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- Herausgeber: John Wiley & Sons
- Kategorie: Fachliteratur
- Sprache: Englisch
IMPACTED THIRD MOLARS Gain confidence in third molar extractions, with advice relevant to general, specialty, and mobile third molar practice dentists Impacted Third Molars, Second Edition, provides dentists with all the information they need to confidently remove impacted third molars, from case selection and imaging to sedation and patient management. Step-by-step surgical procedures support dentists in the successful surgical removal of third molars. The second edition has been updated throughout with new information and advances, and seven new chapters cover local anesthesia, imaging, patient management, platelet rich fibrin, case studies, and mobile third molar practices. The book includes all the information dentists need to efficiently, profitably, and safely remove impacted third molars. Photographs and illustrations depict the concepts described, and a companion website offers video clips. Impacted Third Molars: * Gives dentists all the information they need to consider mobile third molar practice, which provides more freedom, less stress, less overhead, and more profitability * Helps dentists stop referring third molars and remove them early in the teen years before roots develop * Features the author's seven-step procedure for removing impacted third molars * Includes a chapter describing the author's mobile third molar practice, with a procedure manual * Offers procedural videos on a companion website Impacted Third Molars, Second Edition is an essential reference for general dentists and specialists alike.
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Impacted Third Molars
Edited by
John Wayland San Francisco Bay Area, California, USA
Second Edition
This second edition first published 2024
© 2024 John Wiley & Sons, Inc.
Edition History
John Wiley & Sons, Inc. (1e, 2018)
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Library of Congress Cataloging-in-Publication Data
Names: Wayland, John, editor.
Title: Impacted third molars / edited by John Wayland.
Description: Second edition. | Hoboken, NJ : Wiley Blackwell, 2024. | Preceded by Impacted third molars / John Wayland. 2018. | Includes bibliographical references and index.
Identifiers: LCCN 2023003653 (print) | LCCN 2023003654 (ebook) | ISBN 9781119930303 (hardback) | ISBN 9781119930310 (ebook) | ISBN 9781119930327 (epub) | ISBN 9781119930334 (oBook)
Subjects: MESH: Molar, Third--surgery | Tooth, Impacted--surgery | Tooth Extraction--methods
Classification: LCC RK521 (print) | LCC RK521 (ebook) | NLM WU 605 | DDC 617.6/43--dc23/eng/20230620
LC record available at https://lccn.loc.gov/2023003653
LC ebook record available at https://lccn.loc.gov/2023003654
Cover Image: Courtesy of John Wayland
Cover Design: Wiley
Set in 9.5/12.5pt STIXTwoText by Integra Software Services Pvt. Ltd, Pondicherry, India
To my wife and best friend, Betty Yee
Contents
Cover
Title Page
Copyright Page
Dedication
List of Contributors
Preface
1 Anatomy
2 Case Selection
3 Complications
4 Workspace: Equipment, Instruments, and Materials
5 Surgical Principles and Techniques
6 Pharmacology
7 Sedation Techniques
8 Sedation Emergencies and Monitoring
9 Documentation
10 Local Anesthesia
11 Imaging
12 Patient Management
13 PRF
14 Case Studies – Lessons Learned
15 Insurance and Third Molars
16 The Mobile Third Molar Practice
17 My Mobile Practice
18 My Third Molar Journey
Index
End User License Agreement
List of Tables
CHAPTER 02
Table 2.1 ASA physical status...
Table 2.2 Classification of blood...
CHAPTER 03
Table 3.1 Combined findings of...
Table 3.2 Contributing factors in...
Table 3.3 Symptoms and signs...
Table 3.4 Summary of space...
CHAPTER 04
Table 4.1 Characteristics of surgical...
Table 4.2 Author’s...
Table 4.3 Disposable materials used...
CHAPTER 05
Table 5.1 Surgical drill advantage...
Table 5.2 Ideal trough characteristics...
Table 5.3 Ideal section characteristics...
Table 5.4 Third molar crown...
Table 5.5 Removal of third...
CHAPTER 06
Table 6.1 Characteristics of triazolam...
Table 6.2 Characteristics of intravenous...
Table 6.3 Characteristics of oral...
Table 6.4 Characteristics of IV...
Table 6.5 Characteristics of nitrous...
Table 6.6 Characteristics of xylocaine...
Table 6.7 Maximum local anesthetic...
Table 6.8 Concentration of common...
Table 6.9 Characteristics of hydrocodone...
Table 6.10 Characteristics of oxycodone...
Table 6.11 Characteristics of fentanyl...
Table 6.12 Characteristics of IV...
Table 6.13 Characteristics of ibuprofen...
Table 6.14 Characteristics of acetaminophen...
Table 6.15 Efficacy of oral...
Table 6.16 Characteristics of injectable...
Table 6.17 Characteristics of oral...
Table 6.18 Characteristic of amoxicillin...
Table 6.19 Characteristics of clindamycin...
Table 6.20 Characteristics of metronidazole...
CHAPTER 07
Table 7.1 Conditions warranting referral...
Table 7.2 N2O required for...
Table 7.3 Methods for finding...
CHAPTER 10
Table 10.1 Rapid development in...
Table 10.2 Maximum recommended dose...
Table 10.3 Local anesthetics commonly...
Table 10.4 A local anesthetic...
CHAPTER 11
Table 11.1 Average dental radiation...
CHAPTER 12
Table 12.1 Post-extraction bleeding...
CHAPTER 13
Table 13.1 Misch bone density...
Table 13.2 Comfort between the...
List of Illustrations
CHAPTER 01
Figure 1.1 The 12 cranial...
Figure 1.2 The fifth cranial...
Figure 1.3 Sensory innervation of...
Figure 1.4 Mandibular nerve branches...
Figure 1.5a The Maxillary Artery...
Figure 1.5b Branches of the...
Figure 1.6 Buccal fat pad...
Figure 1.7 Submandibular fossa.(Adapted...
Figure 1.8 Third molar roots...
Figure 1.9 Maxillary sinus coronal...
Figure 1.10 Boundaries of the...
CHAPTER 02
Figure 2.1a Health History(Reproduced...
Figure 2.1b Health History Update...
Figure 2.1c Patient Interview(Reproduced...
Figure 2.2 Mallampati classification can...
Figure 2.3 Patients with severe...
Figure 2.4 Surgical difficulty based...
Figure 2.5 Surgical difficulty based...
Figure 2.6 Surgical difficulty by...
Figure 2.7a Conical...
Figure 2.7b Divergent...
Figure 2.8a Long, thin, curved...
Figure 2.8b Short, thick, straight...
Figure 2.9a Wide periodontal ligament...
Figure 2.9b Third molar follicle...
Figure 2.9c Narrow periodontal ligament...
Figure 2.10a Dense bone...
