Woelfel's Dental Anatomy 8th Ed PDF

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I PART COMPARATIVE TOOTH ANATOMY The six chapters in this part of the book provide a detailed description of each type of tooth in an adult and in a child. 1 4 Part 1 | Comparative Tooth Anatomy hen we enter into any new field of study, tooth morphology are the basic foundation for under- W it is i...

Description

PART

I

COMPARATIVE TOOTH ANATOMY The six chapters in this part of the book provide a detailed description of each type of tooth in an adult and in a child.

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4

Part 1 | Comparative Tooth Anatomy

hen we enter into any new field of study, it is initially necessary to learn the particular language of that field. Without an adequate vocabulary, we can neither understand others nor make ourselves understood. Definitions and explanations of terms used in descriptive

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SECTION I

tooth morphology are the basic foundation for understanding subject matter presented in subsequent chapters of this text. You need to learn some basics, similar to learning a foreign language. You will soon become familiar with these dental terms as you continue to use them throughout your professional dental career.

NAMING TEETH BASED ON LOCATION WITHIN THE NORMAL, COMPLETE HUMAN DENTITION

This section is designed to introduce you to terms used when naming teeth based on their normal location in the mouth. All of the teeth in the mouth together are referred to as the dentition [den TISH un]. Humans have two dentitions throughout life: one during childhood, called the primary dentition, and one that will hopefully last throughout adulthood, called the permanent (also known as secondary) dentition. The teeth in the upper jawbones (called the maxillae [mak SIL ee]) collectively form an arch shape known as the maxillary [MACK si lair ee] arch, and those teeth in the lower jawbone (called the mandible) collectively form the mandibular [man DIB yoo ler] arch. Each arch can further be divided into the left and right halves (also known as left and right quadrants since each quadrant contains one fourth of all teeth in that dentition).

of teeth in each lower quadrant, a formula can be used to represent the teeth in the human primary dentition as follows: I 22 C 11 M 22 = 5 upper and 5 lower teeth in each quadrant; 20 teeth in all The classes of primary teeth containing more than one tooth per quadrant (incisors and molars) are subdivided into types within each class. Each type can also be identified by its location within the complete quadrant. The primary incisor closest to the midline separating the right and left quadrants is called a central incisor. The incisor next to, or lateral to, the central incisor is called a lateral incisor. Next in each quadrant is a canine, followed by two types of molars: a first molar behind the canine and then a second molar.

A. COMPLETE PRIMARY DENTITION The complete primary dentition is normally present in a child from the ages of about two to six years. There are 20 teeth in the entire primary dentition (shown in Fig. 1-1): ten in the upper maxillary arch and ten in the lower mandibular arch. This dentition is also called the deciduous [de SIDJ oo us] dentition, referring to the fact that all of these teeth are eventually shed by age 12 or 13, being replaced sequentially by teeth of the permanent dentition. The complete primary dentition has five teeth in each quadrant. The primary teeth in each quadrant are further divided into three classes: incisors [in SI zerz], canines, and molars. Based on location, starting on either side of the midline between the right and left quadrants, the two front teeth in each quadrant of the primary dentition are incisors (I), followed by one canine (C), then two molars (M). Using these abbreviations for the classes of teeth, followed by a ratio composed of a top number representing the number of teeth in each upper quadrant and the bottom number representing the number

LEARNING EXERCISE Using either models of the complete primary dentition or Figure 1-1 while covering up the labels, identify each primary tooth based on its location in the arch. Include, in order, the dentition, arch, quadrant (right or left), type (when applicable), and class. For example, the tooth next to the midline in the lower left quadrant would be identified as the primary mandibular left central incisor.

B. COMPLETE PERMANENT DENTITION The complete permanent (or secondary) dentition is present in the adult. It is composed of 32 teeth: 16 in the upper maxillary arch and 16 in the lower mandibular arch (shown in Fig. 1-2). The permanent dentition has eight teeth in each quadrant, which are divided into

Chapter 1 | Basic Terminology for Understanding Tooth Morphology

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PRIMARY TEETH MAXILLARY Anterior teeth

Incisors

Canine

Canine tral

rs inciso

Po

ste

Lateral incisors

Molars

Molars

Canines

teeth rior

Posterio r te eth

C

en

1st Molars 2nd Molars

LEFT

RIGHT

1st Molars

Molars

Molars

Canines

eth

Lateral incisors

Canine

Posterior te

ior teeth ster Po

2nd Molars

Canine C

en

tral

rs inciso

Incisors

Anterior teeth

MANDIBULAR FIGURE 1-1.

