dental enamel

DENTAL ENAMELDr. Prabhat Saxena

Dept Of Endodontics

S.G.T. Dental College, Gurgaon

Acknowledgements

This seminar has been prepared under the guidance of:

Dr. Suman Yadav (Prof. & Head Of Department)

Dr. S. Vijay Singh (Prof.)Dr. Tarun Gera (Reader)Dr. Suman Yadav (Sr. Lecturer)Dr. Amita Saini (Sr. Lecturer)

Index

Introduction Physical Characteristics Chemical Properties Structures of enamel Enamel rod Striations Direction of rods Hunter-Schreger Bands Incremental Striae Of Retziuz

Index

Gnarled enamel Enamel tufts Enamel lamellae Enamel cuticle Dentino-enamel junction Enamel surface Odontoblast processes & enamel Spindles

Index

Enamel proteins Amelogenins Non – amelogenins

Ameloblastin Enamelin Sulfated glycoproteins Tuftelin

Index

Amelogenesis Light microscopy of amelogenesis Electron microscopy of amelogenesis Destruction of enamel by caries Dissolution of enamel Effects of dental procedure Systemic conditions affecting enamel Regeneration of Dental Enamel Conclusion

Introduction A hard thin translucent

layer of calcified substance which envelops and protects the dentin of the crown of the tooth. It is the hardest substance in the body and is almost entirely composed of calcium salts. Under the microscope, it is composed of thin rods (enamel prisms) held together by cementing substance, and surrounded by an enamel sheath. (From Jablonski, Dictionary of Dentistry, 1992, p286)

Introduction

Enamel is the hardest substance in the body and is almost entirely composed of calcium salts.

The hardness of enamel is an important property as the main role of enamel is to protect the softer underlying dentin of the tooth.

Enamel also serves as the surface for chewing, grinding and crushing of food and this is another reason for its hardness.

Physical Characteristics:2

Enamel is translucent Color -Varies from light yellow to grayish

white the color of dentin and any restorative

dental material underneath the enamel strongly affects the appearance of a tooth.

Thickness : thickest at the cusp, up to 2.5 mm

thinnest at CEJ Specific gravity of enamel is 2.8.


KHN for Enamel : Sound – 355-431 Softened – 149-179 Etched – 88-171KHN for dentin : 68KHN for Cementum :

40KHN for Calculus on

teeth : 86


Refractive index : Enamel : 1.52-1.58 Dentin: 1.553 Cementum: 1.562-1.566 Importance of refractive index: while

matching the shade of a restorative material for purpose of esthetic restoration. The material used should be such that whose refractive index and the density should be close to the refractive index of the enamel.

Composition

96% - mineral 4% - with water

and organic material

Composition

The inorganic content of enamel is a crystalline calcium phosphate (hydroxyapatite) substituted with carbonic ions.

Chemical Properties:2

The bar graph indicates the composition by volume of mineralized tissues in which odontoblast processes have been replaced with peritubular dentin (sclerotic dentin) and the equivalent situation in bone in which osteocyte lacunae are filled with mineral.

Structures Of Enamel

Rods Striations Direction of rods Hunter – Schreger Bands Incremental Lines of Retzius Gnarled Enamel Enamel Tufts Enamel lamellae Enamel Cuticle Dentino-Enamel Junction (DEJ) Enamel Surface Odontoblast processes & enamel Spindles

Enamel Rods 2

number of enamel rods - 5 millions in lower LI to 12 million in upper 1st molars.

From the DEJ the rods run somewhat tortuous courses outward to the surface of the tooth.

Average diameter of rods is 4µm.

Enamel Rods 2

Diameter increases from DEJ toward the surface of the enamel at a ratio of about 1:2.

clear crystalline appearance- permitting light to pass through them.

Shaped – cylinder made up of crystals with long axes that run

parallel to the longitudinal axis of enamel rod. rod sheath - boundary between rod and

interod enamel is delimited by a narrow space containing organic material

Enamel Rods 2

rods surrounded by sheath and separated by interrod substance - a keyhole or paddle-shaped prism.

interrod substance measure about 5µm in breadth and 9µm in length.

longitudinally sections - pass through the “head” or “bodies”of one row of rods and the “tails”of an adjacent row.

