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Orthodontic Tissue Engineering: A 20‐Year Retrospective and Philosophical Polemic©

Neal C. Murphy

Clinical Professor, Departments of Orthodontics & Periodontics, School of Dental Medicine, Cleveland Clinic Campus, Case Western Reserve University, Cleveland, OH, USA

Dedication

This chapter is dedicated to Professor Spiro Chaconas, Founder and Chairman Emeritus, Section of Orthodontics, UCLA School of Dentistry. Professor Chaconas, presently enjoying a well‐deserved retirement in Sothern California, was an exceptional leader, friend, and mentor for over three generations of orthodontists at UCLA. He taught his protégés to enter private practice with confidence and engage the inevitable vicissitudes of our careers – many rather brutal – with professional élan, stoic indifference, transcendent vision, and personal humility. We did.

Thank you, Spiro.

Introductory Rationale

Since 2001, this author – dual‐certified in both orthodontic and periodontic – has collaborated with a number of orthodontists and periodontists in an effort to engineer a novel alveolus bone that could accommodate the full complement of human dentition. This was attempted to liberate a naturally “full” smile from the strictures of skeletal malalignment and so‐called arch length deficiencies. By the year 2023, we were able to develop protocols that achieved that goal and accelerate the rate of tooth movement three to fourfold. In addition, instances of pernicious side effects like apical root resorption and periodontal attachment loss were predictably minimized or nonexistent compared to traditional edgewise therapies. In that regard, our protocols, both surgical and nonsurgical in a phrase, proved to be “faster, safer, and better.” These revelations were brought into high relief by a 20‐year retrospect as attested to by studies cited herein.

Orthodontists’ attempts to enhance the esthetic value of the patients’ lower face are indeed laudable goals. However, the wide‐spread popularity of extraction therapy presents a sobering challenge because it notoriously has been haunted by the unfortunate and unpredictable side effects of premature lower face aging and unsightly flattened (so‐called “dished‐in”) profiles in maturity. Moreover, since these unsightly facial profiles often become most apparent years after active therapy has ended, they are subtle assaults on facial beauty. While evident to the general population, the iatrogenic deformity presents a pattern that is vaguely unsightly but nondescript to laymen. This chapter explains that cell‐ and tissue‐level biology is often ignored in orthodontic curricula and sacrificed by inordinate preoccupations with gross anatomy. But periodontology revels in cell‐level dynamics and affords us, as specialty science integrators, to reveal a universe of new orthodontic science, we call “orthodontic tissue engineering (OTE).”

If dentists claim a desire for “best care,” we must ask how one defines that superlative term. By definition, a superlative is an absolute, and whatever treatment most closely approximates that ideal is reasonably argued as “best.” Is “best care” which is predictable, fastest, with fewest pernicious side effects, least painful, most stable, and most compatible with contemporary cultural values?

This chapter is an attempt to organize a compelling rationale for this new protocol in terms of the underlying cellular dynamics that allow it to achieve case outcome stability superior to the very unstable outcomes that are predictably disappointing in traditional care. Ironically, the new concept of “accelerated orthodontic therapy” was met with political opposition and excessively cynical skepticism by established practitioners. Yet truth prevails and the luddites and clinical nay‐sayers of the 20th century were proven wrong by 21st‐century science. This chapter boldly addressees this controversy as a tribute to intrepid clinicians who preceded us and as a scientific reminder that hard data and scientific epistemological inquiry, however, disruptive to prevailing thought and wishes, will out.

This definition seems sensible to us. Therefore, the aim of this chapter is to describe the ramifications of an emerging perspective and clinical protocol in those terms. Although unheard of by some, the subject is neither new nor novel because it has been evolving over time within the ebb and flow of scientific evolution. It nonetheless brings disruptive issues and protocols that are certainly more predictable, faster, with fewest pernicious side effects, less painful in adjustments, more stable, and more compatible with contemporary cultural values than traditional extraction alternatives. The problem with science is that it has no master. So, it flies in the face of convention and traditional bias.

Late 20th‐century science has delivered a collection of empirical observations and corticotomy protocols that are embodied under the collective rubric, surgically facilitated orthodontic therapy (SFOT) which in this book will be called orthodontically driven osteogenesis (ODO). This term referring to a particular histological reaction, subsumes a number of protocols that are mere variants of the same basic biological phenomena. These terms include but are not limited to “selective alveolar (‐us) decortication” (SAD), decortication without a bone graft, “stem cell orthodontic therapy” (SCOT), “stem cell alveolar therapy” (SCAT), “corticision” when a scalpel is used, “accelerated osteogenic orthodontics” (AOO) where a bone graft is combined with SAD, “periodontal(ly) accelerated osteogenic orthodontics” (PAOO) synonymous with AOO, and here, “orthodontic tissue engineering” (OTE) referring to a 21st century protocol focusing on permanent alveolus bone phenotype alteration. We posit that emerging periodontal sciences, the biology of healing bone, and cell‐level biology, which underlie ODO, are as integral to orthodontics, as civil engineering is to good architectural design. ODO is an example of the clinical science of engineered morphogenetic bone modeling – pioneered by the Russian orthopedist Professor Gavriil Ilizarov – synthesized with traditional orthopedic biomechanics (Figure 1.1). This Russian orthopedic surgeon proved beyond doubt and under great oppression that bone is malleable and can be reshaped to a more physiological form at will. That principle applies to the alveolus bone as well (Figure 1.1).

We pose a challenge to traditional biomechanics to enhance clinical efficacy, ameliorate pernicious side effects, and advance the orthodontic specialty beyond the strictures of simple mechanical art. The issues discussed in this polemic are based on the dual‐certified author’s 50 years of integrating periodontics and orthodontic in an urban private, but academic, practice and 20 years of understanding ODO. It also reflects the combined work of a growing global community of biologists and dentists, formally trained, or passionately interested in reengineering the mass and shape of the foundation of the human dentition. Hence, we write in the first‐person plural, not to imply lock‐step concordance, but rather a general agreement that is compatible with a wide variety of readers. Some repetition will be noticed in this discourse, but that serves as an intentional pedagogical device. The subject matter is quite novel to some readers because we employ a technical prose of molecular biologists, tissue engineers, periodontists, and orthodontists. Moreover, repetition of a new concept within several different contexts can only enrich the conceptualization. Hopefully, the literary device will edify and not distract.

Figure 1.1 This treatment demonstrates what can be done to correct a deformed long bone. The same principle used by Gavriil Ilizarov can be applied to the alveolus bone in correcting dentoalveolar deformities. The leg deformity in (a) represents a deformed bone. (b) The Ilizarov orthopedic device with his surgical protocol can lengthen long bones at the rate of 1 mm/day. (c) Demonstrates an improved esthetic appearance and function. This is what OTE attempts to do with the dental alveolus bone.

Source: Dong et al. (2021)/Reproduced with permission from Tsinghua University Press Ltd.

Our objective here is not to proselytize but rather to serve examples of what can be achieved by others who wish to minimize extraction therapy side effects. But we hope this is received in a provocative manner to stimulate a meaningful dialectical exchange rather than contentious debate, misinformation, distortions, and misrepresentations that have marred the development of this topic. What is practiced by others is beyond our scope of control. So, we do not call for the immediate condemnation of those who are uncomfortable with protocols presented herein. We focus on scientific advances in ancillary biological fields too fascinating to ignore. And, these innovations can serve as both a beacon and safe harbor for those who are dissatisfied with the limits of the status quo. We are here to show a better path but only for those who wish to embark upon it.

We do not seek to condemn legitimate extraction therapy categorically, but we are intentionally provocative...