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The Art and Science of Contemporary Surgical Endodontics

Library of Congress Cataloging-in-Publication Data

Names: Torabinejad, Mahmoud, editor. | Rubinstein, Richard, 1946- editor.

Title: The art and science of contemporary surgical endodontics / edited by Mahmoud Torabinejad, Richard Rubinstein.

Description: Hanover Park, IL : Quintessence Publishing Co Inc, [2017] | Includes bibliographical references and index.

Identifiers: LCCN 2017003236 (print) | LCCN 2017005621 (ebook) | eISBN 9780867158649

Subjects: | MESH: Dental Pulp Diseases--surgery | Dental Pulp--diagnostic imaging | Pulpectomy--methods

Classification: LCC RK351 (print) | LCC RK351 (ebook) | NLM WU 230 | DDC 617.6/342059--dc23

LC record available at https://lccn.loc.gov/2017003236

© 2017 Quintessence Publishing Co, Inc

Quintessence Publishing Co, Inc

4350 Chandler Drive

Hanover Park, IL 60133

www.quintpub.com

5 4 3 2 1

All rights reserved. This book or any part thereof may not be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, or otherwise, without prior written permission of the publisher.

Editor: Leah Huffman

Design: Erica Neumann

Production: Sue Robinson

Printed in China

Foreword

Preface

Contributors

List of Videos

1 Anatomical Zones in Endodontic Surgery

Kenneth R. Wright, Dwight D. Rice, and Zhongrong Luo

2 Histology of Tissues Involved in Surgical Endodontics

Kenneth R. Wright

3 Bone Physiology and Metabolism in Endodontic Surgery

Sarandeep S. Huja and W. Eugene Roberts

4 Radiolucent Periapical Pathosis

Nasser Said-Al-Naief

5 Diagnosis and Treatment Planning

Mahmoud Torabinejad

6 Cone Beam Computed Tomography in Treatment Planning of Periapical Surgery

Mohamed I. Fayad, Bruno C. Azevedo, and Richard Rubinstein

7 Magnification and Illumination in Apical Surgery

Richard Rubinstein

8 Local Anesthesia and Hemostasis

Bradford R. Johnson and Hamid Abedi

9 Soft Tissue Management

Peter Velvart and Ove A. Peters

10 Apical Microsurgery: Application of Armamentaria, Materials, and Methods

Richard Rubinstein and Mohamed I. Fayad

11 Root-End Filling Materials

Masoud Parirokh and Shahrokh Shabahang

12 Surgical Endodontics and the Maxillary Sinus

Roderick W. Tataryn

13 Suturing and Postoperative Instructions

Erik Sahl and Bonnie Retamozo

14 Wound Healing

Kathryn A. Jurosky

15 Adjunctive Procedures

Mahmoud Torabinejad, Tord Lundgren, Dimitris N. Tatakis, and Mohamed I. Fayad

16 Pharmacology in Surgical Endodontics

Karl Keiser

17 Outcomes of Endodontic Surgery

Thomas von Arx and Shane N. White

Index

In February of 1969, I published a paper in the Journal of the New Jersey Dental Association titled “Surgical Endodontics, A Conservative Approach.” According to the Random House Dictionary, conservative is defined as “disposed to preserving existing conditions.” At that time, popular dental semantics referred to the two courses of endodontic action as conservative and surgical. This implies that the surgical approach is radical and the nonsurgical approach is conservative. However, both of these methods try to “preserve existing conditions” by retaining teeth, and therefore both must be considered conservative. In fact, modern endodontic surgery may be more conservative than disassembly, retreatment, and re-restoration. Despite advances in surgical endodontics, this conversation still takes place today.

In 1969, Donald E. Arens was teaching surgical endodontics to graduate students at Indiana University and requested reprints of my paper for the residents. This began a lifelong professional association and a personal friendship. When he decided to codify his teaching materials into a textbook, he joined with William Adams and Roland DeCastro to write Endodontic Surgery (Harper & Row, 1981). I was honored to contribute a chapter to this first English-language textbook devoted to surgical endodontics. The basic premise of the text was that “surgical endodontics is an extension of root canal basic therapy to preserve natural dentition.”

Ten years later, Surgical Endodontics (Blackwell, 1991) by James Gutmann and John Harrison was followed by Practical Lessons in Endodontic Surgery (Quintessence, 1991) by the late Donald E. Arens, Mahmoud Torabinejad, Richard Rubinstein, and myself. This trio of text-books has served our profession well in establishing a scientific basis and offering practical methods for understanding and performing surgical endodontics. In 2001, Color Atlas of Microsurgery in Endodontics (Saunders) by Syngcuk Kim, Gabriele Pecora, and Richard Rubinstein introduced the profession to the modern understanding of true endodontic microsurgery.

Since then, there have been few books that have addressed the surgical needs of modern-day dentists who want to adopt contemporary and evidence-based surgical endodontics methods into their practices. The Art and Science of Contemporary Surgical Endodontics consists of 17 chapters and 31 videos that span its entire scope. It has been assembled and coauthored by Mahmoud Torabinejad and Richard Rubinstein, two leaders in the field of surgical endodontics. Their professional careers, research, and didactic skills complement each other and have produced the new standard for teaching and studying evidence-based surgical endodontics.

