The document discusses the structure, composition, and development of dental enamel, the hardest biological tissue that covers the crown of teeth. It details the physical and chemical properties of enamel, stages of amelogenesis, and the life cycle of ameloblasts, including the significance of specific anatomical features. Multiple elements such as enamel rods, defects, and clinical implications are also addressed, providing a comprehensive overview of this dental tissue.

1. ENAMELENAMEL
DR AMITHA G, BDS, MDSDR AMITHA G, BDS, MDS
ORAL AND MAXILLOFACIAL PATHOLOGYORAL AND MAXILLOFACIAL PATHOLOGY

2. CONTENTSCONTENTS
 INTRODUCTIONINTRODUCTION
 PHYSICAL PROPERTIESPHYSICAL PROPERTIES
 CHEMICAL PROPERTIESCHEMICAL PROPERTIES
 STRUCTURE OF ENAMELSTRUCTURE OF ENAMEL
 DEVELOPMENT OF ENAMELDEVELOPMENT OF ENAMEL
EPITHELIAL ENAMEL ORGANEPITHELIAL ENAMEL ORGAN
AMELOGENESISAMELOGENESIS
LIFE CYCLE OF AMELOBLASTSLIFE CYCLE OF AMELOBLASTS
 AGE CHANGES IN ENAMELAGE CHANGES IN ENAMEL
 DEFECTS OF AMELOGENESISDEFECTS OF AMELOGENESIS
 CLINICAL IMPLICATIONSCLINICAL IMPLICATIONS

3. INTRODUCTIONINTRODUCTION
 Hardest biological tissue
present
as outer most covering of the
crown.
 Epithelial derived hard tissue
, formed by ameloblasts
which cannot be reform
itself.
 Non vital as it is acellular ,
avascular.

4. PHYSICAL PROPERTIESPHYSICAL PROPERTIES
 TRANSLUCENT TISSUE .TRANSLUCENT TISSUE .
 YELLOWISH WHITE TO GRAYISH WHITE.YELLOWISH WHITE TO GRAYISH WHITE.
 THICKNESS VARIESTHICKNESS VARIES
 HARDNESS – 296KHNHARDNESS – 296KHN
 BRITTLEBRITTLE
 SPECIFIC GRAVITY – 2.8SPECIFIC GRAVITY – 2.8
 DENSITY- 2.8 TO 3.0 GM/SQ.CMDENSITY- 2.8 TO 3.0 GM/SQ.CM
 SEMI- PERMEABLESEMI- PERMEABLE

5. ENAMEL
Inorganic
96%
Organic+Water
4%
CHEMICALCHEMICAL PROPERTIESPROPERTIES
•
Crystalline Calcium AMELOGENINS ,
Phosphate ENAMELINS
“HYDROXYAPATITE” and Water

6. STRUCTURES OF ENAMELSTRUCTURES OF ENAMEL
 DEJDEJ
 ENAMEL SPINDLESENAMEL SPINDLES
 SURFACE STRUCTURESSURFACE STRUCTURES
• ENAMEL RODSENAMEL RODS
• INCREMENTAL LINESINCREMENTAL LINES
• HUNTER SCHREGER BANDSHUNTER SCHREGER BANDS
• GNARLED ENAMELGNARLED ENAMEL
• ENAMEL TUFTSENAMEL TUFTS
• ENAMEL LAMELLAEENAMEL LAMELLAE

7. ENAMEL RODSENAMEL RODS
 ENAMEL CONSISTS OF RODS, ROD SHEATH AND INTER-ENAMEL CONSISTS OF RODS, ROD SHEATH AND INTER-
ROD ENAMEL.ROD ENAMEL.
 5 MILLION (MAND LATERAL) TO 12 MILLION (MAX FIRST5 MILLION (MAND LATERAL) TO 12 MILLION (MAX FIRST
MOLAR)MOLAR)
 TORTUOUS COURSE FROM DEJ TO OUTER SURFACETORTUOUS COURSE FROM DEJ TO OUTER SURFACE
 DIAMETER - DEJ :OUTER SURFACE - 1:2DIAMETER - DEJ :OUTER SURFACE - 1:2
 BREADTH – 5UM , LENGTH – 2.5 MMBREADTH – 5UM , LENGTH – 2.5 MM

8. • 3 TYPES:3 TYPES:

9. SUBMICROSCOPIC STRUCTURESUBMICROSCOPIC STRUCTURE
CROSS - SECTIONCROSS - SECTION
• RESEMBLES FISH SCALESRESEMBLES FISH SCALES
• OCCASIONALLYOCCASIONALLY
APPEAR HEXAGONAL,APPEAR HEXAGONAL,
ROUND OR OVAL.ROUND OR OVAL.
• KEY HOLE PATTERNKEY HOLE PATTERN

