Tooth eruption and shedding

DEPARTMENT OF CONSERVATIVE

DENTIST

AND

ENDODONTICS

PRESENTED BY:-

DR. ADITYA SHINDE

GUIDED BY:-

DR.LALITAGUARI MANDKE

TOOTH ERUPTION

&SHEDDING

CONTENTS

DEFINITION PHYSIOLOGIC

TOOTH MOVEMENTS STAGES OF

ERUPTION PATTERN AND

HISTOLOGY THEORIES OF

ERUPTION CHRONOLOGY OF

ERUPTION CONTINUOUS TOOTH

ERUPTION CLINICAL

CONSIDERATIONS SHEDDING OF

PRIMARY TEETH

TOOTH ERUPTIONTOOTH ERUPTIONDEFINITION:-

It is the axial or occlusal movement of the tooth from its developmental position within the jaws to functional position in the occlusal plane.- (orban’s)

Eruption is the movement of the developing teeth within and through the bone and the overlying mucosa of the jaws to appear in the oral cavity and reach the occlusal plane.-(james k. avery)

PHYSIOLOGIC TOOTH PHYSIOLOGIC TOOTH MOVEMENTSMOVEMENTS

These are of various types :-1) Axial or vertical2) Drifting3) Torsion4) Tipping

STAGES OF TOOTH ERUPTIONSTAGES OF TOOTH ERUPTION1) Pre – eruptive tooth

movements.

1) Eruptive / Prefunctional tooth movements

2) Posteruptive tooth movements

PATTERN AND HISTOLOGY OF PATTERN AND HISTOLOGY OF VARIOUS STAGES OF ERUPTIONVARIOUS STAGES OF ERUPTION

PRE – ERUPTIVE TOOTH MOVEMENT These are the movements made by the deciduous and permanent tooth germs within the tissues of jaws before they begin to erupt.

A – enamel organA – enamel organ

B – dental laminaB – dental lamina

C – basal boneC – basal bone

Deciduous TeethDeciduous Teeth

When deciduous tooth germs differentiate , When deciduous tooth germs differentiate , there is good deal of space between them.there is good deal of space between them.

As Tooth germs grow more rapidly than As Tooth germs grow more rapidly than bone – this available space is utilized and bone – this available space is utilized and developing teeth become crowded developing teeth become crowded together especially in the incisor and together especially in the incisor and canine region.canine region.

This crowding is relieved by :-This crowding is relieved by :- - growth in length of infant jaw- growth in length of infant jaw - increase in width- increase in width - increase in height- increase in height

Permanent TeethPermanent Teeth

Permanent teeth with deciduous Permanent teeth with deciduous predecessors also undergo complex predecessors also undergo complex movements before they reach the final movements before they reach the final position from which they will erupt.position from which they will erupt.

These changes in the relative position are These changes in the relative position are basically because of growth of the basically because of growth of the permanent tooth germs and eruptive permanent tooth germs and eruptive movement of the deciduous toothmovement of the deciduous tooth..

Labio-lingual sections on Labio-lingual sections on mandible through central mandible through central

incisorsincisors

A – at birth B – at 4A – at birth B – at 4thth month C – at 10 month C – at 10thth month D – at month D – at 2525thth month month

Unerupted deciduous Unerupted deciduous canine and its canine and its permanent successor permanent successor located lingually and located lingually and apically to it , in a apically to it , in a section of mandible at section of mandible at the age of 6 mnths.the age of 6 mnths.

Deciduous first molar showing germ of permanent first premolar between its roots at the age of about 6 yrs.

Permanent maxillary molar in tuberosity

Dentition shows the erupted deciduous teeth and partially developed crown of permanent teeth at the age of 2 years

HISTOLOGY OF TOOTH MOVEMENT

Bone remodelling occurs within the crypt wall during physiologic tooth movement. At right , osteoblasts are present for bone deposition and are seen as a continuous row of minute spots. At left , osteoclasts are present for bone resorption and are seen as dark spots.

Bone remodelling – selective deposition and removal of bone by osteoblastic and osteoclastic activity.

These movements of both deciduous and permanent tooth germs are a combination of 2 factors :-

1)Total bodily movement2)Eccentric growthPresence of dental follicle.