Noah Chivian, DDS

Professor of Endodontics, Rutgers School of Dental Medicine

Adjunct Professor of Endodontics, University of Pennsylvania, School of Dental Medicine

Director Emeritus, Chivian Department of Dentistry, Newark Beth Israel Medical Center

One of the primary objectives of dentists has always been to prevent tooth loss and save natural dentition. Despite these efforts, many teeth still develop decay or suffer traumatic injury and often require endodontic care. Endodontics is a discipline of dentistry that deals with the morphology, physiology, and pathology of the human dental pulp and periapical tissues, as well as the prevention and treatment of diseases and injuries related to these tissues. The scope of endodontics is wide and includes initial nonsurgical root canal treatment, non-surgical retreatment of unsuccessful treatment, and/or surgical endodontics. Many advances have been made in endodontic surgery in the past 10 to 20 years. These include enhanced magnification and illumination, ultrasonic tips, microinstruments, newer root-end filling materials, and the use of cone beam computed tomography (CBCT). These advances have significantly improved surgical endodontics and have increased the feasibility and predictability of this procedure to save natural dentition.

Like other dental procedures, the practice of surgical endodontics requires two inseparable components: art and science. The art of surgical endodontics consists of executing technical skills during surgical procedures. The science of surgical endodontics includes the basic and clinical sciences related to biologic and pathologic conditions that guide the art of procedures involved in surgical endodontics through the principles and practice of evidence-based treatment. In this textbook, the authors have incorporated evidence-based information when avail able and when appropriate. The textbook is written specifically for advanced students in the field of endodontics, endodontists, and others who would like to incorporate surgical endodontics in their practices.

The Art and Science of Contemporary Surgical Endodontics has been systematically organized to simulate the order of procedures performed in a clinical setting after presenting the necessary information related to the anatomy, histology, and physiology of tissues involved in surgical endodontics, as well as pathologic entities simulating lesions of pulpal origin. The first four chapters are dedicated to the basic sciences of tissues involved in surgical endodontics, followed by an extensive chapter on diagnosis and treatment planning. Several chapters focus on the most recent advances in the art of surgical endodontics related to CBCT, illumination and magnification, local anesthesia and hemostasis, management of soft tissues, removal of osseous tissue, root-end resection, root-end preparation, and root-end filling materials, as well as suturing and postoperative instructions. Following chapters are dedicated to the maxillary sinus and its relation to surgical endodontics; soft and hard tissue healing based on classic literature; and adjunctive surgical procedures such as management of procedural accidents, resorption, root amputation, hemisection, replantation, transplantation, crown lengthening, and grafting materials. A chapter on the pharmacology of surgical endodontics describes the medications that can be used preoperatively and postoperatively to aid healing and provide patient comfort, and the last chapter assesses the outcomes of surgical endodontics based on current evidence. Unique to this book is a DVD set of video clips showing many of the surgical procedures described in the textbook (see page xi).

Therefore, The Art and Science of Contemporary Surgical Endodontics not only teaches the reader how to perform surgical endodontics but also provides him or her with a summary of the science and technology behind technical aspects of surgical endodontics that is concise, current, and easy to follow.

Acknowledgments

We would like to thank the contributing authors for sharing their materials and experiences with us. Their contributions have significantly increased the feasibility and predictability of surgical endodontics and have resulted in saving natural dentition. We would also like to express our appreciation to the editorial staff at Quintessence Publishing, whose collaboration and dedication have made this textbook possible. In addition, we would like to acknowledge the contribution of our colleagues who provided cases that have improved the quality of this textbook. Finally, we would like to thank Mr Daryl Osborne from Educational Support Services at the Loma Linda University School of Dentistry for editing the video clips for our textbook.

