DentalAnatomy Manual

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Dental Anatomy

and Occlusion 2009-2010

RESD 5004 (lecture portion) and 5005 (laboratory portion)

Course Director:

Edward Wright, D.D.S., M.S. (ext. 7-3697)

[email protected]

Restorative Dentistry Faculty, Room# 3.592U

This material falls under the copyright laws and can only be reproduced within these

restrictions.

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Table of Contents Page

Course Syllabus, RESD 5004 (Lecture Portion) ........................................................... 7

Course Syllabus, RESD 5005 (Laboratory Portion) ..................................................... 13

Introduction ................................................................................................................... 20

Chapter 1. Human Dentition I ...................................................................................... 21

A. Tooth Numbering Systems ................................................................................. 31

1. Universal Numbering System ........................................................................ 31

B. Terms of Orientation .......................................................................................... 33

1. Tooth Surfaces ............................................................................................... 34

2. Combining Terms of Tooth Surfaces To Describe Angles ............................ 36

3. Division of Tooth Surfaces ............................................................................ 41

Chapter 2. Human Dentition II ..................................................................................... 42

A. Crown Elevations ............................................................................................... 48

B. Crown Depressions ............................................................................................ 53

C. Embrasures ......................................................................................................... 55

D. Proximal Contacts .............................................................................................. 58

Chapter 3. Anterior Teeth ............................................................................................. 60

A. Overview ............................................................................................................ 60

1. Lobes .............................................................................................................. 60

2. Tooth Outlines ............................................................................................... 62

B. Incisor ................................................................................................................. 63

1. Line Angles .................................................................................................... 63

2. Proximal Contacts .......................................................................................... 70

3. Embrasures ..................................................................................................... 71

4. Contours ......................................................................................................... 74

C. Summary Maxillary Anterior Teeth ................................................................... 76

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1. Maxillary Central Incisors ............................................................................. 76

2. Maxillary Lateral Incisors .............................................................................. 79

3. Maxillary Canines .......................................................................................... 82

D. Review Maxillary Anterior Teeth ...................................................................... 85

E. Summary Mandibular Anterior Teeth ................................................................ 88

1. Mandibular Central and Lateral Incisors ....................................................... 88

2. Mandibular Canines ....................................................................................... 91

F. Review Mandibular Anterior Teeth .................................................................... 94

Chapter 4. Introduction to Your Articulator ................................................................. 97

Chapter 5. Occlusal Contact Relationships and Basic Mandibular Movements .......... 107

A. Static Occlusal Relationships ............................................................................. 108

1. Cusp-to-Marginal Ridge and Cusp-to-Fossa Occlusion ................................ 109

2. Cusp-to-Fossa Occlusion ............................................................................... 111

B. Mandibular Movements ..................................................................................... 112

Chapter 6. Posterior Teeth ............................................................................................ 115

A. Lobes and Associated Structures ....................................................................... 115

B. Angulations of Teeth ......................................................................................... 118

C. Occlusal Table .................................................................................................... 121

D. Vertical Line Angles .......................................................................................... 122

E. Marginal Ridges ................................................................................................. 124

F. Summary of Premolars ....................................................................................... 125

1. Maxillary First Premolar ................................................................................ 125

2. Maxillary Second Premolar ........................................................................... 128

3. Mandibular First Premolar ............................................................................. 131

4. Mandibular Second Premolar ........................................................................ 134

G. Review of Premolars .......................................................................................... 138

H. Summary of Molars ........................................................................................... 142

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1. Maxillary First Molar ..................................................................................... 142

2. Maxillary Second Molar ................................................................................ 145

3. Mandibular First Molar .................................................................................. 148

4. Mandibular Second Molar ............................................................................. 150

I. Review of Molars ................................................................................................ 153

Chapter 7 Primary Dentition ....................................................................................... 158

A. Formation and Calcification of the Primary Teeth ............................................ 158

B. Number of Teeth ................................................................................................ 158

C. Designation of the Primary Dentition ................................................................ 159

D. Comparison of Primary and Permanent Teeth ................................................... 159

E. Morphology of Individual Primary Teeth .......................................................... 161

F. Norms of Primary Dentition Occlusion .............................................................. 165

G. Drawings of Primary Teeth ................................................................................ 166

Chapter 8 Pulp Chambers and Canals ......................................................................... 169

A. Pulp Chambers ................................................................................................... 169

B. Root Canal System ............................................................................................. 170

C. Specific Teeth ..................................................................................................... 171

Chapter 9 Articulators ................................................................................................. 174

A. Non-adjustable Articulator ................................................................................ 174

B. Semi-adjustable Articulators ............................................................................. 176

C. Fully-adjustable Articulator ............................................................................... 180

D. Summary of Articulators .................................................................................... 184

Chapter 10. Mandibular Positions and Movements ..................................................... 185

A. Mandibular Positions ......................................................................................... 185

1. Rest Position .................................................................................................. 185

2. Maximum Intercuspation (MI) ...................................................................... 187

3. Centric Relation (CR) .................................................................................... 187

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B. Mandibular Border and Functional Movements ................................................ 188

1. Sagittal Plane ................................................................................................. 189

2. Frontal Plane .................................................................................................. 192

3. Horizontal Plane ........................................................................................... 196

Chapter 11. Dynamic Occlusal Relationships .............................................................. 201

A. Horizontal Plane ................................................................................................ 202

B. Frontal Plane ...................................................................................................... 206

C. Sagittal Plane ...................................................................................................... 211

Chapter 12. Principles of Anterior Guidance of Occlusion ......................................... 212

Chapter 13. The Temporomandibular Joint ................................................................. 215

Chapter 14. Masticatory Muscles ................................................................................. 220

Appendix:

Dental Anatomy Waxing Instruments ........................................................................... 227

Drip Wax Block Exercise ............................................................................................. 230

Disinfect Extracted Teeth .............................................................................................. 232

Self Test 1 ..................................................................................................................... 234

Self Test 2 ..................................................................................................................... 235

Progressive Wax Block Exercise .................................................................................. 236

Self Test 3 ..................................................................................................................... 238

Cast Landmark Exercise ............................................................................................... 240

#10 Mesial Half Exercise .............................................................................................. 242

#8 Full Crown Exercise ................................................................................................. 244

#8 Class 4 and 5 Composite Exercises .......................................................................... 245

#8 Full Crown Practical Exam ...................................................................................... 247

Comparing Occlusal Contacts Exercise ........................................................................ 248

#8 Maximum Intercuspation Exercise .......................................................................... 250


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Identify Extracted Teeth ................................................................................................ 255

#29 Maximum Intercuspation Exercise ........................................................................ 256





#30 Full Crown Exercise ............................................................................................... 264

#30 Full Crown Practical Exam .................................................................................... 266

#30 Canine Guidance Exercise ..................................................................................... 268

Analysis of Mandibular Movements Exercise .............................................................. 270

Articulator Exercise ...................................................................................................... 282

#30 Canine Guidance Practical Exam ........................................................................... 285

#6-11 Anterior Guidance Exercise ................................................................................ 287

#11-14 Group Function Exercise .................................................................................. 290

Evaluating the Masticatory System ............................................................................... 293

Masticatory and Cervical Palpations ............................................................................. 294

#11-14 Group Function Practical Exam ........................................................................ 296

Dental Anatomy Quick Reference ................................................................................ 299

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Course Syllabus, RESD 5004 (Lecture Portion)

List of Topics Disinfecting Extracted Teeth

Human Dentition I & II

Anterior Teeth I, II, III

Restoring Contours with Composite

Introduction to Your Articulator

Occlusal Contacts and Basic Mandibular Movements

Posterior Teeth I & II

Tooth Identification

Primary Dentition

Pulp Chambers and Canals

Articulators

Mandibular Positions and Movements

Dynamic Occlusal Relationships

Your Articulator

Anterior Guidance of Occlusion

The Temporomandibular Joint

The Masticatory Muscles

Evaluating the Masticatory System

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Chapter 1. Human Dentition I

As the mouth or oral cavity is viewed from the front, it must be noted that the right

side of the mouth is to the viewer's left and the left side of the mouth to the viewer's right.