Figure 2.11 Continuous white lines...
Figure 2.12 A radiolucent band...
Figure 2.13 A radiolucent apex...
Figure 2.14 Narrowing of the...
CHAPTER 03
Figure 3.1 Nerves in close...
Figure 3.2 Radiographic indications of...
Figure 3.3 Superimposition of roots...
Figure 3.4 One study’...
Figure 3.5 IAN “true...
Figure 3.6 Post extraction socket...
Figure 3.7 Chlorhexidine rinse...
Figure 3.8b Dry socket paste...
Figure 3.9 Pericoronitis – food...
Figure 3.10 Pericoronitis bone loss...
Figure 3.11 Fracture of the...
Figure 3.12a #32 Deep Impaction...
Figure 3.12b #32 Deep Impaction...
Figure 3.13 Buccal fat pad...
Figure 3.14a Third molar in...
Figure 3.14b Third molar in...
Figure 3.15 Third molar in...
Figure 3.16 Weider retractor and...
CHAPTER 04
Figure 4.1 Rolling Table Adjusts...
Figure 4.2 Oral surgery Chair...
Figure 4.3 Loupe magnification can...
Figure 4.4 Loupe lighting can...
Figure 4.5a Impact Air 45...
Figure 4.5b Sabra OMS45.(Reproduced...
Figure 4.6a Hall type surgical...
Figure 4.6b Hall type drill...
Figure 4.7a Motor...
Figure 4.7b Foot pedal...
Figure 4.7c Drill...
Figure 4.9 Author’s...
Figure 4.10 “X Cube...
Figure 4.11 Photo of Author...
Figure 4.12a Weider retractor.(Reproduced...
Figure 4.12b Weider retractor in...
Figure 4.13 Wheel and axle...
Figure 4.14a #30 Cryer elevator...
Figure 4.14b #31 Cryer elevator...
Figure 4.15a Seldin elevator #1...
Figure 4.15b Seldin elevator #1...
Figure 4.16 Crane Pick.(Reproduced...
Figure 4.17 Cogswell B.(Reproduced...
Figure 4.18 Incline plane displaces...
Figure 4.19 301 Elevator.(Reproduced...
Figure 4.20 34 elevator.(Reproduced...
Figure 4.21 46R elevator.(Reproduced...
Figure 4.22 Hu-Friedy El3CSM...
Figure 4.23a #19 Warwick-James...
Figure 4.23b #20 Warwick-James...
Figure 4.24a #190 Modified Woodward...
Figure 4.24b #191 Modified Woodward...
Figure 4.25a #6 Potts.(Reproduced...
Figure 4.25b #7 Potts.(Reproduced...
Figure 4.26 Periotome.(Reproduced with..)
Figure 4.27 Proximator.(Reproduced with...
Figure 4.28 Luxator (luxating elevator...
Figure 4.29 Spade Proximator.(Reproduced...
Figure 4.30a Latex glove...
Figure 4.30b Nitrile glove.
Figure 4.31 Surgical masks reduce...
Figure 4.32 Goggles and face...
Figure 4.33 Surgical gowns and...
Figure 4.34 Disposable surgical suction...
Figure 4.35 Polyglycolic acid absorbable...
Figure 4.36 (a) Tapered needle...
Figure 4.37 The 3/8...
Figure 4.38 Scalpel blades are...
Figure 4.39 #12 and #15...
Figure 4.40 Filled 4 ×...
Figure 4.41 Filled gauze 4...
Figure 4.42 Irrigation syringes are...
CHAPTER 05
Figure 5.1 Operating room asepsis...
Figure 5.2 Inspection of flap...
Figure 5.3a Round...
Figure 5.3c Lindemann...
Figure 5.4b S Shape...
Figure 5.4d Modified Triangle...
Figure 5.6 # 9 Periosteal elevator...
Figure 5.7 Minnesota retractor in...
Figure 5.8 Troughing coronal view...
Figure 5.9 Trough complete...
Figure 5.11a Trough deeper on...
Figure 5.11b IAN “safe...
Figure 5.12 Section complete...
Figure 5.14 Ideal section shown...
Figure 5.15 Split with 46R...
Figure 5.16 Elevator delivery with...
Figure 5.17a Debridement of socket...
Figure 5.17b Thorough irrigation of...
Figure 5.18 Single suture closure...
Figure 5.19a #12 blade improves...
Figure 5.19b Flap includes premolar...
Figure 5.20 Delivery with 46R...
Figure 5.21a Laster retractor...
Figure 5.21b Laster retractor in...
Figure 5.22a Removal of bone...
Figure 5.22b Removal of bone...
Figure 5.23a Removal of tissue...
Figure 5.23b Removal of tissue...
Figure 5.24 Passive closure without...
Figure 5.25 Technique for removal...
Figure 5.26 Horizontal section should...
Figure 5.27 Deep vertical impactions...
Figure 5.28 Third molar crown...
CHAPTER 06
Figure 6.1 Pharmacokinetics describes how...
Figure 6.2 Pharmacodynamics describes how...
Figure 6.3 Poppy pod and...
Figure 6.4 Nobel Prize winners...
CHAPTER 07
Figure 7.1 Dr. Horace Wells...
Figure 7.2 Dr. William T...
Figure 7.3 Dr. Niels Jorgenson...
Figure 7.4 Sedation continuum...
Figure 7.6a Nitrous oxide ball...
Figure 7.6b Digital flow meter...
Figure 7.7 Scavenging nasal hood...
Figure 7.8 Pill crusher...
Figure 7.9b IV Administration Set...
Figure 7.9c 22 Gauge Insyte...
Figure 7.10a Antecubital fossa veins...
Figure 7.10b Dorsum of the...
Figure 7.11 Patients vary in...
CHAPTER 08
Figure 8.1 Airway obstruction / respiratory...
Figure 8.2 Allergic reaction and...
Figure 8.3 Emesis and aspiration...
Figure 8.4 Angina pectoris / myocardial...
Figure 8.5 Cardiac arrest algorithm...
Figure 8.6 Hypotension algorithm...
Figure 8.7 Hypertension algorithm.
Figure 8.8 Seizure algorithm...
Figure 8.9 Hypoglycemia algorithm.
Figure 8.10 Syncope algorithm...
Figure 8.11 Finger sensor...
Figure 8.12 Edan M3 pulse...
Figure 8.13 The oxygen dissociation...
Figure 8.14 Capnometer.(Reproduced with..)
Figure 8.15 CO2 sampling nasal...
Figure 8.16 Capnography parameters.(Reproduced...
Figure 8.17a Pretracheal stethoscope bell...
Figure 8.17b Custom earpiece...
CHAPTER 09
Figure 9.1 Malpractice trial judge...
Figure 9.2 Third molar impaction...
Figure 9.3 Intravenous sedation consent...