Mahmoud Torabinejad
Richard Rubinstein

Hamid Abedi, BDS

Lecturer

Department of Endodontics

School of Dentistry

Loma Linda University

Loma Linda, California

Bruno C. Azevedo, DDS, MS

Assistant Professor

Department of Oral and Maxillofacial Radiology

School of Dentistry

University of Louisville

Louisville, Kentucky

Mohamed I. Fayad, DDS, MS, PhD

Clinical Associate Professor

Department of Endodontics

Director of Research

College of Dentistry

University of Illinois at Chicago

Chicago, Illinois

Sarandeep S. Huja, BDS, DDS, MDS, MS, PhD

Associate Dean and Professor, Orthodontics Graduate Program Director

Department of Orthodontics

College of Dentistry

University of Kentucky

Lexington, Kentucky

Bradford R. Johnson, DDS, MHPE

Professor of Endodontics

Department Head and Director of Postgraduate Endodontics

College of Dentistry

University of Illinois at Chicago

Chicago, Illinois

Kathryn A. Jurosky, DDS, MS

Private Practice

Palo Alto, California

Karl Keiser, DDS, MS

Adjunct Associate Professor

Department of Endodontics

School of Dentistry

University of Texas Health Science Center at San Antonio

San Antonio, Texas

Tord Lundgren, DDS

Professor and Chair

Department of Periodontics

School of Dentistry

Loma Linda University

Loma Linda, California

Zhongrong Luo, MD, PhD

Assistant Professor

Department of Pathology and Human Anatomy

School of Medicine

Loma Linda University

Loma Linda, California

Masoud Parirokh, DMD, MSc

Distinguished Professor and Chair of Endodontics

School of Dentistry

Kerman University

Kerman, Iran

Ove A. Peters, DMD, MS, PhD

Professor and Co-chair

Department of Endodontics

Arthur A. Dugoni School of Dentistry

University of the Pacific

San Francisco, California

Bonnie Retamozo, DDS, MSD

Assistant Professor

Department of Endodontics

School of Dentistry

Loma Linda University

Loma Linda, California

Dwight D. Rice, DDS

Associate Professor

Department of Radiologic and Imaging Sciences

Department of Dental Research

School of Dentistry

Loma Linda University

Loma Linda, California

W. Eugene Roberts, DDS, PhD

Professor Emeritus of Orthodontics

Indiana University School of Dentistry

Adjunct Professor of Mechanical Engineering

Purdue University

Indianapolis, Indiana

Richard Rubinstein, DDS, MS

Adjunct Clinical Associate Professor

Department of Cariology, Restorative Sciences and Endodontics

University of Michigan School of Dentistry

Ann Arbor, Michigan

Private Practice Limited to Endodontics

Farmington Hills, Michigan

Erik Sahl, DDS, MSD

Assistant Professor, Director of Advanced Program in Periodontics

Department of Periodontics

School of Dentistry

Loma Linda University

Loma Linda, California

Nasser Said-Al-Naief, DDS, MS

Professor and Chair, Director of Oral and Maxillofacial Pathology Laboratory

Department of Pathology and Radiology

School of Dentistry

Oregon Health & Science University

Portland, Oregon

Shahrokh Shabahang, DDS, MS, PhD

Associate Professor of Endodontics

School of Dentistry

Loma Linda University

Loma Linda, California

Dimitris N. Tatakis, DDS, PhD

Professor and Director of Postdoctoral Program

Division of Periodontology

Assistant Dean for Global Initiatives

College of Dentistry

The Ohio State University

Columbus, Ohio

Roderick W. Tataryn

Private Practice Limited to Endodontics

Spokane, Washington

Mahmoud Torabinejad, DMD, MSD, PhD

Ronald E. Buell Professor of Endodontics

Director of Advanced Program in Endodontics

School of Dentistry

Loma Linda University

Loma Linda, California

Peter Velvart, Dr med dent

Private Practice Limited to Endodontics

Zurich, Switzerland

Thomas von Arx, Prof Dr med dent

Associate Professor and Vice Chairman

Department of Oral Surgery and Stomatology

School of Dental Medicine

University of Bern

Bern, Switzerland

Shane N. White, BDentSc, MA, MS, PhD

Professor of Endodontics

School of Dentistry

University of California, Los Angeles

Los Angeles, California

Kenneth R. Wright, PhD

Associate Professor, Graduate Program Director

Division of Human Anatomy

School of Medicine

Loma Linda University

Loma Linda, California

Description

Duration (min)

Chapter 5

5-1 Gow-Gates block injection

1:57

5-2 Vazirani-Akinosi block injection

1:05

5-3 Second division block injection

0:49

5-4 Infraorbital block

1:55

5-5 Intraosseous injection

2:49

5-6 Periodontal ligament injection

1:41

5-7 Incision and drainage

4:54

5-8 Irretrievable filling materials 1

4:09

5-9 Irretrievable filling materials 2

7:41

5-10 Irretrievable filling materials 3

7:21

5-11 Symptomatic cases during root canal therapy

10:40  

5-12 Symptomatic cases after root canal therapy

7:36

5-13 Exploratory surgery

8:05

Chapter 9

9-1 Full-thickness flap

2:52

9-2 Palatal root surgery

10:33  

9-3 Ochsenbein Luebke flap

1:48

9-4 Papilla base flap

5:37

Chapter 13

13-1 Simple interrupted suture

1:18

13-2 Figure-eight suture

1:05

13-3 Interrupted simple sling suture

1:36

13-4 Continuous independent sling suture

2:13

13-5 Horizontal mattress suture

1:05

13-6 Simple interrupted suture removal

0:29

13-7 Continuous sling suture removal

0:37

Chapter 15

15-1 Repair of external resorption by tooth replantation

7:03

15-2 Tooth replantation

5:20

15-3 Transplantation

7:56

15-4 Root amputation

5:26

15-5 Hemisection

1:45

15-6 Crown lengthening

7:04

15-7 Guided tissue regeneration

8:54

https://www.youtube.com/playlist?list=PLTqXxSXjMEYBSO-DT9SlhJA6CSt8cXFFB

The authors have attempted to present a complete collection of surgical videos representative of all regions of the mouth, but they recognize that there are emerging technologies, methods, and approaches that are too expansive to be included at this time. Future editions of this textbook will include videos reflecting new advances and developments in surgical endodontics.

The oral environment is a complex region formed of a mixture of hard and soft tissues. Its functions include chewing, swallowing, and speech, as well as acting as an accessory airway. Maintenance of a healthy dentition is imperative to the overall well-being of the individual and proper functioning of the alimentary system. An in-depth understanding of the structure and function of the oral apparatus is required to provide proper care to oral structures and tissues.

In addition to posing the risk of damaging parts of the tooth, endodontic procedures also risk damaging tissues and anatomical structures surrounding the tooth root.1 It is therefore essential to have a thorough understanding of the anatomy of the jaws and in particular the parts of these bones housing neurovascular structures or pneumatic spaces. In this chapter, we examine the anatomy of the maxillary sinus, the mandibular canal with its branches (the mental canal/foramen and the incisive canal), and the incisive canal and palatine foramina of the maxilla, as well as their relationships to the roots of teeth. But first we examine the anatomy of the oral region in general.