The teeth are in two arches - an upper and a lower. The upper arch, or maxillary

arch, of teeth is set in the upper, immobile jaw (Figure 1-1). The lower arch, or

mandibular arch, of teeth is set in the dynamic or movable member of the jaws, the

mandible (Figure 1-2). Later as the individual teeth are discussed, maxillary and

mandibular teeth will be described as moving across each other; however, it must always

be remembered that only the mandibular arch is the movable member.

Figure 1-1 Maxilla (left side) Figure 1-2 Mandible (left side)

There are three planes of orientation utilized in anatomical descriptions of the

skull. These are the frontal plane (parallel to the face), horizontal plane (parallel to the

floor), and sagittal plane (parallel to the sides of the head), Figure 1-3.

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Figure 1-3 Planes of orientation

Each arch is divided in half, as is the remainder of the head, at the mid-sagittal

plane (midline). Each half arch is termed a quadrant. There are, therefore, two quadrants

per arch and a total of four quadrants.

There are 16 permanent teeth in each arch. There are eight permanent teeth in each

quadrant or half arch. Therefore, there are 32 teeth in the permanent dentition or in a

complete set of permanent teeth.

Humans also have another set of teeth called the primary dentition, or deciduous

teeth (baby teeth). Each of these two sets have characteristics that are unique to each set

(primary or permanent) of teeth. Set traits are used to distinguish between the two

dentitions. These will be discussed later.

Throughout the mouth, the teeth vary in size and shape, providing differing

functions. The various teeth may be separated by characteristics termed class traits. The

four classes of teeth are:

1. Incisors - These are eight teeth whose crowns are designed for cutting or incising

(Figure 1-4). Their "biting" edges are termed incisal edges. These are the first two

teeth closest to the midline in each quadrant, and are named the Central Incisor

(first) and Lateral Incisor (second). Therefore, there are two incisors in each

quadrant (a central and a lateral incisor); four incisors in each arch (two central

incisors and two lateral incisors); and eight incisors in each set.

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2. Canines (Cuspids) - These are four teeth with long pointed crowns designed for

piercing, tearing or holding food (Figure 1-5); they also have incisal edges. They

are the third teeth from the midline in each quadrant. There is, therefore, one

canine in each quadrant; two canines in each arch; and four canines in each set.

Figure 1-4 Figure 1-5

Maxillary and mandibular incisors Maxillary and mandibular canines

3. Premolars (Bicuspids, older terminology) - These eight teeth are holding and

grinding teeth (Figure 1-6). The premolars make the transition from the thinner,

sharper incisors and pointed canines, to the large grinding surfaces of the molars,

which are the largest teeth in the "back" of the mouth. The premolars are the

fourth and fifth teeth from the midline in each quadrant and are termed the first

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premolar and second premolar, respectively. Therefore, there are two premolars in

each quadrant, four premolars in each arch, and eight premolars in each set.

4. Molars - These are the 12 large grinding teeth (Figure 1-7). They are the 6th, 7th

and 8th teeth from the midline in each quadrant. Named from "front" to "back",

(anterior to posterior), they are the first molar (or 6 year molar), second molar (or

12 year molar), and the third molar (or "wisdom" tooth).

Figure 1-6 Figure 1.7

Maxillary and mandibular premolars Maxillary and mandibular molars

NOMENCLATURE:

When naming a specific tooth, the dentition or set is identified first, then the arch,

quadrant, and specific tooth name are identified - IN THAT ORDER, i.e., permanent

(set), maxillary (arch), right (quadrant), second premolar (tooth).

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The primary or deciduous set of teeth will not be covered at this time. In this course, if

"permanent" is omitted in naming a specific tooth, it should be understood to be a

permanent tooth, i.e., mandibular left second molar.

A visual tour (Figure 1-8) of the maxillary and mandibular dental arches from the

midline permits us to observe the various forms of the working surfaces of the teeth.

Tooth form varies from having simple cutting edges (incisors), to having single cusps

(canines), to a more complex makeup (premolars), and finally to the most complex of all

teeth (molars), with their multi-cusp occlusal surfaces.

Figure 1-8 A. Incisors; B. Canines; C. Premolars; and D. Molars.

INCISORS

As can be seen in Figure 1-9, the incisors have horizontal cutting blades. The function of

the incisors is to cut the food that is passed into the mouth. Figure 1-10 demonstrates

how the blades cut into the food, permitting the rest of the dentition to continue the

process of mastication as the food is transported by the tongue to the posterior teeth.

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Figure 1-9 Incisors in slight open Figure 1-10 Incising food

and closed positions

CANINES

The canines (or cuspids) have colloquially been called "eye teeth." Each canine

has two blades which incline towards each other to form the cusp.

The function of canines in mastication is to pierce, tear, and rip the food as it is

introduced into the mouth. These teeth are able to handle great physical stress, since they

are extremely strong and well anchored in the corners of the arches. The cusp of the

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canine is called a "guiding cusp." According to some concepts of occlusion, its purpose

is to separate the posterior teeth during chewing.

PREMOLARS

The premolars are characterized by two cone-shaped cusps. The noted exception is

the mandibular second premolar, which often has a sharp lingual developmental groove

dividing the lingual cusp. The premolars functions as millers, mincers, and mullers of

food.

These teeth have cusps on the cheek (buccal) and tongue (lingual) sides. Based

upon how the teeth occlude with the opposing teeth, the cusps are classified as either a

supporting cusp (also called centric holding, functional, and stamp cusp) or a guiding

cusp (also called non-functional and shear cusp). Note that opposing teeth are in opposite

arches occluding each other, while adjacent teeth are in the same arch next to each other.

When teeth are in correct alignment and the posterior teeth are occluding, the

supporting cusp of the posterior teeth (Figure 1-11) is located between a supporting and

guiding cusp of an opposing tooth. Conversely, the guiding that is located buccal or

lingual to the occlusal table and forms one side of a fossa.

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Figure 1-11 Supporting and Guiding Cusps

The premolars mull food through the movement of the mandibular supporting cusp

along the maxillary supporting and guiding cusps of their opposing teeth, while the

maxillary premolar supporting cusps simultaneously mull the food in a similar manner.

MOLARS

The molars are large, milling teeth with anatomical differences that are related to

each molar's specific location within the dental arch. The maxillary molars consist of: 1)

right and left first molars (six-year molars), each with three large cuspids, a small cusp

located at the distolingual corner, and a fifth cusp on the lingual surface of the

mesiolingual cusp (termed cusp of Carabelli); 2) right and left second molars (twelve-

year molars), each of which follows the same pattern as the first molar but is smaller and

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does not have the cusp of Carabelli; and 3) right and left third molars (wisdom teeth),

each of which follows a similar pattern as the second molar but is smaller (Figure 1-12).

The mandibular molars consists of: 1) right and left first molars (six-year molars),

each of which is a large five-cusp tooth; 2) right and left second molars (twelve-year

molars), each of which is usually a four-cusp tooth; and 3) right and left third molars

(wisdom teeth), each of which is usually also a four-cusp tooth (Figure 1-12).

Figure 1-12 The maxillary and mandibular molars

The molars have as their specific function the mastication of food. They

principally accomplish this through the action of the supporting and guiding cusps. The

sharp ridges and grooves of the guiding cusps are responsible for the shearing, and the

movement of the supporting cusps in and out of their respective opposing fossae provides

the milling action. Both the supporting cusps and the guiding cusps of all the posterior

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teeth, particularly the molars, participate in the final mulling of the food before the bolus

enters the digestive tract.

If we were to choose which teeth are the most important, we would select the

canines and first molars. The maxillary and mandibular canines are firmly buttressed in

the corner of the arches, and the maxillary first molars are anchored in the zygomatic

processes of the maxilla (Figure 1-13).

Figure 1-13 Locations of the canine and the first molar

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A. Tooth Numbering Systems

A tooth numbering system enables us to rapidly identify the teeth and speeds our

dental communication. The ability to rapidly associate each number with the specific

tooth must be developed as soon as possible.

There are three prominent numbering systems, the Universal, Palmer

(Zsigmondy/Palmer), and International Numbering Systems. The Universal Numbering

System is the most common system used in the United States. The Palmer Numbering

System uses brackets around the number to designate in which quadrant the tooth is

located. Since this is not conducive to typewriters or computers, it has fallen from favor.

