NOMENCLATURE,CHRONOLOGY AND MORPHOLOGY OF PRIMARY DENTITION

NOMENCLATURECHRONOLOGY &

MORPHOLOGY OF PRIMARY

DENTITION

By : Prateek KariyaMDS 1ST Year

Dept Of Pedodontics & Preventive Dentistry

CONTENTS::: INTRODUCTION NOMENCLATURE DENTAL FORMULAE TEETH NUMBERING SYSTEMS CHRONOLOGY ERUPTION MORPHOLOGY CLINICAL IMPLICATIONS REFERENCES.

INTRODUCTION:::

The first step in understanding dental anatomy is to learn the nomenclature, or the system of names used to describe or classify the material included in the subject.

A knowledge of the development of the teeth and their emergence into the oral cavity is applicable to clinical practice as well as to archaeology, demography, forensics and palaeontology.

The word dentition refers to all of the teeth in the upper jaw bone (maxilla) and lower jaw bone (mandible).

The upper teeth are called maxillary

teeth and together form an arch shape known as maxillary arch of teeth.

The lower teeth are called mandibular teeth, collectively forming the mandibular arch of teeth.

Importance and Functions of Primary Teeth:

Sidney B Finn: Clinical pedodontics , 4th edition

Mechanical preparation of child’s food for digestion and assimilation.

Maintenance of space for permanent teeth. Stimulation of growth of the jaws Development of speech Cosmetic function.**Therefore, premature loss of deciduous teeth is to be

avoided.

Human exhibits.

DIPHYODONT

THECODONT

HETERODONT

Nomenclature:::

The system of names , used to describe or classify the material included in the subject.

Deciduous tooth( Baby, primary, milk)…one of the temporary set of teeth of a

mammal that are replaced by permanent teeth.

Permanent tooth…successor dentition which is permanent ,

which may not be the case because of dental caries periodontal diseases and trauma.

Dental formulae:::

2 1 2 3 I C P M = 16 2 1 2 3

2 1 2 I C M = 10 2 1 2

Primary / deciduous teeth:

Permanent teeth:

Ash MM, Nelson S. Wheeler’s Dental Anatomy

Tooth numbering systems:::

Zsigmondy / Palmer notation system: ADA in 1947 recommended this method as the numbering method of choice. In United States it is often

referred as Palmer notation

By Adolph Zsigmondy ,1861 for permanent dentitionModified in 1874 for primary

dentition.Palmer,1870 independently

E D C B A A B C D E E D C B A A B C D E

A B C D E F G H I J T S R Q P O N M L K

Universal numbering system Recommended by ADA in 1968.

( By: Parreidt,1882)

55 54 53 52 51 61 62 63 64 65 85 84 83 82 81 71 72 73 74 75

FDI ( Federation Dentaire Internationale):

Two digit system

Adopted by WHO & IADR . Also known as ISO-3950 notation.

By Roger L,1987

Viktor Haderup of Denmark in 1891: EUROPEAN numbering system. Eg : +01 maxillary left central

incisor 01+ maxillary right central

incisor -01 mandibular left central

incisor 01- mandibular right central

incisor

http://knol.google.com/k/-/-/3mflbd6iv8q1u/44m5m5/european-deciduous-tooth.jpg

8 7 6 5 4 3 2 1 1 2 3 4 5 6 7 8 8 7 6 5 4 3 2 1 1 2 3 4 5 6 7 8

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 32 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17

18 17 16 15 14 13 12 11 21 22 23 24 25 26 27 28 48 47 46 45 44 43 42 41 31 32 33 34 35 36 37 38

FDI

Universal numbering system

Zsigmondy system:

Permanent Dentition

8+ 7+ 6+ 5+ 4+ 3+ 2+ 1+ +1 +2 +3 +4 +5 +6 +7 +8 8- 7- 6- 5- 4- 3- 2- 1- -1 -2 -3 -4 -5 -6 -7 -8

Viktor Haderup

FDI Notation

Zsigmondy / Palmer Notation

European Tooth numbering System

Universal Tooth Numbering System

http://knol.google.com/k/-/-/3mflbd6iv8q1u/44m5m5/fdi-deciduous-tooth.jpg

http://knol.google.com/k/-/-/3mflbd6iv8q1u/44m5m5/european-permanent-tooth.jpg

http://knol.google.com/k/-/-/3mflbd6iv8q1u/44m5m5/european-deciduous-tooth.jpg

http://knol.google.com/k/-/-/3mflbd6iv8q1u/44m5m5/american-permanent-tooth.jpg

http://knol.google.com/k/-/-/3mflbd6iv8q1u/44m5m5/american-deciduous-tooth.jpg

Chronology:::

Definition: the study which deals with the timings of the various stages of tooth development, starting with the initiation of the first dental tissue laid down to the emergence of tooth into the oral cavity and its completion of calcification.