Bodily movement of crown during pre-eruptive phase

2)ERUPTIVE / PREFUNCTIONAL TOOTH MOVEMENT

PATTERN OF TOOTH MOVEMENT

The tooth moves from its position within the bone of the jaw to its functional position in occlusion , and the principal direction of movement is occlusal or axial.

However , it is important to recognize that jaw growth is normally occurring while most teeth are erupting , so that movements in planes other than axial are superimposed on eruptive movement.


5 major events takes place :-5 major events takes place :-1) The secretory phase of

amelogenesis is completed just before the onset of root formation and prefunctional eruption.

There is a relation between the cessation of mineralisation and activation of the epithelial cells beyond the enamel – forming area.

2)The intraosseous stage 2)The intraosseous stage occurs when root occurs when root formation begins as a formation begins as a result of the proliferation result of the proliferation of both the epithelial root of both the epithelial root sheath and the sheath and the mesenchymal tissue of mesenchymal tissue of the dental papilla and the dental papilla and dental follicle.dental follicle.

Prefunctional eruptive stage in formation of

root

3)The supraosseous stage begins when the erupting tooth moves occlusally through the bone of the crypt and the connective tissue of the oral mucosa , so that the reduced enamel epithelium covering the crown comes into contact with the oral epithelium.

Crown tip approaching oral epitheliumCrown tip approaching oral epithelium

As this occurs , the reduced enamel epithelium of the crown proliferates and forms a firm attachment with the oral epithelium. A fused , double layer over the erupting crown is then formed.

Contact and fusion of REE and oral mucosa

4)The tip of the crown enters the oral cavity 4)The tip of the crown enters the oral cavity by breaking through the center of the by breaking through the center of the double – layered epithelial cells.double – layered epithelial cells.

the cusp tip causes degeneration of the the cusp tip causes degeneration of the membrane – beginning stage of clinical membrane – beginning stage of clinical eruption. eruption.

- Dentogingival junction – lateral borders - Dentogingival junction – lateral borders of oral mucosaof oral mucosa

- Junctional or attachment epithelium – - Junctional or attachment epithelium – REE-rest of enamel epitheliumREE-rest of enamel epithelium

- One - half to two - thirds of the roots are - One - half to two - thirds of the roots are formed.formed.

Clinical appearance of crown

5)The erupting tooth continues to move occlusally at a maximum rate , and there is gradual exposure of more of the clinical crown.

Primary tooth at the end of Primary tooth at the end of

eruptive phase .Permanent eruptive phase .Permanent

successorsuccessor

in preeruptive phasein preeruptive phase

Significant changes also occur in :- - the tissues overlying the teeth - the tissues around the teeth - the tissues underlying the teeth

CHANGES IN TISSUES OVERLYING TEETH Initial change – alteration of the connective

tissue of the dental follicle – forms pathway for eruption.

Influx of monocytes and osteoclasts.

Future eruption pathway appears as a zone in which :-

connective tissue fibers have disappeared

Cells have degenerated and in number

decrease number of blood vessels

Terminal nerves have broken up and degenerated.

These changes are due to loss of blood supply to that area and release of enzymes.

Development of eruptiveDevelopment of eruptive

pathway overlying thepathway overlying the

crown.crown.

Resorption of the overlying bony crypt.Resorption of the overlying bony crypt.

Developing eruption pathway and gubernaculum dentisDeveloping eruption pathway and gubernaculum dentis

REE comes in contact with oral mucosa – they proliferate and fuse into one membrane

Fusion and rupture of REE and oral epithelium

Gubernacula

r canals

CHANGES IN TISSUES AROUND THE TEETHCHANGES IN TISSUES AROUND THE TEETH

Development of Development of PDL fibers and PDL fibers and modification of modification of alveolar bonealveolar bone

A-early fiber A-early fiber formationformation

B-bone changesB-bone changes

C-furthur fiber C-furthur fiber development development near occlusion , near occlusion , with fibers more with fibers more dense. dense.

CHANGES IN TISSUES UNDERLYING THE TEETH

Changes in fundic Changes in fundic bone during bone during eruptive eruptive movement.movement.

Formation of bone Formation of bone ladder in the ladder in the fundic region.fundic region.