The International Numbering System uses two numbers, one identifies the tooth as

either primary or permanent and the quadrant in which the tooth is located, and the other

number designates the tooth's location in the quadrant. This numbering system has been

adopted by some international organizations, such as the World Health Organization. So

you may encounter this system if you provide dental care in a foreign country. Examples

of these numbering systems are provided in the review sections for the various teeth.

1. Universal Numbering System In 1968 the American Dental Association recommended the use of the Universal

Numbering System. It designates one letter (A through T) for each primary tooth and one

number (1 through 32) for each permanent tooth (Figure 1-14). The Universal

Numbering System will be utilized throughout this course and in your predoctoral dental

education.

Numbering begins in the maxillary right quadrant with the third molar being #1

and the second molar #2, the first molar #3, and so forth around the maxillary arch to the

maxillary left third molar, which is #16. Numbering then drops to the mandibular left

third molar (#17) and continues from left to right around the mandibular arch to the

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mandibular right third molar (#32). The tooth need not be present in the oral cavity to

receive its number. The maxillary right first molar is always #3 - whether present or not.

Figure 1-14 Universal Numbering System

It is good to learn the numbers of certain "key" teeth or groups of teeth such as the

canines, which are numbered 6, 11, 22, and 27 and the first molars which are numbered

3, 14, 19, and 30, (Figure 1-15). Then one may count from those points to number the

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adjacent teeth (teeth next to each other) until sufficient practice has been accomplished to

have rapid association of each tooth with its specific number.

Figure 1-15 Key tooth numbers

B. Terms of Orientation

In orienting oneself between front and back, structures toward the front of the

mouth are anterior, and structures toward the back are posterior. Anterior teeth are

incisors and canines, while posterior teeth are premolars and molars (Figure 1-16). The

term medial is used to orient structures toward the middle of the head and the term lateral

indicates structures or movements away from the mid-sagittal plane (Figure 1-17).

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Figure 1-16 Anterior and Figure 1-17 Mid-sagittal plane

posterior teeth

1. Tooth Surfaces The crown of the tooth can be thought of as having five sides or surfaces (Figure 1-

18) and the various surfaces of the teeth have names (Figure 1-19). The surfaces of the

anterior teeth are named as follows:

a. Labial or facial - surface of a tooth toward the lips.

b. Lingual - surface of a tooth toward the tongue. For the maxillary teeth only, the

term palatal surface is used interchangeably with the term lingual surface; the

bone and soft tissue forming the "roof of the mouth" is the palate.

c. Mesial - surface of a tooth toward the midline of the arch.

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d. Distal - surface of a tooth away from the midline of the arch.

e. Incisal edge - the biting or incising edge.

The mesial surface of one tooth normally contacts the distal surface of the tooth

anterior to it. In the case of the central incisors, the mesial surface of the right central

incisor contacts the mesial surface of the left central incisor since they meet or contact at

the midline. The place where two adjacent teeth touch is termed the contact area.

The posterior teeth also have 5 surfaces, named as follows:

a. Buccal or facial - the surface of the tooth toward the cheek (corresponds to the

labial surface of anterior teeth). Facial may be used when speaking of the outer

surface of anterior or posterior teeth and is interchangeable with labial or

buccal.

b. Lingual - surface toward the tongue (same as anterior teeth). For the maxillary

teeth only, the term palatal surface is also used interchangeably with the term

lingual surface.

c. Mesial - surface of a tooth toward the midline of the arch (same as anterior

teeth).

d. Distal - surface of a tooth away from the midline of the arch (same as anterior

teeth).

e. Occlusal - the biting or chewing surface.

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Figure 1-18 Sides of teeth Figure 1-19 Surface names

Proximal surfaces are surface between two teeth. All proximal surfaces are mesial

or distal surfaces, but not all mesial and distal surfaces are proximal surfaces.

2. Combining Terms of Tooth Surfaces To Describe Angles

(Corners) Terms for the tooth surfaces are often combined to indicate an area which includes

or is formed by two or more surfaces. For example, the mesiolabial line angle is

understood to be the junction of the mesial and labial surfaces forming a line and angle.

There are two types of tooth angles: line angles and point angles. Two surfaces

make up a line angle, while three surfaces make up a point angle. When the type of angle

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is not specified, the number of surfaces combined indicates the type of tooth angle, i.e.,

mesiolabio-incisal angle is a point angle.

a. Tooth Line Angles

Line angles are corners or angles formed by the junction of two surfaces which

form it. There are eight line angles for each tooth (Figures 1-18 and 1-20 to 1-22). The

line angles for the anterior teeth are:

1. Mesiolabial (or labiomesial) - the angle where the mesial and labial surfaces

join.

2. Distolabial (or labiodistal) - the angle where the distal and labial surfaces join.

3. Mesiolingual (or linguomesial) - the angle where the mesial and lingual surfaces

join.

4. Distolingual (or linguodistal) - the angle where the distal and lingual surfaces

join. (It gets a little obvious by now!!)

5. Labio-incisal (or incisolabial) - the angle where the labial and incisal surfaces

join.

6. Linguo-incisal (or incisolingual) - the angle where the lingual and incisal

surfaces join.

7. Mesio-incisal (or incisomesial) - the angle where the mesial and incisal surfaces

join.

8. Disto-incisal (or incisodistal) - (guess what?) The angle where the distal and

incisal surfaces join.

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Figure 1-20 Anterior line angles Figure 1-21 Anterior line angles

The line angles for the posterior teeth are:

1. Mesiobuccal (or buccomesial)

2. Distobuccal (or buccodistal)

3. Mesiolingual (or linguomesial)

4. Distolingual (or linguodistal)

5. Bucco-occlusal (or occlusobuccal)

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6. Linguo-occlusal (or occlusolingual)

7. Disto-occlusal (or occlusodistal)

8. Mesio-occlusal (or occlusomesial)

Figure 1-22 Posterior line angles

NOTE: Some texts list only six line angles for anterior teeth, because the mesial and

distal incisal angles of anterior teeth are rounded, the mesio-incisal and disto-incisal line

angles are considered to be non-existent. They are spoken of as mesial and distal incisal

angles only.

BUT: Eight line angles for each tooth will be utilized in this course; however, one

should have an understanding of variations in terminology.

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b. Tooth Point Angles

Point angles are corners formed by the junction of three surfaces. The point angle

takes its name from the surfaces which formed it. There are four "point angles" for each

tooth (Figures 1-18 and 1-23).

The point angles of the anterior teeth are:

1. Mesiolabio-incisal

2. Distolabio-incisal

3. Mesiolinguo-incisal

4. Distolinguo-incisal

The point angles of the posterior teeth are:

1. Distobucco-occlusal

2. Mesiobucco-occlusal

3. Distolinguo-occlusal

4. Mesiolinguo-occlusal

Note that the order of the surfaces within the word describing the point angle may

vary; e.g. mesiolabio-incisal may also be mesio-incisolabial, labiomesio-incisal, labio-

incisomesial, incisolabio-mesial, or incisomesiolabial.

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Figure 1-23 Posterior point angles

3. Division of Tooth Surfaces Tooth surfaces, a portion of a tooth, or contacts of teeth can be divided into

sections, commonly in thirds. The labial surface is routinely divided into cervical or

gingival third, middle third, and incisal third (Figure 1-24). The buccal surface is

similarly divided into cervical or gingival third, middle third and occlusal third.

Figure 1-24 Division of facial surface with adjacent tooth contacts marked

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Chapter 2. Human Dentition II

The bone that surrounds the teeth is termed the alveolar bone (also referred to as

the alveolar process), Figure 2-1. The tooth socket is termed the alveolus (plural -

alveoli).

Figure 2-1 Alveolar bone or alveolar process

Each tooth is attached to the alveolus (boney socket) by fibers, which are

collectively termed the periodontal ligament. This fibrous tissue extends from the walls

of the alveolus to the layer of bone-like tissue called cementum, which covers the root of

the tooth. The remaining portion of the tooth not covered by cementum is covered by the

hardest mineralized tissue in the body called enamel. The portion of tooth covered by

enamel is the anatomical crown (Figure 2-2). The junction of the enamel and cementum

is the boundary between anatomical crown of the tooth and the root of the tooth and is

termed the cementoenamel junction (CEJ) or cervical Line. The CEJ is not a distinct

structure, but merely a distinct location. Cervical lines have great importance in dentistry

and will be covered later and in other courses.