CHAPTER 10
Figure 10.1 Injection site for...
Figure 10.2 Landmarks for inferior...
Figure 10.3 Target area of...
Figure 10.4 An imaginary line...
Figure 10.5 Insertion below the...
Figure 10.6 Syringe parallel with...
Figure 10.7 Injection site at...
CHAPTER 11
Figure 11.1 Sir Wilhelm Conrad...
Figure 11.1a and 11.1b...
Figure 11.2a and 11.2b...
Figure 11.3 a,b,c...
Figure 11.4 Superimpositiona continuous, unbroken...
CHAPTER 12
Figure 12.1 Communication.Einar Faanes...
Figure 12.2 The sedation continuum...
Figure 12.3 Rester’s...
CHAPTER 13
Figure 13.1 Robert E. Marx...
Figure 13.2 SCILOGEX clinical centrifuge...
Figure 13.3a BectonDickenson Vacutainer and...
Figure 13.3b Red blood collection...
Figure 13.3c Blood draw with...
Figure 13.4a Unbalanced...
Figure 13.4b Balanced.
Figure 13.5a Blood after centrifuge...
Figure 13.5b Fibrin clot removed...
Figure 13.5c Metal trays for...
CHAPTER 14
Figure 14.1 Preop panoramic X...
Figure 14.2 Not the actual...
Figure 14.3 Full bony impacted...
Figure 14.4 25-year-old...
Figure 14.5 16-year-old...
Figure 14.5a BMI 66.1...
Figure 14.5b 5’1...
Figure 14.6 Pain lower left...
Figure 14.7 Weider retractor and...
Figure 14.8 Laceration of lip...
Figure 14.9 Maxillary third molar...
Figure 14.10a Infratemporal fossa in...
Figure 14.10b Infratemporal fossa boundaries...
CHAPTER 15
Figure 15.1 Full bony impactions...
Figure 15.2 Third molars with...
CHAPTER 16
Figure 16.1a and 16.1b...
CHAPTER 18
Figure 18.1 50% of collections...
Figure 18.2 Portable suction unit...
Figure 18.3 X Cube motor...
Figure 18.4 Sedation permit.
Guide
Cover
Title Page
Copyright Page
Dedication
Table of Contents
List of Contributors
Preface
Begin Reading
Index
End User License Agreement
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List of Contributors
Jamieson Brady, DDS
Faculty, Bay Area IV Wisdom Private Practice, Chicago, IL. SUNY Buffalo School of Dental Medicine, 2016 University at Buffalo summa cum laude Dental Degree in 2016 Oral & Maxillofacial Surgery internship at Chicago Cook County Hospital Member of the American Dental Association
Matthew Diercks, DDS
Faculty, Bay Area IV Wisdom Private Practice, University of the Pacific School of Dentistry Private Practice, Los Gatos, CA Faculty, Bay Area IV Wisdom University of the Pacific Dental Degree in 1998 Member of the American Dental Association
Andy Le, DDS
Faculty, Bay Area IV Wisdom Private Practice, San Leandro, CA Faculty, Bay Area IV Wisdom Marquette University Dental Degree in 2001 Diplomat of the American Board of Oral Implantology and Implant Dentistry Fellow of the International Congress of Oral Implantology Member of the American Dental Association.
Preface
Most dentists receive minimal exodontia training in dental school. All difficult extractions and surgical procedures are referred to specialty programs: OMFS, AEGD, and GPR. Exodontia courses are hard to find after dental school, especially courses for the removal of impacted third molars. Most oral surgeons are reluctant to share their third molar knowledge. Very few general dentists have the third molar experience or training to pass on to their colleagues.
The removal of third molars is one of the most common procedures in dentistry. The majority of impacted third molars are removed by oral surgeons who also do hospital procedures, including orthognathic, cleft palate, TMJ, reconstructive, and other complex surgical procedures. Compared to complex oral surgery, the removal of third molars is a relatively simple procedure that can be done safely by most general practitioners.
Why Should YOU Remove Third Molars?
The removal of impacted third molars is a predictable and profitable procedure that benefits your practice and patients. Proper case selection and surgical procedure will minimize complications and can be learned by any dentist. The author has removed more than 25,000 wisdom teeth with no significant complications (i.e., no permanent paresthesia).
Fear of the unknown is a common barrier preventing dentists from removing third molars. They often ask themselves, “Is this third molar too close to the inferior alveolar nerve? How much bleeding is normal? What should I do if there’s infection?” You probably asked similar questions with your first injection, filling, root canal, or crown. Now those procedures are routine. The removal of third molars, including impactions, will also become routine.
It’s estimated that 10 million wisdom teeth are removed in the United States every year. Imagine a dentist who refers only one third molar patient per month for the removal of four third molars. If the cost per patient averaged $1500, including sedation, this dentist would refer $360,000 in 20 years! Conversely, the dentist could have treated his own patients and used the $360,000 to fund a retirement plan, pay off a mortgage, or send his or her children to college.
Your patients don’t want to be referred out of your office. They prefer to stay with a doctor and staff that they know and trust.
Prophylatic Removal of Third Molars Controversy
There is no debate about the removal of third molars when pain or pathology is present. However, the prophylactic removal of third molars is controversial. There are many studies published to support either side of this controversy. However, the author believes common sense would support prophylactic removal.
Most patients with retained third molars will develop pathology. Third molars are difficult to keep clean. Every hygienist routinely records deep pockets near retained third molars. Caries are commonly found on third molars or the distal of second molars.
It is well documented that early removal of wisdom teeth results in fewer surgical complications. The incidence of postoperative infections and dry socket is also reduced.
Intended Audience
This book is intended for general dentists who would like to predictably, safely, and efficiently remove impacted third molars. It can be read cover to cover or by selected areas of interest. Emphasis has been placed on practical and useful information that can be readily applied in the general dentistry office.
1 Anatomy
Third molar surgical complications can be minimized or eliminated with proper case selection, surgical protocol, and a thorough knowledge of oral anatomy. Removal of third molars, including impactions, can become routine. A brief review of oral anatomy related to third molars is the first step in your journey to become proficient in the safe removal of impacted third molars. The structures relevant in the safe removal of third molars are:
Nerves
Blood vessels
Buccal fat pad
Submandibular fossa
Maxillary sinus
Infratemporal fossa
Nerves
In classical anatomy there are 12 paired cranial nerves (I–XII) providing sensory and motor innervation to the head and neck. (See Figure 1.1.)
Figure 1.1 The 12 cranial nerves emerge from the ventral side of the brain. (Drawing by Michael Brooks).