By Tandon S .Textbook of pedodontics . 2nd edition

Types of chronologies : 1-- age of attainment chronologies based on

tooth emergence. (Logan & Kronfeld,1933

Schour & Massler,1941) 2-- age prediction chronologies based on

being in a stage.(Goldstein H,1979) 3-- maturity assessment scale used to

assess whether a subject of known age is in front of or behind compared with a refrence population.

(Wolanski,1966)

Originally chronology for dentition was based on the data of Logan and Kronfeld (1933)

Later a careful review of data was done by various researchers like > Massler and Shour (1941), > Moorrees ,Fanning and Hunt(1963), > Kraus and Jordan(1965) & > Nystrom(1977).

Logan and Kronfeld, 1933.

Schour & Massler 1941

Lunt RC , Law DB : J Am Dent Assoc 89:8720-879,1974. SD(standard deviation)

Lunt and Law , 1974

Tandon S. :Textbook of pedodontics.2nd edition 1998

Eruption:::

Definition : “Eruption is defined as the axial or occlusal movement of the tooth from its developmental position within the jaws to its functional position in the occlusal plane.”

Teeth are formed in the jawbone, and must grow through the bone and covering gum into the mouth.

The permanent tooth begins to grow under the baby tooth.

The root of the baby tooth begins to dissolve (resorb), and the baby tooth becomes loose.

When the crown erupts, it is covered by a cuticle or covering that protects the enamel. The cuticle slowly worn away by chewing and tooth brushing.

Types of eruption: I }

o 1-Continuously growing.o 2-Continuously extruding.o 3-Continuously invested teeth.

II }o 1- Active eruption.o 2-Passive eruption.

Continuously growing : Tooth formation and eruption occurs

throughout the life.

These teeth have extensive wear.

Eruption velocity (rapid)increases whenever the velocity of wear increases and when antagonist teeth is removed

Ex : rodents and lyomorphs

Continuously extruding: Teeth stop forming once root formation is

complete.

Moderate occlusal wear.

Height of clinical crown is maintained by eruption of tooth & apical migration of surrounding epithelial attachments without simultaneous deposition of alveolar bone.

As occlusal wear progresses the tooth eventually loosens and exfoliates

Ex : cattle and sheep

Continuously invested teeth: Teeth stops forming after a predictable

amount of root development. Differs from continuous extruding type

of eruption in alveolar bone remolding in response to eruption.

With normal attrition, the clinical crown shortens as the tooth erupts to maintain vertical height and occlusal function.

Ex : human teeth.

Active eruption:

Passive eruption:

Physiologic tooth movement :o 1 > PRE ERUPTIVE TOOTH MOVEMENTo 2 > ERUPTIVE TOOTH MOVEMENTo 3 > POST ERUPTIVE TOOTH MOVEMENT

PRE ERUPTIVE TOOTH MOVEMENT

It is preparatory to eruptive phase

It consists of movements of the developing and growing tooth germs within the alveolar process before root formation to maintain their position in the expanding jaws

This is accomplished by both bodily movement and eccentric growth.

ERUPTIVE TOOTH MOVEMENT :

During this phase, tooth moves from its developmental position in jaws to its functional position in occlusion.

While the main direction of eruptive force is axial, movements also occurs in other planes accounting for tilting and drifting.

Eruption rate of teeth are greatest at the time crown emerges ,which differ according to tooth type.

POST ERUPTIVE TOOTH MOVEMENT :

In the post eruptive phase the tooth makes movements primarily to accommodate the growth of jaws

These movements following eruption are those made by the tooth after it has reached its functional position in the occlusal plane.

They may be divided into three categories:

o Movements made to accommodate the growing jaws.

o Those made to compensate for continued occlusal wear.

o Those made to accommodate interproximal wear.

Mechanism of tooth eruption:::

Initial theories that doesn’t explain tooth eruption satisfactorily.

oVascular pressure and blood vessel thrust.oPulpal pressure and Pulpal growth.oTraction by periodontal fibroblasts.oCushion Hammock Ligament Theory

Theories that most convincingly explain tooth eruption in man and other mammalian species.

oRoot elongation theory.oAlveolar bone remodeling theory.