Maxillary and mandibular primary dentition.

four classes: incisors, canines, premolars (PM; a new class for permanent teeth), and molars. Based on location, the two permanent front teeth in each quadrant are incisors (I), followed by one canine (C), then two premolars (PM), and finally three molars (M). The dental formula for the human permanent dentition is as follows: I 22 C 11 PM 22 M 33 = 8 upper and 8 lower teeth on either side, 32 teeth in all The classes of permanent teeth containing more than one tooth per quadrant (namely, incisors, premolars, and molars) are subdivided into types within each class. Each type can be identified by location within the quadrant. As in the primary dentition, the permanent incisor closest to the midline between the right and the

left quadrants is called a central incisor; the incisor next to, or lateral to, the central incisor is called a lateral incisor. Next in the arch is a canine, followed by a first premolar, then a second premolar. Continuing around toward the back in each quadrant are three molars: a first molar, a second molar, and finally a third molar (sometimes referred to as a wisdom tooth). As noted by comparing the formulas for primary and permanent teeth, differences exist. Although central and lateral incisors and canines are similarly positioned in both dentitions, permanent dentitions have a new category of teeth called premolars, which are located between canines and molars. Premolars are positioned in the spaces left where the primary molars were located earlier in life. Behind the premolars, there are three instead of two molars.

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Part 1 | Comparative Tooth Anatomy

PERMANENT TEETH MAXILLARY Anterior teeth

Incisors Canine

Canine

Premolars

Canines

eth or te te r i

Posterior t eet h

Premolars

s Po

Ce s nt r al incisor Lateral incisors

1st Premolars 2nd Premolars

Molars

Molars

1st Molars

2nd Molars

3rd Molars

LEFT

RIGHT 3rd Molars

2nd Molars

Molars

Molars 1st Molars

rior Poste

2nd Premolars

Canines Lateral incisors

Premolars

Premolars Canine

Central incisors

Po ste

th tee

rio r te e th

1st Premolars

Canine

Incisors

A n t e rio r t e e th

MANDIBULAR FIGURE 1-2.

Maxillary and mandibular permanent dentition.

Two other terms are used to categorize or distinguish groups of teeth by their location: anterior and posterior teeth. Anterior teeth are those teeth in the front of the mouth, specifically, the incisors and the canines. Posterior teeth are those in the back of the mouth, specifically, the premolars and the molars.

LEARNING EXERCISE Using either models of the complete permanent dentition or Figure 1-2 while covering up the labels, identify each permanent tooth based on

Learning Exercise, cont.

its location in the arch. To identify each tooth accurately, include in order, the dentition, arch, quadrant, type (if applicable) and the class. For example, the last adult tooth in the lower right quadrant is correctly identified as the permanent mandibular right third molar.

Chapter 1 | Basic Terminology for Understanding Tooth Morphology

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Review Questions 1. How many teeth are present in one quadrant of a complete adult (permanent) dentition? a. 5 b. 8 c. 10 d. 20 e. 32 2. What class of teeth is present in the permanent dentition that is NOT present in the primary dentition? a. Incisors b. Canines c. Premolars d. Molars 3. In a permanent dentition, the fifth tooth from the midline is a a. Canine b. Premolar c. Molar d. Incisor

SECTION II

4. Posterior teeth in the permanent dentition include which of the following? a. Premolars only b. Molars only c. Premolars and molars only d. Canines, premolars, and molars 5. Which permanent tooth erupts into the space previously held by the primary second molar? a. First molar b. Second molar c. First premolar d. Second premolar

ANSWERS: 1—b, 2—c, 3—b, 4—c, 5—d

Select the one best answer.

