Endodontic Radiology

Bettina Basrani

• Publisher: Wiley-Blackwell
• Year: 2012
• Print ISBN: 9780470958490
• eBook ISBN: 9781118292815
• Edition: 2
• Topic: Medicine
• Subtopic: Dentistry

Endodontic Radiology, 2nd edition, is a unique reference that examines all aspects of radiographic imaging related to endodontics. Dr. Bettina Basrani and a team of prestigious international contributors build upon traditional radiographic techniques and include the latest information available on digital radiographs and cone beam computed tomography. More than an overview of equipment, the book delves into radiographic interpretation, differential diagnosis, technical difficulties and special circumstances when taking radiographs during the endodontic treatment, and how to choose the correct radiographic technique to obtain the desired images. Chapters explain general radiographic techniques; intraoral techniques; standard radiographs and interpretation; digital radiographs and their manipulation, storage, and interpretation; and CBCT principles, techniques, and clinical considerations.

Part 1
General Principles and Techniques

---

Chapter 1 General Principles of Radiology in Endodontics

Chapter 2 Intraoral Radiographic Principles and Techniques

Chapter 3 Special Situations

Chapter 4 Intraoral Digital Imaging

Chapter 5 Radiographic Considerations before the Endodontic Treatment Is Initiated

Chapter 6 Radiographic Analysis of Anomalous Tooth Forms and Morphological Variations Related to Endodontics

---

1

General Principles of Radiology in Endodontics

Anda Kfir and Bettina Basrani

“… And God said: Let there be light. And there was light. And God saw the light, which it was good; and God divided the light from the darkness …”

(Genesis 1:3–4, The Bible, King James version)

Endodontics is the branch of dentistry in which radiology plays a critical indispensable role. Radiology illuminates what otherwise would be dark and hidden zones and allows the dentists to visualize areas not accessible by other diagnostic means. It is the use of oral radiographs which enables visualization of the bone around the apices of the teeth, as well as the results of the root canal treatments, and as such it has allowed turning endodontics into a scientific professional entity (Grossman, 1982).

History of Dental Radiology

The many developments over the years in the field of dental radiology cannot be adequately appreciated without looking back to the discovery of X-radiation.

The Cathode Tube

The first step occurred in 1870. Wilhelm Hittorf found that a partially evacuated discharged tube could emit rays able to produce heat and cause a greenish-yellow glow when they strike glass. By placing a magnet within easy reach and changing the path of the rays Varley determined that these rays were negatively charged particles and they were later called electrons. It was Goldstein from Germany who called the streams of charged particles “cathode rays.” He was followed by William Crooks, an English chemist, who redesigned the vacuum tube which subsequently was known as Hittorf–Crookes tube. In 1894, Philip Lenard studied the cathode rays’ behavior with the aid of a tube with an aluminum window. He placed screens with fluorescent salts outside the aluminum window and found that most of the rays could penetrate the window and make the fluorescent screen glow. He noticed that when the tube and screens were separated, the light emitted decreased. When they were separated by 8 cm, the screens would not fluoresce.

Radiographs

Dr. Wilhelm Conrad Roentgen from Würzberg, Germany, studied rays emitted from a tube in a darkened room; he noticed that some crystals of barium platinocyanide from a table nearby became fluorescent The observation was made on the evening of Friday, November 8, 1895. Roentgen understood that the tube was emitting some hitherto unknown kind of ray which produced the fluorescence and called this rays “X-rays” because the nature of the rays was unknown and uncertain. He also noticed that if a metallic object was placed between the tube and screen, it cast a shadow, and he reported a number of “shadow-pictures” he had photographed. One was the shadow of a set of weights in a closed box; another was a piece of metal whose homogeneity was revealed by the X-rays. But the most interesting picture was of the bones of his wife’s hand which was exposed to the rays for 15 minutes. This was the first radiograph taken of the human body and represented the beginning of practicing radiology in medicine and dentistry.