Sequence of tooth eruption:

A B D C E

A B D C E

Sequence of tooth eruption: Deciduous teeth:

A B D C E

A B D C E

By: Sato and Ogiwara ,1971

Lunt and Law,1974suggested that lateral incisor ,first molar and canine tend to erupt earlier in maxilla than in the mandible

Permanent dentition:

OR

6 1 2 4 5 3 7 86 1 2 3 4 5 7 8

6 1 2 4 3 5 7 86 1 2 3 4 5 7 8Moyers,1988

VARIATIONS IN SEQUENCE OF ERUPTION

The mandibular first permanent molars are often the first permanent teeth to erupt. They are quickly followed by the mandibular central incisors. Lo and Moyers(1953) found little or no clinical significance to the eruption of the incisors before the molars.

After analyzing serial records of 16,000 children in Newburgh and Kingston, New York, Carlos and Gittelsohn(1965) concluded that the average eruption time of the lower central incisors was earlier than that of the first molars by about 1.5 months in both boys and girls.

Of considerable interest was the gender difference in the eruption sequence of permanent teeth.

The mandibular canine erupted before the maxillary and mandibular first premolars in girls. In boys the eruption order was reversed—the maxillary and mandibular first premolars erupted before the mandibular canine.(Moslemi M,2004)

Moyers(1988) stated that the most common sequence of eruption of permanent teeth in the mandible is first molar, central incisor, lateral incisor, canine, first premolar, second premolar, and second molar.

The most common sequence for the eruption of the maxillary permanent teeth is first molar, central incisor, lateral incisor, first premolar, second premolar, canine, and second molar.

It is desirable that the mandibular canine erupt before the first and second premolars. This sequence aids in maintaining adequate arch length and in preventing lingual tipping of the incisors.

Lingual tipping of the incisors not only causes a loss of arch length but also allows the development of an increased overbite. An abnormal lip musculature or an oral habit that causes a greater force on the lower incisors than can be compensated by the tongue allows a collapse of the anterior segment.

A deficiency in arch length can occur if the mandibular second permanent molar develops and erupts before the second premolar. Eruption of the second permanent molar first encourages mesial migration or tipping of the first permanent molar and encroachment on the space needed for the second premolar.

The untimely loss of primary molars in the maxillary arch, which allows the first permanent molar to drift and tip mesially , results in the permanent canine's being blocked out of the arch, usually to the labial side. Its eruption before the premolars and canine can cause a loss of arch length, just as in the mandibular arch.

The eruption of the maxillary canine is often delayed because of an abnormal position or devious eruption path.

Morphology:::

Differences Deciduous teeth are fewer in number and

smaller in size but the deciduous molars are wider mesiodistally than the premolars. The deciduous anteriors are narrower mesiodistally than their permanent successors.

Their enamel is thinner and whiter in appearance. Side by side, this is obvious in most young patients.

The crowns are rounded. The deciduous teeth are constricted at the neck (cervix).

The roots of deciduous anterior teeth are longer and narrower than the roots of their permanent successors.

The roots of deciduous molars are longer and more slender than the roots of the permanent molars. Also, they flare greatly.

The cervical ridges of enamel seen on deciduous teeth are more prominent than on the permanent teeth. This 'bulge' is very pronounced at the mesiobuccal aspect of deciduous first molars.

Mammelons are not present in deciduous incisors

MAXILLARY CENTRAL INCISOR:

average measurements in Millimeters.

Length overall

Crown length

Root length

MD diameter of crown

MD diameter at cervix

LL diameter of crown

LL diameter at cervix

16.0 6.0 10.0 6.5 4.5 5.0 4.0

D M

NOTATION RIGHT LEFT

UNIVERSAL E F

FDI 51 61

PALMER A A

EUROPEAN 01+ +01

Labial aspect:

Lingual aspect:

DM

Mesial and distal aspects:

Mesial aspect

Incisal aspect:

Special characteristics:

The primary maxillary central incisor is the only primary or secondary incisor where the mesiodistal crown dimension is greater than the incisocervical crown dimension.

The cingula of maxillary incisor “extends much farther incisally” than the cingulaof secondary incisors.

The cingula of maxillary anterior teeth are large and “seem to bulge”, encompassing about one-third of the incisocervical crown dimension.