Enamel Rods 2

bodies of the rods are nearer occlusal and incisal surfaces, whereas the tails point cervically.

cross section –crystals are irregular in shape and have an average thickness of about 30 nm & width of about 90µm.

Directions of rods Rods are oriented at

right angles to the dentin surface.

Deciduous tooth – cervical & central parts-

Horizontal Near incisal edge or tip

of the cusps - increasingly oblique direction until they are almost vertical in the region of the edge or tip of the cusps

Directions of rods

Permanent teeth – occlusal two third

of the crown – oblique direction to vertical at cusp tips.

cervical region - deviate from horizontal in an apical direction.

Directions of rods

Importance: while cavity preparation, unsupported enamel must be removed as they contain unsupported enamel rods by a dentin base and are readily fractured by pressure from mastication or hand instument.

Hunter – Schreger Bands1

an optical phenomenon produced by changes in direction between adjacent groups of rods.

longitudinal ground sections - viewed by reflected light

are found in the inner two thirds of the enamel.

Bands are dark & light alternating zones that can be reversed by altering the direction of incident illumination.

Hunter – Schreger Bands1

originate at the DEJ and pass outward, ending at some distance from the outer enamel surface.

Incremental Lines of Retzius1

Ascribed as weekly rhythm in enamel production resulting in a structural alteration of the rod

ground sections of calcified teeth- appear as brownish bands

longitudinal section - series of dark lines extending from the DEJ toward the tooth surface in cross-section they appear as concentric rings.

Incremental Lines of Retzius1

the cervical parts -they run obliquely

transverse section- the incremental lines of retzius appear as concentric circles

Gnarled Enamel1

Over the cusps of teeth the rods appear twisted around each other in a seemingly complex arrangement known as gnarled enamel.

rods undulate back and forth within the planes. This undulation in vertically directed rods around a ring of small circumfrence readily explains gnarled enamel.

A, Gnarled enamel; B, Enamel spindle

Gnarled Enamel1

Importance: the orientation of rod heads and tails and gnarling of enamel rods provide strength by resisting, distributing, and dissipating impact forces.3

Enamel Tufts2

project from the DEJ for a short distance into the enamel.

Like geologic faults. Best seen in transverse

sections of enamel. Appear to be branched

& contain greater concentrations of enamel proteins than the rest of the enamel.

Enamel Tufts2

occur developmentally because of abrupt changes in the direction of groups of rods that arise from different regions of the scalloped DEJ.

consist of hypocalcified enamel rods and interprismatic substance.

Enamel Tufts2

Importance: these projections arise in dentin, extend into the enamel in the direction of long axis of the crown , and play a role in spread of dental caries.3

Enamel lamellae2

extend for varying depths from surface of enamel and consists of linear, longitudinally oriented defects filled with organic material.

Organic material may derive from trapped enamel organ components or connective tissue surrounding the developing tooth.

Enamel lamellae2

3 types of lamellae : Type A – composed of poorly calcified rods

segments Type B – consists of degenerated cells Type C – lamellae arising n erupted teeth where

the cracks are filled with organic matter, presumably originating from saliva.

• Importance: they contain mostly organic material, which is a weak area predisposing a tooth to the entry of bacteria and dental caries.

Enamel Cuticle:2

Also called as Nasmyth’s membrane

It covers the entire crown of the newly erupted tooth but is probably soon removed by mastication.

Visible with light microscope because of its wavy course.

Basal lamina is secreted by ameloblasts when enamel formation is completed.

Enamel Cuticle:2

Finally, erupted enamel is normally covered by a pellicle, which is apparently a precipitate of salivary proteins.

Pellicle re-forms within hours after an enamel surface is mechanically cleaned.

Dentino-Enamel Junction (DEJ):2

surface of dentin at DEJ is pitted.

Into the shallow depressions of dentin fit rounded projections of enamel.

The convexities of scallops are directed towards the dentin

SEM –junction is a series of ridges rather than spikes, arrangement increases the adherence between dentin and enamel.

Dentino-Enamel Junction (DEJ):2

The shape and nature of junction prevents shearing of enamel during function.

