Chronology of Human Dentition & Tooth Numbering System
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Transcript of Chronology of Human Dentition & Tooth Numbering System
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SUBMITTED TO: SUBMITTED BY:
DEPARTMENT OF PEDODONTIC NAVJOT KAUR
& PREVENTIVE DENTISTRY BDS IV PROF.
ROLL NO. 43
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CHRONOLOGY DEFINITION:
Chronos - Time
Logos StudyIt is defined as the study which deals with the
timing of various stages of tooth development,starting with initiation of the first dental tissuelaid down to the emergence of the tooth into theoral cavity & its completion of calcification.
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Originally it was based on the data of Logon &Kronfeld (1933).
Modified by:
Massler & Shour (1941),
Moorrees, fanning & hunt (1963),
Kraus & jordan (1965),Nystrom (1977).
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TIMING OF CROWN & ROOT
DEVELOPMENTPRIMARY TEETH PERMANENT TEETH
Crown completion
Eruption
Root completion
Crown completion
Eruption
Root completion
Incisors
Canine &molars
4-6 months
6-12 months
1 year
3-4 years
3 years
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NOLLA STAGES OF TOOTHDEVELOPMENT (1952)
Stage 0 : absence of crypt
Stage 0 : absence of crypt
Stage 1 : presence of crypt
Stage 2 : initial calcification
Stage 3 : 1/3rdof crown completed
Stage 4 : 2/3rdof crown completed
Stage 5 : crown almost completed
Stage 6 : crown completed
Stage 7 : 1/3rdof root completed
Stage 8 : 2/3rdof root completed
Stage 9 : root completed , apex open
Stage 10 : apical foraman closed
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A
B
C
D
E
F
G
H
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DECIDUOUS DENTITION Initiationof hard tissue development for all
deciduous teeth occurs between 3.5 & 4.5intrauterine months.
Crownget mineralized halfway by birth andbecome fully formed during first 12 month.
Roots are completed b/w the age of 1.5 & 3years.
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TOOTH FIRST EVIDENCE OF
CALCIFICATION(weeks in utero)
CROWN
COMPLETED(months)
ERUPTION
(months)
ROOT
COMPLETED(years)
UPPER
A 14 1 10 (8-12) 1
B 16 2 11 (9-13) 2
C 17 9 19 (16-22) 3
D 15 6 16 (13-19) 2
E 19 11 29 (25-33) 3
LOWER
A 14 2 8 (6-10) 1B 16 3 13 (10-16) 1
C 17 9 20 (17-23) 3
D 15 5 16 (14-18) 2
E 18 10 27 (23-31) 3
CHRONOLOGY OF PRIMARY DENTITION
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SEQUENCE OF ERUPTION OF
PRIMARY TEETH
AB D C E
A B D CE
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PERMANENT DENTITION Mineralization of 1stpermanent molar commences
at birth & is followed by the other teeth during
first 3.5 years of postnatal life.
Crown completion takes place at an age of 7 years.
Mineralization ceases at an av. Age of 15-16 yearswith completion of roots of 2ndmolars.
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Mineralization stages of 3rdmolar:
Initiation 9 years
Crown completion 13 years
Root formation 20 years
Development of central incisors is more rapid.
Development of canine & 2ndmolars the slowest.
Root development alone takes on an av. From 6-7
years.
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TOOTH ERUPTION Derived from erumpere, meaning to break out.Axial or occlusal movement of tooth from its
developmental position within jaw to its functionalposition in the occlusal plane.
Eruption is only a part of physiological toothmovement.
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TYPES OF ERUPTION3 types:
Continuously growing
Continuously extruding
Continuously invested teeth.
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TYPES OF ERUPTION Continuously growing:
formation & eruption occurs throughout the life. formed from proliferative base.
Crown & roots are similar morphologically.
Extensive wear.
Eruption velocity increases whenever velocity ofwear increases.
E.g. incisors of rodent.
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TYPES OF ERUPTION Continuously extruding:
Teeth stop forming once root formation is complete. Moderate occlusal wear.
Height is maintained by apical migration ofsurrounding epithelial attachment, without
simultaneous deposition of alveolar bone. Tooth eventually loosen & exfoliate completely.