TOOTH IDENTIFICATION SYSTEMS: UNIVERSAL, WORLD DENTAL FEDERATION (INTERNATIONAL), AND PALMER NUMBERING SYSTEMS

The making and filing of accurate dental records is an important task in any dental practice. To do so expeditiously, it is necessary to adopt a type of code or numbering system for teeth. Otherwise, for each tooth being charted, one must write something like “maxillary right second molar mesio-occlusodistal amalgam restoration with a buccal extension” (11 words, or 81 letters). Simplified by using the Universal Numbering System (and other standard abbreviations to denote tooth restoration surfaces described later in Chapter 10), this same information would be “2MODBA” (only six symbols). The Universal Numbering System was first suggested by Parreidt in 1882, and officially adopted by the American Dental Association in 1975. It is accepted by third-party providers and is endorsed by the American Society of Forensic Odontology. Basically, the Universal Numbering System uses No. 1 through 32 for the 32 teeth in the permanent dentition, starting with 1 for the maxillary right third molar, going around the arch to the maxillary left third molar as 16; dropping

down on the same side, the left mandibular third molar becomes 17, and then the numbers increase around the lower arch to 32, which is the lower right third molar. This numbering system is used for each permanent tooth in the illustration in Figure 1-3. For the 20 teeth in the primary dentition, 20 letters of the alphabet are used from A through T. The letter A represents the maxillary right second molar, sequentially around the arch and through the alphabet to J for the maxillary left second molar, then dropping down on the same side to K for the mandibular left second molar, and then clockwise around the lower arch to T for the mandibular right second molar. This system is used to identify each primary tooth in the illustration in Figure 1-4. There are also two other numbering systems, the Palmer Tooth Notation System, and the World Dental Federation (International) System used in other countries. The World Dental Federation notation (also known as the Federation Dentaire Internationale or FDI System) uses two digits for each tooth, permanent

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Part 1 | Comparative Tooth Anatomy

PERMANENT TEETH MAXILLARY Anterior teeth Incisors Canine 7

10

rs ntra l i n ci s o Lateral incisors

5

11 Premolars

12

4

13

1st Premolars

3

14

2nd Premolars

Molars

eth or te te r i

Canines

s Po

Posterior t eet h

Canine

Ce

6 Premolars

9

8

Molars

1st Molars

2

15 2nd Molars

1

16

3rd Molars

LEFT

RIGHT 3rd Molars

32

17 2nd Molars

18

1st Molars

Poste

2nd Premolars

30

19

1st Premolars

rior th tee

29 Premolars

20

Canines Lateral incisors

28 27

26 25

Canine

24 23

Central incisors

Molars

rio r te e th

31

21 22

Premolars

Po ste

Molars

Canine

Incisors A n terior te eth

MANDIBULAR FIGURE 1-3.

The occlusal and incisal surfaces of the maxillary and mandibular adult dentition are shown here. The Numbers 1 to 32 on the teeth represent the Universal Numbering System commonly used for record keeping in the United States, and used in this book.

or primary. The first digit denotes the quadrant (right or left) and arch (maxillary or mandibular) and dentition (permanent or primary) as follows: PERMANENT DENTITION 1 = Permanent dentition, maxillary, right quadrant 2 = Permanent dentition, maxillary, left quadrant 3 = Permanent dentition, mandibular, left quadrant 4 = Permanent dentition, mandibular, right quadrant PRIMARY DENTITION 5 = Primary dentition, maxillary, right quadrant 6 = Primary dentition, maxillary, left quadrant 7 = Primary dentition, mandibular, left quadrant 8 = Primary dentition, mandibular, right quadrant

The second digit denotes the tooth position in each quadrant relative to the midline, from closest to the midline to farthest away. Therefore, the second digits 1 through 8 stand for the permanent central incisor (1) through the permanent third molar (8) and 1 through 5 stands for the primary central incisor (1) through the primary second molar (5). The adult tooth Numbers 1 to 8 within each quadrant (1 through 4) are illustrated in Figure 1-5. Combining the first and second digits, numbers within the range 11 through 48 represent permanent teeth. For example, 48 is a permanent mandibular right third molar since the first digit, 4, indicates the mandibular right quadrant for a permanent tooth, and the second digit, 8, indicates the eighth tooth from