The trigeminal nerve(V), the fifth cranial nerve, is responsible for sensations of the face and motor functions of the muscles of mastication. This cranial nerves derives its name from the fact that each trigeminal nerve (one on each side of the pons) has three major branches: the ophthalmic nerve (V1), the maxillary nerve (V2), and the mandibular nerve (V3). (See Figure 1.2.) The ophthalmic and maxillary nerves are purely sensory, while the mandibular nerve has sensory and motor functions. (See Figure 1.3.)
Figure 1.2 The fifth cranial nerve and three branches of the trigeminal nerve: (1) the ophthalmic nerve, (2) the maxillary nerve, and (3) the mandibular nerve. (by Henry Vandyke Carter / Wikimedia commons / Public Domain).
Figure 1.3 Sensory innervation of the three branches of the trigeminal nerve. (by Madhero88 / Wikimedia commons / CC BY 3.0).
The mandibular nerve (V3) is the largest of the three branches or divisions of the trigeminal nerve, the fifth (V) cranial nerve. (See Figure 1.4.) It is made up of a large sensory root and a small motor root. The mandibular nerve exits the cranium through the foramen ovale and divides into an anterior and posterior trunk in the infratemporal fossa. The mandibular nerve divides further into 9 main branches, 5 sensory and 4 motor.
Figure 1.4 Mandibular nerve branches from the main trunk; anterior, and posterior divisions. (Drawing by Michael Brooks).
The infratemporal fossa also contains many blood vessels in addition to nerves. This becomes important during the removal of high, palatally placed, maxillary third molars. These teeth may be displaced into the infratemporal fossa which contains these vital structures.
The five sensory branches of the mandibular nerve control sensation to teeth, tongue, mucosa, skin, and dura.
Inferior Alveolar – exits the mental foramen as the mental nerve and continues as the incisive nerve.
The nerve to mylohyoid is a motor and sensory branch of the inferior alveolar nerve
The nerve to anterior belly of the digastric muscle is a motor branch of the inferior alveolar nerve
Mean inferior alveolar nerve diameter is 4.7 mm.
1
Lingual – lies under the lateral pterygoid muscle, medial to and in front of the inferior alveolar nerve.
Carries the chorda tympani nerve affecting taste and salivary flow.
May be round, oval, or flat and varies in size from 1.53 mm to 4.5 mm.
2
Average diameter of the main trunk of the lingual nerve is 3.5 mm.
3
Auriculotemporal – innervation to the skin on the side of the head.
Buccal or long buccal – innervation to the cheek and second and third molar mucosa.
Meningeal – innervation to dura mater.
The four motor branches of the mandibular nerve control the movement of eight muscles, including the four muscles of mastication: the masseter, the temporal, and the medial and lateral pterygoids. The other four muscles are the tensor veli palatini, tensor tympani, mylohyoid, and the anterior belly of the digastric. Nerves to the tensor veli tympani and tensor palatini are branches of the medial pterygoid nerve. Nerves to the mylohyoid and anterior belly of the digastric muscles are branches of the inferior alveolar nerve.
Masseteric
Deep temporal
Lateral pterygoid
Medial pterygoid
Nerve Complications Following the Removal of Impacted Third Molars
Injury to the inferior alveolar, lingual, mylohyoid, and buccal nerves may cause altered or complete loss of sensation of the lower 1/3 of the face on the affected side.
The majority of serious nerve complications result from inferior alveolar or lingual nerve injuries. Most surgical injuries to the inferior alveolar nerve and lingual nerve cause temporary sensory change, but in some cases they can be permanent. Injury to these nerves can cause anesthesia (loss of sensation), paresthesia (abnormal sensation), hypoesthesia (reduced sensation), or dysesthesia (unpleasant abnormal sensation). Injury to the lingual nerve and associated chorda tympani nerve can also cause loss of taste of the anterior 2/3 of the tongue.
Damage to the mylohyoid nerve has been reported to be as high as 1.5% following lower third molar removal, but this is probably due to the use of lingual retraction.4 Most third molars can be removed by utilizing a purely buccal technique. Utilizing this technique, it is not necessary to encroach on the lingual tissues or to remove distal, distolingual, or lingual bone.5
A search of the literature found no specific reports of long buccal nerve involvement (AAOMS white paper, March 2007), although one article did note long buccal involvement when the anatomical position was aberrant. In this case, the long buccal nerve was coming off the inferior alveolar nerve once it was already in the canal and coming out through a separate foramen on the buccal side of the mandible.6 Long buccal nerve branches are probably frequently cut during the incision process, but the effects are generally not noted.7
Blood Vessels
Life-threatening hemorrhage resulting from the surgical removal of third molars is rare. However, copious bleeding from soft tissue is relatively common. One source of bleeding during the surgical removal of third molars is the inferior alveolar artery and/or vein. These central vessels can be cut during sectioning of third molars leading to profuse bleeding. The path of vessels leading to the inferior alveolar neurovascular bundle begins with the common carotid arteries and the heart.
The common carotid arteries originate close to the heart and divide to form the internal and external carotid arteries. The left and right external carotid arteries provide oxygenated blood to the areas of the head and neck outside the cranium. These arteries divide within the parotid gland into the superficial temporal artery and the maxillary artery. The maxillary artery has three portions; maxillary, pterygoid, and pterygomaxillary. (See Figures 1.5a and 1.5b.)
Figure 1.5a The Maxillary Artery. (Henry Gray / Wikimedia commons / Public Domain).
Figure 1.5b Branches of the maxillary artery depicting maxillary, pterygoid, and pterygomaxillary portions. (by Henry Vandyke Carter / Wikimedia commons / Public Domain).
The first portion of the maxillary artery divides into five branches. The inferior alveolar artery is one of the five branches of the first part of the maxillary artery. The inferior alveolar artery joins the inferior alveolar nerve and vein to form the inferior alveolar neurovascular bundle within the mandible. Three studies confirm that the inferior alveolar vein lies superior to the nerve and that there are often multiple veins. The artery appears to be solitary and lies on the lingual side of the nerve, slightly above the horizontal position.8
Bleeding during and after third molar impaction surgery is expected. Local factors resulting from soft-tissue and vessel injury represent the most common cause of postoperative bleeding.9 Systemic causes of bleeding are not common, and routine preoperative blood testing of patients, without a relevant medical history, is not recommended.10
Hemorrhage from mandibular molars is more common than bleeding from maxillary molars (80% and 20%, respectively),11 because the floor of the mouth is highly vascular. The distal lingual aspect of mandibular third molars is especially vascular and an accessory artery in this area can be cut leading to profuse bleeding.12,13 The most immediate danger for a healthy patient with severe post-extraction hemorrhage is airway compromise.14
Most bleeding following third molar impaction surgery can be controlled with pressure. Methods for hemostasis will be discussed further in Chapter 3.
Buccal Fat Pad
The buccal fat pad is a structure that may be encountered when removing impacted third molars. It is most often seen when flap incisions are made too far distal to maxillary second molars. It is a deep fat pad located on either side of the face and is surrounded by the following structures. (See Figure 1.6.)
