anatomy and morphology of teeth

ماکروسکوپیک خصوصیات به راجع که است علمی

نها تنوع و ناهنجار و هنجار دندانهاینها ارتباط و ا

با ا

کند می صحبت جونده سیستم اجزاء و هم

Primary dentition

Mixed dentition

Permanent dentition

سالگی ٦ماهگی تا ٦از

سالگی ١٢سالگی تا ٦از

سالگی تا زمانی که دندانها در ١٢از

دهان هستند

Primary dentition

Mixed dentition

Permanent dentition

دوره های دندانی

Introduction Dentition is the term used to describe the natural teeth

in the jawbones. The dental assistant must know the names, locations, and functions of the teeth.

The dental assistant must also understand

the various systems of numbering the teeth, as well as the patterns of tooth

eruption and occlusion.

Copyright © 2009, 2006 by Saunders, an imprint of Elsevier Inc. All rights reserved.

Presenter

Presentation Notes

Why do we number the teeth in each dentition? What occurs during tooth eruption? What does “occlusion” mean? How many teeth are in each dentition? What is the term for the four sections of the divided dental arches? What are the terms for the front teeth and the back teeth?

The Primary Dentition The first set of 20 primary teeth is called the primary

dentition. This dentition is commonly referred to as the “baby

teeth.” You may also hear the term deciduous dentition. This

is an older and less frequently used dental term to describe the primary dentition.


Presenter

Presentation Notes

Do you still have any of your shed primary teeth? Why were the primary teeth once called deciduous?

Fig. 11-1 Facial and buccal view of a primary dentition.


Presenter

Presentation Notes

Are baby teeth important, or should parents just let them decay and fall out? Do you notice how white these teeth are? Why are they whiter than permanent teeth?

The Mixed Dentition Mixed dentition generally occurs between the ages of 6

and 12 years. Both primary and permanent teeth are present during this transitional period.

The mixed-dentition period begins with the eruption of the first permanent tooth, which is a permanent mandibular first molar.

This period ends with shedding of the last primary tooth.


Presenter

Presentation Notes

Why can the mixed-dentition period be difficult for the child? (The mixed-dentition period is often a difficult time for children because color differences between the primary and permanent teeth become apparent and they may notice the difference in crown size between the larger permanent teeth and the smaller primary teeth. Some children may notice crowding of the teeth as they shift during eruption.)

Fig. 11-2 Facial and buccal view of a mixed dentition.


Presenter

Presentation Notes

Why is this the mixed dentition? Which teeth are primary teeth and which are permanent teeth? Why, as shown here, do orthodontists start therapy during this time?

The Permanent Dentition The permanent dentition is the final, or adult,

dentition. This period begins with shedding of the last primary

tooth. Growth of the jawbones slows and eventually stops. There is very little growth of the jaw overall during this

period because puberty has passed.


Presenter

Presentation Notes

After the eruption of the permanent canines and premolars and the second permanent molars, around age 14 or 15, the permanent dentition is complete except for the third molars, eruption of which is not completed until the subject is between the ages of 18 and 25 years. The permanent dentition includes eruption of all the permanent teeth, except for teeth that are congenitally (from the time of birth) missing or impacted and cannot erupt (usually the third molars).

Fig. 11-3 Facial and buccal view of a permanent dentition.


Presenter

Presentation Notes

The permanent dentition is the final, or adult, dentition. Why is this called the permanent dentition? Why are these teeth yellower than the primary teeth?

The Dental Arches The maxillary arch (upper), which is actually part

of the skull, is fixed and not capable of movement. The teeth are set in the maxilla bone.

The mandibular arch (lower) is capable of movement through the action of the temporomandibular joint. The mandible is the bone that supports the lower arch of teeth, hence the name “mandibular arch.”

Occlusion is the natural contact between the maxillary and mandibular teeth in all positions.


Presenter

Presentation Notes

How is each arch divided for treatment in the dental office? How is occlusion assessed?

Quadrants Dividing the maxillary and mandibular arches into

halves yields four sections, which are called quadrants. Each quadrant of permanent dentition contains eight

permanent teeth and a quadrant of primary dentition contains five teeth.


Presenter

Presentation Notes

Remember that as one looks into the patient’s oral cavity, the directions are reversed.

Fig. 11-4 A, Primary dentition separated into quadrants. B, Permanent dentition separated into quadrants. (From Finkbeiner B, Johnson C: Comprehensive dental assisting, St Louis, 1995, Mosby.)