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Figure 2-2 Crown, roots, and supporting tissues

The tissue covering the bone and surrounding the teeth is called gingiva (gingival

tissue), and patients often refer to it as the gums. The gingiva may be divided into

attached gingiva and free gingiva. The portion of the gingiva adjacent to the teeth and

firmly attached to the alveolar bone is termed the attached gingiva. Gingiva that extends

coronally (toward the crown) from the attached gingiva is the free gingiva or marginal

gingival. The tissue covering the bone apical to the attached gingiva is a thin vascular

tissue, not attached firmly to the underlying bone called the alveolar mucosa (Figure 2-3).

The linear junction of the attached gingiva with the free gingiva is termed the free

gingival groove. The junction of the attached gingival with the alveolar mucosa is

termed the mucogingival junction.

The most occlusal or incisal extent of the gingiva on a tooth is called the gingival

margin. It varies considerably according to many factors such as age, health of tissue,

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tooth location, etc. You will need to understand the difference between the terms

marginal gingiva (free gingiva) and gingival margin.

Figure 2-3 Free and attached gingiva

There is a very small space or potential space between the free gingiva and the

tooth. This small space encircling the crown is the gingival sulcus. It is bounded by the

tooth (usually the enamel of the crown) and the epithelium covering the free gingiva. The

"bottom" of the gingival sulcus is the most occlusal extent of the epithelial attachment

(Figure 2-4). This epithelial attachment is a bond around the tooth where the gingival

epithelium forms a union with the tooth. This attachment is extremely important and will

be discussed in many succeeding courses.

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Figure 2-4 Gingival sulcus and epithelial attachment

Periodontium is a collective term referring to all the tissues (bone, gingiva, etc.)

that surround and support the teeth. When one views healthy gingiva (collective term for

the gingival tissues), it should be noted that the gingiva covers a portion of the anatomical

crown. The portion of the crown visible in the mouth (not covered by the gingiva) is

termed the clinical crown. It is important to distinguish between the clinical crown and

the anatomical crown.

The main inner bulk of the tooth is hard tissue termed dentin. The dentin

surrounds the "nerve" or pulp of the tooth and is covered by enamel in the anatomical

crown and by cementum in the root. The junction of the enamel and dentin (inside the

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crown of the tooth) is termed the dentinoenamel junction (DEJ). This would be visible as

a line in cross sections of the anatomical crown. The junction of the dentin and

cementum (inside the root of the tooth) is termed the cementodentinal junction, (CDJ),

Figure 2-4.

The soft pulp tissue containing the tooth's vascular as well as the nerve supply,

occupies an irregular central cavity inside the tooth termed the pulp cavity. The pulp

cavity can be divided into 3 general portions, 1) the central portion in the anatomical

crown is termed the pulp chamber, 2) the thin channel(s) extending from the pulp

chamber down the center of the root(s) is (are) termed the pulp canal(s), and 3) the small

projections extending occlusally or incisally within the pulp chamber are termed pulp

horns (Figure 2-5).

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Figure 2-5 Pulp cavity

Anatomical areas of the crown are often separated into crown elevations and crown

depressions. Many surfaces of crowns are described as concave or convex. Concave

surfaces are depressions. Convex surfaces bulge outward or are elevated from the surface

(Figure 2-6).

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Figure 2-6 Convex and concave surfaces

A. Crown Elevations

a. Cusps - Elevated projections or points on the crowns of teeth. They are the peaks of

the occlusal surfaces of posterior teeth and the incisal portion of canine crowns.

Incisors do not possess cusps, while canines normally exhibit one cusp, premolars

two or three cusps, and molars four or five. The cusp tip is the most occlusal

termination of the cusp (Figure 2-7).

b. Mamelons - Small, rounded projections of enamel on the incisal ridges of newly

erupted anterior teeth. They are the incisal terminations of the three labial lobes.

They are usually worn away soon after eruption (Figure 2-8).

36

Figure 2-7 Cusps and cusp tips Figure 2-8 Mamelons

c. Tubercles - Small bumps or cusp-like projections found on the crowns of teeth. They

are variable in size and shape. Tubercles are often thought of as mini-cusps. They are

not a consistent characteristic of teeth.

d. Lobes - One of the primary anatomical divisions of the tooth crown, usually

separated by identifiable developmental grooves (discussed under Crown

Depressions). Lobes are represented by cusps and mamelons and cingula.

e. Cingulum (Plural: cingula) - The rounded eminence in the cervical third of the

lingual surface of anterior teeth (Figure 2-9).

f. Marginal ridges - The linear elevations found at the mesial and distal terminations

of the occlusal surface of posterior teeth. They are also found on anterior teeth, but

are less prominent, forming the lateral margins of the lingual surface (Figures 2-10

and 2-11).

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Figure 2-9 Cingulum Figure 2-10 Marginal ridges of maxillary

anterior teeth

Figure 2-11 Marginal ridges of posterior teeth

38

g. Triangular ridges - Linear ridges on posterior teeth, which run from the cusp tips to

the central area of the occlusal surface. In the mesiodistal cross-section, they tend to

have a triangular shape (Figure 2-12).

h. Transverse ridge - A combination of two triangular ridges which cross the occlusal

surface on a posterior tooth, one from the buccal and one from the lingual. Thus a

transverse ridge is simply a union of two triangular ridges (Figure 2-12).

i. Oblique ridge - A special type of transverse ridge (composed of two triangular

ridges), only present on maxillary molars. It crosses the occlusal surface in an

oblique direction from the distobuccal cusp tip to the mesiolingual cusp tip (Figure 2-

12).

Figure 2-12 Triangular, transverse, and oblique ridges

j. Cusps ridges - Each cusp has four cusp ridges extending in different directions

(mesial, distal, facial and lingual) from its tip. They vary in size, shape and sharpness

(Figure 2-13). The cusp ridge which extends toward the central portion of the

occlusal surface is a triangular ridge. The cusp ridges are named by the direction

39

toward which they extend from the cusp tip. Mesial and distal cusp ridges are also

termed mesial and distal cusp arms (Figure 2-13). In this course, the cusp ridge(s) on

the occlusal table will always be referred to as a triangular ridge. The cusp ridge on

the buccal or lingual surface will be referred to as the buccal or lingual ridge. The

ridges on the facial and lingual surfaces of the teeth are rounded and not precise

ridges.

Figure 2-13 Posterior cusp ridges

k. Inclined plane - The sloping area partially bordered by the crests of two cusp ridges.

Normally, each cusp has four inclined planes, two on the occlusal table (form the

triangular ridge) and two form the buccal or lingual surfaces of the cusp. Inclined

planes are named by combining the names of the two cusp ridges between which they

lie (Figure 2-14).

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Figure 2-14 Inclined Planes and Occlusal Table

B. Crown Depressions

a. Fossa (Plural - fossae) - An irregular concavity, on the surface of a tooth. There is

normally a rather large, shallow fossa on the lingual surface of an anterior tooth

(Figure 2-10), while each posterior tooth exhibits two or more fossae of varying size

and shape on the occlusal surface. There are no distinct borders to locate a fossa.

Fossae are just deeper portions of the occlusal surface, separated by various ridges

(Figure 2-15). It is important to note that all of the fossae on the tooth's occlusal

surface are the same depth. This is a very important feature to remember when you

begin to wax posterior teeth.

41

Figure 2-15 Posterior Tooth Fossae and Grooves

b. Sulcus (Plural - sulci) - A long, narrow depression, usually V-shaped in cross section,

located on the occlusal surface of each posterior tooth. A primary developmental

groove is found at the bottom of the sulcus and the sides are inclined planes of

triangular ridges.

c. Primary Developmental Groove - A groove or line which denotes the border where

the primary parts, or lobes, of the tooth crown have coalesced. The primary

developmental groove that travels mesiodistally along the center of the tooth is called

the central developmental groove (Figure 2-15).

d. Supplemental (secondary) Developmental Groove - An auxiliary groove that

branches from the primary developmental groove. Its location is not related to the

junction of primary tooth parts. All grooves that are not primary developmental

grooves are considered supplemental developmental grooves for this course (Figure

2-15).

e. Triangular fossa - A depressed area that is formed by the joining of three

developmental grooves. A pit is normally the deepest portion of a fossa.

f. Pit - A small depressed point that is formed by two or more grooves. The premolars

generally have mesial and distal pits at the base of the triangular fossae. Molars

42

generally have mesial and distal pits at the base of the triangular fossae in addition to

a central pit formed by the convergence of developmental groves.