MAXILLARY LATERAL INCISOR:


Length overall

Crown length

Root length





15.8 5.2 11.0 5.0 3.7 4.0 3.7

NOTATION RIGHT LEFT

UNIVERSAL D G

FDI 51 62

PALMER B B

EUROPEAN 02+ +02

Labial aspect Lingual aspect

M D

D M

La

DM

LiLa

Li

Incisal aspect Mesial aspect

MAXILLARY CANINE:

average measurements in Millimeters

Labial aspect:

Length overall

Crown length

Root length





19.0 6.0 13.0 7.0 5.1 7.0 5.5

MD

NOTATION RIGHT LEFT

UNIVERSAL C H

FDI 53 63

PALMER C C

EUROPEAN 03+ +03

Lingual aspect:

M D

Mesial and Distal aspect:

Mesial aspect Distal aspect

LI LA LIL

A

Incisal aspect:

D M

Special characteristics: The primary maxillary canine has a

mesial proximal contact that is located cervical to the distal proximal contact, the only primary tooth with this characteristic .This unique primary dentition feature is shared with the secondary mandibular first premolar.

The primary maxillary canine has the longest root of any primary tooth.

MANDIBULAR CENTRAL INCISOR:


Labial aspect:

Length overall

Crown length

Root length





14.0 5.0 9.0 4.2 3.0 4.0 3.5

M D

x

2x

NOTATION RIGHT LEFT

UNIVERSAL P O

FDI 81 71

PALMER A A

EUROPEAN 01- -01

Lingual aspect:

D M

Mesial and Distal aspect:

Mesial aspect Distal aspect

LaLi

Li La

Incisal aspect:

DM

Li

La


The incisal edge of the primary mandibular central incisor is horizontally straight,the only primary incisor to display this trait.

MANDIBULAR LATERAL INCISOR:


Length overall

Crown length

Root length





15.0 5.2 10.0 4.1 3.0 4.0 3.5

NOTATION RIGHT LEFT

UNIVERSAL Q N

FDI 82 72

PALMER B B

EUROPEAN 02- -02


MD M D

La LiLa

Li


MANDIBULAR CANINE :


Length overall

Crown length

Root length





17.5 6.0 11.5 5.0 3.7 4.8 4.0

NOTATION RIGHT LEFT

UNIVERSAL R M

FDI 83 73

PALMER C C

EUROPEAN 03- -03


D M

M D

La

D M

LiLa Li


MAXILLARY FIRST MOLAR :


Universal notation is B or I.

Buccal aspect: It is much wider mesiodistally at contact areas than

at cervix. The buccal surface is smooth with little evidence of

developmental grooves. The cervical line is convex towards the root and is

higher mesially than distally. The roots: are slender and long, All three roots are seen from this aspect.

Length overall

Crown length

Root length





15.2

5.1 10.0 7.3 5.2 8.5 6.9

PMB

DB

Lingual aspect: The crown converges

considerably in a lingual direction The mesiolingual cusp is the

longest and sharpest of all cusps. The lingual root is larger than the

others

MBC

Mesial aspect: crown is much wider at cervical

third than at occlusal third. cervical ridge buccally appears

over developed (a typical characteristic of this tooth).

Only mesiobuccal and lingual roots are seen from this aspect.

lingual root appears long and slender and extends lingually.

It curves buccally at the apical third

MB Li

Distal aspect: crown is narrower and shorter

distally then mesially. distobuccal cusp is long and sharp,

distolingual is poorly developed. The prominence of the cervical ridge

seen from the mesial aspect at the cervical third does not continue distally.

cervical line is similar to the distal or straight.

All three roots may be seen from this aspect, but the distobuccal root is superimposed on the mesiobuccal

Occlusal aspect:

rectangular Usually have four cusps but it

may appear somewhat like maxillary premolars.

The occlusal surface has three fossae:

A buccal developmental groove extending from the central fossa between MB and DB cusps.

It looks a bit like an upper 1st premolar.

MB

Ml

DB

DL

an oblique ridge may be present. The distal marginal ridge is thin and poorly

developed than the mesial

MAXILLARY SECOND MOLAR :

average measurenments in Millimeters.

Length overall

Crown length

Root length





17.5 5.7 11.7 8.2 6.4 10.0 8.3Universal notation is A or J. Resembles the 6-year permanent maxillary first molar which erupts distal to it except that: It is smaller in size.

The deciduous crown is more constricted at the cervix with a more prominent cervical ridge buccally.

The roots are more slender and almost twice as long as the crown.

They flare out greatly at the middle and apical thirds.

The root trunk is almost absent

Lingual aspectBuccal aspect

Mesial aspect Occlusal aspect

Distal aspect


The maxillary second molar has the greatest root divergence of any primary molar with an average separation of 12.6 millimeters between the lingualsurface of the lingual root and the facial surface of the mesiofacial root(Kramer/Ireland).