Importance: the depth of cavity preparation should be always be beyond DEJ to take the cushioning effect of dentin and to reduce hypersensitivity to cavity preparation.

Enamel Surface1-2

The striae of retzius often extend from DEJ to outer surface of enamel, where they end in shallow furrows known as perikymata.

Perikymata runs in circumfrentially horizontal lines across the face of crown.

CEJ- 30 perikymata per millimete

occlusal or incisal edgeof a surface - 10 perikymata per mm

Enamel Surface1-2

A relatively structureless layer of enamel, approx. 30µm thick, has been described in 70% of permanent teeth and all deciduous teeth.

surface layer no prism outlines are visible, and all of the apatite crystals are parallel to one another and perpendicular to striae of retzius.

Enamel Surface1-2

Neonatal line or neonatal ring - enamel of deciduous teeth develops partly before and partly after birth. The boundary between the two portions of enamel in the deciduous teeth is marked by an accentuated incremental lines of retzius

Enamel Surface1-2

Importance : the enamel surface initially has circular depressions indicating where the enamel rods end. These concavities vary in depth and shape, and they may contribute to the adherence of plaque material, with a resultant caries attack, especially in young people.3

Odontoblast processes & enamel Spindles2

Occasionally odontoblast processes pass across the DEJ into the enamel, those thickened at the end are termed as enamel spindles.

originate from processes of odontoblast that extend into the enamel epithelium before hard substance were formed.

Odontoblast processes & enamel Spindles2

direction of odontoblast processes and spindles in enamel corresponds to the original direction of the ameloblast – at right angles to the surface of dentin.

Importance: spindles serve as pain receptors, thereby explaining enamel sensitivity experienced by some patients during tooth preparation.

Enamel Proteins1

They are two main types of proteins : Amelogenins Non – amelogenins

Ameloblastin Enamelin Sulfated glycoproteins Tuftelin

AMELOGENINS

Physical characteristics: Major secretory forms : 25kDa, 23kDa, 20kDa N-terminal domain is tyrosine rich One phosphate occurs on serine 16 Central part of protein is leucine rich

Properties: Accumulate during the secretory stage Undergo minor short-term and major long term

degradation Regulate growth in thickness and width May also nucleate crystals

AMELOBLASTIN

Also known as amelin or sheathlin

Physical characteristics: Native: 62-70kDa in deep zones fragmented of 13-

17kDa in peptides.

Properties: Undergoes rapid degradation. Intact molecules occur near the enamel forming

surface. Mostly fragmented forms are found in deeper zones. Promotes mineral formation and crystal elongation.

ENAMELIN

Physical characteristics: Native :140 to 150kda(pig enamelin)

89 and 65kDa 32kDa in deep regions phosphorylated at 3 sites,O-glycosylated.

Properties : Small degradation in secondary

stage,which decreases in deep zones,where the molecule binds hydroxyapatite.

Crystal nucleation and growth.

SULFATED GLYOPROTEIN

Physical properties: 65kDa in the rat. N-glycosylatedProperties : Short half life

TUFTELIN

Physical properties: 55kDaProperties: Believed to localize specifically at the

DEJ and to participate in its establishment

Possible role in cell signaling Not specific to enamel

Enzymes 1

Metalloproteinase : Physical characteristics: EnamelysinProperties: Short term processing

Enzymes 1

Serine ProteinasePhysical characteristics: Enamel matrix serine proteinaseProperties: Bulk degradation

Enzymes 1

Phosphatase:Physical characteristics: Alkaline and acid

AMELOGENESIS:1

Ameloblasts: Cylindrical epithelial cells in the innermost layer

of the ENAMEL ORGAN. Their functions include contribution to the development of the dentinoenamel junction by the deposition of a layer of the matrix, thus producing the foundation for the prisms (the structural units of the DENTAL ENAMEL), and production of the matrix for the enamel prisms and interprismatic substance. (From Jablonski's Dictionary of Dentistry, 1992)Year introduced: 1965.

AMELOGENESIS1

It Is a 2 step process. 1st step produces a

partially mineralized (approx 30%) enamel.

a 2nd step involves significant influx of additional mineral coincident with the removal of organic material and water to attain greater than 96% mineral content.