Figure 1.6 Buccal fat pad. (By Otto Placik / Wikimedia commons / CC BY 3.0).
Anterior – angle of the mouth
Posterior – masseter muscle
Medial – buccinator muscle
Lateral – platysma muscle, subcutaneous tissue, and skin
Superior – zygomaticus muscles
Inferior – depressor anguli oris muscle and the attachment of the deep fascia to the mandible
Zhang, Yan, Wi, Wang, and Liu reviewed the anatomical structures of the buccal fat pad in 11 head specimens (i.e., 22 sides of the face).
The enveloping, fixed tissues and the source of the nutritional vessels to the buccal fat pad and its relationship with surrounding structures were observed in detail. Dissections showed that the buccal fat pad can be divided into three lobes – anterior, intermediate, and posterior, according to the structure of the lobar envelopes, the formation of the ligaments, and the source of the nutritional vessels. Buccal, pterygoid, pterygopalatine, and temporal extensions are derived from the posterior lobe. The buccal fat pad is fixed by six ligaments to the maxilla, posterior zygoma, and inner and outer rim of the infraorbital fissure, temporalis tendon, or buccinator membrane. Several nutritional vessels exist in each lobe and in the subcapsular vascular plexus forms. The buccal fat pads function to fill the deep tissue spaces, to act as gliding pads when masticatory and mimetic muscles contract, and to cushion important structures from the extrusion of muscle contraction or outer force impulsion. The volume of the buccal fat pad may change throughout a person’s life.15
Submandibular Fossa
The submandibular fossa is a bilateral space located in the mandible, medial to the body of the mandible, and below the mylohyoid line. (See Figure 1.7.) It contains the submandibular salivary gland which produces 65–70% of our saliva.
Figure 1.7 Submandibular fossa. (Adapted from Henry Vandyke Carter, via Wikimedia Commons).
Third molar roots are often located in close proximity to the submandibular space. (See Figure 1.8.) The lingual cortex in this area may be thin or missing entirely. Therefore, excessive or misplaced force can dislodge root fragments or even an entire tooth into the adjacent submandibular space.16
Figure 1.8 Third molar roots near submandibular fossa. (Reproduced with permission of Dr. Jason J. Hales, DDS).
Patients presenting with partially impacted third molars can develop pericoronitis. This localized infection can spread to the submandibular, sublingual, and submental spaces. Bilateral infection of these spaces is known as Ludwig’s angina.17 Prior to the advent of antibiotics this infection was often fatal due to concomitant swelling and compromised airway.
Maxillary Sinus
The maxillary sinus is a bilateral empty space located within the maxilla, above the maxillary posterior teeth. It is pyramidal in shape consisting of an apex, base, and four walls. (See Figure 1.9 and Box 1.1.)
Figure 1.9 Maxillary sinus coronal view. (by Henry Vandyke Carter / Wikimedia commons / Public Domain).
Box 1.1 Boundaries of the maxillary sinus.
Apex – pointing towards the zygomatic process
Anterior wall – facial surface of the maxilla
Posterior wall – infratemporal surface of the maxilla
Superior – floor of the orbit
Inferior – alveolar process of the maxilla
Base – cartilaginous lateral wall of the nasal cavity
The size and shape of the maxillary sinus varies widely among individuals and within the same individual. The average volume of a sinus is about 15 ml (range between 4.5 and 35.2 ml).18
Maxillary third molar teeth and roots are often in close proximity to the maxillary sinus. The distance between the root apices of the maxillary posterior teeth and the sinus is sometimes less than 1 mm.19 Complications related to the removal of maxillary third molars include sinus openings, displacement of roots or teeth into the sinus, and postoperative sinus infections.
Infratemporal Fossa
The infratemporal fossa is an irregularly shaped space located inferior to the zygomatic arch and posterior to the maxilla. Six structures form its boundaries. (See Figure 1.10 and Box 1.2.)
Figure 1.10 Boundaries of the infratemporal fossa. (Reproduced with permission from Joanna Culley BA(hons) IMI, MMAA, RMIP).
Box 1.2 Boundaries of the infratemporal fossa.
Anterior: posterior maxilla
Posterior: tympanic plate and temporal bone
Medial: lateral pterygoid plate
Lateral: ramus of the mandible
Superior: greater wing of the sphenoid bone
Inferior: medial pterygoid muscle
Although rare, there are documented cases of maxillary third molars displaced into the infratemporal fossa. Unlike the maxillary sinus, the infratemporal fossa is not an empty space. It contains many vital structures including nerves, arteries, and veins. A third molar displaced into the infratemporal fossa is considered a major complication. Dentists removing impacted maxillary third molars should understand the anatomy of the infratemporal fossa.
This chapter is not intended to be a comprehensive review of oral anatomy, but instead is a review of structures relevant to third molars. This knowledge is essential to avoid surgical complications. Although no surgical procedure is without risk, most impacted third molars can be removed safely and predictably.
An important key to avoid complications is deciding when to refer to an oral surgeon. This will be different for each dentist depending on experience and training. “When to refer” may be the most important factor to consider prior to treating your patients. Case selection, including surgical risk and difficulty, is discussed in the next chapter.
References
1
Svane TJ. Vascular Characteristics of the Human Inferior Alveolar Nerve,
J Oral Maxillofacl Surg
. 1986;44:431.
2
Graff-Radford SB, Evans RW. Disclosures.
Headache
. 2003;43(9): 9.
3
Zur KB, Mu L, Sanders I. Distribution pattern of the human lingual nerve.
Clin Anat
. 2004 Mar;17(2):88–92.
4
Carmichael FA, McGowan DA. Incidence of nerve damage following third molar removal: a West of Scotland Surgery Research Group study.
Brit J Oral Maxillofac Surg
. 1992;30:78.
5
Gargallo-Albiol J, Buenechea-Imaz R, Gay-Escoda C. Lingual nerve protection during surgical removal of lower third molars.
J Oral Maxillofac Surg
. 2000;29:268.
6
Singh S. Aberrant buccal nerve encountered at third molar surgery.
Oral Surg Oral Med Oral Pathol
. 1981;52:142.
7
Merrill RG. Prevention, treatment, and prognosis for nerve injury related to the difficult impaction.
Dent Clin North Am
. 1979;23:471.
8
Pogrel MA, Dorfman D, Fallah H. The anatomic structure of the inferior alveolar neurovascular bundle in the third molar region.
J Oral Maxillofac Surg
. 2009 Nov;67(11):2452–4.
9
Allen FJ. Postextraction hemorrhage. A study of 50 consecutive cases.
Br Dent J
. 1967;122(4):139–43.