C. Embrasures

The contact area is the area of interproximal contact between two adjacent teeth.

Since the proximal surfaces of the teeth (mesial and distal) are considerably larger in area

than the proximal contact area, there is a space between the two teeth that surrounds the

interproximal contact where the teeth do not touch. This space is termed an embrasure.

This space is actually a continuous space that surrounds the contact area and

increases in width, as one moves facial, cervical, lingual or occlusal from the

interproximal contact. Embrasures form an irregular area similar to a "doughnut" with

the "hole" at the contact area (Figure 2-16).

Figure 2-16 Anterior Teeth Embrasures

Portions of this space (embrasure) are given several names according to location.

The openings or spaces between the teeth, facial and lingual to the contact area, are

termed the facial embrasure and lingual embrasure, respectively. The small V-shaped

area between the teeth that is occlusal or incisal to the contact area is termed the occlusal

or incisal embrasure.

The embrasure space cervical to the contact area is termed the interproximal

embrasure, interproximal space, gingival embrasure, or cervical embrasure. This

43

triangular area between the crest of the alveolar bone and the contact area is normally

filled by a pointed projection of the free gingiva termed the interdental papilla or gingival

papilla (Figure 2-17).

Figure 2-17 Interdental papilla or gingival papilla

Embrasures serve as spillways for the food during mastication and allow for proper

protection and stimulation of the periodontium necessary to maintain healthy tissues. If

an imaginary line were drawn in a faciolingual direction bisecting any embrasure space,

the two portions (a mesial portion and a distal portion) should be approximately equal in

size and shape. It should follow from this that the portion of each tooth that forms the

sides of the embrasures must be nearly mirror images of each other. This is necessary to

provide our symmetrical embrasures.

1. Facial or Lingual View. a. The contact evenly divides the embrasure space mesiodistally.

b. Gingival embrasures decrease in size (mainly occlusogingival height) from anterior

to posterior. They increase in width (buccolingually) from anterior to posterior

(Figures 2-18 and 2-19).

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Figure 2-18 Maxillary anterior tooth embrasures, labial view. (This photo is of a

typodont; note that gingival embrasures would be filled with gingival papillae in a

healthy patient).

Figure 2-19 Maxillary posterior tooth embrasures, buccal view.

2. Incisal or Occlusal View. a. The interproximal contacts of the anterior teeth are approximately centered

labiolingually for the thickness of the tooth at that height. Lingual embrasures are

generally wider than labial embrasures (Figure 2-20).

45

Figure 2-20 Maxillary central incisors reduced to expose contact, incisal view.

b. The interproximal contacts of posterior teeth are generally buccal to the buccolingual

center (Figure 2-21). The lingual embrasures are also wider than the buccal

embrasures of the posterior teeth.

Figure 2-21 Maxillary posterior tooth embrasures, occlusal view.

D. Proximal Contacts

The contacts between adjacent teeth (interproximal contacts) are very important for

arch stability and the health of the periodontium. Their buccolingual and occlusogingival

location, in addition to their size (surface area) are critical. In a mesiodistal direction,

they should be centered over the interproximal space. This allows the proximal

46

embrasures to be divided into equal halves and allows a symmetrical gingival papillae to

occupy the space.

Contact areas become more gingivally located from anterior to posterior in each

quadrant when viewed from the facial or lingual. The majority of this occlusogingival

effect is due to the crowns becoming shorter. On each tooth, the distal contact area is

generally more cervical than the mesial contact area.

The surface area of the proximal contacts increases in size from anterior to

posterior. Anterior teeth have relatively small proximal contact areas that are centered

labiolingually, while posterior teeth have larger contact areas that are generally located

buccal to the buccolingual center (Figures 2-18 through 2-21). The contact areas become

larger with function (as an individual ages), because as one chews, the adjacent teeth rub

against each other, causing contact areas to wear, and proximal contact areas to increase

in size.

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Chapter 3. Anterior Teeth

A. Overview

When someone smiles or talks, the anterior teeth are the most noticeable of the

dentition and their shape, alignment, and color are generally extremely important to our

patients. It is tremendously difficult to make a single anterior tooth or all of the anterior

teeth look natural and pleasing. Since esthetics is so important to our patients, throughout

your dental career you will probably continually take classes on how to improve your

anterior restorations.

When calipers are used to compare the mesial to distal dimensions for the

maxillary central incisor and the maxillary lateral incisor, this naturally occurring ratio

was found to be 1.2 to 1.0. There are other ratios that are used by viewing the anterior

teeth from the front and other areas of the body. Additional information can be obtained

by reading Chapter 3 of your Operative Dentistry Textbook.

1. Lobes Lobes are major anatomical divisions of the tooth and understanding their extent

will help one better visualize the developmental grooves or depressions that separate

them. The lobes are named according to their location, similar to the way in which

surfaces and line angles are named.

All anterior teeth have four lobes: three labial lobes, termed the mesiolabial,

middle labial (or simply labial) and distolabial lobe. The fourth lobe is represented by the

cingulum and termed the lingual lobe (Figure 3-1).

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Figure 3-1 Maxillary anterior teeth lobes

In incisor teeth, mamelons are the rounded incisal terminations of the three labial

lobes. Remember, these mamelons are usually worn away shortly after the teeth erupt

into the mouth.

The separation of the three facial lobes creates two slight vertical depressions in

the labial surface of anterior teeth. These are termed the mesiolabial and distolabial

developmental depressions. The canines have larger, vertical labial surface depressions

with a fairly prominent ridge (the middle labial lobe) between them (Figure 3-2). The

lingual lobe of each anterior tooth forms the cingulum, and there are only very subtle

depressions from its junction with the rest of the tooth.

Figure 3-2 Labial depressions on maxillary anterior teeth

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2. Tooth Outlines Geometric shapes (Figures 3-3 to 3-7) are used to roughly describe the tooth shape

from various views. These shapes should be known for the National Board Dental

Examination Part I that you will take next year.

Figure 3-3 General tooth outlines

Figure 3-4 Geometric shape for Figure 3-5 Geometric shape for

incisal view of lateral incisor occlusal view of mandibular first molar

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B. Incisors

Looking at a smiling mouth, one observes the facial surfaces of the eight incisors.

The facial surface of each incisor crown has a trapezoidal outline with the shorter of the

parallel sides at the gingival aspect and the longer at the incisal (Figure 3-6). From a

proximal view (mesial or distal), all incisors have a triangular outline (Figure 3-7). Try

to visualize this triangular-trapezoidal shape in three dimensions to begin to form a visual

image of the incisors.

Figure 3-6 Trapezoidal facial outline Figure 3-7 Triangular proximal outline

1. Line Angles All teeth have four vertical line angles (two facial and two lingual). These form

the mesial and distal "boundaries" of the labial and lingual surfaces. Surfaces and line

angles in the vertical plane are also described as axial surfaces and axial line angles,

respectively. Examine the vertical line angles on the labial surface (mesiolabial and

distolabial line angles) of the maxillary incisors.

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a. Labial Line Angles

From a facial view, the mesiolabial line angles of the maxillary central incisors are

relatively long and straight when compared to the distolabial line angles which are

somewhat shorter and more curved. The same relationship is true for the maxillary

lateral incisor, although the lateral incisor shows more curvature of both line angles

(Figure 3.8).

Figure 3-8 Maxillary anterior teeth's facial line angles

Viewing the incisal edges of these teeth, the maxillary central incisor at the

mesiolabial line angle appears square or close to 90. The maxillary central incisor at the

distolabial line angle is more rounded (greater than 90 angle), Figure 3-9. Mesiodistally

along the facial surface between these boundaries, the incisal one-third is relatively flat

except for two very slight vertical depressions.

If the teeth are tipped slightly to the lingual, and the middle and gingival thirds of

the facial surface are observed, mesiodistally incisors have a greater convexity as the

gingival margin is approached. The line angles also become slightly more rounded (less

distinct) as the gingival line is approached (Figure 3-10). The labial surface of the

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maxillary lateral incisor has a similar form to the maxillary central incisor except the

lateral incisor is more round or more convex in all locations.