3)POST-ERUPTIVE / PREFUNCTIONAL TOOTH MOVEMENT

PATTERN OF TOOTH MOVEMENTAre those that :- 1) Maintain the position of erupted tooth while the jaw continues to grow. 2) compensates for occlusal and proximal wear.


Increased Increased density of density of PDL fibersPDL fibers

Vascularisation Vascularisation of pulp and of pulp and PDL fibersPDL fibers

above diagram shows Myelinated above diagram shows Myelinated nerves at left and blood vessels at nerves at left and blood vessels at

right sideright side

Ultrastructure of Ultrastructure of interstitial space interstitial space in PDL along with in PDL along with nerves & blood nerves & blood

vesselsvessels

Posteruptive changes : attrition and compensative formation of cementum

Formation of Formation of junctional junctional epithelium.epithelium.

A , B – A , B – preeruptivepreeruptive

C – C – prefunctional prefunctional eruptiveeruptive

D-E-F-functional D-E-F-functional occlusionocclusion

THEORIES OF TOOTH MOVEMENTTHEORIES OF TOOTH MOVEMENT

THEORIES

BONE REMODELLING`

ROOT GROWTH

HYDROSTATIC PRESSURE

PERIODONTAL LIGAMENTTRACTION

BONE REMODELLINGBONE REMODELLING Selective deposition and resorption of bone brings

about eruption.

Bone remodelling of the crypt wall , clearly is important to achieve tooth eruption.

The intense metabolic activity in the alveolar bone taking place around the moving tooth requires the presence of dental follicle.

Experiments have shown that when tooth germ is removed but the follicle is left in position , the eruptive pathway still forms in bone indicating dental follicle and not bone as the major determinant in tooth eruption.

determines position of tooth

Thus , dental follicle plays important role in bone

remodelling by stimulating osteoclasts & osteoblast coordinates bony changes

This theory is still recognized , as the persons genetically lacking in osteoclasts

have retarded tooth eruption.

ROOT GROWTHROOT GROWTH Root growth theory considers growth in

root length to be responsible for tooth eruption , as the growing root presses against the socket base & opposite force pushes the tooth to erupt.

Although at first glance this may seem an obvious mechanism , root formation is unlikely to be the cause of tooth eruption.

the basis of this theory is questionable due to certain facts :-Some teeth move a greater distance than the length of their fully formed roots.Some teeth still erupt after root formation has been completed.Rootless teeth also erupt.If root formation is responsible for eruption , it would be expected that the onset of root formation and eruptive movement would coincide.

If root formation results in an eruptive force , there is the requirement of a fixed base , but the bone at the base of the root cannot act as a fixed base as pressure on the bone results in its resorption.

Presence of CUSHION – HAMMOCK LIGAMENT.

Root growth theory is now considered to be unimportant for tooth eruption , but it is true that root growth is necessary for eruption as it gives attachment to periodontal fibers.

HYDROSTATIC / VASCULAR PRESSUREHYDROSTATIC / VASCULAR PRESSUREThis theory is based on the fact that dental papilla is highly vascular.It is known that teeth move in synchrony with the arterial pulse , so local volume changes can produce limited tooth movement.Ground substance can swell upto 50% with the addition of water , and a differential pressure sufficient to cause tooth movement between the tissues above and below the erupting tooth has been reported in the dog.Again, whether such pressures are the prime movers of teeth is debatable because surgical excision of the root , and therefore the local vasculature , does not prevent tooth eruption.

PERIODNTAL LIGAMENT PERIODNTAL LIGAMENT TRACTIONTRACTION

Amongst all 4 theories PDL traction theory has Amongst all 4 theories PDL traction theory has strongest evidence in its favor.strongest evidence in its favor.

The transseptal fibers running between adjacent The transseptal fibers running between adjacent teeth across the alveolar process draw teeth across the alveolar process draw neighboring teeth together & maintain them in neighboring teeth together & maintain them in contact.contact.

As long as PDL is viable tooth movement occurs.As long as PDL is viable tooth movement occurs. Specialized fibroblasts present in PDL – Specialized fibroblasts present in PDL –

myofibroblasts.myofibroblasts. These by virtue of their contractile forces exhibit These by virtue of their contractile forces exhibit

fibronexus.fibronexus.

Through fibronexus they transmit forces to the collagen bundles.