The Bony Framework

Maxilla

The maxilla forms much of the midportion of the face, the borders of the nasal aperture, part of the margin of the orbits, and most of the hard palate and the support for the upper lip and teeth (Fig 1-1). Branches from the maxillary artery supply most of the maxillary region, and sensory innervation is provided by the maxillary division of the trigeminal nerve, designated as cranial nerve V2.

Fig 1-1 The maxilla shown from an anterior angulation. Borders of the maxilla include the floor of the orbit, the zygomatic bone, and the lateral borders of the nasal cavity. The alveolar process forms the inferior boundary.

Associated with the nasal cavity are four sets of paranasal sinuses, found in the frontal, maxillary, sphenoid, and ethmoid bones. The largest of the paranasal sinuses, the maxillary sinus, is housed in the body of the maxilla (Fig 1-2). This pneumatic space is roughly pyramid shaped, with the base of the pyramid formed by the medial wall of the sinus, which is also the lateral wall of the nasal cavity. The medial wall of the sinus is actually formed by parts of five bones—the maxilla, the lacrimal bone, the inferior nasal concha, the perpendicular plate of the palatine bone, and the uncinate process of the ethmoid bone. The ostium of the sinus drains to the middle meatus, the space inferior to the middle nasal concha, on the lateral nasal wall (Fig 1-3). The posterior wall of the sinus faces the maxillary tuberosity, the roof forms the floor of the orbit, and the floor of the sinus extends inferiorly into the alveolar ridge of the maxilla, most commonly in the area of the second premolar and first and second molars. Innervation of the mucosa lining the maxillary sinus is provided by the posterior, middle, and anterior superior alveolar nerves and the infraorbital nerve, all branches of V2. The blood supply is primarily from branches of the maxillary artery accompanying these nerve branches, as well as the descending palatine artery, which accompanies the greater and lesser palatine nerves, and sometimes the posterior superior alveolar artery. During endodontic surgery, it is important to be aware of the position of the posterior superior alveolar nerve to avoid damaging it.

Fig 1-2 The maxillary sinus is housed in the body of the maxilla. This pneumatic space is roughly pyramid shaped, with the base of the pyramid formed by the medial wall of the sinus, which is also the lateral wall of the nasal cavity. Note the presence of a sinus septum (arrow).

Fig 1-3 A coronal section of the maxillary sinus using cone beam computed tomography (CBCT) imaging. Note the close proximity of the root tips to the floor of the sinus (red arrows).

The maxillary sinus, like all the paranasal sinuses, is lined by respiratory mucosa, comprising pseudostratified ciliated columnar epithelium with goblet cells overlying a rather thin lamina propria that adheres to the periosteum covering underlying bone (mucoperiosteum). The mucosa covering the floor of the sinus—the sinus membrane—is often somewhat thickened and is sometimes referred to as the Schneiderian membrane clinically (Figs 1-4 and 1-5).

Fig 1-4 Coronal CBCT image of a slightly thickened sinus membrane (arrows).

Fig 1-5 The mucosa covering the floor and walls of the sinus is sometimes referred to as the Schneiderian membrane clinically. The arrows point to a section left during the dissection. Notice its thin, delicate nature.

The alveolar process or ridge is the portion of the maxilla that houses the roots of the teeth. The cortical plate forming the outer walls of this ridge is relatively thin, allowing the infiltration of anesthetics. Below the midpoint of the inferior orbital rim, an infraorbital foramen provides passage for the infraorbital nerve, a continuation of the maxillary nerve (V2), along with infraorbital vessels. A canine eminence shows the location of the root of the canine tooth. Medial to this eminence is an incisive fossa, and lateral to the eminence is a canine fossa (Fig 1-6).

Fig 1-6 The canine eminence (yellow arrows) shows the location of the root of the canine tooth. Medial to this eminence is an incisive fossa (blue arrows), and lateral to the eminence is a canine fossa (red arrows).

The hard palate is formed primarily by the two lateral palatine processes of the maxilla, which fuse in the midline to form the intermaxillary, or median palatine, suture. Two transverse palatine sutures separate the posterior borders of the palatine processes of the maxilla from the horizontal plates of the palatine bones, which form the posterior third of the hard palate. These sutures are sometimes incomplete laterally, forming greater palatine foramina that transmit the greater palatine nerves and vessels. Posterior to the greater palatine foramina are smaller lesser palatine foramina, located within the pyramidal processes of the palatine bones and transmitting the lesser palatine nerves and vessels. Just posterior to the maxillary central incisors lies the incisive fossa, into which open incisive canals by way of incisive foramina, transmitting the nasopalatine nerves and sphenopalatine vessels from the nasal cavity (Fig 1-7).

Fig 1-7 (a and b) Remarkable features of the hard palate include the intermaxillary suture (blue arrows), greater palatine foramina (red arrows), and lesser palatine foramina (green arrows). Note the supplemental foramina (yellow arrows) in the posterior region (b).