MANDIBULAR FIRST MOLAR :

Universal notation is L or S. Buccal aspect :

The mesial cusp is larger than the distal. The point of bifurcation is very close to the

cervical line. Mesial outline of the crown is almost straight from

the contact area to the cervix. Distal outline converges toward the cervix

more than usual Roots are long and slender, and spread greatly at

apical third beyond outline of crown. No developmental groove

Length overall

Crown length

Root length





15.8 6.0 9.8 7.7 6.5 7.0 5.3

Lingual aspect:

The crown and root converge lingually to a marked degree on the mesial surface.

The opposite is true distally. The mesiolingual cusp is longer and

sharper, more than any of the other cusps.

The distolingual cusp is rounded and well developed.

It is separated from the mesiolingual by the lingual developmental groove.

Mesial marginal ridge is well developed

The crown length is more uniform mesially and distally on the lingual aspect than on the buccal.

The cervical line is almost straight

M D

Mesial aspect: Roughly rhomboidal crown. The buccal outline shows a

considerable bulge at the cervical third,(characteristic which differentiate this tooth from the deciduous second molar and the permanent mandibular molars)

The lingual outline extends out lingually beyond the confines of the root base.

The mesiobuccal and the mesiolingual cusps together with the well-developed marginal ridge, are in view.

The cervical line slopes coronally buccolingually.

The root is flat and almost square. A developmental depression usually

extends almost on the full length of the root.

B Li

Distal Aspect: This differs from the mesial

aspect in the following: There is less curvature at the

cervical third of the crown buccally. The length of crown buccally and

lingually is more uniform, the cervical line extends almost

straight across buccolingually. The distobuccal and distolingual

cusps are not as long and sharp as the two mesial cusps.

The distal marginal ridge is not as straight and well-defined as the mesial marginal ridge

The distal root is rounder and shorter and tapers more apically

BLi

Occlusal aspect : Rhomboidal. The central developmental groove

extends between the central pit and the mesial pit separating the mesiobuccal and the mesiolingual cusps.

The mesiolingual cusp is the largest and best developed of all cusps.

The buccal developmental groove extends buccally from the central pit,equally dividing the mesiobuccal and distobuccal cusps.

The lingual developmental groove extends lingually from the central pit, separating the mesiolingual and the

distolingual cusps.

MBC

DBC

MLCDLC

MANDIBULAR SECOND MOLAR :

average measurements in

Millimeters.

Universal notation is K or T.

Length overall

Crown length

Root length





18.8 5.5 11.3 9.9 7.2 8.7 6.4

Resembles the permanent mandibular first molar except for the following:

The deciduous molar is smaller in size Crown is more constricted at the cervix. Mesiobuccal, distobuccal and distal cusps equal in

size. ( distal cusp of permanent molar is smaller than the

other two). The deciduous tooth crown is narrower buccolingually

in comparison with the mesiodistal measurement, than in the permanent molar.

The roots are more slender than those of the permanent molar

They are also twice as long as the crown. They flare out greatly and have a very short or no root

trunk, ( a well developed root trunk is seen on the

permanent molar)

Buccal aspect Lingual aspect

Occlusal aspectMesial aspect

Distal aspect

Clinical implications:::

The susceptibility to dental caries is a function of exposure time to the oral environment and morphological type.

A complete primary dentition plays an important part in mastication.

The increase in prevalence of dental caries among the tooth types reverses their order of eruption.

A lack of space associated with premature loss of deciduous teeth is a significant factor in the development of malocclusion.

We should pay more attention to permanent teeths when we are treating the primary teeth.

Refrences :::

Ash MM, Nelson S. Wheeler’s Dental Anatomy, Physiology and Occlusion. 8th ed. Saunders; 2002.

Tandon S. :Textbook of Pedodontics. 2nd edition. Paras Publication, 2008.

Sidney B Finn: Clinical Pedodontics, 4th edition 2001. Kraus BS, Jordan RE: the human dentition before birth,

Philedelphia, 1965. Schour I, Massler M: Studies in tooth development,the

growth pattern of human teeth part II,J Am Dent Assoc 27:1981,1940.

Sato S, Ogiwara Y :Biostatistics study of eruption order of deciduous teeth, Bull Tokyo dent Coll 12:45, 1972.

Roger’s Spencer L 1987, Personal identification from human remains ,Springfield Dentition.

Lunt RC and Law DB :a review of the chronology of deciduous teeth , J Am Dent Assoc 89:87,1974

Tencate AR, Copeland E. Oral Histology. 5th ed. Mosby; 1998. Moyers RE: Handbook of Orthodontics, 4th edition , Chicago,

Mosby, 1988. Mc Donald. Dentistry for the Child and Adolescent.8th

edition. Mosby ,2004.

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NOMENCLATURE,CHRONOLOGY AND MORPHOLOGY OF PRIMARY DENTITION