AMELOGENESIS1

subdivided into 3 main functional stages:

presecretory, secretory, maturation stages

Light microscopy of Amelogenesis1

At late bell stage: in the region of cervical loop the low columnar cells of the inner dental epithelium are identifiable.

Peripheral to the inner dental epithelium lie the stratum intermedium, stellate reticulum, and outer dental epithelium.


Basement membrane is present between the outer dental epithelium and the dental follicle.

inner dental epithelium is traced coronally in a crown stage tooth germ – cells become tall and columnar, and the nuclei – aligned at the proximal ends of the cells adjacent to the stratum intermedium.

dentin formation initiates - Cells of inner dental epithelium (ameloblast) begin sectreting enamel proteins that accumulate and become partially mineralized to form the inner layer of enamel which does not have any rods.


As 1st increment of enamel is formed , ameloblasts move away from the dentin surface.

production and organization of the enamel is the development Tomes process, - juts into and interdigitates with the newly forming enamel.

gives the junction of picket-fence or saw tooth appearance.

When secretion of full thickness enamel is complete , ameloblasts enter the maturation stage.


post secretory transition – ameloblasts shorten and re structure themselves into squatter maturation cells.

Cells from stratum intermedium, stellate reticulum, and outer dental epithelium reorganize so that the recognizing individual cell layer is no longer possible.

Blood vessels invaginate deeply into these cells, without disrupting the basement membrane – to form a convoluted structure referred to as papillary layer.


When enamel is fully mature - ameloblast layer and the adjacent papillary layer regress and constitute the reduced enamel epithelium.

REE - no longer involved in the secretion and maturation of enamel, continues to cover it and has a protective function.

protective phase:composition of enamel can still be modified.

reduced dental epithelium remains until the tooth erupts.


When tooth erupts – REE on incisal region is destroyed & those at cervical areas interacts with the oral epithelium to form junctional epithelium.

Electron Microscopy of Amelogenesis1

Presecretory Stage:1. Morphogenic Phase: During the bell stage of tooth development,

the shape of the crown is determined. Cells of dental epithelium are separated

from dental papilla by basement membrane. cells of inner dental epithelium are cuboidal

or low columnar, with large centrally lacated nuclei and poorly developed Golgi elements in the proximal portion of cell, where a junctional complex occurs.

Morphogenic Phase

Mitochondria and other cytoplasmic components are scattered throughout the cell.

Presecretory Stage:

2. Differentiation Phase:1

As Cells differentiate into ameloblasts, they elongate and their nuclei shift proximally toward the stratum intermedium.

Basement membrane supporting them is fragmented by cytoplasmic projections and disintegrates during mantle dentin formation.

golgi complex increases in volume and migrates distally from its proximal position to occupy major portion of the supranuclear cytoplasm.

Differentiation Phase:1

amount of RER increases mitochondria clusters in the proximal region 2nd junctional complex develops at the distal

extremity of the cell, compartmentalizing the ameloblast into a body and distal extension called Tome’s process

ameloblast becomes a polarized cell, with majority of its organelles situated in the cell body distal to the nucleus.

Differentiation Phase:1

production of enamel proteins start even before the basement membrane separating preameloblasts and preodontoblasts is lost.

Adjacent ameloblasts are aligned closely with each other.

junctional complexes encircle the cells at their distal and proximal extremeties.

Secretory Stage:1

Golgi complex is extensive and forms a cylindrical organelle surrounded by numerous cisternae of RER, occupying a large part of the supranuclear compartment.

mRNA for enamel proteins is translated by ribosomes on the membrane of the RER, and thus synthesized proteins are translocated into the cisternae.

Proteins they progress through the golgi complex and are packaged into membrane bound secretory granules.

Secretory Stage:1

Granules migrate to the distal extremity of the cell, that is into Tomes process.

content of secretory granules is released against the newly formed mantle dentin.

The 1st hydroxyapatite crystals formed interdigitates with the crystals of dentin.

As initial layer is formed, ameloblast migrate away from dentin surface and develop the distal portion of Tome’s process as an outgrowth of the proximal portion.

Secretory Stage:1

When distal portion of Tomes process is established, secretion of enamel proteins become staggered and is confined to 2 sites.