The oral portion of the maxilla is covered by mucosa. The buccal or vestibular surface of the maxilla is covered by alveolar mucosa, which transitions to attached gingiva at the mucogingival junction. On the palatal side, the mucosa covering the hard palate transitions to the gingiva covering the tooth-bearing alveolar process. Much of the hard palate is covered by a mucoperiosteum, characterized by the attachment of collagen fibers in the lamina propria that blend with the underlying periosteum, without an intervening submucosa. A median palatine mucosal raphe indicates the location of the median palatine suture. Anteriorly, immediately posterior to the central incisors, a small midline incisive papilla indicates the location of the incisive fossa, and projecting laterally from the midline is a series of mucosal ridges called palatine rugae. Posterior to this lies a fatty region underlying the mucosa as well as a glandular region that contains numerous mucoserous minor salivary glands, or palatine glands. The mucosa of the hard palate transitions to the mucosa covering the soft palate, a muscular and glandular structure that blends laterally into the palatoglossal and palatopharyngeal folds, or anterior and posterior pillars of the fauces, the opening of the oral cavity into the oropharynx. The soft palate, also called the palatine velum, terminates posteriorly in the midline by a small muscular projection, the uvula, which serves to close off the oropharynx from the nasopharynx during swallowing.

The posterolateral border of the hard palate, just posterior to the greater and lesser palatine foramina, articulates or fuses with the pterygoid process of the sphenoid bone. This process is made up of medial and lateral pterygoid plates, which run vertically just posterior to the hard palate. Between the two pterygoid plates lies the pterygoid fossa, and above that is a small scaphoid fossa. The lateral and medial pterygoid muscles have attachments to the lateral pterygoid plate, and the tensor veli palatini muscle attaches to the scaphoid fossa of the medial pterygoid plate. At the inferior tip of the medial pterygoid plate, just posterior to the lateral aspect of the hard palate, is a hooklike process called the hamulus (Fig 1-8). The tendon of tensor veli palatini hooks over the hamulus before inserting into the soft palate. The hamulus also serves as a point of attachment for the pterygomandibular raphe and for the superior pharyngeal constrictor. Overactive pterygoid muscles can generate myofascial pain, which can mimic endodontic symptoms.

Fig 1-8 (a) At the inferior tip of the medial pterygoid plate, just posterior to the lateral aspect of the hard palate, is a hooklike process called the hamulus (red arrows). (b and c) The medial (red arrows) and lateral (blue arrows) pterygoid plates of the sphenoid bone seen in axial view in dry skull and CBCT images. (d) Coronal CBCT image showing the medial (red arrows) and lateral (blue arrows) pterygoid plates.

Neurovascular supply to the maxilla

Blood supply. The maxilla with its associated soft tissues and teeth are supplied primarily by the maxillary artery, a terminal artery that branches from the external carotid artery deep to the ramus of the mandible and travels through the infratemporal fossa, where it gives off branches to the muscles of mastication and surrounding structures. The inferior alveolar artery originates from this portion of the maxillary artery. The maxillary artery then passes through the pterygomaxillary fissure to provide blood supply to the palate via the descending palatine artery; the walls of the nasal cavity and anterior palate via branches of the sphenopalatine artery; the mucosa of the maxillary sinus and the maxillary teeth via the posterior, middle, and anterior superior alveolar arteries; and the floor of the orbit and part of the face via the infraorbital artery. The blood supply to this region is supplemented by the facial/angular artery and its superior labial and lateral nasal branches, as well as the ascending palatine and tonsillar branches.

Nerve supply. The maxillary region of the face and oral cavity are both supplied primarily by branches of the maxillary division of the trigeminal nerve (V2). This nerve branches from the trigeminal ganglion in the middle cranial fossa and passes through the foramen rotundum to enter the upper part of the pterygopalatine fossa. In this fossa, the maxillary nerve is connected to the pterygopalatine ganglion, a parasympathetic ganglion, by two small pterygopalatine (sphenopalatine) nerves. These little nerves conduct sensory fibers to the ganglion, from which they are distributed to the nasal and oral regions. Preganglionic parasympathetic fibers from the superior salivatory nucleus in the pontine tegmentum of the brain stem travel with the facial nerve to the geniculate ganglion, where they leave the facial nerve as the greater petrosal nerve. This nerve travels in a small groove on the floor of the middle cranial fossa, joining with the deep petrosal nerve, which is composed of postganglionic sympathetic fibers from the superior cervical ganglion. Together, the greater and deep petrosal nerves combine to form the nerve of the pterygoid canal (Vidian nerve), which passes through the pterygoid canal to enter the pterygopalatine fossa. The preganglionic parasympathetic fibers synapse in the pterygopalatine ganglion, from which postganglionic fibers are distributed with sensory fibers from V2 to the nasal and oral regions. Postganglionic sympathetic fibers from the deep petrosal nerve accompany the post-ganglionic parasympathetic and sensory fibers. Major branches from the pterygopalatine ganglion include lateral nasal branches, the nasopalatine nerve, greater and lesser palatine nerves, posterior superior alveolar nerves, and the infraorbital nerve, which gives rise to the middle and anterior superior alveolar nerves. A small zygomatic branch divides into zygomaticotemporal and zygomaticofacial nerves, which supply skin and soft tissues in the zygomatic region of the face. From the zygomatic nerve, a small communicating branch carries postganglionic fibers to the lacrimal nerve, a branch of the ophthalmic division of the trigeminal nerve, to provide stimulation for lacrimal gland secretion. The posterior, middle, and anterior superior alveolar nerves supply the pulps and periodontium of maxillary teeth and the mucosa of the maxillary sinus.