10
Suchman AL, Mushlin AI. How well does activated partial thromboplastin time predict postoperative hemorrhage?
JAMA
. 1986;256(6):750–3.
11
Jensen S. Hemorrhage after oral surgery. An analysis of 103 cases.
Oral Surg Oral Med Oral Pathol
. 1974;37(1):2–16.
12
Funayama M, Kumagai T, Saito K, Watanabe T. Asphyxial death caused by post extraction hematoma.
Am J Forensic Med Pathol
. 1994;15(1):87–90.
13
Goldstein BH. Acute dissecting hematoma: a complication of an oral and maxillofacial surgery.
J Oral Surg
. 1981;39(1):40–3.
14
Moghadam HG, Caminiti MF. Life-threatening hemorrhage after extraction of third molars: case report and management protocol.
J Can Dent Assoc
. 2002;68(11):670–5.
15
Zhang HM, Yan YP, Qi KM, Wang JQ, Liu ZF. Anatomical structure of the buccal fat pad and its clinical adaptations.
Plast Reconst Surg
. 2002;109(7):2509–18; discussion 2519–20.
16
Aznar-Arasa L, Figueiredo R, Gay-Escoda C. Iatrogenic displacement of lower third molar roots into the sublingual space: report of 6 cases.
Int J Oral Maxillofac Surg
. 2012;70:e107–15.
17
Vijayan A, et al. Ludwigs angina: report of a case with extensive discussion on its management.
URJD
. 2015;5(2):82–86.
18
Kim JH.
A review of the maxillary sinus
. Sinus, OK: Perio Implant Advisory.
19
Hargreaves KM, Cohen S, web editor, Berman LH, editor.
Cohen’s pathways of the pulp
, 10th edition. St. Louis, MO: Mosby Elsevier, 2010, 590,592.
2 Case Selection
The best way to avoid complications when removing impacted third molars is to select patients and surgeries that are commensurate with your level of training and experience. Will you treat medically compromised patients? Or, will you only remove impacted third molars for healthy teens? Have you removed thousands of impactions? Or, are you about to remove your first maxillary soft tissue impaction? This chapter will help you decide which third molar surgery patients should be referred to a maxillofacial surgeon or kept in your office. It will also help you know when you are ready to move to the next level of difficulty.
Medical Evaluation
The medical evaluation includes a complete health history/patient interview, physical assessment, clinical exam, and psychological evaluation of the patient. The removal of impacted third molars is an invasive surgical procedure with risk of complications higher than most dental procedures. Furthermore, patients are often apprehensive and have anxiety about the procedure.
Health History and Patient Interview
A thorough health history and patient interview should be completed prior to treatment. The primary purpose of a patient’s health history is to attempt to find out as much about each patient as possible, so that the patient can be treated safely and knowledgeably. A health history form, completed by the patient, should be reviewed before interviewing the patient. The American Dental Association’s 2014 Health History form is provided as an example. (See Figures 2.1a, 2.1b, and 2.1c.)
Figure 2.1a Health History (Reproduced by permission of ADA).
Figure 2.1b Health History Update (Reproduced by permission of ADA).
Figure 2.1c Patient Interview (Reproduced by permission of ADA).
The patient’s health history can be subpoenaed in court cases, such as a malpractice suit, or when disciplinary action is taken against a dental professional by a regulatory board. Medical evaluation documents can be used as legal evidence and must be thorough and comprehensive.
The patient interview is an essential part of a medical evaluation. It’s not uncommon to have an unremarkable health history, only to learn during the interview that the patient has a history of health issues and medication. Good interview technique requires open-ended questions and active listening. Open-ended questions always begin with What, How, When, or Where. These questions cannot be answered with a simple yes or no answer. Yes or no questions should be limited to the health history form.
CAMP is a useful mnemonic to remember key interview questions.
Chief complaint – What brings you to the office?
Allergies – What are you allergic to? What else?
Medications – What medications do you take? What medications have you taken previously?
Past Medical History – What medical problems have you had in the past and when did you have them?
Physical Assessment
The American Society of Anesthesiologist’s (ASA) physical classification system is a useful guide when deciding to refer third molar surgical patients.1 (See Table 2.1.)
Table 2.1 ASA physical status classification system.
Classification
Description
ASA 1
Normal healthy
ASA 2
Mild systemic disease
ASA 3
Severe systemic disease
ASA 4
Disease is a constant threat to life
ASA 5
Not expected to survive without operation
ASA 6
Declared brain dead patient donating organs
A study published in the Journal of Public Health Dentistry in 1993 evaluated the general health of dental patients on the basis of the physical status classification system of the American Society of Anesthesiologists. A total of 4,087 patients completed a risk-related, patient-administered questionnaire. On the basis of their medical data, a computerized ASA classification was determined for each patient: 63.3% were in ASA class I, 25.7% in class II, 8.9% in class III, and 2.1% in class IV. Eighty-nine percent of patients in this study were ASA Class I or II.2
Another study measured the medical problems of 29,424 dental patients (age 18 years and over) from 50 dental practices in the Netherlands. This study found that the number of patients seen with hypertension, cardiovascular, neurological, endocrinological, infectious, and blood disease increased with age.3
Kaminishi states that the number of patients over age 40 requiring third molar removal is increasing. Over a five-year period, 1997–2002, the incidence almost doubled to 17.9%. This age category is known to be high risk for third molar surgery. At equal or higher risk is the rapidly growing number of patients seeking third molar surgery that are moderately or severely medically compromised.4
There are no absolute case selection recommendations based on these studies. However, most experts agree that ASA I and II patients can be treated safely in a dental office setting. Medically compromised ASA III patients are taking medications that do not adequately control their disease. The author recommends referral of medically compromised ASA III patients and the elderly. Alternatively, an anesthesiologist can sedate these patients. Fortunately, the majority of patients seen for third molar impaction surgery are relatively young, healthy, ASA I and II patients.
The physical assessment begins at first contact with the patient.
Overall appearance – What is their overall appearance? Is the patient obese, elderly, frail?
Lifestyle – Do they use drugs or alcohol in excess? Do they have an active lifestyle?
Vital signs – multiple blood pressure readings are recommended.
Every patient considering the removal of impacted third molars should have their vital signs checked at the surgery consultation and on the day of surgery. Patients with hypertension are more prone to cardiovascular complications. Hypertension can be diagnosed with simple blood pressure readings. This is especially important if the patient will be sedated because a baseline recording is needed to compare with readings during the procedure. According to the US Department of Health and Human Services, desired systolic pressure ranges from 90 to 119. The desired diastolic range is 60–79.5 (See Table 2.2.)
Table 2.2 Classification of blood pressure for adults.