Secretion from the 1st site, along with that adjoining ameloblasts, results in the formation of enamel partitions (interred) that delimit the pit in which resides the distal portion of Tomes process.

Secretion from the 2nd sites later fills this pit with matrix that regulates the formation of so-called rod enamel.

Secretory Stage:1

Formation of interred enamel is always a step ahead.

distal portion of Tomes process lengthen as the enamel layer thickens and gradually thinner as the rod growing in diameter presses it against the wall of the interred cavity.

When the outer portion of the enamel layer formed

Ameloblasts become shorter and loses its distal portion of Tomes process

Secretory Stage:1

Rods form in relation to the distal portion of Tomes process, the final few do not contain any rods.

The enamel layer is composed of a rod containing layer sandwiched between thin rodless initial and final layers.

Maturation Stage:

Amelogenesis is a slow developmental process

upto two-third of the formation time can be occupied by the maturation stage.1

Divinto 2 phases:1. Transitional Phase2. Maturation Proper

Transitional Phase:

After full thickness of immature enamel has formed

ameloblasts undergo significant morphologic changes

reduction in height of the ameloblast and a decrease in their volume and organelle content occurs.

ameloblasts undergo programmed cell death (apoptosis).

Maturation Proper

Ameloblasts become involved in the removal of water and organic material from the enamel, and additional inorganic material is introduced.

Modulation of cells occur , the cyclic creation, loss & recreation of a highly invaginated ruffle-ended apical surface possessing a ruffled border or a smooth border

Ruffle ended ameloblasts - endocytotic activity and contains numerous lysosomes, calcium binding proteins, membrane associated calcium ATPase that appear to promote the pumping of calcium ions into the maturing enamel.

Maturation Proper

Smooth ended ameloblasts leak small proteins and other molecules,show little endocytotic activity.

Interstitial fluids that may leak during the smooth ended phase may contribute to neutralizing pH of the enamel fluid.

Active incorporation of mineral ions into crystal occurs

Just as ameloblasts complete the transitional phase and begin the first series of modulation cycles, they deposit a basal lamina at their now-flattened apex.

Maturation Proper

Basal lamina adheres to enamel surface, and the ameloblasts attach to it by means of hemidesmosomes.

basement membrane constituents such as laminin and type IV collagen.

cells are involved in establishing crown pattern ,they are small and low columnar with centrally placed nuclei, and they undergo frequent mitosis.

Final phase is protection of the newly formed enamel surface until the time of tooth eruption

Age Changes:

Enamel is a non-vital tissue that is incapable of regeneration

Destruction Of Enamel By Caries

The high mineral content of enamel, makes it susceptible to a demineralization process which often occurs as dental caries.

Tooth caries are caused when acids dissolve tooth enamel:

Ca10(PO4)6(OH)2(s) + 8H+(aq) → 10Ca2+(aq) + 6HPO42-(aq) +

2H2O(l)

Sugars from candies, soft drinks, and even fruit juices play a significant role in tooth decay, and consequently in enamel destruction.

Destruction Of Enamel By Caries

mouth contains a great number and variety of bacteria, and when sucrose, the most common of sugars, coats the surface of the mouth, some intraoral bacteria interact with it and form lactic acid.

decreases the pH hydroxylapatite crystals of enamel

demineralize, allowing for greater bacterial invasion deeper into the tooth.

Dissolution Of Enamel By Caries:3

Enamel is composed of very tightly packed hydroxyapatite crystallites, organised into long columnar rods (prisms).

The striae of retzius have relatively higher organic content.

Both the striae and inherent spaces in prism boundaries provide sufficient porosity to allow movement of water and smaller hydrogen ions.

Enamel acts as a molecular sieve by allowing free movements of small molecules and blocking the passage of larger molecules and ions.


Movement of ions through carious enamel result in acid dissolution of the underlying dentin before actual cavitation of the enamel surface.

striae form horizontal lines of greater permeability in the enamel, they probably contribute to the lateral spread of smooth surface lesions.

Long axis of the apatite crystallites within the head (body) is aligned almost parallel to the rod long axis, and the crystallites incline with increasing angles (upto 65o) to prism axis in the tail region.


dissolution process occurs more in the head regions of the rods, the tail regions and the periphery of the head regions are relatively resistant to acid attack.