Roentgen continued to study the X-rays and found that the beam could be diminished in relation to what was placed in its path. The only material that completely absorbed the beam was lead. He went on with his experiments and finally defined the following features of X-rays: (1) they are able to distinguish between various thicknesses of materials; (2) they cause certain elements to fluoresce; (3) they are made of pure energy with no mass; (4) they go in straight lines; and (5) they are not detectable by human senses. Roentgen’s great work revolutionized the diagnostic capabilities of the medical and dental professions, and he was awarded with the first Nobel Prize in Physics in 1901. In modern terms, X-ray radiation is a form of electromagnetic radiation with a wavelength from 0.01 to 10 nm. It is emitted from a metal anode (usually tungsten, molybdenum, or copper) when subjected to a stream of accelerated electrons coming from the cathode.

Dental Radiographs

It was Otto Walkhoff, a German dentist, who made the first dental radiograph 14 days after Roentgen’s discovery.

He placed a glass photographic plate wrapped in black paper and rubber in his mouth and submitted himself to 25 minutes of X-ray exposure. In that same year, W.J. Morton, a New York physician, made the first dental radiograph in the United States using a skull and also took the first whole body radiograph. A dentist from New Orleans, Dr. C. Edmund Kells, made the first intraoral radiograph on a patient in 1896. Kells exposed his hands to X-rays every day for years by holding the plates and trying to adjust the quality of the beam in order to achieve clear images. Unfortunately, this exposure led to the development of cancer in his hand which resulted in the amputation of his arm, demonstrating the potential risk and harmful effects of X-rays. Three years later (1899), Kells used the X-ray to determine tooth length during root canal therapy.

Radiograph Machines

William H. Rollins, a Boston dentist, developed the first dental X-ray unit in 1896, as well as intraoral film holders. He was the first one to publish a paper on the potential dangers of X-rays. Rollins proposed the use of filters to suspend the dangerous parts of the X-ray beam, the use of collimation, and the practice of covering the patient with lead to prevent X-ray penetration. Rollins also pointed out the importance of setting safe and harmful dose limits. In 1913, William D. Coolidge, an electrical engineer, developed a high vacuum tube that contained a tungsten filament, which became the first modern X-ray tube. Further in 1923, Coolidge and the General Electric Corporation immersed an X-ray tube, in oil, inside the head of an X-ray machine. This eliminated the accidental exposure to high voltage shock, cooled the tube, and served as a model for all modern dental X-ray machines. From that time on, the dental X-ray machine did not change much until 1957 when a variable kilovoltage dental X-ray machine was introduced, followed by the long-cone head in 1966.

Dental X-Ray Film

Dental X-ray films also changed through the years; from the original glass photographic plates, hand-wrapped dental X-ray packets in 1896, to the prewrapped intraoral films manufactured by the Eastman Kodak company which were first introduced in 1913. The current high-speed, double-emulsion films require a very short exposure time and were designed to further reduce X-ray exposure.

The bisecting oral radiographic technique was first introduced in 1904 by Weston Price, and the bite-wing technique was introduced by H. Raper in 1925. The paralleling technique was originally introduced in 1896 by C.E. Kells and reformed in 1947 by F.G. Fitzgerald with the introduction of the long-cone (see Table 1.1) (Cieszynski, 1925).

Table 1.1 Milestones in the history of dental radiography.

1895	Discovery of X-rays	W.C. Roentgen
1896	First dental radiograph	0. Walkhoff
1901	First paper on risks of X-radiation	W.H. Rollins
1913	First prewrapped dental films	Eastman Kodak Company
1913	First X-ray tube	W.D. Coolidge
1923	First dental X-ray machine	Victor X-ray Corporation
1947	Introduction of long-cone Paralleling technique	F.G. Fitzgerald
1957	First variable kilovoltage dental X-ray machine	General Electric

Hazards of X-Ray Radiation

Ionizing radiation can have harmful effects. The largest man-made source of exposure of radiation to humans is from medical and dental radiographic examinations. Yet one should keep in mind that we are also exposed to other sources and types of radiation. These include radiation from building materials and luminous goods (i.e., television, computer), as well as natural sources (i.e., cosmic rays, soil).

The risk effects depend on the dose received, the frequency of exposure, and the type of tissue i...

Table of contents

• Cover
• Title page
• Copyright page
• Dedication
• About the Editor
• Contributors
• Foreword
• Preface
• Acknowledgments
• Part 1: General Principles and Techniques
• Part 2: Endodontic Disease
• Part 3: Sequence of Endodontic Treatment
• Part 4: Teaching and Research
• Part 5: Advanced Techniques
• Part 6: Clinical Cases
• Index