Presenter

Presentation Notes

Which ones are the maxillary and mandibular arches? How are the arches divided?

Fig. 11-5 Permanent dentition separated into sextants. (From Finkbeiner B, Johnson C: Comprehensive dental assisting, St Louis, 1995, Mosby.)


Presenter

Presentation Notes

How is a sextant different from a quadrant in the mouth? Would it take longer to polish a sextant or quadrant?

Sextants Sometimes it is necessary to divide the dentition into

six parts, each called a sextant. Maxillary right posterior Maxillary anterior Maxillary left posterior Mandibular right posterior Mandibular anterior Mandibular left posterior


Presenter

Presentation Notes

How many teeth are in each sextant of the mouth?

Anterior Teeth The anterior teeth are the incisors and canines. They are visible when we smile. These teeth are aligned to form a smooth, curving arc

from the distal (back of the) canine on one side of the arch to the distal canine on the opposite side.


Presenter

Presentation Notes

To assist in describing their location and functions, the teeth are classified as anterior (toward the front) or posterior (toward the back). How many incisors are there in the primary dentition? How many incisors are there in the permanent dentition? How many canines are there in either the primary or the permanent dentition?

Posterior Teeth The premolars and molars. The posterior teeth are aligned with little or no

curvature. These teeth appear to be in an almost straight line.


Presenter

Presentation Notes

What is the other name for premolars? How many premolars are in there in the permanent dentition? How many molars? How are the posterior teeth aligned in contrast with the anterior teeth?

تاج دندان

ناتوميك ا

كلينيكال

ريشه دندان

ناتوميك ا

كلينيكال

مينا

عاج

سمنتوم

اتاق پالپ پالپ دندان

كانالهاي ريشه

لثه

سمنتوم

PDL

لوئل استخوان ا

Types and Functions of Teeth Human beings eat both meat and plants. To accommodate this variety in diet, teeth are

designed for the cutting, tearing, and grinding of different types of food.

The permanent dentition is divided into four types of teeth: Incisors Canines Premolars Molars


Presenter

Presentation Notes

How do the teeth help during mastication (chewing food)?

Types of Teeth in the Primary Dentition The primary dentition has:

Incisors Canines Molars

There are no premolars in the primary dentition.


Presenter

Presentation Notes

What tooth type is absent in the primary dentition? What tooth types are the same in the permanent and primary dentitions?

Fig. 11-6 A, Occlusal view of the permanent dentition. The types of teeth are identified using the Universal/National System. (From Bath-Balogh M, Fehrenbach MJ: Illustrated dental embryology, histology, and anatomy, ed 2 St Louis, 2005, Saunders.)


Presenter

Presentation Notes

The permanent teeth are numbered from 1 to 32 in accordance with the Universal/National Numbering System. Numbering begins with the upper right third molar, works around to the upper left third molar, drops to the lower left third molar, and works around to the lower right third molar. What teeth are usually extracted from the permanent dentition? What tooth is the first to erupt into the permanent dentition?

Incisor Teeth Incisors are single-rooted teeth with relatively sharp,

thin edges. Located at the front of the mouth, the incisors are

designed to cut food without the application of heavy force.

Incisor means “that which makes an incision or cut.”

The tongue side, or lingual surface of the incisor is shaped like a shovel to help guide food into the mouth.


Presenter

Presentation Notes

Ask your students to feel their incisors with their tongues and to note the sharp, thin edges of these teeth.

Canine Teeth Canine teeth are also known as cuspids. They are located at the “corners” of the arch. The canines are designed for cutting and tearing food. They are the longest teeth in the human dentition. Canine teeth have the longest roots of all teeth and are

usually the last teeth to be lost. Because of its sturdy crown, long root, and location in

the arch, the canine is referred to as the cornerstone of the dental arch.


Presenter

Presentation Notes

Why are canines called “canines”?

Premolar Teeth There are four maxillary and four mandibular

premolars. The premolars, also known as bicuspids, are a cross

between canines and molars. The pointed buccal cusps hold the food while

the lingual cusps grind it. The premolars are not as long as canines and also have

a broader surface made for chewing food.


Presenter

Presentation Notes

With your tongue, feel the cusps of your premolars. Ask students whether they have all of their premolars. Often the first premolar is extracted to satisfy spacing requirements in orthodontic therapy.

Molar Teeth Molars are much larger than premolars and usually

have four or more cusps. The function of the 12 molars is to chew or grind food. The molars have more cusps than do the other teeth.