Mandible

The mandible, a horseshoe-shaped bone forming the chin and lower jaw, is the only movable bone in the head (other than the ossicles in the middle ear) (Fig 1-9). The body of the mandible is the horizontal portion of the bone supporting the teeth, and the ramus is the more vertical posterior portion articulating with the temporal bone. Anteriorly in the midline is the symphysis menti, a site of fusion of two mandibular primordia during the embryologic development of the mandible that forms much of the chin. Extending outward and downward from the midline is a triangular-shaped mental protuberance; its two inferior angles are known as mental tubercles. Two incisive fossae are found just superior to the tubercles. A mental foramen is located laterally about midway between the lower margin of the body of the mandible and the alveolar crest, at approximately the level of the first premolar or slightly more posteriorly, although the position is variable. An oblique line begins partway back along the body, starting near the inferior border and terminating as the anterior border of the ramus and leading up to the triangle-shaped coronoid process. The posterior border of the ramus meets the inferior border of the body of the mandible at the (gonial) angle of the mandible. The area just anterior and superior to the angle is roughened, indicating the area of attachment for the masseter muscle. Superior to the posterior border of the ramus is the condylar process, formed of the rounded condyle that articulates with the mandibular or glenoid fossa of the temporal bone, with a narrow neck of the mandible just proximal to the condyle. Just inferior to the medial aspect of the condyle is the pterygoid fovea, a point of attachment for the lateral pterygoid muscle. The depression along the superior border of the ramus, between the condyle and coronoid process, is the mandibular notch, which allows passage of the masseteric nerve and vessels going to supply the masseter muscle.

Fig 1-9 Anterior view of the mandible.

On the medial or deep surface of the ramus of the mandible, roughly midway between the inferior border of the mandible and the mandibular notch and approximately midway between the anterior and posterior borders of the ramus, is the mandibular foramen through which the inferior alveolar nerve and vessels enter the mandible to be distributed to the mandibular teeth and soft tissues. Just anterosuperior to the mandibular foramen, a triangular bony protuberance, the lingula, serves as an attachment for the sphenomandibular ligament as well as a landmark for administration of inferior alveolar nerve blocks. In the midline of the anterior aspect of the mandible, on its deep surface, the genial tubercles or spines serve as attachments for the genioglossus and geniohyoid muscles. Extending posteriorly along the body of the mandible is the oblique mylohyoid line, which serves as the attachment for the mylohyoid muscle. Superoanterior to the mylohyoid line is the sublingual fossa, and inferoposterior to the mylohyoid line is the submandibular fossa. These two fossae house the major salivary glands with the same names. Extending anteroinferiorly from the mandibular foramen is the mylohyoid groove, which accommodates the nerve going to the mylohyoid and anterior digastric muscles. A roughened area on the inner surface of the angle of the mandible is the attachment of the medial pterygoid muscle (Fig 1-10).

Fig 1-10 The internal or deep surface of the mandible. Note the submandibular fossa (green arrows), the mylohyoid line (red arrows), the lingula (blue arrow), and the mandibular foramen (yellow arrow).

The muscular tongue fills most of the oral cavity proper (the space interior to the dental arches) and is separated from the mandibular dental arch by the sublingual sulcus (floor of the mouth). The mucosa of the sulcus overlies several important structures: the submandibular duct, the lingual nerve, and more inferiorly the hypoglossal nerve, in addition to the vena comitans of the hypoglossal nerve. In the anterior region of the floor of the mouth are the sublingual glands, one on either side of the tongue, forming sublingual folds (plicae). The tongue is attached to the floor of the mouth and dental arch by the midline lingual frenulum. The mucosa of the floor of the mouth, as with the maxilla, transitions to gingiva on the medial aspect of the alveolar process of the mandible. Each lip also has a midline frenulum that attaches the lip to the alveolar bone of its associated dental arch. An overactive frenulum can cause mucogingival defects, which can have implications for esthetics and for endodontic implant placement.

Neurovascular supply to the mandible and associated structures

Blood supply. The mandibular region is supplied primarily by branches from the facial, lingual, and maxillary arteries. The facial artery is a branch of the external carotid artery, entering the facial region by curving around the inferior border of the mandible about midway between the mental tubercle and the angle of the mandible, and then running diagonally toward the corner of the mouth and then just lateral to the nose, where it becomes the angular artery. The facial artery gives off submental, inferior, and superior labial branches and a lateral nasal branch. The lingual artery supplies the tongue by way of deep lingual and dorsal lingual branches. The sublingual artery supplies the floor of the mouth, the sublingual salivary gland, and surrounding muscles.

The inferior alveolar artery originates from the maxillary artery in the infratemporal fossa and travels with the inferior alveolar nerve through the mandibular foramen into the mandibular canal, where it gives off branches to the pulp and periodontium of mandibular teeth. A mental artery branches off, passes through the mental foramen with the mental nerve, and supplies the lower lip and chin area. A buccal artery, also from the maxillary artery, supplies much of the buccal region, anastomosing with the facial artery.

Nerve supply. The primary nerve supply to the mandibular region is via the mandibular division of the trigeminal nerve (V3). Branches from this nerve supply both sensory and motor innervation. The mandibular nerve (V3) emerges from the trigeminal ganglion by passing through the foramen ovale into the infratemporal fossa, where it gives off motor branches to the muscles of mastication along with tensor tympani and tensor veli palatini, and supplies the mylohyoid muscle and the anterior belly of the digastric muscle. The lingual nerve supplies general sensation to the anterior two-thirds of the tongue, the mucosa covering the floor of the mouth, and lingual gingiva associated with mandibular teeth. The buccal nerve supplies the skin of the buccal region and the buccal mucosa and buccal gingiva for both mandibular and maxillary teeth. The inferior alveolar branch travels through the mandibular foramen, giving off branches to tooth pulp and periodontium, and terminates by giving off mental and incisive branches, which supply the chin, lower lip, and gingiva in the region of the mandibular incisors.