These collagen bundles apart from undergoing remodelling are also inclined at the correct angle to bring about eruptive movement – basic requirement for tooth movement

It is concluded that the force for tooth eruption is most probably generated by the contractile property of fibroblast of ligament along with other conditions (presence of follicle) which must be present so that this contraction can be used for tooth eruption.

Hence eruption is a multifactorial phenomenon.

A –fibroblastsA –fibroblasts

B –adherence type B –adherence type intercellular intercellular junctionsjunctions

C – fibronexus, C – fibronexus, attached to collagen attached to collagen by fibronectinby fibronectin

D – deposition of D – deposition of collagencollagen

E – resorption of E – resorption of collagencollagen

CHRONOLOGY OF PRIMARY CHRONOLOGY OF PRIMARY TEETH TEETH

CHRONOLOGY OF PERMANENT TEETHCHRONOLOGY OF PERMANENT TEETH

CHRONOLOGY OF PRIMARY DENTITION

CHRONOLOGY OF PERMANENT DENTITION

CLINICAL APPLICATIONCLINICAL APPLICATION the the ““six/foursix/four”” rule for primary tooth rule for primary tooth

emergence means that 4 teeth will emergence means that 4 teeth will emerge for each 6 months of age.emerge for each 6 months of age.

Thus , age of 6 months = 4 teethThus , age of 6 months = 4 teeth

12 months = 8 teeth12 months = 8 teeth



30 months = 20 teeth.30 months = 20 teeth.

CONTINUOUS TOOTH CONTINUOUS TOOTH ERUPTONERUPTON Eruption does not cease when teeth meet

their antagonists but continues throughout life.

It consists of :- 1)active eruption 2)passive eruptionActive eruption – is the movement of teeth in

the direction of the occlusal plane.Passive eruption – is the exposure of the

teeth by apical migration of the gingiva.

Anatomic crown – the portion of the tooth covered by enamel.Anatomic root – the portion of the tooth covered by cementum.Clinical crown – the part of the tooth that has been denuded of its gingiva and projects into the oral cavity.Clinical root – the portion of the tooth covered by periodontal tissues.When the teeth reach their functional antagonists , the gingival sulcus and junctional epithelium are still on enamel and the clinical crown is approximately 2/3rds of the anatomic crown.“Gottlieb” believed that active and passive eruption proceed together.Active eruption is coordinated with attrition

CLINICAL CONSIDERATION

1) DEFICIENCY OF VITAMIN C

Necessary for the formation of collagen fibers

& Cross – linkages between collagen fibers.

Deficiency – collagen fibers poorly formed in the pdl and tooth fails to erupt or erupts slowly and very late.

2) TEETHING PROBLEMS

Gum adjacent to erupting teeth shows acute reaction and pain – acute inflammatory response

Systemic manifestations – as general malaise , fever , and sometimes diarrhea.

PREMATURE ERUPTIONPREMATURE ERUPTION

PRIMARY TEETHPRIMARY TEETH

Occurs infrequently1)Natal teeth & Neonatal teeth – ( Massler

and Savara 1950)- Taking only time of

eruption as reference , natal teeth are those observed in the oral cavity at birth. Neonatal teeth are those that erupt during the first 30 days of life.

2) 2) Ostepblastic activities inside the tooth Ostepblastic activities inside the tooth germ area related to bone germ area related to bone remodelling phenomenaremodelling phenomena

3) 3) HypovitaminosisHypovitaminosis

4)4)Systemic conditions or syndromes such as Systemic conditions or syndromes such as – –

Ellis – Van Creveld syndromeEllis – Van Creveld syndrome

Hallemann – Steriff syndromeHallemann – Steriff syndrome

Cleft palateCleft palate

5) 5) Envirnmental factors eg polychlorinated Envirnmental factors eg polychlorinated biphenylsbiphenyls

DIAGNOSIS –is important for DIAGNOSIS –is important for maintenance of natal and neonatal maintenance of natal and neonatal teeth of the normal dentition.teeth of the normal dentition.

Premature loss of primary dentition Premature loss of primary dentition may cause loss of space and collapse may cause loss of space and collapse of developing mandibular arch with of developing mandibular arch with consequent malocclusion in consequent malocclusion in permanent dentition.permanent dentition.