Category
Systolic, mm Hg
Diastolic, mm Hg
Hypotension
< 90
< 60
Normal
90–119
60–79
Prehypertension
120–139
80–89
Stage 1 hypertension
140–159
90–99
Stage 2 hypertension
160–179
100–109
Hypertensive emergency
>180
>110
As of 2000, nearly one billion people, approximately 26% of the adult population of the world, had hypertension.6 Forty-four percent of African American adults have hypertension.7
Clinical Exam
Access is particularly important during the removal of impacted third molars. Poor access can make the procedure much more difficult. Patients with orthodontics in progress, small mouths, short anterior posterior distance, large tongues, and limited opening can make the removal of impacted third molars nearly impossible. A useful guide to evaluate access is the Mallampati airway classification. See Figure 2.2.
Figure 2.2 Mallampati classification can be used to predict airway management and oral access. (By Jmarchn / Wikimedia commons / CC BY 3.0).
Class IV patients are typically patients with square faces, short necks, and large tongues. The coronoid process will move close to maxillary third molars during translation, severely limiting access. In addition, these patients may have small arch size and limited soft tissue opening. A prudent dentist would consider referring these patients to a maxillofacial surgeon.
Psychological Evaluation
The psychological and emotional status of impacted third molar patients is an important factor in their successful treatment. Dr. Milus House has been credited with developing a system to classify the psychology of denture patients. Although this system was devised in 1937 to evaluate denture patients, it is still applicable today for third molar patients. Class I and II patients are most likely to have a positive treatment result. (See Box 2.1.)
Box 2.1 House’s emotional and psychological patient classification.
Class 1: Philosophical – Accepts dentist’s judgement and instructions, best prognosis.
Class 2: Exacting – Methodical and demanding, asks a lot of questions, good prognosis.
Class 3: Indifferent – Doesn’t care about dental treatment and gives up easily, fair prognosis.
Class 4: Critical – Emotionally unfit, never happy, worst prognosis.
In a study conducted in 2007, National Institute of Mental Health researchers examined data to determine how common personality disorders are in the United States. 5,692 adults, ages 18 and older, answered screening questions from the International Personality Disorder Examination (IPDE).
The researchers found that the prevalence for personality disorders in the United States is 9.1%.8 Nearly 10% of dental patients ages 18 and older may have some form of personality disorder!
Patients who have psychological and emotional challenges may be less compliant and unable to cope with the stress of surgical procedures.(See Figure 2.3.) The author recommends referral of these patients to a maxillofacial surgeon or treatment with an anesthesiologist
Figure 2.3 Patients with severe anxiety should be treated with GA. (Edvard Munch / Wikimedia Commons / Public domain).
Radiographic Assessment
A thorough evaluation of radiographs is essential to avoid surgical complications. Resolution, contrast, and clarity should not be compromised. Panoramic radiographs are ideal for viewing structural relationships. They allow for visualization of the third molar’s relationship to the following structures: inferior alveolar nerve canal, maxillary sinus, ramus, and second molar. Intraoral films further delineate the third molar periodontal ligament, root structure, and position. Most third molar surgeries can be completed safely with high-quality panoramic and intraoral films.
Cone beam CT scans have yet to become the standard of care in outpatient oral surgery. However, a CT scan may be appropriate for patients with fully developed roots near vital structures. For example, CT imaging may be appropriate when intimate contact with the inferior alveolar nerve is suspected after reviewing panoramic films or when a third molar is located near the palate.
The following factors are important when assessing radiographs.
Position
Depth
Angulation
Combined root width
Root length, size, and shape
Periodontal ligament and follicle
Bone elasticity and density
Position relative to the inferior alveolar canal
Position
The anterior posterior position of impacted third molars is always a significant factor. Third molars positioned in or near the ramus will have limited access. The position of mandibular third molars can be classified in relation to the second molar and ascending ramus. (See Figure 2.4.) Mandibular third molars are classified as Class I position when there is sufficient room for eruption between the second molar and ascending ramus. The tooth should have no tissue covering the distal aspect. Class II mandibular third molars do not have sufficient room for normal eruption. Some of the third molar is in the ramus. Mandibular third molars are Class III when the majority of the third molar is in the ramus.
Figure 2.4 Surgical difficulty based on AP distance, second molar, and ramus. (Reproduced by permission of Robert J. Whitacre).
A Class III position, short anterior posterior distance, will severely limit access to maxillary impactions.
Depth
The depth of mandibular third molars can be classified relative to the occlusal surface and CEJ of the adjacent second molar. A mandibular third molar is Depth A when it is even with or above the occlusal surface of the second molar. It is Depth B when it is located between the occlusal surface and CEJ of the second molar. It is Depth C when it is located below the second molar CEJ. Surgical difficulty increases in direct proportion to depth for both mandibular and maxillary third molars. (See Figure 2.5.)
Figure 2.5 Surgical difficulty based on depth relative to second molar. (Reproduced by permission of Robert J. Whitacre).
This classification system produces 9 possible outcomes when position and depth are combined. IA would be considered the easiest position and depth while IIIC would be the most difficult position and depth. This system is often attributed to Gregory and Pell. It is a modification of the classification developed by George B. Winter.
Angulation
Angulation refers to the mandibular third molar longitudinal axis relative to its adjacent second molar longitudinal axis. Mandibular impaction angulations can be mesioangular (43%), horizontal (3%), vertical (38%), or distoangular (6%).9
The long axis of mesioangular impactions is tilted toward the second molar. The mesioangular impacted third molar is notorious for third molar pain. Its crown is often partially erupted leading to localized infection and pericoronitis. They represent 43% of all impactions and are usually the easiest to remove with a straight surgical handpiece. The long axis of horizontal impactions is perpendicular or nearly perpendicular to the second molar long axis. Horizontal impactions are the second easiest surgical angulation after the mesioangular. Inexperienced surgeons often mistake this angulation for the most difficult surgical angulation. Horizontal impactions represent 3% of all impactions. The vertical impaction long axis parallels the long axis of the second molar. Vertical impactions are considered to be more difficult than horizontal impactions due to access. This is especially true for deep vertical impactions. The vertical impaction represents 38% of impacted third molars. Finally, the distoangular mandibular impaction is tilted toward the ramus. The path of removal is toward the ramus. (See Figure 2.6.) This is the reason why this angulation is considered the most difficult of all mandibular third molar impactions. Fortunately, they only account for 6% of mandibular third molar impactions. All of these impactions can be in buccal version or lingual version. The remaining 10% of mandibular impactions are transverse or inverted. A transverse impaction is growing toward the cheek or tongue. Inverted impactions are “upside down.”
Figure 2.6 Surgical difficulty by angulation – 4 most difficult.
The surgical difficulty when removing maxillary impactions is opposite of mandibular impactions. Mesioangular impactions are normally more difficult than distoangular impactions.