Anatomical Danger Zones in Endodontic Surgery

In performing endodontic surgery, a number of anatomical, histologic, and neurovascular structures are vulnerable to damage. In order to avoid damaging these structures, a thorough understanding of the anatomy and histology associated with the areas adjacent to the roots of the teeth is imperative. The remainder of this chapter focuses on these “danger areas,” while chapter 2 focuses on the histology of the oral cavity.

Maxillary sinus (antrum of Highmore)

The maxillary sinus is one of the first of the paranasal sinuses to form during fetal development.2 As a person ages, the maxillary sinus expands laterally and inferiorly, until its floor finally lies about 4 to 5 mm inferior to the level of the floor of the nasal cavity.3–5 In edentulous areas, the sinus floor can drop to become nearly level with the height of the alveolar ridge; this pneumatization of the sinus has implications for oral surgical procedures such as implant and apical endodontic surgery. As the floor of the sinus continues to descend, it comes to lie in proximity to the apices of maxillary teeth (Fig 1-11), primarily the second premolar and the first and second molars.3 In rare cases, the floor of the sinus can extend as far anteriorly as the canine root.3 With time, the bone forming the floor of the sinus can thin considerably, allowing the roots to protrude into the sinus3 (Fig 1-12). Eberhardt et al6 showed in a CT study that the apex of the mesiobuccal root of the maxillary second molar was closest to the sinus floor. This relationship can often be adequately seen with panoramic radiography, but CT provides better resolution7 (Fig 1-13). Nimigean et al4 reported that alveolar recesses (depressions between root apices) were present in 52% of cases, increasing the risk of penetration into the antrum during surgical procedures. They described three different relationships between tooth roots and the floor of the sinus: (1) one in which there is a thick layer of bone between the root and the floor, (2) one in which there is only a very thin layer of bone between root and antrum, and (3) one in which the root apices penetrate into the floor of the sinus, with the roots being covered only by the sinus membrane.8–11 In the study by Nimigean et al,4 the buccal roots of the first and second molars were most likely to penetrate the sinus floor.

Fig 1-11 (a) Coronal CBCT image showing roots extending well superior to the floor of the sinus (red arrows). (b) The dissection also shows the floor of the sinus dropping down between the root apices (blue arrow).

Fig 1-12 (a and b) Notice the small fenestrations into the floor of the sinus; in addition, one can appreciate the close proximity of the greater palatine nerve to the palatal roots of the maxillary second and third molars (blue arrows). The CBCT image is aligned in the coronal plane of the first molar, showing the mesial buccal and palatal root.

Fig 1-13 (a) Panoramic reconstruction from a CBCT scan showing the relationship between the sinus floor and root apices. (b) CBCT image showing a multiplanar reconstruction (MPR).

The sinus membrane, the mucosa lining the maxillary sinus (Fig 1-14), is formed of an epithelial layer of pseudostratified ciliated columnar tissue (respiratory epithelium) sitting on a lamina propria; it is attached to the periosteum lining the bone, which forms the walls of the sinus. While Testori12 states that the normal thickness of this membrane is 0.13 to 0.5 mm, Janner et al13 reported that the thickness varies from 0.16 to 34.61 mm, with the mucosa being thicker in men than in women, and suggested that any thickening greater than 2 mm is pathologic. Srouji et al14 showed that the deeper layer of the membrane contains osteoprogenitor cells that could potentially be stimulated to differentiate into osteoblasts, which could then build up the sinus floor. When procedures affecting the floor of the maxillary sinus are performed (eg, for placing implants), the sinus membrane is often elevated from the floor of the sinus, so that it remains intact during the procedure. It has been shown that damage to the membrane can make the sinus more susceptible to infection and other complications.15 Yildirim et al16 showed that in cases where the floor of the sinus is indented by maxillary teeth, the mucosa tends to be thicker than the floors of sinuses without indentations.

Many maxillary sinuses are partially or completely divided into smaller compartments by bony septa, often called Underwood’s septa12,17–21 (see Fig 1-2). Maestre-Ferrin et al17 report that between 13% and 35.3% of sinuses have some sort of septum. Krennmair et al20 suggest that these septa often result from bone resorption of the floor of the sinus after tooth loss or from increased pneumatization over time. According to Krennmair et al,20 these septa tend to form most frequently in the anterior part of the sinus, but other studies reported prevalence in other locations.22–25 Most of the septa are oriented vertically, but Güls¸en et al19 report on two cases showing horizontal septation of the sinus and suggest that this will affect the ability to elevate the sinus membrane to place implants. It is important to examine the sinus radiographically for septa before performing procedures that could disturb the floor or membrane of the maxillary sinus. Partial blockage of the ostium, anthroliths in the sinus, and other benign to aggressive pathologies might be present on CBCTs and should be evaluated whenever the sinus is present in the scan (Fig 1-15).

The function of the paranasal sinuses remains largely unknown. Theories include roles such as humidification and warming of inspired air, assisting in regulating intranasal pressure, increasing the surface area of the olfactory membrane, lightening the skull to maintain proper head balance, imparting resonance to the voice, absorption of shocks to the head, contributing to facial growth, and perhaps as evolutionary remains of useless air spaces.3 When radiographic imaging includes these areas, any abnormalities should be noted.