E.g. cheek teeth of cattle & sheep.
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TYPES OF ERUPTION Continuously invested teeth:
Similar to continuously extruding, but thealveolar bone remodels in response to eruption.
With normal attrition, the clinical crownshortens & tooth erupts to maintain vertical
height & occlusal function & bring the alveolarbone with it.
E.g. human teeth.
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PHYSIOLOGICAL TOOTH
MOVEMENTConsist of :
a. Preeruptive tooth movement
b. Eruptive tooth movementc. Posteruptive tooth movement
PREERUPTIVE TOOTH
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PREERUPTIVE TOOTHMOVEMENT
It is a movement positioning the tooth & its cryptwithin growing jaws preparatory to tooth eruption.
Change in the position of tooth germ is a result of
Body movement of tooth germ Growth of tooth germ
Relative change in position of associated deciduous andpermanent tooth germs
The permanent molars , which have no deciduouspredecessors, also exhibit movement.
All these movement occurs in association with growthof jaw .
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ERUPTIVE TOOTH MOVEMENT
During this phase, tooth moves from its position within thebone of the jaw to its functional position in occlusion.
Principal direction of movement is occlusal or axial.
PREFUNCTIONAL TOOTH MOVEMENT movement oftooth after its appearance in the oral cavity till it attains thefunctional position.
Tooth erupts about 4 mm in 14 weeks.
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POST ERUPTIVE TOOTH
MOVEMENT These are the movement that-
1. Maintain the position of an erupted tooth whilejaws continues to grow and
2. Compensate for occlusal and proximal wear.
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MECHANISM OF TOOTH
MOVEMENT The mechanism that brings about tooth movement is
still debatable & is likely to be a combination of anumber of factors.
Main factors include Bone remodeling
Root growth
Vascular pressure
Ligament traction
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THEORIES OF ERUPTIONBone growth theory
Root growth theory
Vascular pressure theoryPeriodontal ligament traction theory
Constriction of pulp
Pulp growth
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BONE REMODELING THEORY
Selective deposition & resorption of bone bringsabout eruption.
It is important to permit tooth movement. Experiment establishes absolute requirement for
dental follicle to achieve bony remodeling & tootheruption.
It is the follicle that provide s the source of newbone forming cell & conduit for osteoclasts.
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ROOT FORMATION THEORY
Proliferating root impinges on fixed case, thus convertingan apically directed force into occlusal movement.
Root formation follows crown formation and involves
cellular proliferation & formation of new tissue that mustbe accommodated by either movement of crown of thetooth or the resorption of bone at the base of socket.
Translation of the root growth into occlusal movement
requires fixed base .Advocates of this theory postulated the existence of
cushion hammock ligament , that provide fixed base
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CONTRADICTIONS Cushion hammock ligament cannot act as fixed
base.
Some teeth move a distance greater than the rootlength & eruptive movement also occur aftercompletion of root formation.
Experimental resection preventing further root
formation does not stop eruptive tooth movement.
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VASCULAR PRESSURE THEORYA local increase in the tissue fluid pressure in
periapical region is sufficient to move the tooth.
Teeth move in synchrony with arterial pulse, so local
volume changes can produce limited tooth movement. Factors in favour of this theory are-
Increase in hydrostatic pressure induced by hypotensivedrugs increases the rate of eruption while stimulation of
sympathetic nerves decreases rate of eruption. No. of capillaries increases with the eruption rate & their
distribution varies; more no. of capillaries are seen nearthe base of crypt than the alveolar crest.
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PERIODONTAL LIGAMENT
TRACTION THEORY Cells & fibers of ligament pull the tooth into occlusal.
There is is good deal of evidences that the eruptiveforce resides in dental follicle- periodontal ligamentcomplex.
Abnormalities of dental follicle as shown in certaindiseases are associated with delayed tooth eruption.
Drugs that interrupt proper formation of collagen inligament also interfere with eruption.
PDL fibroblast have a ability to contract & transmitcontractile forces to extracellular environment.