Head

Tail

Effects of dental procedures

Cavity Preparation: Most dental restorations involve the

removal of enamel. Remove decayed enamel if present Aesthetics is another reason for the

removal of enamel Removing enamel is necessary when

placing crowns and veneers to enhance the appearance of teeth.

Cavity Preparation:

In both of these instances, it is important to keep in mind the orientation of enamel rods because it is possible to leave enamel unsupported by underlying dentin, leaving that portion of the prepared teeth more vulnerable to fracture.

Acid-etching techniques

Act by dissolving minerals in enamel, etchants remove the outer 10 micrometers on the enamel surface and makes a porous layer 5–50 micrometers deep.

roughens the enamel microscopically and results in a greater surface area on which to bond.

Acid-etching techniques

Three types of patterns formed by acid-etching:

1. Type 1 is a pattern where predominantly the enamel rods are dissolved

2. type 2 is a pattern where predominantly the area around the enamel rods are dissolved.

3. type 3 is a pattern where there is no evidence left of any enamel rods

Tooth whitening5

Tooth whitening or tooth bleaching are procedures that attempt to lighten a tooth's color in either of two ways:

1. Chemical action2. Mechanical action

Tooth whitening5

Chemically- bleaching agent is used to carry out an oxidation reaction in the enamel and dentin.

hydrogen peroxide and carbamide peroxide are used.

Tooth whitening5

A tooth whitening product with an overall low pH can put enamel at risk for decay or destruction by demineralization

Tooth whiteners in toothpastes work through a mechanical action.

They have mild abrasives which aid in the removal of stains on enamel.

Systemic conditions affecting enamel Chronic bilirubin

encephalopathy: which can result from erythroblastosis fetalis, is a disease which has numerous effects on an infant,

cause enamel hypoplasia and green staining of enamel.

Systemic conditions affecting enamelErythropoietic

porphyria: genetic disease

resulting in the deposition of porphyrins throughout the body.

deposits also occur in enamel and leave an appearance described as red in color and fluorescent.

Systemic conditions affecting enamelCeliac disease: an auto-immune

disorder triggered by gluten allergies, also commonly results in demineralization of the enamel.

Systemic conditions affecting enamelAmelogenesis

Imperfecta: autosomal dominant

condition that results in enamel that is not completely mineralized.

enamel easily flakes off the teeth, which appear yellow because of the revealed dentin.

Systemic conditions affecting enamelAccording to Jr. Dent Res. Vol.84(12);

2005;pg- 1117-1126:6

Amelogenesis Imperfecta is caused by mutation in 5 genes (AMELX, ENAM, KLK4, MMP-20 & DLX3).

Alteration in AMELX gene are responsible for X-linke44d AI.

Mutation in the ENAM ,KLK4, MMP-20 gene cause AI with AI with the autosomal pattern of inhertance.

Recently, a mutation within the DLX3 gene has been described and associated with AIHHT.

Drugs Related to tooth discoloration:7

1. Drugs related to extrinsic tooth discoloration:

Chlorhexidine (jensen- 1977) Oral iron salts (Dental Practitioners

Formulary, 2004) Coamoxiclav (garcia-Lopez et al, 2001)2. Drugs related intrinsic tooth discoloration: Fluoride Tetracyclines Ciprofloxacin


Fluoride: discoloration or damage to tooth structure may

occur when the daily intake of the fluoride ions from sources such as water, toothpastes, precribed drops & tablets is high while the enamel is undergoing pre-eruptive formation & maturation.

adverse effect is a permanent hypomineralization of enamel, characterized in its mildest form as small, barely visible, white flecks found primarily on cusp tips and on facial surface.(DenBesten, 1999).

Fluorosis


Tetracyclines : females exposed to tetracyclines during

2nd or 3rd trimester of pregnancy may give birth to a child who will have discolored teeth.

The teeth may become bright yellow upon development, and stains will eventually turn to grey or brown overtime.(Driscoll et al , 1993)

Tetracyclines Stains


Ciprofloxacin : when given i.v. to infants at dosages of

10-40mg/kg/day to treat infections with Klebsiella – has been associated with greenish discoloration of the teeth when they erupted, and the discoloration could not be removed (Lumbiganon et al , 1991).