There are four or five cusps on the occlusal (biting) surface of each molar, depending on the tooth’s location.

Maxillary and mandibular molars differ greatly from each other in shape, size, and numbers of cusps and roots.


Presenter

Presentation Notes

How many types of molars does the permanent dentition have? The primary dentition? Ask students: Do you have all your molars? Many times, because of impaction or spacing considerations, the third molar is extracted. What is the name for the space between adjacent teeth? What is the name of the area where adjacent teeth physically touch? What is the name of the triangular space near the gingiva between adjacent teeth?

ماکزيالری يا منديبوالر

دائمی يا شيری راست يا چپ

ثنايا ميانی کناری

نيش

آسيا کوچک اول دوم

آسيا بزرک اول

دوم

سوم

نامگذاري نمادي دندانهاPalmer Universal FDI

Tooth Surfaces Occlusal surfaces: posterior teeth Incisal surfaces: anterior teeth Lingual surfaces Buccal or facial surfaces Mesial surfaces Distal surfaces


Presenter

Presentation Notes

The facial surface is the surface closest to the face. The lingual surface is the surface of mandibular and maxillary teeth that is closest to the tongue. The masticatory surface is the chewing surface. On anterior teeth, it is the incisal surface (or incisal edge), and it is the occlusal surface for posterior teeth. The mesial surface is the surface of the tooth toward the midline. The distal surface is the surface of the tooth distant from the midline.

Fig. 11-7 Surfaces of the teeth and their relationships to other oral cavity structures, to the midline, and to other teeth. (From Bath-Balogh M, Fehrenbach MJ: Illustrated dental embryology, histology, and anatomy, ed 2, St Louis, 2005, Saunders.)


Presenter

Presentation Notes

What tooth surfaces usually get the most wear? What surfaces usually have the most caries? Which surfaces require the retraction of the tongue with the use of a mirror for the gingival tissue to be seen? What surfaces are hard to see without a mirror? Which surfaces may require the reflection of light off a mirror to be seen?

نامگذاری سطوح دندا�ا

Anatomic Features of the Teeth Anatomic features of the teeth help maintain their

positions in the arch and protect the tissues during mastication. Contours Contacts Embrasures


Presenter

Presentation Notes

Why do teeth have anatomic features?

Fig. 11-8 Tooth contours. A, Normal contour. B, Inadequate contour. C, Overcontouring.


Presenter

Presentation Notes

Every tooth has a curved surface except when the tooth is fractured or worn. Some surfaces are convex (curved outward); others are concave (curved inward). Although the general contours vary, the general principle that the crown of the tooth narrows toward the cervical line is true for all types of teeth. What is the term for the junction of two tooth surfaces?

Fig. 11-9 Example of a permanent anterior tooth with the contact area and height of contour identified. (From Bath-Balogh M, Fehrenbach MJ: Illustrated dental embryology, histology, and anatomy, ed 2, St Louis, 2005, Saunders.)


Presenter

Presentation Notes

A proper contact relationship between adjacent teeth: Prevents food from being trapped between the teeth Stabilizes the dental arches by holding the teeth in either arch in positive contact with each other Protects the interproximal gingival tissue from trauma during mastication Where is the contact area on this maxillary central incisor on its labial view? Is this the same as its height of contour on its proximal surfaces? Note that the height of contour is not the same on this tooth’s buccal and lingual surfaces.

Embrasures When two teeth in the same arch touch, their

curvatures next to the contact areas form spaces called embrasures.

An embrasure is a triangular space in a gingival direction between the proximal surfaces of two adjoining teeth in contact.

Embrasures are continuous with the interproximal spaces between the teeth.

All tooth contours, including contact areas and embrasures, are important in the function and health of the oral tissues.


Presenter

Presentation Notes

Ask the students the following question: Can you feel the embrasures of your teeth with your tongue?

Fig. 11-10 Embrasures may diverge facially, lingually, occlusally, or apically.


Presenter

Presentation Notes

Curvatures adjacent to the contact areas form spaces called embrasures.

برجستگيهاي سطح دندان

Cingulum

Mamelon

Ridge

Tubercle

Height of Countour

Line Angle

Point Angle

Terminology برجستگيهاي سطح دندان

Cingulum

Mamelon

Ridge

Tubercle

Height of Countour

Line Angle

Point Angle

Terminology • فرورفتگيهاي سطح دندان• Fossa • Groove • Sulcus • Pit

تقسيم به يک سوم

anatomy and morphology of teeth

Health & Medicine