Chapter 1

Introduction to endodontology

Claes Reit, Gunnar Bergenholtz and Preben Hørsted-Bindslev

Endodontology

The word “endodontology” is derived from the Greek language and can be translated as “the knowledge of what is inside the tooth”. Thus, endodontology concerns structures and processes within the pulp chamber. But what about “knowledge”? What does it actually mean to “know” things? Most people would probably say that knowledge has something to do with truth and providing reasons for things. It is often believed that dental and medical knowledge is simply scientific knowledge – science is based on research and deals with how things are constructed and work. But as practicing dentists we also need other types of knowledge. Although it is important to know about tooth anatomy and how to produce good root canal preparations for example, we must also develop good judgment and ability to make the “right” clinical decisions. There are at least three different forms of knowledge that the dental practitioner requires and, in a tradition that goes all the way back to Aristotle, we will refer to the Greek terms for these forms: episteme, techne and phronesis (1).

Episteme

Episteme is the word for theoretical–scientific knowledge. The opposite is doxa, which refers to “belief” or “opinion”. There is a massive body of epistemic knowledge within endodontology, for example on the biology of the pulp, the microorganisms that inhabit root canals, the procedures and materials used in the clinical practice of endodontology (endodontics) and the outcome of endodontic therapies. Science produces “facts”. It must be understood that modern science is an industry and is affected by many factors, both internal and external. Although this is not the place to discuss the philosophy of science, the concept of “truth” and the growth of scientific knowledge is not unproblematic. There has been substantial contemporary philosophical discussion reflecting on epistemic knowledge, and the interested reader is referred to one of the many good introductory texts that are available (3).

The results of science are presented in lectures, articles and textbooks. So from a student’s point of view the learning situation is rather straightforward, provided that the subject is structured well and ample time given for reading and reflection. This book, in large part, is composed of epistemic knowledge.

Techne

The first person to challenge the deeply intrenched theoretical concept of knowledge was the British philosopher Gilbert Ryle. In his book The Concept of Mind (10) he introduces “knowing-how” and distinguishes it from “knowing-that”. “Knowing-how” is practical in nature and concerns skills and the performance of certain actions. This concept of knowledge implies the ability not only to do things, but also to understand what you are doing. To say that you have practical knowledge, it is not enough to produce things out of mere routine or habit. You have to “know” what you are doing and be able to argue about it. Practice must be combined with reflection. The idea that there is a tacit or silent dimension of knowledge has had a great impact on the contemporary discussion. Michael Polanyi, for example, said that “We know more than we can tell” (9). When trying to explain how we master practical things such as riding a bicycle or recognizing a face, it is not possible to articulate verbally all the knowledge that we have. Certain important aspects are “tacit”. Likewise, it is not sufficient to teach students about root canal preparation simply by asking them to read a book or presenting the subject matter in a lecture. It has to be demonstrated. Knowledge is very often transmitted by the act of doing.

A substantial body of endodontic knowledge must be characterized as techne. It is not possible to learn all about the procedures in endodontology by studying a textbook. Observing a good clinical instructor, watching other dentists at work, performing the procedures oneself and reflecting on what has been learned are all important.

Phronesis

According to Aristotle, phronesis is the ability to think about practical matters. This can be translated as “practical wisdom” (5) and is concerned with why we might decide to act in one way rather than in another. When thinking about the “right” action or making the “right” decision we enter the territory of moral philosophy. The person who has practical wisdom has good moral judgment. Modern ethical thinking has been influenced significantly by ideas that originated during the enlightenment. Morality is concerned with human actions and there are certain principles that can separate “right” from “wrong” decisions. Jeremy Bentham (2) and the utilitarians launched the utility principle and Immanuel Kant (6) invented the categorical imperative, each creating a tradition with great impact on today’s medical ethics and decision making.

Aristotle, on the other hand, believed that there are no explicit principles to guide us. He understood practical wisdom as a combination of understanding and experience and the ability to read individual situations correctly. He thought that phronesis could be learnt from one’s own experience and by imitating others who had already mastered the task. He stressed the cultivation of certain character traits and the habit of acting wisely.

The clinical situation demands that the dentist exercises practical wisdom, “to do the right thing at the right moment”. In order to develop phronesis, theoretical studies of moral theory and decision-making principles might be helpful. Neoaristotelians such as Martha Nussbaum (8) have suggested that reading literature should be part of any academic curriculum, the idea being that it increases our knowledge and understanding of other people. However, the essence of phronesis has to be learnt from practice.

Concepts of endodontology

From the above it can be concluded that endodontology encompasses not only theoretical thinking but also the practical skills of a craftsperson and the practical thinking needed for clinical and moral judgment. Unfortunately, through the years, undue prestige has been given to theoretical–scientific thinking and this has hindered the development of a rational discussion of the other types of knowledge. The serious student of endodontology has to investigate all three aspects, but, as argued above, there are limits to what can be communicated within the covers of a textbook.

The dawn of modern endodontology

It all started with a speech at the McGill University in Montreal. In the morning of October 3, 1910, Dr William Hunter gave a talk entitled “The role of sepsis and antisepsis in medicine”. Hunter said that:

“In my clinical experience septic infection is without exception the most prevalent infection operating in medicine, and a most important and prevalent cause and complication of many medical diseases. Its ill-effects are widespread and extend to all systems of the body. The relation between these effects and the sepsis that causes them is constantly overlooked, because the existence of the sepsis is itself overlooked. For the chief seat of that sepsis is the mouth; and the sepsis itself, when noted, is erroneously regarded as the result of various conditions of ill-health with which it is associated – not, as it really is, an important cause or complication.

“Gold fillings, gold caps, gold bridges, gold crowns, fixed dentures, built in, on, and around diseased teeth, form a veritable mausoleum of gold over a mass of sepsis to which there is no parallel in the whole realm of medicine or surgery. The whole constitutes a perfect gold trap of sepsis.”

The cited text was published in the Lancet in 1911. But Hunter’s words rapidly spread and were intensively discussed among laymen and given banner headlines in the newspapers. Essentially, Hunter proposed that microorganisms from a dental focus of infection can spread to other body compartments and cause serious systemic disease. The fear that illnesses and even those of chronic or of unknown origin were caused by oral infections, brought thousands of people to the waiting rooms of dentists with demands to have their teeth removed. As a result of the focal infection theory teeth were extracted in enormous numbers.

Although not directly stated by Hunter, teeth with necrotic pulps were seen as one of the main causes of “focal infection”. Laboratory studies had disclosed the presence of bacteria in the dead pulp tissue. In the 1920s, dental radiography came into general use and radio-lucent patches around the apices of teeth with necrotic pulps indicating an inflammatory bone lesion were possible to detect. If such teeth were extracted and cultured, microorganisms were often recovered from the attached soft tissue. It became virtually incontestable that pulpally diseased teeth should be removed.

Reflecting on this period in the history of dentistry, Grossman (4) wrote: “The focal infection theory promulgated by William Hunter in 1910 gave dentistry in general, and root canal treatment in particular, a black eye from which it didn’t recover for about 30 years.” However, in hindsight, this period can also be regarded as the dawn of modern endodontology. Researchers started to question and oppose the clinical consequences of the focal infection theory. Microbiologists began mapping out the microflora of infected root canals. Pathologists investigated the />

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