Combined Root Width
Combined root width is always a significant factor. A tooth with a conical root will be easier to remove than one with divergent roots. The roots of teeth with multiple roots are often divergent. The removal of these teeth will be more difficult when the combined root width is greater than the tooth width at the CEJ. Third molars with divergent roots may require sectioning. (See Figures 2.7a and 2.7b.)
Figure 2.7a Conical.
Figure 2.7b Divergent.
Root Length, Size, and Shape
Root length, size, and shape are always significant factors, but are often overlooked. Third molar roots that are long, thin, or curved may fracture leaving root fragments that are difficult to remove. The root fragments may be near vital structures such as the inferior alveolar nerve, maxillary sinus, infratemporal fossa, or submandibular fossa. It’s always prudent to carefully assess quality radiographs to avoid root fracture. Sectioning may be required. (See Figures 2.8a and 2.8b.)
Figure 2.8a Long, thin, curved.
Figure 2.8b Short, thick, straight.
Periodontal Ligament and Follicle
The periodontal ligament and follicle are always significant factors. A periodontal ligament space or follicle visible on a radiograph is a positive sign. These spaces allow for movement of the tooth with elevators and forceps. Periotomes, luxators, and proximators can be wedged into this space to luxate a tooth or root. (See Figure 2.9a.)
Figure 2.9a Wide periodontal ligament.
A dental follicle is always present with developing third molars. This structure differentiates into the periodontal ligament as the tooth develops.10 The dental follicle provides a space larger than the periodontal ligament space. (See Figure 2.9b.) The follicular space is one reason oral surgeons recommend removing third molars early, usually in the teenage years
Figure 2.9b Third molar follicle.
Tooth ankylosis can be defined as the fusion of bone to cementum resulting in partial or total elimination of the periodontal ligament. An ankylosed tooth, or one with a narrow periodontal ligament, has no space for the insertion of instruments. This condition is in dramatic contrast to a developing third molar with follicular space. (See Figure 2.9c.)
Figure 2.9c Narrow periodontal ligament.
Bone Density and Elasticity
Density is defined as the degree of compactness of a substance. Elasticity is the ability of an object or material to resume its normal shape after being stretched or compressed. Both of these characteristics play a profound role in the removal of impacted third molars. Compact bone is very dense, strong, and stiff bone. Cancellous bone is softer and weaker than compact bone, but is more elastic. Radiographs can provide indications of bone density. (See Figures 2.10a and 2.10b.) Age-related weakening of bony elasticity makes extractions more difficult and mandibular fracture more likely.11
Figure 2.10a Dense bone.
Figure 2.10b Elastic bone.
Position Relative to the Inferior Alveolar Canal
Superimposition
Proper interpretation of a quality panoramic radiograph can significantly reduce inferior alveolar nerve injuries. Many, if not most, general dentists assume that any third molar with roots extending to or beyond the radiographic inferior alveolar canal is at high risk of paresthesia. However, most third molar roots that appear to be near or beyond the canal are actually buccal or lingual to the nerve. This condition, known as superimposition, is indicated on a panoramic radiograph by continuous white lines created by the inferior alveolar canal bone. Superimposed tooth roots are buccal or lingual to the canal and IAN injury is unlikely. (See Figure 2.11.)
Figure 2.11 Continuous white lines indicate superimposition. (Drawing by Michael Brooks).
Grooving
The inferior alveolar canal develops before third molar roots. Grooving of the third molar root is caused by a third molar root developing in close proximity to the IAN. Thinning of the developing root is caused by contact with the inferior alveolar canal. This condition, known as grooving, is indicated on radiographs by a radiolucent band where the canal crosses over the third molar root. The canal’s radiographic white lines are not visible on the radiograph. Grooving increases the possibility of IAN paresthesia. (See Figure 2.12.)
Figure 2.12 A radiolucent band and loss of white lines indicates grooving. (Drawing by Michael Brooks).
Notching
Notching, like grooving, is caused by the developing tooth contacting the inferior alveolar canal. In this case, the tooth root develops directly above the canal. This is seen on a radiograph as a radiolucent third molar apex and loss of the top white line as the canal passes over the root. The dark apex may also indicate an open apex for young patients whose third molar roots are still developing. Notching increases the possibility of IAN paresthesia. (See Figure 2.13.)
Figure 2.13 A radiolucent apex and loss of the top white line indicates notching. (Drawing by Michael Brooks).
Perforation
In rare cases, the developing third molar root completely encircles the inferior alveolar canal. This is seen on the radiograph as a narrowing, radiolucent band where the canal crosses over the third molar root. The top and bottom white lines are not visible on the radiograph. (See Figure 2.14.)
Figure 2.14 Narrowing of the IAN canal and loss of white lines indicates perforation. (Drawing by Michael Brooks).
Other radiographic signs of intimate root contact with the inferior alveolar canal include canal deflection, root deflection, bifid roots, and root narrowing. A detailed discussion of these radiographic signs, including several studies, can be found in Chapter 3, “Complications.”
Early Third Molar Removal
Age may be the most significant factor in case selection. Several studies have shown that teenage patients have fewer surgical and postoperative complications.
A prospective study evaluated the surgical and postsurgical complications of 9,574 patients who had 16,127 third molars removed. It was concluded that removal of mandibular third molar teeth during the teenage years resulted in decreased operative and postoperative morbidity.
The study showed that increased numbers of complications (alveolar osteitis, infection, and dysesthesias) occur in the removal of impacted third molars of older patients. This study suggests that, when indicated, third molars should be removed during the teenage years, thereby decreasing the incidence of postoperative morbidity.12
Another study estimated the frequency of complications after mandibular third molar surgery as related to patient age. 4,004 subjects had a total of 8,748 mandibular third molars removed. The mean age was 39.8 =/–13.6 years, with 245 subjects (6.1%) age 25 and younger. The study concluded that increased age (>25 years) appears to be associated with a higher complication rate for mandibular third molar extractions.13
The American Association of Oral and Maxillofacial Surgeons published a white paper in 2007. They reviewed 205 publications related to various aspects of third molars. The effects of age on various parameters relating to third molars are so important that the AAMOS findings related to age are included verbatim in this chapter by permission of AAMOS (Reproduced by permission of the American Association of Oral and Maxillofacial Surgeons).
The Effects of Age on Various Parameters Relating to Third Molars14
Symptomatology and Age: “A study of 1,151 patients from 13–69 years of age with third molars showed that of those who had symptoms, pain was the most common symptom (35.3%), followed by swelling (21.7%), discomfort from food impaction (3.6%), and purulent discharge (3%). The frequency of each increased generally with age. Slade also noted that 37% of patients presenting with wisdom tooth problems reported pain and swelling as the indication for seeking treatment. Additionally, this study noted that Health Related Quality of Life indicators were reported more frequently as patients got older.”
Periodontal Pathology and Age:
