Eruption & shedding

CONTENTS

• INTRODUCTIONeruption of teeth• STAGES IN TOOTH ERUPTION• THEORIES OF ERUPTION• PUTATIVE MOLECULES IN TOOTH

ERUPTION SIGNALING CASCADE• CURRENT CONCEPTS IN TOOTH

ERUPTION• TEETH ERUPTION CHART

EXFOLIATION of teeth• PATTERN OF EXFOLIATION• FACTORS THAT AFFECT SHEDDING• MECHANISM OF RESORPTION AND

SHEDDING• APPLIED ANATOMY• CONCLUSION• REFERENCES

ERUPTION

The word eruption properly means “cutting of the tooth through the gum”

It derives from the latin erumpere, meaning “to break out’’

Tooth eruption is defined as the process of movement of a tooth from its developmental position within the jaws to its functional position in the oral cavity.

ACTIVE TOOTH ERUPTION

• The term active tooth eruption implies the emergence of crown into the oral cavity.

• This eruptive process is usually divided into 3 stages

1. Preeruptive stage 2.Eruptive stage 3.Post eruptive stage

Intra-oral phase

TOOTH ERUPTION

Pre-oral phase

PREERUPTIVE STAGE

• This movement is made by both deciduous and permanent tooth germs within tissues of the jaw before they begin to erupt.

• It is also known as ‘Follicular phase of eruption’

• Cahill DR, Marks SC Jr. Tooth eruption: Evidence for the central role of the dental follicle. J Oral Path 1980; 9

PREERUPTIVE STAGE

• The preeruptive stage begins as the crown starts to develop.

• The eruptive movement associated is of two varities:

1.Spatial 2.Excentric

PREERUPTIVE STAGE

• Total bodily movement of the tooth germ• Growth in which one part of the tooth germ

remains fixed while the rest continues to grow, leading to a change in the center of the tooth germ.

ERUPTIVE STAGE

During the phase of eruptive tooth movement the tooth moves from its position within the bone of the jaw to its functional position in occlusion.

The eruptive or prefunctional stage begins with the development of root.

The principal direction of movement is occlusal or axial.

ERUPTIVE STAGE

• Eruptive tooth movements are involved in primary eruption, supraeruption, impaction, alveolar compensation following wear, as well as failure of eruption.

• During this phase of eruption,the movement of tooth takes place at the rate of 4mm in 14weeks.

RELATIVE POSITION OF PRIMARY AND PERMANENT INCISOR TEETH

Preeruptive period

Prefunctional eruptive period.

RELATIVE POSITION OF PRIMARY AND PERMANENT MOLAR TEETH.

Preeruptive period

Prefunctional eruptive period.

• This stage continues until the erupting teeth meet the opposing teeth.

• The tooth movement tends to be occlusal and facial,more facial in case of anteriors.

Once the teeth meet in occlusion, their further eruption separates the jaws

TOOTH ERUPTION

Once the teeth meet in occlusion, they influence each other mechanically

POSTERUPTIVE STAGE

• The stage begins when the teeth come into occlusion and continues until they are lost or death occurs.

• The type of movement is axial and mesial migration.

POSTERUPTIVE STAGE

• Also acts as a compensatory mechanism.

• It is most active between the ages of 14 and 18 years of age.

EXPERIMENTAL STUDY RESULT

• Compagnon and Woda studied the unopposed upper first molar in both healthy mouths and those with some periodontal pathology present.

• The study found that after 10 years of remaining unopposed, this periodontal migration reversed and root exposure occurred.Compagnon D, Woda A. Supra-eruption of the unopposed maxillary molar. J Prosthet

Dent 1991: 66(29).

DRIFTING e.g., mesially, laterally

AXIAL - in long axis of the tooth

Basil

ROTATORY

TILTING

By root growth & bone remodelling

By bone remodelling & PDL reorganization

TOOTH MOVEMENTS OCCURING IN ERUPTION

POST ERUPTIVE STAGE

Gingival recession onto & down the cementum with loss of alveolar-crest bone

PASSIVE ERUPTION

Raising the banana, then peeling the banana

ERUPTION RHYTHM CIRCARDIAN RHYTHM

• The mean daily eruption velocity was seen to be 71µm / day.

• It is also believed that the effect of eruption significantly increases in supine position overnight.

• Berkovitz BK. How teeth erupt. Dent Update 1990: 206–210.

• The tertiary maturation of the erupting tooth needs much more time than it is supposed in literature.

• Possibly the completion is in accord with the decline of the caries activity at the end of the second decade of lifetime

• With the aid of polarizing microscopy, electron microprobe, microhardness testing (Vickers) and scanning electron microscopy different stages of posteruptive maturation from human and other mammalian teeth were analysed.

Zentrums für Zahn-, Mund- und Kieferheilkunde der Martin-Luther-Universität Halle-Wittenberg. Maturation of enamel and tooth eruption ; Dtsch Stomatol. 1991;41(9)

• There are few physical as well as chemical studies of post-eruptive changes in enamel, although it is widely believed that the surface layer of tooth enamel reacts shortly after eruption, mainly by the exchange of ions, and that the caries-susceptibility decreases with the increase of post-eruptive age.

• Matsumoto Daisuke ;A Study of Post-eruptive Maturation in Immature Permanent Teeth. Analysis by Enamel Biopsy in Lower Central Incisors; Journal of the Japanese Association for Dental Science; 2002(21)

HISTOLOGY OF TOOTH ERUPTION

• While the root continues to lengthen,the tooth begins to move toward the surface of the oral cavity.

• During the intraosseous phase,the rate of osteoclastic activity averages 1 to 10 μm per day,it increases to about 75μm per day once the tooth escapes from its bony cell.

DIAGRAM OF RUFFLED BORDER OF AN OSTEOCLAST

STAGES OF TOOTH ERUPTION.

HISTOLOGY OF TOOTH ERUPTION (permanent tooth)

• The fibrous cord,the gubernacular cord leads the way and with the help of macrophages and osteoclasts,breaks down the bone between the tooth and the surface oral epithelium.

Gubernacular cord of fibrous tissue

Gubernacular cord runs through a canal left in the bony crypt, where the dental lamina extended down to establish the germ for the 2nd tooth

Permanent tooth

Go Gubba!!


• As the successional tooth erupts ,its gubernaculum canal is widened rapidly by local osteoclastic activity , delineating the eruptive pathway for the tooth.


• In a dried skull holes can be identified which are the once containing the gubernacular canals.

HUMAN JAWS AT 8 TO 9 YEARS OF AGE, DURING THE MIXED DENTITION PERIOD

• The relationship between primary and permanent teeth during the mixed dentition period.

THEORIES OF ERUPTION

• Ten Cate recognized that the process of tooth eruption is not precisely understood, and that text described the four possible mechanisms for eruption, that have been investigated.

These are• Root formation, during which space for the

growing root is accommodated by occlusal movement of the tooth crown.

• Hydrostatic pressure within the periapical tissues pushing the tooth occlusally.

• Bony remodelling

• Pulling of the tooth in an occlusal direction by the cells and fibres of the periodontal ligament.

Deposition of alveolar bone?

MECHANISMS OF ERUPTION

Formation of the root

Construction & Reorganization of PDL

Remodelling of bone overall

FURTHER INFLUENCES from: tooth/teeth in occlusion; muscle actions

CAUSES OF ERUPTION(THEORIES…… )

1. Root growth 2.alveolar bone formation and changes 3.periodontal ligament traction 4.vascular pressure in dental tissues 5.The role of tooth itself

ROOT GROWTH

• It has been said that the increase in root length,or root elongation,forces the tooth into oral cavity.

• But many experiments

disproved this concept, but probably has a relationship to the process.

Marks SC Jr, Cahill DR. Experimental study in the dog of the non-active role of the tooth in the eruptive process. Archs Oral Biol 1984; 29

ALVEOLAR BONE FORMATION AND CHANGES

• The alveolar process forms in areas where teeth are developing and is deficient in areas where teeth fail to develop.

• Alveolar bone changes involve both formation and resorption,and these metabolic events are dependent on the presence of the various parts of the dental sac or dental follicle.

• The cycle of bone development is rythmic both in crest and crypt of the alveolar bone, i.e instances of osteoblastic followed by osteoclastic activity.

• In multirooted teeth the interradicular bone seems to have a fairly significant role in the eruption process.


• The Marks and Cahill study eloquently demonstrated that the dental follicle needs to be present for tooth eruption of final tooth position.

Cahill DR, Marks SC Jr. Tooth eruption: Evidence for the central role of the dental follicle. J Oral Path 1980; 9(189).

• Bony remodelling occurs around the erupting follicle regardless of the presence of a tooth crown or tooth, suggesting that the remodelling process may be under the control of the dental follicle.

• These experiments however, provide no evidence that the follicle is involved in determination.

Berkovitz BK. How teeth erupt. Dent Update 1990: 206–210.

PERIODONTAL LIGAMENT TRACTION

• Periodontal ligament has a role to play,probably more so toward the end of the eruption than at the beginning.

• It was believed that the contractile fibers play a role in eruption,but it is not proved.

• Ten Cate looked for evidence to support the theory of the periodontal ligament having a major role in determining tooth eruption.

• Strong evidence exists to show that the periodontal ligament, which is derived from the dental follicle, provides the force required for eruption.

• Although informative, this study consisted of histological observations, and did not provide sufficient data on the origins of the tissues studied.

• Ten Cate AR, Deporter DA, Freeman E. The role of fibroblasts in the remodeling of periodontal ligament during physiological tooth movement. Am J Orthod 1976; 69: 155–168.

VASCULAR PRESSURE IN DENTAL TISSUE

• THE VASCULAR PRESSURES are present in pulpal tissues as well as in the periodontal ligament.

• These pulsating pressure not only enhance cellular activity but seem to have a direct eruptive role.


• The hydrostatic theory was investigated by Van Hassel and McMinn again using dogs, who found that the tissue pressure apical to the erupting tooth was greater than occlusally, theoretically generating an eruptive force.

Van Hassell H J, McMinn RG. Pressure differential favouring tooth eruption in the dog. Archs oral Biol 1972; 17

• However, no association was demonstrated between the magnitude of the force and the rate of eruption.

• Van Hassell H J, McMinn RG. Pressure differential favouring tooth eruption in the dog. Archs oral Biol 1972; 17

ROLE OF TOOTH ITSELF

• A study by Marks and Cahill using dogs, showed the tooth itself played no part in the eruptive process

• So it becomes an unanswered fact that tooth it self plays a role in its eruption………………..???

Then what causes tooth eruption??

Tooth eruption is definitely a multifactorial process involving all or few factors of the above.

More research is now being focused on the biochemistry and cell and molecular biology aspects of the subject.

That’s good!!

• Ten Cate's theories have been further studied by Berkovitz, who also agreed that no one hypothesis can fully explain the mechanism of tooth eruption. He proposed a multifactorial concept of tooth eruption.

PUTATIVE MOLECULES IN TOOTH ERUPTION SIGNALING CASCADE

Bone morphogenic protein-2

Osteoprotegerin Nuclear factor κβ Runt related

transcription factor-2 Interleukin 1α

BMP-2

OPG NF κβ RUNX-2

IL-1 α

Wise GE,Frazier-Bowers S,D’SouzaRN: Crit Rev Oral Biol Med 2002; 13:323

CURRENT CONCEPTS IN TOOTH ERUPTION

• The dental follicle is a loose connective tissue layer that surrounds the erupting tooth.

• The follicle is necessary for tooth eruption.

• Specific cellular changes occur in and around the follicle when a tooth erupts.

CURRENT CONCEPTS. . .

• An eruption pathway is formed when the bone and roots of deciduous teeth are resorbed—events initiated by the dental follicle during eruption.

• Because tooth eruption depends on the dental follicle and activities around it, studies of the follicle may shed some light on eruption mechanism.

CURRENT CONCEPTS. . .

• selective fragmentation of dental follicle protein DF-95 correlates with the presence of elevated levels of follicular collagenase and stromelysin, and with the onset of movement.

• Developmental Bilogy programme.1999: 126(13) 2911-2920,Company of Biologists

CURRENT CONCEPTS. . . A dramatic decrease in these

metalloproteinases followed initiation of movement.

A biochemical and cell biological model for regulation of tooth eruption is proposed based upon these new and existing data.

CURRENT CONCEPTS. . .• CONTROL OF ERUPTION:

Hormonal control mechanisms

Physical control mechanisms

5 YEAR OLD MOUTH…

TEETH ERUPTION CHART…

1 32 54 760YEARS

YOUNG CHILD’S ERUPTION SEQUENCE

Time of emergence

Root formingCrown forming

KEY

10 2nd Molar

20 Incisor

20 Cuspid

20 2nd PreMolar

Deciduous

Permanent

10 Incisor

10 Cuspid

1 32 54 760YEARS

YOUNG CHILD’S ERUPTION SEQUENCE

10 2nd Molar

20 Incisor

20 Cuspid

20 2nd PreMolar

PRIMARY TEETH ERUPTION CHART

IMPORTANCE OF PRIMARY TEETH

Help a child to chew and speak• Hold space for the adult

teeth & guide teeth during eruption

• Aid in jaw and face formation• Influence the child’s overall health

PERMANENT TEETH ERUPTION CHART

SHEDDING OF TEETH

EXFOLIATION• The physiologic process resulting in the elimination

of the deciduous dentition is called shedding or exfoliation.

• The main factors which play role in shedding of teeth are the odontoclast and pressure from the successional tooth.

• External pressures generated by cheeks and tongue also play a minor role in shedding

PATTERN OF EXFOLIATION

• Shedding or exfoliation occurs as a result of progressive resorption of roots of the teeth and their supporting tissue,the periodontal ligament.

• In general,the pressure generated by the growing and erupting permanent tooth dictates the pattern of deciduous tooth resorption.

PATTERN OF EXFOLIATION• At first the pressure is directed against the vestibular

direction, resorption of the roots of the deciduous incissors and canines begins on their lingual surfaces.

• Later, the developing tooth germs occupy a position directly apical to the deciduous tooth.


• In case of mandibular molars,the permanent tooth erupts lingual to the still functioning deciduous tooth.

• Resorption of the roots of deciduous molars often begins on their inner surfaces and bicuspids are found between them.


• The areas of early resorption are repaired by the deposition of a cementum-like tissue.

Osteoclasts resorbing bone

PDL fibers incorporated in bone as Sharpey’s fibers

FUNCTIONAL ERUPTION & TOOTH MOVEMENT

Osteoblasts laying down bundle bone

Cellular cementum added to apex Compensates for occlusal wear?

Occlusal wear

Bony interdental septum

Basil

FACTORS THAT PLAY ROLE IN SHEDDING

1.Odontoclast

2.Pressure

ODONTOCLAST

• When root resorption is almost complete,these odontoclasts degenerate,and mononuclear cells emerge from pulpal vessels and migrate to the predentin surface.

• Less is known about the resorption of soft tissues as it sheds.

ODONTOCLAST

• Just before exfoliation,resorption ceases as the odontoclasts migrate away from the dentin surface.

• The tooth sheds with some pulpal tissues intact.

10/Deciduous tooth

PDL attachment is surprising persistent

Close to EXFOLIATION of Deciduous 10 Tooth

Bone trabeculae added by layers at base of alveolus

Odontoclasts have resorbed most of deciduous root

Pulp is left alive

Bone remodellling has brought 20 tooth under 10

20 tooth would be LARGER than shown

20 tooth

PRESSURE

• The pressure exerted by the erupting permanent teeth seem to play an important role in resorption of deciduous teeth.

• The local pressure is responsible for initiation of resorption.

• In addition to this local pressure, heavy masticatory and muscular forces play a role in resorption.

MECHANISM OF RESORPTION AND SHEDDING

• The mechanism involved in bringing about tooth resorption and exfoliation are not yet fully proven, however it is clear that the odontoclast attaches to the hard tissue surface peripherally, thereby creating a sealed space lined by the ruffled border .

STARTING EXFOLIATION of DECIDUOUS MOLAR I

ALVEOLAR BONE

DENTINE

ENAMEL

Permanent Tooth under deciduous molar, & between its roots

Inter-radicular septum of bone also houses 2nd tooth germ & is its crypt

Root resorption by osteoclasts

PDL

PULP

EXFOLIATION of DECIDUOUS MOLAR II

ALVEOLAR BONE

DENTINE

ENAMEL

Focal erosion along this line leaves a ROOT FRAGMENT which may be retained

Resorbed dentine partly repaired by new cementum

Crypt bone eroded here

PDL

PDL is disrupted in regions of root resorption & repair

EXFOLIATION of DECIDUOUS MOLAR III

Erosion of bone and the deciduous root is not steady & continuous, but may cease briefly, when some repair of eroded cementum & dentine can occur (by cementum). Bone remodelling also goes on, and the alveolus and crypt are changing all the time - repeated all along the jaw

DENTINE

ENAMEL

MECHANISM OF RESORPTION AND SHEDDING

• The membrane of the ruffled border acts as a proton pump, adding hydrogen ions to the extracellular environment and acidifying it so that the mineral dissolution occurs.

APPLIED ANATOMY

PREMATURE ERUPTION :• Premature eruption of teeth occurs

infrequently, for example in case of Riga fede diesease we see early eruption (natal teeth).

• They erupt in the first 30days of life and the teeth most often involved are deciduous mandibular incissors.

• The etiology is unknown, but experimental studies report this to be an endocrinal cause.

• Premature eruption of permanent teeth is usually a sequela of the premature loss of deciduous teeth, and here again an endocrinal disturbance is considered.

DELAYED TOOTH ERUPTION

1. Bonnet-Dechaume-Blanc syndrome2.Cleidocranial dysplasia3.Coffin syndrome4.Cornelia de Lange syndrome5.Cytotoxic therapeutic agents6.Down syndrome7.Gaucher’s syndrome

8.Frontometaphyseal dysplasia9.congenital hypothyroidism10.Rutherfurd syndrome11.Osteopetrosis12.Radiotherapy13.Muccopolysachridosis Type 6

THE EFFECT OF PREMATURE LOSSOF THE FIRST PERMANENT MOLAR

• Diminished local function• Drifting of teeth• Mid line deviation• Continued eruption of opposing teeth

ERUPTION SEQUESTRUM

• It is a tiny irregular spicule of bone overlying the crown of an erupting permanent molar.

• In most cases,this fragment probably undergoes total resorption prior to eruption.

ERUPTION HEMATOMA

• A bluish purple, elevated area of tissue, commonly called an eruption hematoma.

• The blood-filled cyst is most frequently seen in the primary second molar or the first permanent molar regions

DIMINISHED LOCAL FUNCTION

• Diminished local function result in a reduction in chewing efficiency as great as 50%.

• Shifting of the load of mastication to the unaffected side.

• An unhygienic condition of the unused side

INFRA OCCLUSION

• This is the preferred term for submerged or ankylosed teeth.

• It describes teeth that have failed to achieve

or maintain their occlusal relationship to adjacent and opposing teeth.

INFRA OCCLUSION

• 1-9% MALE = FEMALE• Primary > Permanent• Mandibular first

primary molar most frequently affected

INFRA OCCLUSION

• There is a higher incidence of infra occlusion associated with missing permanent successors, but the lower deciduous molars are at the same occlusal level as the other deciduous teeth at this stage and therefore not yet infra occluded.

INFRA OCCLUSION

• The lower second premolar is the most commonly congenitally absent tooth after the third molars.

• There is no root resorption of the lower second primary molars apparent

INFRA OCCLUSION

• Female patient age 14• No relevant medical history• Congenitally absent lower second premolars Lower second primary molars not

infraoccluded• No root resorption apparent

ANKYLOSIS

• Thought to be due to an imbalance in the normal pattern of resorption and repair in primary teeth.

• Trauma and infection have been suggested as precursors.

ANKYLOSIS

• Most likely cause here is congenitally absent lower permanent second premolars.

• If the teeth are ankylosed they will be more difficult to remove, and may require minor oral surgery

EMBEDDED TEETH

• These are teeth that fail to erupt in the oral cavity due to various local factors

ECTOPIC ERUPTION

• Term used to describe a tooth or teeth that erupt in an abnormal position.