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Thus acc. to this theory, eruption of teeth
could be brought about by a combination of
events involving:Contractile forces by fibroblast
Transmitted to ECC & collagen
Tooth movement
Via fibronexuses
At appropriate inclination
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MECHANISM OF POSTERUPTIVE
TOOTH MOVEMENT Mechanism of axial movement is similar to that of
eruptive tooth movement.
Mesial drift involves a combination of 2 separateforces resulting from occlusal contact of teeth &contraction of transseptal ligaments b/w teeth.
When jaws are clenched, bringing teeth into
contact, force is generated in a mesial directionbecause of summation of cuspal planes & becausemany teeth have a mesial inclination.
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SHEDDING OF DECIDUOUS
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SHEDDING OF DECIDUOUSTEETH
Physiological process resulting in elimination ofdeciduous dentition is called shedding orexfoliation.
Shedding is a result of progressive resorption of roots
of teeth & their supporting tissue , periodontalligament .
Pressure generated by the growing & eruptingpermanent tooth dictates the pattern of deciduous
tooth resorption.
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First sign of root resorption is seen in deciduous CI &first molar by the age of 4-5 year.
In CI resorption starts on lingual side.
In molars from inner surfaces of root.
Resorption of deciduous incisors takes place morerapidly (1.5-2 yr) than that of canine & molars(2.5-5.7
yr.) .
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Mechanism of shedding Pressure from the erupting successional tooth plays a
key role because the odontoclasts appear at predictedsites of pressure.
Unlike osteoblast, cementoblasts are not responsiveto hormone & cytokines. Therefore prior to resorptioncementoblastic layer has to be damaged probably byinflammatory process .
Reduced enamel ep. of erupting tooth release somesubstances to initiate this process.
Predentin resist resorption more than any other hardtissue.
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Odontoclast
Attaches to hard tissue surfaces through clear zone
Sealed space lined by ruffled border
Microenvironment
Ruffled border act as proton pump
Acidify ECenvironment
Dissolution ofmineral
Secretion of lysosomal enzyme into sameenvironment
Degrade organicmatrix
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FACTORS AFFECTING
SHEDDINGWhen a successional tooth germ is missing ,
shedding of the deciduous tooth is delayed .
Forces of mastication.
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Clinical considerationsRemnants of deciduous teeth
Retained deciduous teeth
Submerged deciduous teeth
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TOOTH NUMBERING SYSTEMVARIOUS NUMBERING SYSTEMS ARE:
Universal system
Symbolic systemFDI system
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UNIVERSAL SYSTEM PERMANENT DENTITION: permanent teeth are numbered from
1-32.
The following universal notation designates the entire
permanent dentition:
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
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ADVANTAGES OF UNIVERSAL
SYSTEM OF NOTATIONAcceptable to computer language.
Less confusing than palmer notation
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SYMBOLIC SYSTEM It is also known as zsigmondy/palmer notation or
palmer notation system.
Introduced by adolph zsigmondy in 1861 & thenmodified for primary dentition in 1874.
Given by Palmerin 1870.
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SYMBOLIC SYSTEM In this system arches are divided into quadrantswith the entire primary dentition being notated as :
E D C B A A B C D E
E D C B A A B C D E
e.g. max right central incisors- A|
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SYMBOLIC SYSTEM PERMANENT DENTITION:
It is a four quadrant symbolic system, in which beginning
from central incisors , teeth are numbered 1 through 8.
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
E.g. right max 1stmolar6|
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LIMITATIONS OF PALMER
NOTATIONSIt is generally incompatible with computer and word
processing systems.
More confusing.
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FDI SYSTEM Proposed by Federation Dentaire
Internationale(FDI).
Adopted byWHO& other such as IADR.
It is atwo digit system given for both primary andpermanent dentition.
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FDI system of tooth notation for
primary teeth 5- right max. quadrant
6- left max. quadrant
7- left mand. Quadrant 8- right mand. Quadrant
55 54 53 52 51 61 62 63 64 65
85 84 83 82 81 71 72 73 74 75
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FDI notation for permanent teeth In this first digit indicate that is 1-4 & second digit
indicate tooth within the quadrant.
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
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Thankyou