Chapter 1 | Basic Terminology for Understanding Tooth Morphology

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PRIMARY TEETH MAXILLARY Anterior teeth Incisors

D

E

F

Canine

G

rs inciso

H

Molars

B

1st Molars

A

Molars

I

Canines

teeth rior

Lateral incisors

ste

C

tral

Po

en

C

Posterio r te eth

Canine

J

2nd Molars

RIGHT

LEFT

K 1st Molars

Molars

Molars

Canines

L

Lateral incisors

R Canine

eth

S

Posterior te

ior teeth ster Po

2nd Molars

T

M Q

P O

C

en

tral

N

Canine

rs inciso

Incisors Anterior teeth

MANDIBULAR FIGURE 1-4.

The occlusal and incisal surfaces of the maxillary and mandibular primary dentition are shown here. The letters A to T represent the Universal Numbering System for primary teeth commonly used for record keeping in the United States.

the midline in that quadrant, namely, the third molar. Numbers within the range 51 through 85 represent primary teeth. For example, 51 is a primary maxillary right central incisor since the first digit, 5, indicates the maxillary right quadrant for a primary tooth, and the second digit, 1, indicates the first tooth from the midline in that quadrant, namely, the central incisor. If the Universal number for a tooth were 32, the World Dental Federation number would be 48. All of the tooth numbers are shown in Table 1-1. The Palmer Notation System is used by many orthodontists and oral surgeons. It utilizes four different bracket shapes to denote each of the four quadrants. The specific bracket surrounds a number (or letter), which denotes the specific tooth within that quadrant.

The specific brackets are designed to represent each of the four quadrants of the dentition, as if you were facing the patient as seen in Figure 1-5. is upper right quadrant is upper left quadrant is lower right quadrant is lower left quadrant The permanent teeth in each quadrant are numbered from 1 (nearest to the arch midline) to 8 (farthest from the midline) as in the International System. For example, 1 is a central incisor, 2 is a lateral incisor, 3 is a canine, and so forth. The bracket shapes used to identify each quadrant as you are facing a patient, and the tooth numbers (1–8) within each quadrant, are

Part 1 | Comparative Tooth Anatomy

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Table 1-1

MAJOR TOOTH IDENTIFICATION SYSTEMS UNIVERSAL

INTERNATIONAL (FDI)

Left

Right

Left

MAXILLARY TEETH

Right

E D C B A

F G H I J

A B C D E

A B C D E

51 52 53 54 55

61 62 63 64 65

MANDIBULAR TEETH

PRIMARY DENTITION

PALMER NOTATION Left

Central incisor Lateral incisor Canine First molar Second molar Central incisor Lateral incisor Canine First molar Second molar

P Q R S T

O N M L K

A B C D E

A B C D E

81 82 83 84 85

71 72 73 74 75

Central incisor Lateral incisor Canine First premolar Second premolar First molar Second molar Third molar

8 7 6 5 4 3 2 1

9 10 11 12 13 14 15 16

1 2 3 4 5 6 7 8

1 2 3 4 5 6 7 8

11 12 13 14 15 16 17 18

21 22 23 24 25 26 27 28

Central incisor Lateral incisor Canine First premolar Second premolar First molar Second molar Third molar

25 26 27 28 29 30 31 32

24 23 22 21 20 19 18 17

1 2 3 4 5 6 7 8

1 2 3 4 5 6 7 8

41 42 43 44 45 46 47 48

31 32 33 34 35 36 37 38

MANDIBULAR TEETH

PERMANENT DENTITION

Right

MAXILLARY TEETH

TOOTH

illustrated in Figure 1-5. To identify a specific tooth, you place the number of the correct tooth within the bracket that indicates the correct quadrant. For example, the lower left central incisor would be 1, the lower left second premolar would be 5, and the upper right canine would be 3. For primary teeth, the same four brackets are used to denote the quadrants, but five letters of the alphabet A through E represent the primary teeth in each quadrant (with A being a central incisor, B a lateral incisor, C a canine, etc.). Comparing the Universal System with the Palmer System, the permanent maxillary right second molar would be No. 2 using the Universal System, but would be 7 using the Palmer system. If you are confused, refer to Table 1-1 for clarificat...