Regeneration of Dental enamel:

Tissue engineering of Enamel – Dentin Complex Structures by M. Honda et al , Univ. Of tokyo, Japan.

Repoted on a new technique for culturing cells that have the capacity to produce enamel.

Epithelial cells extracted from the developing teeth of 6 month old pig continue to proliferate when they are cultured on top of a special feeder layer of cells ( 3T3-J2 cell line).


The crucial steps boosts the number of dental epithelial cells available for enamel production.

In this study researchers seeded the cultured dental epithelial cells onto collagen sponge scaffolds, along with cells from the middle of tooth ( dental mesenchymal cells).

The scaffolds were then transferred into the abdominal cavity of rats, where conditions were favourable for the cells in the scaffolds to interact and develop.


When they were removed after 4 weeks , the remnant of the scaffolds were found to contain enamel-like tissue.


STEM CELL RESEARCH: progress in stem cell research and in tissue

engineering promises novel prospects for tissue regeneration in dental practice in the future.

Stem cells have been discovered in many adult tissues, including teeth, and stem cells from embryos have the potential to form all adult tissues.

Embryonic stem cells can now be cultured and even produced from adult cells by the nuclear transfer.


USE OF STEM CELLS, METHOD OF TISSUE ENGINEERING, USE OF DENTAL TISSUES AND TOOTH BIOLOGICAL SUBSTITUTE:

The present invention is related to the use of animal species stem cells for obtainment of a tooth

biological substitute, in whole or in part, to be implanted in an organism of the same strain. Cells can be adult cells.

Tissue engineering for culture of cells for dental tissue formation for obtainment of a tooth biological substitute and the obtained biological substitute.

Regeneration of Dental enamel: Dental tissues for treatment of subjects which

suffered loss, fails or lacks of those said tissues and to the cosmetic use of dental tissue.

It is known by dental regeneration state of art, either partial or total, that synthetic material promotes a dental element functional repairing but not anatomical and functional structure regeneration.

Such methods comprise the metallic implantations field, mainly bone integrated dental implantations.

Regeneration of Dental enamel:The present invention still aims a method of

tissue engineering for culturing cells which are capable to form dental tissue for obtainment of biological tooth substitute comprising:

obtaining cells capable to form dental tissue from stem cells;

culturing cells from (a)wherein the cells are initially cultivated in the

absence of bovine serum and/or bovine fetal serum;

Regeneration of Dental enamel:b) seeding cultivated cells in a

biodegradable material scaffold; and

c) implanting the scaffold assembly into organism of the same animal strain which cells are capable to form dental tissue, from which the original dental cells came from.

Conclusion:

In recent years there has been increasing progress in identifying stem cells from adult tissues and their potential application in tissue engineering. These advances provide a promising future for tooth replacement/regeneration.

Refrences

1. Tencate’s Oral Histology, development, structures and function – Antonio Nanci 6th edition

2. Orban’s Oral histology and enbryology – 11th edition

3. Sturdevant’s – Art & Science of Operative Dentistry – 4th edition

4. Bioengineered Teeth from tooth Bud cells –Pamela C. Yelick et al, Dent Cli. N. Am. , Vol. 50, 2006; pg 191-203

5. The effect of 16 % carbamibe peroxide on enamel ; Marjaneh Ghavamnasiri et al – Can. Den Asso. Vol 34, no. 11, nov’2006; pg 873-876.

6. Genes & related Proteins involved in asmelogenesis imperfecta, G. Stephanopoulos et al – J Dent Res 84 (12) 2005; 1117-1126

7. Drug-induced Disorders of teeth – C.J. Tredwin et al, J. Den. Res. 84(7) 2005; pg 596-602.

8. Fluorosis: A new model and new insights – J.D. Barlett; J Den Res, 84(9) 2005; pg 832-836.

dental enamel

Documents

enamel sheath

hardness of enamel

interod enamel

unsupported enamel rods

number of enamel rods

rods enamel prisms

organic material enamel

p286 introduction enamel