• The prevalence of ectopic eruption was significantly higher in the mandible.

doi: 10.2319/072506-306.1 The Angle Orthodontist: Vol. 77, No. 5, pp. 773–778. Prevalence of Ectopic Eruption, Impaction, Retention and Agenesis of the Permanent Second

Molar ,Lars Bondemark;Jola Tsiopa

ECTOPIC ERUPTION

• It is believed that ectopic eruption is due to an abnormal change in position of the dental follicle, delayed loss of primary tooth, loss of space in the alveolar arch.

• But, not yet the true reason for this condition is concluded.

EPSTEIN PEARLS,BOHN NODULES ,DENTAL LAMINA CYSTS

• Epstein pearls are formed along the midpalatine raphe. (remnants of epithelial tissue trapped along the raphe)

• Bohn nodules are formed along the buccal and lingual aspects of the dental ridges and on the palate away from the raphe. (remnants of mucous gland tissue).

• Dental lamina cysts are found on the crest of the maxillary and mandibular dental ridges (remnants of the dental lamina).

TEETHING

• Teething is a term limited by common usage to eruption of primary teeth.

• Clinical features: 1.Local signs 2.Systemic signs

RESEARCH RESULTS OF EXFOLIATED TOOTH

I . EXFOLIATED TOOTH IN STEM CELL RESEARCH It is studied that exfoliated human deciduous tooth

contains multipotent stem cells [stem cells from human exfoliated deciduous teeth (SHED)]i.e highly proliferative, clonogenic cells capable of differentiating into a variety of cell types including neural cells, adipocytes, and odontoblasts

After in vivo transplantation, SHED were found to be able to induce bone formation, generate dentin, and survive in mouse brain along with expression of neural markers.

• SHED are not only derived from a very accessible tissue resource but are also capable of providing enough cells for potential clinical application.

• *Craniofacial and Skeletal Diseases Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD 20892; †Mesenchymal Stem Cell Group, Division of Haematology, Institute of Medical and Veterinary Science, Australia

• Because bones and permanent teeth accumulate lead, exfoliated deciduous teeth have been utilized as retrospective markers of cumulative exposure in epidemiological surveys.

• Relationships between serial blood lead levels and exfoliated tooth dentin lead levels: Models of tooth lead kinetics ;JCTI;1993;53(5)

REFERENCES• Brand and isselhard, anatomy of orofacial structures Text book of dental

anatomy,2004,7th edition.• Orban,Oral histology and embryology,2001,12th edition.• Ten cate’s, Text book of oral histology, 2008,7th edition.• Marks SC Jr, Cahill DR. Experimental study in the dog of the non-active role of the

tooth in the eruptive process. Archs Oral Biol 1984; 29(311).• Cahill DR, Marks SC Jr. Tooth eruption: Evidence for the central role of the dental

follicle. J Oral Path 1980; 9(189).• Moxham BJ. The effects of some vaso-active drugs on the eruption of the rabbit

mandibular incisor. Archs Oral Biol 1979;24(681). • Berkovitz BK. How teeth erupt. Dent Update 1990: 206–210. • Van Hassell H J, McMinn RG. Pressure differential favouring tooth eruption in the

dog. Archs oral Biol 1972; 17(183). • Ten Cate AR, Deporter DA, Freeman E. The role of fibroblasts in the remodeling of

periodontal ligament during physiological tooth movement. Am J Orthod 1976;69(155).

• Compagnon D, Woda A. Supra-eruption of the unopposed maxillary molar. J Prosthet Dent 1991: 66(29).

• Relationships between serial blood lead levels and exfoliated tooth dentin lead levels: Models of tooth lead kinetics ;JCTL;1993;53(5)

• Wise GE,Frazier-Bowers S,D’SouzaRN: Crit Rev Oral Biol Med 13:323,2002)• Developmental Biology programme, Vol 126, Issue 13 2911-2920,

Copyright © 1999 by Company of Biologists The Angle Orthodontist: Vol. 77, No. 5, pp. 773–778. Prevalence of Ectopic

Eruption, Impaction, Retention and Agenesis of the Permanent Second Molar ,Lars Bondemark;Jola Tsiopa

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Eruption & shedding