Figure 3-9 Incisal edges Figure 3-10 Labial contours

When the mesiolabial and distolabial line angles of the mandibular incisors are

observed from the facial aspect, they are fairly uniform and straight (Figure 3-11). When

these line angles are observed from the incisal aspect, they are very near 90. The labial

surfaces between these line angles are also relatively flat with only slight rounding as the

dentinoenamel junction (DEJ) is approached.

Figure 3-11 Mandibular incisor facial line angles

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b. Lingual Line Angles

On the lingual surfaces of the maxillary incisors, observe how the mesiolingual and

distolingual line angles coincide fairly well with the mesial and distal marginal ridges

(Figure 3-12). Marginal ridges of anterior teeth were defined previously as the mesial

and distal terminations of the lingual surfaces of anterior teeth. Some maxillary central

incisors will have very prominent marginal ridges, while other teeth have less distinct

marginal ridges.

The incisal one-third of the lingual surface between the marginal ridges is flat to

slightly concave. In the middle and gingival thirds of the lingual surface, this concavity

between the marginal ridges changes into a convexity, the cingulum. The cingulum does

not lie in the center of the tooth, but is displaced distally. The lingual surface of the

maxillary lateral incisor is similar except the marginal ridges, fossa, and cingulum may

be slightly more distinct than for the central incisors (Figure 3-12).

Figure 3-12 Maxillary incisor lingual surfaces

The marginal ridges of some mandibular incisors are distinct, while others are not

well defined. When well formed, the marginal ridges are only distinct in the incisal third.

They blend into the cingulum as slight depressions in the middle and gingival thirds. The

54

remainder of the mandibular incisors lingual surface is less concave and the cingulum is

less convex in comparison to the maxillary incisors (Figure 3-13).

Figure 3-13 Mandibular incisor lingual surfaces

c. Incisal Line Angles

When incisors erupt, they have mamelons, which rapidly wear away. The

mandibular incisors often occlude with the lingual surfaces of the maxillary incisors near

the incisal edges. As an individual protrudes and retrudes the mandible, the incisal edges

rub across each other, forming a distinct wear pattern. The incisal surfaces of the

maxillary incisors wear with an incline toward the lingual surface, while the incisal

surfaces of the mandibular incisors wear with an inclination toward the labial surface

(Figure 3-14).

The labio-incisal and linguo-incisal line angles are the incisal boundaries of the

labial and lingual surfaces, respectively. Mesiodistally, these line angles form fairly

parallel arcs (Figure 3-15).

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Figure 3-14 Incisal edge wear Figure 3-15 Incisal line angles

Mesio-incisal and disto-incisal line angles are used to describe the two incisal

"corners" as seen in a facial view. The mesio-incisal line angle of the maxillary central

incisor is approximately a right angle, while the lateral incisor's line angle is slightly

more rounded (Figure 3-16).

The disto-incisal line angle of the maxillary central incisor is obtuse or more

rounded than its mesio-incisal line angle. Similarly, the disto-incisal line angle of the

maxillary lateral incisor is more rounded than in the central incisors (Figure 3-17).

Figure 3-16 Maxillary incisor Figure 3-17 Maxillary incisor

Mesio-incisal line angles disto-incisal line angles

The mesio-incisal and disto-incisal line angles of the mandibular incisors are all

acute or approach 90. The disto-incisal angle of the mandibular lateral incisors is the

only line angle that is slightly rounded (Figure 3-18).

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Figure 3-18 Mandibular incisor mesio-incisal and disto-incisal line angles

The teeth tend to have a faciolingual taper (or lingual convergence), which is

especially prevalent among the anterior teeth. In architecture, if stone blocks are used to

build an arch, they must be wider on the outer surface than on the inner surface (Figure 3-

19). This arch of blocks may be used to simulate an arch of teeth. All but one of the

teeth are wider on their facial than on their lingual surfaces (Figure 3-20). The one

exception: the maxillary first molar, which is wider on the lingual aspect than on the

facial aspect.

Figure 3-19 Faciolingual taper Figure 3-20 Lingual convergence of

maxillary teeth

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2. Proximal Contacts Proximal contacts must be observed from two different views. From an incisal

view of anterior teeth, all contacts are centered labiolingually in the incisal and middle

thirds of the teeth, depending on the location of the tooth in the arch (Figure 3-21). From

a facial view, the contact between the maxillary central incisors is near the incisal edge.

In the anterior teeth, the more distal the contact is from the midline, the more cervical it is

located (Figure 3-22).

Figure 3-21 Maxillary incisor proximal Figure 3-22 Maxillary incisor proximal

contacts, incisal view contacts, facial view

Although the exact location of proximal contacts vary, the "average" dentition has

the contacts in the following locations and these will be used in this course and may be

seen on your National Board Dental Examination Part I:

Maxillary Tooth Mesial Contact Distal Contact

Central Incisor I 1/3 I & M 1/3 Lateral Incisor I & M 1/3 M 1/3 Canine I & M 1/3 M 1/3

Definitions:

I 1/3 - Incisal one-third of proximal surface

M 1/3 - Middle one-third of proximal surface

I & M 1/3 - Junction of incisal and middle thirds of proximal surface

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In the mandibular arch, the proximal contacts of the anterior teeth are near the

incisal edge. In general, the proximal contacts move slightly more gingival the more

distal the tooth's location. The middle one-third is not reached until the distal of the

canine (Figure 3-23).

Figure 3-23 Mandibular incisor proximal contacts, frontal view

Mandibular Tooth Mesial Contact Distal Contact

Central Incisor I 1/3 I 1/3 Lateral Incisor I 1/3 I 1/3 Canine I 1/3 M 1/3

3. Embrasures Place a large rubber band around the facial surfaces of the maxillary dentiform

(Figure 3-24). It should be near the incisal edges of the anterior teeth. This will make the

facial embrasures easier to visualize from an incisal view. Note the curvature of the

rubber band around the anterior segment. The rubber band will make the facial

embrasures appear as small triangular shaped spaces. Note the shapes and relative sizes

of these embrasures. Note especially the shape of the portions of the teeth that form the

59

other two sides of this triangular space. Note the "regular" or uniform appearance of the

embrasures (Figure 3-25).

Figure 3-24 Rubber band on typodont Figure 3-25 Rubber band bordering

embrasures

For the embrasures to have this symmetrical form, the portions of the two adjacent

teeth that form each embrasure must be of very similar form. These adjacent parts of the

two teeth forming the embrasure are approximate mirror images of each other.

Remove one of the maxillary central incisors from the dentiform. Place a mouth

mirror against the mesial surface of the central incisor remaining in the dentiform (Figure

3-26).

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Figure 3-26 Embrasures should "mirror image" each other

Study the embrasures formed between the central incisor and its image. When

forming a tooth in wax, the borders of the wax pattern that form the embrasure with the

adjacent tooth can be shaped to form an ideal embrasure. These border positions can then

act as landmarks in forming the remainder of the tooth. This ability to form the border

portions of teeth in proper relationship to adjacent structures will be a skill vital to

success in carving teeth to correct form.

The incisal and gingival embrasures should also be studied at this time. Review

the mesial and distal incisal angles of the incisors; these angles are the "sides" of the

embrasures. Study the characteristics of each embrasure individually, i.e., the incisal

embrasure between the two maxillary central incisors is a very small, V-shaped area

(Figure 3-27). The characteristic shape is dictated by the nearly square form of the

mesio-incisal angles and the location of the proximal contact in the incisal one-third.

Compare the incisal embrasures among the other anterior teeth. The incisal embrasures

in both arches generally become slightly wider (more open) the more distal their location

is in the arch. Incisal embrasures also become slightly taller as the proximal contacts

move gingivally.

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Figure 3-27 Incisal and gingival embrasures

4. Contours The tooth's contours are its convexities and concavities. The height-of-contour is

the tooth's maximal bulge on the facial, lingual, mesial, or distal surface, measured in the

incisocervical or occlusocervical direction. The height-of-contour is usually expressed as

being in the cervical, middle, or occlusal third of the tooth. These heights of contour

must be memorized for the facial and lingual surfaces and the interproximal contacts for

the mesial and distal surfaces. These will be asked in test questions for this course and

the National Board Dental Examination Part I.

