverse bacteria. The clinical ramifications of this evolution were to place greater emphasis on the oral cavity as a microbial ecosystem and not just a locus for plaque accumulation. Thus, the mechanical removal of plaque remained central, but came to be understood as a necessary part of preventing harmful biofilms from reaching a stubborn maturity. Similarly, the importation of biofilm research into dentistry underscored that oral health was not simply about dealing with problems when they arose but also about maintaining a favourable microbial balance within the mouth and preventing oral biofilms from becoming dysbiotic and disease-promoting.

3D printing: From science fiction to clinical tool

As any deniat will appreciate, 3D printing is becoming increasingly important across many areas of dentistry. Rather than relying solely on devices and restorations manufactured off-site, dental practices can now rapidly fabricate a wide range of personalised dental products from digital designs within the comfortable confines of the clinic. This is something that an earlier generation of dentists might not have believed possible, a spectacular technology belonging to the realm of science fiction, not routine dental treatment.

This is, in fact, where 3D printing was initially anticipated: not in dentistry, not even in science, but in science fiction. The idea thus appeared in this fictive literary universe before the technology was eventually developed and went on to reconfigure the world of digital dentistry. In his short story Things Pass By, published in 1945, American writer Murray Leinster described a machine, the Constructor, capable of shaping figures and objects out of liquid plastic—not far from the actualisation of such technology decades later. It was during the 1980s, that hallowed decade of accelerating digitalisation, that 3D printing made its greatest initial strides. But, yet again, dentistry was nowhere to be seen on this field of innovation. Rather, 3D printing found its early direct applications in spheres such as the automotive, aerospace and consumer product industries, where it was used primarily to quickly create prototypes that could later be upscaled to mass production. The technology was rare and correspondingly expensive, placing early commercial systems far beyond ordinary clinical use.

3D printing was eventually appropriated by dentistry. The manner in which this occurred closely resembled the integration of AI, namely, a fortuitous coincidence of format. 3D printing depended on digital 3D models which it could then physically reproduce in a range of physical materials. As alluded to earlier, from the 1980s into the early 2000s, dentistry, operating independently of this trend, began to generate an increasing volume of digital data, including 3D models generated through intra-oral scanning, CAD software and CBCT data. This 3D visual information was then functionally repurposed for use in additive manufacturing. The images were not designed for 3D printing, and neither was 3D printing designed for dentistry; they had to be creatively merged at a specific technological juncture.

Dentistry: The appropriating science

None of this is to gainsay the immense creativity that exists within dentistry and the myriad important developments that have erupted within the field itself. The point, which I hope to have illustrated through the examples in this article, is rather that what we routinely call “dentistry” is not a closed field of thought and practice that evolves according to its own internal dynamics but is rather a thoroughly open network whose forward drive depends crucially on the identification, adoption and creative repurposing of innovations that occur in cognate industries and sciences. Seen in this way, the potential sources of innovation within dentistry are exponentially multiplied and potentially limitless.