Fig 1-14 A portion of the sinus membrane (red arrows) was left on the anterior floor of the maxillary sinus. Note the double ostium (blue arrows) in the posterior superior portion of the sinus.

Fig 1-15 A small sinus septum is present on this CBCT image (red arrows). The sinus membrane is also visible on this reconstruction (blue arrows).

Maxillary incisive fossa and canals

The maxillary incisive canal (Fig 1-16), so named because of its proximity to the maxillary incisors, is a cylindric or funnel-shaped tube connecting the nasal cavity with the oral cavity and transmitting the nasopalatine nerve. The sphenopalatine artery, a terminal branch of the maxillary artery, anastomoses with the greater palatine artery in the canal. The incisive canal opens in the hard palate just posterior to the central incisors by way of the incisive fossa. The incisive canals are larger, and the bone anterior to the canal is thicker in men than in women.26–28 The bone anterior to the canal thins with age, even in dentulous patients. The canal is shorter in edentulous patients than in dentulous patients.27 Careful attention should be paid when performing apical surgery, root canal therapy, or implant surgery in close proximity to this area.

Fig 1-16 (a) The incisive canal opens in the hard palate just posterior to the central incisors by way of the incisive fossa (red arrow). (b) CBCT image of the incisive canal and foramen. 1, coronal; 2, sagittal; 3, superior axial; 4, middle axial; 5, inferior axial.

Greater palatine foramen

While traditional textbooks29 describe the greater palatine foramen as being at the lateral extremity of the transverse palatine suture or opposite the maxillary second molar, it is actually more posteriorly located—either opposite or posterior to the third molar, about 1.5 cm from the median suture, and about 0.2 cm from the posterior border of the hard palate30–32; it can be as far as 0.47 cm from the posterior margin of the hard palate in some ethnic groups.31 The opening is most often in an inferior or vertical position and less commonly in an anterior or horizontal position,30 although this varies with ethnicity.32 A bony projection similar to the lingula is occasionally present along the posterior boundary of the foramen, separating it from the lesser palatine foramen.30

The lesser palatine foramen is located posterior to the greater palatine foramen. Although there is typically only one on each side, there can be two or more foramina per side. The most common position of the lesser palatine foramen is at the junction of the palatine bone and the inner lamella of the pterygoid plate.31

The greater palatine foramen is the opening for the greater palatine canal (Fig 1-17), which transmits the greater and lesser palatine nerves and the descending palatine artery, which then branches into greater and lesser palatine arteries before exiting their respective foramina. The walls of the greater palatine canal are formed anteriorly by the infratemporal surface of the maxilla, posteriorly by the pterygoid process of the sphenoid bone, and medially by the perpendicular plate of the palatine process.33 The close proximity of these structures, especially when dealing with palatal surgical approaches to the maxillary second and third molars (see Fig 1-12), requires vigilant attention to minimize possible postsurgical complications.

Fig 1-17 The greater palatine canal is in close proximity to the maxillary palatal root of the second molar and should be given great care in surgical planning and treatment. The red arrows indicate the position of the canal and foramen in multiplanar CBCT imaging as well as dry skull anatomy.

Greater palatine nerve

Before or after exiting the greater palatine foramen, the greater palatine nerve splits into several branches that supply sensory and secretory fibers to the mucous membranes of the hard palate and palatal gingiva.34 Because of this branching pattern, one should avoid incisions without first dissecting out these vital structures.

Mandibular canal

The mandibular canal begins at the mandibular foramen on the inner surface of the ramus of the mandible and continues downward and forward in the body of the mandible, approximately midway between the superior and inferior borders of the mandible (Fig 1-18). However, there is variation in the vertical position of the canal.35 In one study,36 it was reported that the average distance between the inferior border of the mandible and the mandibular canal was 10.52 mm. The mean maximum diameters of the mandibular canal, inferior alveolar nerve, inferior alveolar artery, and inferior alveolar vein were 2.52, 1.84, 0.42, and 0.58 mm, respectively.36 Gowgiel37 reported that the canal was located near the lingual cortical plate and that there was thicker cortical and trabecular bone on the buccal side of the canal than on the lingual side. Monaco et al38 showed that the roots of third molar teeth can be located either buccal or lingual to the mandibular canal or that the canal can pass between the roots. They also showed that with an impacted third molar (Fig 1-19), the roots can cause a deviation or a narrowing of the canal.39 On radiographs, the mandibular canal often appears as a pair of parallel white lines with a dark region between them. On CBCT scans, the canal often appears as round or oval in cross section but sometimes is not readily visible. Wadu et al40 reported that there is a lot of variation in the radiographic appearance of the canal, as well as the actual composition of the canal wall—what appears to be radiopaque cortical bone on radiographs often turns out to be porous and trabecular in dissections.

Fig 1-18 The mandibular canal shown in MPR CBCT reconstruction as well as dissection. The red arrows show the course of the canal and nerve. In this case, the canal loops in the anterior region (blue arrow). This looping must be considered for surgical treatments in this area.

Fig 1-19 Impacted third molar. The roots can cause deviation or narrowing of the canal. Red highlighting emphasizes the proximity of the roots to the canal. This MPR CBCT reconstruction shows that care must be taken when planning treatment.

The roots of molars can be located lingual or buccal to the canal, or the canal can be located apical to the roots. In some cases the canal passes between the roots, and in rare cases the roots go around the canal and then rejoin.41 In some cases the canal runs in the lower half of the body of the mandible, and in some cases the upper half.424343444539