In Figure 3-28, observe the tooth's contour coronal to the gingival tissue and think

about the tooth's height-of-contour locations.

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Figure 3-28 Height-of-contour

Using the typodont, view the contour of the anterior teeth immediately adjacent to

the gingiva on the facial and lingual surfaces. Note that the tooth does not have a bulge

above the gingiva. Each height-of-contour is the convexity incisal to the CEJ. It must be

noted that in an ideal gingiva to tooth relationship, the undercut area (area cervical to the

height-of-contour) of the tooth is covered by the gingiva.

The angulations of the teeth in the arch also influence the tooth contour. This is

best illustrated by removing a maxillary central incisor from the arch and noting the bulge

of the cingulum when the tooth is positioned vertically. Replace the tooth firmly into the

typodont and note the relationship of the lingual gingiva to the cingulum. The height of

the gingiva and the tooth's labial angulation result in a tooth that does not have undercuts

that would tend to retain plaque.

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C. Summary Maxillary Anterior Teeth

1. Maxillary Central Incisor Labial View (Figure 3-29)

1. Anatomical crown length is greater than width.

2. Facial crown outline is trapezoidal with shorter parallel side at the cervical.

3. Incisal outline (edge) is relatively straight.

4. Mesial outline is only slightly convex (relatively straight).

5. Mesial contact area is in incisal one-third.

6. Distal outline is more convex (more rounded) than mesial outline.

7. Distal contact area is at junction of incisal and middle thirds.

8. Mesio-incisal angle is acute or near right angle.

9. Disto-incisal angle is more rounded than mesio-incisal.

10. Single root is basically cone shaped with a blunt apex.

11. Apex of root is usually slightly distal to long axis of tooth.

Lingual View (Figure 3-30)

1. There is shallow lingual fossa in the incisal and middle one-third of the lingual surface.

2. Lingual fossa boundaries are the incisal ridge, mesial and distal marginal ridges and the cingulum.

3. Cingulum is located slightly to the distal of center, or it can be said that the mesial side of the cingulum is longer than the distal side.

4. Crown and root taper lingually, therefore some of mesial and distal surfaces can be seen from a lingual view.

64

Figure 3-29 Maxillary central incisor, Figure 3-30 Maxillary central incisor,

facial view lingual view

Mesial View (Figure 3-31)

1. The crown is triangular in outline with the base at the cervical.

2. The labial outline is just slightly curved.

3. The lingual outline is slightly convex in the cingulum area and reverses to be slightly concave in the incisal two-thirds.

4. The anatomical crown is widest labiolingually in the cervical one-third.

5. A line drawn through the long axis of the tooth will bisect the apex of the root and the incisal edge.

6. The cervical line is curved more incisally than on any other tooth.

65

Distal View (Figure 3-32)

Note: The distal view characteristics that are the same as the mesial view are

not repeated, i.e., triangular outline, etc.

1. The incisal one-third of the crown appears to be thicker than from a mesial view due to the more rounded curvature of the distolabial area.

2. Curvature of cervical line is less than on mesial.

Figure 3-31 Maxillary central incisor, Figure 3-32 Maxillary central incisor,

mesial view distal view

Incisal View (Figure 3-33)

1. The outline is roughly triangular with the base being the broad labial surface and the tooth converging lingually.

2. Incisal edge is relatively straight mesiodistally and bisects labiolingual diameter.

3. Crest of cingulum is located slightly to the distal of the center of the lingual surface.

4. Mesial and distal contact areas are located near the centers of the proximal surfaces labiolingually.

66

5. Distolabial line angle is more obtuse than mesiolabial line angle.

6. Slight developmental depressions are on the labial surface.

Figure 3-33 Maxillary central incisor, incisal view

2. Maxillary Lateral Incisor Labial View (Figure 3-34)

1. Crown is smaller than the central incisors crown and the difference between the crowns length and width is more apparent than with the central incisor.

2. Crown outline is trapezoidal.

3. Incisal outline is more curved than the central incisor's outline.

4. Mesial outline is slightly rounded.

5. Mesial contact area is in the incisal one-third.

6. Distal outline is very convex or rounded.

7. Distal contact area is in the middle one-third.

8. Mesio-incisal line angle is slightly rounded.

9. Disto-incisal line angle is distinctly curved or rounded.

10. Root is pointed and as long or longer than the central incisors root.

11. Root apex is most often curved sharply to the distal.

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1. Lingual fossa is usually deeper than the central incisors fossa.

2. Mesial and distal marginal ridges are more prominent than the central incisors marginal ridge.

3. The cingulum is more rounded than the central incisors cingulum.

4. There is often a linguogingival fissure on the distal side of the cingulum, that can

run below the CEJ and cause localized periodontal problems.

Figure 3-34 Maxillary lateral incisor, Figure 3-35 Maxillary lateral incisor,



1. The crown is triangular in outline with the base of the triangle relatively narrower than the central incisors.

2. The labial outline is slightly curved.

3. The lingual outline is slightly concave in the middle and cervical thirds.

4. The incisal edge and apex of the root are on a line through the long axis of the tooth.

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1. As in the central incisor, the incisal one-third of the crown appears thicker than in the mesial view due to the curvature of the distolabial line angle to the lingual.

Figure 3-36 Maxillary lateral incisor, Figure 3-37 Maxillary lateral incisor,



1. The outline is similar to, but shows more convexity labially and lingually than the central incisor. This provides more of an ovoid outline compared to the central incisor's triangular outline.

2. The incisal edge is slightly convex to the labial. The incisal ridge is more prominent (curved more lingually) than with the central incisors.

3. The crest of the cingulum is slightly to the distal of the center of the tooth.

4. Mesial and distal contact areas are centered labiolingually.

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Figure 3-38 Maxillary lateral incisor, incisal view

3. Maxillary Canine Labial View (Figure 3-39)

1. The cusp tip of is slightly mesial to center of crown.

2. Mesial outline is slightly convex.

3. Mesial contact area is at the junction of incisal and middle one-third.

4. Distal outline is very convex at contact area with a concave outline in the cervical third.

5. Distal contact area is in the center of the middle one-third of the distal surface of the crown.

6. The mesial cusp arm (cusp arms are the length from the cusp tip to the respective incisoproximal angle) is shorter than the distal cusp arm. Both have slight developmental depressions.


1. Has the most prominent cingulum in the mouth.

2. There is a well-developed lingual ridge in the center running incisocervical from the cusp tip to the cingulum. It is most prominent in the incisal one-third near the cusp tip and blends into the lingual surface toward the cingulum.

3. Mesial and distal marginal ridges are well developed.

4. There are sometimes slight concave mesial and distal fossae, bordered by the lingual ridge and the mesial and distal marginal ridges.

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Figure 3-39 Maxillary canine, Figure 3-40 Maxillary canine,



1. The outline of the crown is triangular.

2. The labial outline is slightly convex.

3. Lingual outline is a fairly straight slope in the incisal one-half and very convex in

the cingulum area.

4. When wear has taken place, the worn cusp tip and cusp arm will face lingually.

5. The cusp tip is labial to the root apex.


1. There is a definite concavity in the distal surface of the crown between the contact area and the CEJ.

2. The distal marginal ridge is heavier than its mesial counterpart.

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Figure 3-41 Maxillary canine, Figure 3-42 Maxillary canine,



1. Mesial and distal contact areas are centered labiolingually.

2. The cusp ridges (mesial & distal cusp arms) are approximately centered labiolingually or slightly labial to the center.

3. There are two developmental depressions on the labial surface. The mesial developmental depression is very slight and confined mainly to the incisal portion, while the distal is more concave and extends more cervically than the mesial.

Figure 3-43 Maxillary canine, incisal view

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D. Review Maxillary Anterior Teeth

Figure 3-44 Review maxillary anterior teeth, labial, incisal and lingual views

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Figure 3-45 Review maxillary anterior teeth, mesial and distal views

1. Maxillary Central Incisor Right Left Proximal Contact locations: Universal Code: 8 9 Mesial: incisal third International Code: 1-1 2-1 Distal: junction of incisal and middle thirds Palmer Notation: 1| |1 No. of terminal roots: 1 Height-of-Contour: No. of pulp horns (facial view): 3 Facial: cervical third No. of cusps: none Lingual: cervical third No. of developmental lobes: 4 Identifying characteristics: The largest and most prominent incisor. Disto-incisal angle is more rounded than mesio-incisal. Prominent lingual features are cingulum, lingual fossa, and marginal ridges. It may have lingual pit. Has a large, simple pulp cavity with one root canal. It is not likely to have longitudinal grooves on root.

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Average Anatomic Average Average Mesiodistal Crown Height Root Length Crown Width

10.5 mm 13.0 mm 8.5 mm

2. Maxillary Lateral Incisor Right Left Proximal Contact locations: Universal Code: 7 10 Mesial: junction of incisal and middle thirds International Code: 1-2 2-2 Distal: middle third Palmer Notation: 2| |2 No. of terminal roots: 1 Height-of-Contour: No. of pulp horns (facial view): 2 Facial: cervical third No. of cusps: none Lingual: cervical third No. of developmental lobes: 4 Identifying characteristics: Is similar to, but smaller than the maxillary central incisor. Has more prominent marginal ridge and lingual fossa than central incisor and occasionally has a DL developmental groove along the distolingual aspect that may travel through the gingival attachment and sometimes along the root. Usually has two rather than three pulp horns. Has apical accessory canals more frequently than other incisors. Average Anatomic Average Average Mesiodistal Crown Height Root Length Crown Width

9.0 mm 13.0 mm 6.5 mm

3. Maxillary Canine Right Left Proximal Contact locations: Universal Code: 6 11 Mesial: junction of incisal and middle thirds International Code: 1-3 2-3 Distal: middle third Palmer Notation: 3| |3 No. of terminal roots: 1 Height-of-Contour: No. of pulp horns (facial view): 1 Facial: cervical third No. of cusps: 1 Lingual: cervical third No. of developmental lobes: 4

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Identifying characteristics: Is the largest single rooted tooth in the mouth. Its cingulum is centered mesiodistally. Its prominent facial ridge is off-center, toward the mesial. It has a distinct lingual ridge running incisocervical, two lingual fossae on both sides of the ridge, and a prominent cingulum. Average Anatomic Average Average Mesiodistal Crown Height Root Length Crown Width

10.0 mm 17.0 mm 7.5 mm

E. Summary Mandibular Anterior Teeth

1. Mandibular Central and Lateral Incisors Labial View (Figure 3-46)

1. The crowns appear to be approximately twice as long as they are wide. The lateral incisor is wider (about 0.5 mm) than the central incisor, with most of the extra width on the distal surface.

2. The crown outline is trapezoidal.

3. Incisal outline is straight.

4. Mesial and distal outlines are straight.

5. The distal side of the lateral is often shorter than the mesial side causing the incisal edge (which is straight) to slope downward in a distal direction.

6. Mesial and distal contact areas are in the incisal one-third near the incisal angles. The distal contact area of the lateral incisor is slightly more cervical than the other three contact areas.

7. The mesio-incisal angles of central and lateral incisors are sharp.

8. The disto-incisal angle of the central is sharp and the disto-incisal angle of the lateral is slightly rounded.

9. There are no developmental depressions on the labial surface.

10. Roots are thin and tapered and often curved slightly to the distal.

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1. Lingual surfaces of both central and lateral are smooth and rounded with no distinct lingual fossae.

2. Mesial and distal marginal ridges are only very minor elevations.

3. Some mandibular incisors have distinct mesial and distal marginal ridges. They are prominent only in the incisal one-third.

4. The cingulum (or cingula) are much less distinct than in their maxillary

counterparts.

Figure 3-46 Mandibular central and Figure 3-47 Mandibular central and

lateral incisors, facial view lateral incisors, lingual view

Mesial and Distal Views (Figures 3-48 and 3-49)

1. The crowns have a very pointed triangular outline.

2. The labial outline of the crowns is curved in the cervical one-third and is then straight from the crest of this curvature to the incisal edge.

3. The incisal edge is lingual to the long axis of the tooth.

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4. The incisal surface, when worn, angles to the labial.

5. The cervical lines extend about 1 mm more apically on the lingual side than on the labial side.

6. The roots taper evenly to a blunt apex and have mesial and distal depressions in the proximal root surfaces.

Figure 3-48 Mandibular central Figure 3-49 Mandibular lateral

incisor, mesial view incisor, distal view


1. The incisal edge of the central incisor is lingual to the center of the tooth and

straight.

2. The incisal edge of the lateral incisor is lingual to the center of the tooth, but slants to the distolingual to start the curve of the arch.

3. Both teeth converge lingually.

4. The proximal contacts are centered labiolingually.

5. The lateral incisor appears twisted on its axis in a distolingual direction in comparison to the symmetrical central.

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Figure 3-50 Mandibular central and lateral incisors, incisal view

2. Mandibular Canine Labial View (Figure 3-51)

1. Compared to the maxillary canine, the crown is narrower and as long or longer.

2. The mesial outline is straight and in line with the mesial outline of the root.

3. The mesial contact area is in the incisal one-third.

4. The distal outline is concave cervical to the contact area, but not to the degree of that in the maxillary canine.

5. The distal contact area is at the junction of incisal and middle one-third.

6. The mesial cusp arm is shorter and more horizontal than the distal cusp arm. The distal cusp arm slopes apically.


1. The lingual surface is relatively flat and smooth.

2. The cingulum is poorly developed.

3. The marginal ridges are only very slight elevations.

4. The root narrows more lingually than the root of the maxillary canine.

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Figure 3-51 Mandibular canine, Figure 3-52 Mandibular canine,


Mesial and Distal Views (Figures 3-53 and 3-54)

1. The labial outline is fairly straight incisal to the slight cervical curvature.

2. The lingual outline is slightly more concave and slopes more apically than the maxillary lingual outline due to the less prominent cingulum in the mandibular.

3. The cusp tip is lingual to the root apex.

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Figure 3-53 Mandibular canine, Figure 3-54 Mandibular canine,



1. The labial outline is less convex than the maxillary canine.

2. The cusp tip and mesial cusp arm are inclined slightly to the lingual.

Figure 3-55 Mandibular canine, incisal view

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F. Review Mandibular Anterior Teeth

Figure 3-56 Review mandibular anterior teeth, labial, incisal and lingual views

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1. Mandibular Central Incisor Right Left Proximal Contact locations: Universal Code: 25 24 Mesial: incisal third International Code: 4-1 3-1 Distal: incisal third ___ ___

Palmer Notation: 1| |1 No. of terminal roots: 1 Height-of-Contour: No. of pulp horns (facial view): generally 1 Facial: cervical third No. of cusps: none Lingual: cervical third No. of developmental lobes: 4 Identifying characteristics: The mesio-incisal and disto-incisal angles are very similar and acute. Has less prominent lingual features than on maxillary incisors. From a proximal view, the incisal edge is displaced toward the lingual. The root is flat and the faciolingual wider than the mesiodistal. Average Anatomic Average Average Mesiodistal Crown Height Root Length Crown Width

9.0 mm 12.5 mm 5.0 mm

2. Mandibular Lateral Incisor Right Left Proximal Contact locations: Universal Code: 26 23 Mesial: incisal third International Code: 4-2 3-2 Distal: incisal third ___ ___

Palmer Notation: 2| |2 No. of terminal roots: 1 Height-of-Contour: No. of pulp horns (facial view):generally 1 Facial: cervical third No. of cusps: none Lingual: cervical third No. of developmental lobes: 4 Identifying characteristics: Compared to the mandibular central incisor, its crown is slightly wider mesiodistally. The distal end of the incisal edge is rotated toward the lingual. Its root is larger than the mandibular central incisor root.

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Average Anatomic Average Average Mesiodistal Crown Height Root Length Crown Width 9.5 mm 14.0 mm 5.5 mm

3. Mandibular Canine Right Left Proximal Contact locations: Universal Code: 27 22 Mesial: incisal third International Code: 4-3 3-3 Distal: middle third ___ ___

Palmer Notation: 3| |3 No. of terminal roots: 1 or 2 Height-of-Contour: No. of pulp horns (facial view): 1 Facial: cervical third No. of cusps: 1 Lingual: cervical third No. of developmental lobes: 4 Identifying characteristics: Compared to the maxillary canine, its crown is longer, narrower, and has with less prominent lingual features. The cusp tip is inclined to the lingual and the distal end of the incisal edge is rotated to the lingual. It has the longest root in the mandibular

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