PERMANENT TEETHPERMANENT TEETH

Premature eruption of permanent Premature eruption of permanent teeth is usually a sequel of teeth is usually a sequel of premature loss of deciduous tooth.premature loss of deciduous tooth.

Occasionally ,cases occur involving Occasionally ,cases occur involving the entire dentition – possibility of an the entire dentition – possibility of an endocrine dysfunction – endocrine dysfunction – hyperthyroidism.hyperthyroidism.

DELAYED ERUPTION

Associated with systemic conditions like rickets , cretinism , endocrine deficiencies and cleidocranial dysplasia or may be genetic

Sometimes local factors – act as barrier Retained deciduous tooth-ankylosed due to trauma

Fibrosis of gingiva

Loss of deciduous tooth and drifting of adjacent teeth

PREMATURE LOSS Without closure – early eruption of its Without closure – early eruption of its

successor.successor. Closure due to drifting of adjacent teeth – Closure due to drifting of adjacent teeth –

delayeddelayed or no eruption.or no eruption.

IMPACTED TEETH 33rdrd molars due to lack of space molars due to lack of space canines due to their late eruption time.canines due to their late eruption time.

ERUPTION CYST

It is a form of dentigerous cyst & is It is a form of dentigerous cyst & is frequently associated with erupting frequently associated with erupting deciduous or permanent teeth in childrendeciduous or permanent teeth in children

It is essentially a dilatation of the normal It is essentially a dilatation of the normal follicular space about the crown of the follicular space about the crown of the erupting tooth – contains tissue fluid or erupting tooth – contains tissue fluid or blood blood

Clinically – appears as a circumscribed , Clinically – appears as a circumscribed , fluctuant , often translucent swelling of fluctuant , often translucent swelling of the alveolar ridge over the site of the alveolar ridge over the site of erupting tooth.erupting tooth.

ERUPTION HEMATOMAERUPTION HEMATOMA

Blood – appears purple or deep blue - referred to as eruption hematoma.Cause of development is not known

Requires no treatment – tooth generally erupts into the oral cavity without significant delay – sometimes a small portion of tissue overlying the tooth is removed to facilitate eruption.

SHEDDING OF PRIMARY TEETH

Definition :Shedding is the exfoliation of the primary teeth caused by physiological resorption of their roots.(James k. Avery)Causes :1.Loss of root2.Loss of bone3.Increased force

1. Loss of root : Pressure from growing

and erupting permanent teeth induces the

differentiation of osteoclast which results in resorption

of the primary root.

Resorption shortens the root and causes loss of attachment fibers of the periodontal ligament.

2. Loss of bone : Weakening of the supporting tissues of the primary teeth occurs as a result of root resorption and modifications of the alveolar bone. Supporting structures are weakened also by facial growth of the alveolar bone , which occurs to provide sufficient space for positioning of the permanent teeth.

3. Increased force : Increased masticatory forces on the weakened teeth are a result of muscular growth , this amplifies compression of the periodontal ligaments and promotes resoption of the teeth and alveolar bone.

CONCLUSION

Eruption is the movement of the teeth through the bone of the jaw and the overlying mucosa, to appear and functional in the oral cavity.

Active eruption is the result of occlusal movement of the tooth. Clinical eruption begins with the appearance of the crown tip in

the oral cavity and continues until the tooth comes into occlusion. The periodontal fibers are organizing to stabilize the erupting

tooth, the root dentinogenesis follows as the bone in the fundic region organizes in response to the change in root length.

Shedding of the primary teeth is the result of progressive resorption of their root through the activity of the osteoclast or odontoclast.

Disturbance of the resorption process results in abnormal behavior of the primary teeth, some primary teeth may be retained because of the absence or impaction of their permanent successors, others may be ankylosed and submerged.

In rare cases, teeth may appear in the oral cavity of newborn or neonatal infants, and are called preprimary teeth.

1 – Oral development and histology, James k Avery , thieme publications (3rd edition) .

2 - Oral Histology – A.R. Ten Cate, Mosby Publications (3rd edition).

3 - Orban’s Oral Histology and Embryology – Mosby Publications(10th edition).

4 - Principles of Anatomy and Oral Anatomy for Dental Students – M.E. Atkinson and F.H. White (1st edition) Churchill Livingstone Publishers.

REFERENCES

Tooth eruption and shedding

Health & Medicine

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