10. DIRECTION OF ENAMEL RODSDIRECTION OF ENAMEL RODS

11. INCREMENTAL LINESINCREMENTAL LINES
• STRAIE OF RETZIUSSTRAIE OF RETZIUS
• CROSS – STRIATIONSCROSS – STRIATIONS
• NEONATAL LINENEONATAL LINE

12. INCREMENTAL LINES OF RETZIUSINCREMENTAL LINES OF RETZIUS
• APPEAR AS BROWNISH BANDS IN GROUND SECTIONS OF ENAMELAPPEAR AS BROWNISH BANDS IN GROUND SECTIONS OF ENAMEL
• REPRESENTS INCREMENTAL DEPOSITION OF THE ENAMEL, I.E.REPRESENTS INCREMENTAL DEPOSITION OF THE ENAMEL, I.E.
SUCCESSIVE APPOSITION OF LAYERS OF ENAMEL.SUCCESSIVE APPOSITION OF LAYERS OF ENAMEL.
• REPRESENT WEEKLY RHYTHM.REPRESENT WEEKLY RHYTHM.

13. LONGITUDINALLONGITUDINAL
SECTIONSECTION TRANSVERSE SECTIONTRANSVERSE SECTION

14. SIGNIFICANCESIGNIFICANCE
 THESE LINES BECOME PROMINENTTHESE LINES BECOME PROMINENT
DURING CARIOUS ATTACKS.DURING CARIOUS ATTACKS.
 REFLECT VARIATION IN STRUCTUREREFLECT VARIATION IN STRUCTURE
AND MINERALIZATION DURING GROWTH.AND MINERALIZATION DURING GROWTH.
 HELPS IN CHRONOLOGICAL MAPPINGHELPS IN CHRONOLOGICAL MAPPING
OF DENTAL DEVELOPMENTOF DENTAL DEVELOPMENT

15. STRIATIONSSTRIATIONS
 DARK TRANSVERSE LINES SEEN CROSSING THE ENAMEL GIVING ADARK TRANSVERSE LINES SEEN CROSSING THE ENAMEL GIVING A
STRIATED APPEARANCE TO THE ENAMEL RODS.STRIATED APPEARANCE TO THE ENAMEL RODS.
 REPRESENTS DAILY INCREMENTS OF GROWTH DURING ENAMELREPRESENTS DAILY INCREMENTS OF GROWTH DURING ENAMEL
FORMATION.FORMATION.
 RATE OF ENAMEL FORMATION IS APPROX. 4 UM/DAY.RATE OF ENAMEL FORMATION IS APPROX. 4 UM/DAY.

16. NEONATAL RING OR NEONATAL LINESNEONATAL RING OR NEONATAL LINES ::
• ACCENTUATED INCREMENTALACCENTUATED INCREMENTAL
LINE OF RETZIUSLINE OF RETZIUS
• BOUNDARY BETWEEN PRE-BOUNDARY BETWEEN PRE-
NATAL AND POST-NATALNATAL AND POST-NATAL
ENAMELENAMEL
• USUALLY SEEN IN THEUSUALLY SEEN IN THE
DECIDUOUS TEETH ANDDECIDUOUS TEETH AND
PERMANENT FIRST MOLARS.PERMANENT FIRST MOLARS.
PRENATAL ENAMEL POSTNATAL ENAMEL
NEONATAL LINE

17. HUNTER SCHREGER BANDSHUNTER SCHREGER BANDS ::
 OPTICAL PHENOMENONOPTICAL PHENOMENON
PRODUCED BYPRODUCED BY
CHANGE IN DIRECTIONCHANGE IN DIRECTION
BETWEEN ADJACENTBETWEEN ADJACENT
GROUPS OF RODS.GROUPS OF RODS.
 ALTERNATING LIGHTALTERNATING LIGHT
AND DARK BANDS AREAND DARK BANDS ARE
SEEN IN LONGITUDINALSEEN IN LONGITUDINAL
SECTIONS UNDERSECTIONS UNDER
OBLIQUE REFLECTEDOBLIQUE REFLECTED
LIGHT.LIGHT.
 USUALLY FOUND INUSUALLY FOUND IN
INNER 2/3 OF ENAMEL ,INNER 2/3 OF ENAMEL ,
STARTING FROM DEJ.STARTING FROM DEJ.

19. • SIGNIFICANCESIGNIFICANCE
 FUNCTIONAL ADAPTATIONFUNCTIONAL ADAPTATION
MINIMIZING THE RISK OFMINIMIZING THE RISK OF
CLEAVAGE IN AXIAL DIRECTIONCLEAVAGE IN AXIAL DIRECTION
DUE TO MASTICATORY FORCES.DUE TO MASTICATORY FORCES.

20. GNARLED ENAMELGNARLED ENAMEL
• A COMPLEXA COMPLEX
ARRANGEMENT OFARRANGEMENT OF
RODS WHICHRODS WHICH
INTERTWINEINTERTWINE
IRREGULARLY NEARIRREGULARLY NEAR
THE CUSPAL AREA ORTHE CUSPAL AREA OR
INCISAL REGION.INCISAL REGION.
Gnarled Enamel

21. GNARLED ENAMELGNARLED ENAMEL

22. SIGNIFICANCESIGNIFICANCE
 NOT SUBJECTED TONOT SUBJECTED TO
CLEAVAGE AS ISCLEAVAGE AS IS
REGULAR ENAMELREGULAR ENAMEL
 DOES NOT YIELDDOES NOT YIELD
READILY TO THE PRESSUREREADILY TO THE PRESSURE
OF BLADED, HANDOF BLADED, HAND
CUTTING INSTRUMENTS INCUTTING INSTRUMENTS IN
TOOTH PREPARATION.TOOTH PREPARATION.

23. DENTINO-ENAMEL JUNCTIONDENTINO-ENAMEL JUNCTION
• ALSO CALLED AS AMELO-DENTINAL JUNCTION.ALSO CALLED AS AMELO-DENTINAL JUNCTION.
•
DEJ is Scalloped in cross section with
convexities directed towards Dentin

24. SIGNIFICANCESIGNIFICANCE
 Scalloping is a functional adaptation to increase
the surface area for enamel
 Lateral spread of dental caries.
 Stress distribution and resist enamel crack
propagation.

25. IN SOMEIN SOME
PATHOLOGICALPATHOLOGICAL
CONDITIONS LIKE -CONDITIONS LIKE -
*DENTINOGENESIS*DENTINOGENESIS
IMPERFECTAIMPERFECTA
* EHLER- DANLOS* EHLER- DANLOS
SYNDROMESYNDROME
DEJ BECOMES FLATDEJ BECOMES FLAT
AND SO ENAMELAND SO ENAMEL
GETS EASILYGETS EASILY
CHIPPED OFF.CHIPPED OFF.

26. ENAMEL TUFTSENAMEL TUFTS
• ARISE AT THE DEJ & REACH INTOARISE AT THE DEJ & REACH INTO
ENAMEL TO ABOUT 1/5 TO 1/3 OFENAMEL TO ABOUT 1/5 TO 1/3 OF
ITS THICKNESSITS THICKNESS
• CONSISTS OF HYPOCALCIFIEDCONSISTS OF HYPOCALCIFIED
RODS & INTERPRISMATICRODS & INTERPRISMATIC
SUBSTANCESUBSTANCE
• CONSISTS OF HIGHEST ENAMELCONSISTS OF HIGHEST ENAMEL
PROTEIN CONCENTRATIONPROTEIN CONCENTRATIONEnamel Tufts
Enamel Spindle

27. • ACCORDING TOACCORDING TO
TENCATES, THESETENCATES, THESE
DEVELOP BECAUSEDEVELOP BECAUSE
OF ABRUPTOF ABRUPT
CHANGES IN THECHANGES IN THE
DIRECTION OFDIRECTION OF
GROUP OF RODSGROUP OF RODS
THAT ARISE FROMTHAT ARISE FROM
DEJ.DEJ.
• BEST VISUALISED INBEST VISUALISED IN
TRANSVERSETRANSVERSE
SECTIONSECTION

28. ENAMEL LAMELLAEENAMEL LAMELLAE
 THIN LEAF LIKE HYPO-THIN LEAF LIKE HYPO-
CALCIFIEDCALCIFIED
STRUCTURES.STRUCTURES.
 EXTEND FROM OUTEREXTEND FROM OUTER
ENAMEL – DEJ.ENAMEL – DEJ.
 FORMED DUE TOFORMED DUE TO
STRESS AND STRAINSSTRESS AND STRAINS
CREATED DURINGCREATED DURING
ENAMEL MATURATION ,ENAMEL MATURATION ,
ALSO CALLED ASALSO CALLED AS
GEOLOGICAL FAULTS.GEOLOGICAL FAULTS.

29.  BASED ON CONTENTS OFBASED ON CONTENTS OF
LAMELLAE THEY ARELAMELLAE THEY ARE
DIVIDEDDIVIDED
TYPE A – ONLY ENAMEL--TYPE A – ONLY ENAMEL--
POORLY CALCIFIED RODPOORLY CALCIFIED ROD
SEGMENTSEGMENT
TYPE B –MAY REACHTYPE B –MAY REACH
DENTIN-- DEGENERATEDDENTIN-- DEGENERATED
CELLSCELLS
TYPE C –MAY REACHTYPE C –MAY REACH
DENTIN-- ORGANICDENTIN-- ORGANIC
MATTER FROM SALIVAMATTER FROM SALIVA

30. • BEST VISUALISED INBEST VISUALISED IN TRANSVERSETRANSVERSE
SECTIONSECTION
• LAMELLAE – C.T. - CEMENTUMLAMELLAE – C.T. - CEMENTUM
FORMATION.FORMATION.
- ENAMEL ORGAN- ENAMEL ORGAN
CELLS- HORNIFIED CUTICLECELLS- HORNIFIED CUTICLE
• LAMELLAE ARE SITE OF WEAKNESSLAMELLAE ARE SITE OF WEAKNESS
FOR CARIES INITIATION.FOR CARIES INITIATION.

31. ENAMEL SPINDLESENAMEL SPINDLES
• IS THE THICKENEDIS THE THICKENED
ODONTOBLAST PROCESSODONTOBLAST PROCESS
PASSING ACROSS THE DEJPASSING ACROSS THE DEJ
TO ENAMEL.TO ENAMEL.
• APPEARS DARK INAPPEARS DARK IN
TRANSMITTED LIGHT WHENTRANSMITTED LIGHT WHEN
SEEN IN GROUNDSEEN IN GROUND
SECTIONS.SECTIONS.
Commonly seen in
region of cusp where
most crowding of
odontoblasts occur

32. • BEST SEEN INBEST SEEN IN LONGITUDINALLONGITUDINAL
SECTIONSECTION
SIGNIFICANCESIGNIFICANCE
- SUDDEN SENSITIVITY- SUDDEN SENSITIVITY
EXPERIENCED DURINGEXPERIENCED DURING
CAVITY CUTTING AS THE BURCAVITY CUTTING AS THE BUR
REACHES THE DEJ.REACHES THE DEJ.

33. SURFACE STRUCTURES OF ENAMELSURFACE STRUCTURES OF ENAMEL
• STRUCTURELESS LAYER OF ENAMELSTRUCTURELESS LAYER OF ENAMEL
• CRACKSCRACKS
• ROD ENDSROD ENDS
• PERIKYMATA AND IMBRICATION LINESPERIKYMATA AND IMBRICATION LINES
OF PICKERAL.OF PICKERAL.

34. RODLESS ENAMELRODLESS ENAMEL
• RELATIVELY 30 UM THICK.RELATIVELY 30 UM THICK.
• NO PRISM OUTLINES SEEN,NO PRISM OUTLINES SEEN,
SO PRISMLESS ENAMEL.SO PRISMLESS ENAMEL.
• SEEN IN 70% PERMANENT,SEEN IN 70% PERMANENT,
AND IN ALL DECIDUOUS TEETH.AND IN ALL DECIDUOUS TEETH.
• COMMON IN CERVICALCOMMON IN CERVICAL
AREAS, LEAST AT CUSP TIPSAREAS, LEAST AT CUSP TIPS

35. CRACKSCRACKS ::
• NARROW FISSURE LIKENARROW FISSURE LIKE
STRUCTURES SEEN ONSTRUCTURES SEEN ON
ALMOST ALL SURFACESALMOST ALL SURFACES
• OUTER EDGES OF ENAMELOUTER EDGES OF ENAMEL
LAMELLAELAMELLAE
• DISAPPEARS ONDISAPPEARS ON
DECALCIFICATION.DECALCIFICATION.
• ORIGINATE AT RIGHTORIGINATE AT RIGHT
ANGLES FROM THE DEJANGLES FROM THE DEJ

36. PERIKYMATAPERIKYMATA
 WAVE-LIKE TRANSVERSEWAVE-LIKE TRANSVERSE
STRUCTURESSTRUCTURES
 PARALLEL TO EACH OTHERPARALLEL TO EACH OTHER
AND TO CEJAND TO CEJ
 30 PER MM NEAR CEJ30 PER MM NEAR CEJ
10 PER MM IN10 PER MM IN
CUSPAL/INCISAL AREA.CUSPAL/INCISAL AREA.
 ABSENT IN OCCLUSAL PARTABSENT IN OCCLUSAL PART
OF PRIMARY TEETH ANDOF PRIMARY TEETH AND
PRESENT IN POSTNATALPRESENT IN POSTNATAL
CERVICAL AREASCERVICAL AREAS

37. • BELIEVED TO BE THE EXTERNAL MANIFESTATIONS OF STRIAE OF RETZIUSBELIEVED TO BE THE EXTERNAL MANIFESTATIONS OF STRIAE OF RETZIUS

38. ENAMEL ROD ENDSENAMEL ROD ENDS
• CIRCULAR DEPRESSIONSCIRCULAR DEPRESSIONS
• SHALLOWEST – CERVICAL REGIONSSHALLOWEST – CERVICAL REGIONS
DEEPEST – INCISAL OR OCCLUSAL SURFACESDEEPEST – INCISAL OR OCCLUSAL SURFACES
SIGNIFICANCESIGNIFICANCE
 CONTRIBUTE TO ADHERENCE OF PLAQUE MATERIALCONTRIBUTE TO ADHERENCE OF PLAQUE MATERIAL
WITH A RESULTANT CARIES ATTACKWITH A RESULTANT CARIES ATTACK

39. DEVELOPMENT OF ENAMELDEVELOPMENT OF ENAMEL
• EPITHELIAL ENAMEL ORGANEPITHELIAL ENAMEL ORGAN
• LIFE CYCLE OF AMELOBLASTSLIFE CYCLE OF AMELOBLASTS
• AMELOGENESISAMELOGENESIS

40. ENAMEL ORGANENAMEL ORGAN
1.OUTER ENAMEL EPI(OEE)1.OUTER ENAMEL EPI(OEE)
2.STELLATE RETICULUM2.STELLATE RETICULUM
3.STRATUM INTERMEDIUM3.STRATUM INTERMEDIUM
4.INNER ENAMEL EPI(IEE)4.INNER ENAMEL EPI(IEE)

42. AMELOGENESISAMELOGENESIS
• ENAMEL FORMATION.ENAMEL FORMATION.
• IT IS SLOW DEVELOPMENTALIT IS SLOW DEVELOPMENTAL
PROCESSPROCESS
• CAN TAKE AS LONG AS 5 YRSCAN TAKE AS LONG AS 5 YRS
Ref:Ten Cate:Oral histology development ,structure&function

43. TWO STEP PROCESSTWO STEP PROCESS
•ORGANIC MATRIX FORMATIONORGANIC MATRIX FORMATION
•MINERALIZATIONMINERALIZATION
: PRODUCES PARTIALLY MINERALIZED: PRODUCES PARTIALLY MINERALIZED
ENAMEL(30%)ENAMEL(30%)
: INFLUX OF ADDITIONAL MINERAL: INFLUX OF ADDITIONAL MINERAL
COINCIDENT WITH REMOVAL OF ORGANICCOINCIDENT WITH REMOVAL OF ORGANIC
MATERIAL AND WATERMATERIAL AND WATER

44. component Secretory
stage
mid
maturation
Late
maturation
Water 5 3 1
Mineral 29 93 95
Protein 66 4 4
Ref:Ten Cate:Oral histology development ,structure&function

45. STAGES OF AMELOGENESISSTAGES OF AMELOGENESIS
• PRE SECRETORY STAGEPRE SECRETORY STAGE
• SECRETORY STAGESECRETORY STAGE
• MATURATION STAGEMATURATION STAGE
STAGES OF AMELOBLASTSSTAGES OF AMELOBLASTS
• MORPHOGENETIC STAGEMORPHOGENETIC STAGE
• DIFFERENTIATING /ORGANIZINGDIFFERENTIATING /ORGANIZING
• FORMATIVEFORMATIVE
• MATURATIVEMATURATIVE
• PROTECTIVEPROTECTIVE
• DESMOLYTICDESMOLYTIC
Ref:Ten Cate:Oral histology development ,structure&function

46. PRE SECRETORY STAGEPRE SECRETORY STAGE
• DIFFERENTIATING AMELOBLASTSDIFFERENTIATING AMELOBLASTS
ACQUIRE THEIR PHENO TYPEACQUIRE THEIR PHENO TYPE
• CHANGE POLARITYCHANGE POLARITY
• DEVELOP AN EXTENSIVE PROTEINDEVELOP AN EXTENSIVE PROTEIN
SYNTHETIC APPARATUSSYNTHETIC APPARATUS
• PREPARE TO SECRETE THE ORGANICPREPARE TO SECRETE THE ORGANIC
MATRIX OF ENAMELMATRIX OF ENAMEL
Ref:Ten Cate:Oral histology development ,structure&function

47. SECRETORY STAGESECRETORY STAGE
• AMELOBLASTS ELABORATE AND ORGANIZEAMELOBLASTS ELABORATE AND ORGANIZE
ENTIRE ENAMEL THICKNESSENTIRE ENAMEL THICKNESS
•
Ref:Ten Cate:Oral histology development ,structure&function
As initial layer is formed , ameloblasts migrate away
from dentin surface and develop Tomes process.

48. DEVELOPMENT OF TOMES PROCESSDEVELOPMENT OF TOMES PROCESS
• THE SURFACES OF AMELOBLAST FACING THETHE SURFACES OF AMELOBLAST FACING THE
DEVELOPING ENAMEL IS NOT SMOOTH. THERE ISDEVELOPING ENAMEL IS NOT SMOOTH. THERE IS
AN INTERDIGITATION OF CELLS &THE ENAMELAN INTERDIGITATION OF CELLS &THE ENAMEL
RODS THAT THEY PRODUCE.RODS THAT THEY PRODUCE.
• PROJECTION OF AMELOBLAST INTO MATRIX ISPROJECTION OF AMELOBLAST INTO MATRIX IS
CALLED AS TOMES PROCESS CONTAININGCALLED AS TOMES PROCESS CONTAINING
ABUNDANT R.E.R. & MITOCHONDRIA.ABUNDANT R.E.R. & MITOCHONDRIA.

50. -- THE BULK OF EACH ROD ISTHE BULK OF EACH ROD IS
FORMED BY ONEFORMED BY ONE
AMELOBLAST. WHERE AS 3AMELOBLAST. WHERE AS 3
OTHERS CONTRIBUTE TO THEOTHERS CONTRIBUTE TO THE
TAIL OF EACH ROD.TAIL OF EACH ROD.
- EACH ROD IS FORMED BY- EACH ROD IS FORMED BY
4 AMELOBLASTS AND EACH4 AMELOBLASTS AND EACH
AMELOBLASTS CONTRIBUTESAMELOBLASTS CONTRIBUTES
TO 4 DIFFERENT RODS.TO 4 DIFFERENT RODS.

51. DISTAL TERMINAL BARSDISTAL TERMINAL BARS
• DURING FORMATION OF TOMES PROCESSDURING FORMATION OF TOMES PROCESS
TERMINAL BARS APPEAR AT DISTAL ENDTERMINAL BARS APPEAR AT DISTAL END
WHICH SEPARATE TOMES PROCESS FROMWHICH SEPARATE TOMES PROCESS FROM
REST OF CELLSREST OF CELLS
• STRUCTURALLY, LOCALISED CONDENSATIONSTRUCTURALLY, LOCALISED CONDENSATION
OF CYTOPLASMIC SUBSTANCE CLOSELYOF CYTOPLASMIC SUBSTANCE CLOSELY
ASSOCIATED WITH THICKENED CELLASSOCIATED WITH THICKENED CELL
MEMBRANEMEMBRANE

52. MATURATION STAGEMATURATION STAGE
• AMELOBLASTS MODULATE AND TRANSPORTAMELOBLASTS MODULATE AND TRANSPORT
SPECIFIC IONS REQUIRED FOR CONCURRENTSPECIFIC IONS REQUIRED FOR CONCURRENT
ACCRETION OF MINERAL.ACCRETION OF MINERAL.

53.  * EACH ROD MATURES FROM DEPTH TO SURFACE AND SEQUENCE OF* EACH ROD MATURES FROM DEPTH TO SURFACE AND SEQUENCE OF
MATURING RODS IS FROM CUSPS OR INCISAL EDGES TOWARDS CERVICALMATURING RODS IS FROM CUSPS OR INCISAL EDGES TOWARDS CERVICAL
LINE.LINE.

54. LIFE CYCLE OF AMELOBLASTS:LIFE CYCLE OF AMELOBLASTS:
DIFFERENTIATION OF AMELOBLASTS IS MOST ADVANCEDDIFFERENTIATION OF AMELOBLASTS IS MOST ADVANCED
IN INCISAL EDGES OR TIPS OF CUSPS AND LEAST ININ INCISAL EDGES OR TIPS OF CUSPS AND LEAST IN
CERVICAL LOOP.CERVICAL LOOP.
LIFE CYCLE IS DIVIDED IN TO 6 STAGESLIFE CYCLE IS DIVIDED IN TO 6 STAGES
1. MORPHOGENIC STAGE1. MORPHOGENIC STAGE
2. ORGANIZING STAGE2. ORGANIZING STAGE
3. FORMATIVE STAGE3. FORMATIVE STAGE
4. MATURATIVE STAGE4. MATURATIVE STAGE
5. PROTECTIVE STAGE5. PROTECTIVE STAGE
6. DESMOLYTIC STAGE.6. DESMOLYTIC STAGE.

56. 1.1. MORPHOGENIC STAGE :MORPHOGENIC STAGE :
• HERE CELLS ARE SHORT AND COLUMNARHERE CELLS ARE SHORT AND COLUMNAR
WITH LARGE OVAL NUCLEI WHICH FILLSWITH LARGE OVAL NUCLEI WHICH FILLS
ENTIRE CELL BODY.ENTIRE CELL BODY.
• MITOCHONDRIA ARE EVENLY DISTRUBUTEDMITOCHONDRIA ARE EVENLY DISTRUBUTED
IN ENTIRE CYTOPLASM.IN ENTIRE CYTOPLASM.
• GOLGI APPARATUS AND CENTRIOLES AREGOLGI APPARATUS AND CENTRIOLES ARE
LOCATED IN THE PROXIMAL ENDS OF THELOCATED IN THE PROXIMAL ENDS OF THE
CELLS.CELLS.

57. 22. ORGANISING STAGE:. ORGANISING STAGE:
THE INNER ENAMEL EPITHELIUM INTERACTSTHE INNER ENAMEL EPITHELIUM INTERACTS
WITH ADJ C/T CELLS, WHICH DIFFERENTIATESWITH ADJ C/T CELLS, WHICH DIFFERENTIATES
INTO ODONTOBLASTS.INTO ODONTOBLASTS.
• AA REVERSAL OF FUNCTIONAL POLARITYREVERSAL OF FUNCTIONAL POLARITY OFOF
CELLS TAKES PLACE AS THERE IS MIGRATIONCELLS TAKES PLACE AS THERE IS MIGRATION
OF GOLGI APPARATUS AND CENTRIOLES -OF GOLGI APPARATUS AND CENTRIOLES -
PROXIMAL ENDS TO DISTAL ENDS, ANDPROXIMAL ENDS TO DISTAL ENDS, AND
MITOCHONDRIA MIGRATES TOWARDS THEMITOCHONDRIA MIGRATES TOWARDS THE
PROXIMAL PART OF THE CELLS.PROXIMAL PART OF THE CELLS.

58. • DURING TERMINAL PHASE OF THEDURING TERMINAL PHASE OF THE
ORGANIZING STAGE,ORGANIZING STAGE, THE FORMATION OFTHE FORMATION OF
DENTINDENTIN BEGINS.BEGINS.
• WHEN DENTIN FORMS IT CUTS OFFWHEN DENTIN FORMS IT CUTS OFF
AMELOBLASTS FROM THEIR ORIGINAL SOURCEAMELOBLASTS FROM THEIR ORIGINAL SOURCE
OF NOURISHMENT, AND FROM HERE THEY AREOF NOURISHMENT, AND FROM HERE THEY ARE
SUPPLIED BY CAPILLARIES THAT SURROUNDSUPPLIED BY CAPILLARIES THAT SURROUND
THEM THEREBYTHEM THEREBY REVERSAL OF NUTRITIONREVERSAL OF NUTRITION..

59. 3.3. FORMATIVE STAGEFORMATIVE STAGE::
-- AFTER THE 1AFTER THE 1STST
LAYER OF DENTIN IS FORMEDLAYER OF DENTIN IS FORMED
AMELOBLASTS ENTER INTO FORMATIVE STAGE.AMELOBLASTS ENTER INTO FORMATIVE STAGE.
- DURING THE FORMATION OF ENAMEL MATRIX THE- DURING THE FORMATION OF ENAMEL MATRIX THE
AMELOBLASTS RETAIN THE SAME LENGTH ANDAMELOBLASTS RETAIN THE SAME LENGTH AND
ARRANGEMENT.ARRANGEMENT.
- INITIATION OF SECRETION OF ENAMEL MATRIX- INITIATION OF SECRETION OF ENAMEL MATRIX..
- AMELOBLASTS DEVELOPS BLUNT CELL PROCESSES ON- AMELOBLASTS DEVELOPS BLUNT CELL PROCESSES ON
THEIR SURFACES CALLED ASTHEIR SURFACES CALLED AS TOMES PROCESSTOMES PROCESS..

61. 44.. MATURATIVE STAGE:MATURATIVE STAGE:
OCCURS AFTER MOST OF THE THICKNESSOCCURS AFTER MOST OF THE THICKNESS
OF ENAMEL MATRIX HAS BEEN FORMED INOF ENAMEL MATRIX HAS BEEN FORMED IN
THE OCCLUSAL OR INCISAL AREAS BUT INTHE OCCLUSAL OR INCISAL AREAS BUT IN
CERVICAL AREAS IT IS STILL IN PROGRESS.CERVICAL AREAS IT IS STILL IN PROGRESS.
- HERE AMELOBLASTS ARE SLIGHTLY- HERE AMELOBLASTS ARE SLIGHTLY
REDUCED IN LENGTH AND ARE CLOSELYREDUCED IN LENGTH AND ARE CLOSELY
ATTACHED TO ENAMEL MATRIX.ATTACHED TO ENAMEL MATRIX.
- AND AMELOBLASTS- AND AMELOBLASTS DISPLAY RUFFLEDDISPLAY RUFFLED
BORDER AND SMOOTH BORDERBORDER AND SMOOTH BORDER
ALTERNATIVELYALTERNATIVELY DISPLAYING THE RESORPTIVEDISPLAYING THE RESORPTIVE
AND SECRETOSY PHASES.AND SECRETOSY PHASES.

62. 55.. PROTECTIVE STAGEPROTECTIVE STAGE::
- WHEN ENAMEL GETS COMPLETELY DEVELOPED AND- WHEN ENAMEL GETS COMPLETELY DEVELOPED AND
HAS FULLY CALCIFIED AMELOBLASTS – S I AND OEE -HAS FULLY CALCIFIED AMELOBLASTS – S I AND OEE -
FORMSFORMS REDUCED ENAMEL EPITHELIUMREDUCED ENAMEL EPITHELIUM WHICHWHICH
PROTECTS THE MATURED ENAMEL.PROTECTS THE MATURED ENAMEL.
6.6. DESMOLYTIC STAGE:DESMOLYTIC STAGE:
- HERE EPITHELIAL CELLS- HERE EPITHELIAL CELLS ELABORATE ENZYMESELABORATE ENZYMES THATTHAT
ARE ABLE TO DESTROY C/T FIBRES BY DESMOLYSIS.ARE ABLE TO DESTROY C/T FIBRES BY DESMOLYSIS.
- PREMATURE DESTRUCTION OF REDUCED ENAMEL- PREMATURE DESTRUCTION OF REDUCED ENAMEL
EPITHELIUM MAY PREVENT ERUPTION OF TEETH.EPITHELIUM MAY PREVENT ERUPTION OF TEETH.

63. DEFECTS OF AMELOGENESIS
Amelogenesis Imperfecta
Hypoplasia due to environmental factors

64. AMELOGENESIS IMPERFECTAAMELOGENESIS IMPERFECTA
 HEREDITARY DEFECTS OFHEREDITARY DEFECTS OF
ENAMELENAMEL
 ECTODERMALECTODERMAL
DISTURBANCE-DEFECT INDISTURBANCE-DEFECT IN
CODING GENE FORCODING GENE FOR
AMELOGENIN.AMELOGENIN.
 THERE ARE DIFF TYPES OFTHERE ARE DIFF TYPES OF
AI LIKE;AI LIKE;
1.HYPOPLASTIC1.HYPOPLASTIC
2.HYPOCALCIFIED2.HYPOCALCIFIED
3.HYPOMATURATIVE3.HYPOMATURATIVE

65. HYPOPLASTICHYPOPLASTIC
• INCOMPLETE/DEFECTIVEINCOMPLETE/DEFECTIVE
FORMATION OFFORMATION OF
ORGANIC MATRIXORGANIC MATRIX
• INJURY DURINGINJURY DURING
FORMATIVE STAGE OFFORMATIVE STAGE OF
ENAMEL DEVELOPMENT.ENAMEL DEVELOPMENT.
• ABNORMAL THICKNESSABNORMAL THICKNESS
OR SHAPEOR SHAPE
• NORMAL HARDNESS ANDNORMAL HARDNESS AND
COLOR.COLOR.

66. HYPOCALCIFIEDHYPOCALCIFIED
• DISTURBANCE INDISTURBANCE IN
EARLYEARLY
MINERALIZATION OFMINERALIZATION OF
ENAMEL.ENAMEL.
• IT APPEARS NORMALIT APPEARS NORMAL
IN THICKNESS.IN THICKNESS.
• SOFT AND CAN BESOFT AND CAN BE
REMOVED EASILYREMOVED EASILY
WITH BLUNTWITH BLUNT
INSTRUMENT.INSTRUMENT.

67. HYPOMATURATIONHYPOMATURATION
 INTERRUPTION IN LATE MATURATIONINTERRUPTION IN LATE MATURATION
STAGE.STAGE.
 LESS HARD, TRANSLUCENT BUT NOT SOFTLESS HARD, TRANSLUCENT BUT NOT SOFT
 NORMAL IN THICKNESSNORMAL IN THICKNESS
 CAN BE PIERCED BY LITTLE FIRMCAN BE PIERCED BY LITTLE FIRM
PRESSURE.PRESSURE.

68. ENVIRONMENTAL ENAMEL HYPOPLASIAENVIRONMENTAL ENAMEL HYPOPLASIA

69. CAUSESCAUSES
• NUTRITIONALNUTRITIONAL
DEFICIENCYDEFICIENCY
• EXANTHEMATOUSEXANTHEMATOUS
FEVERFEVER
• SYSTEMICSYSTEMIC
CONDITIONSCONDITIONS
• CONGENITALCONGENITAL
CONDITIONSCONDITIONS
• BIRTH INJURIESBIRTH INJURIES
• CHEMICALSCHEMICALS
• IDIOPATHICIDIOPATHIC

70. ENAMEL HYPOPLASIA OF RENAL RICKETSENAMEL HYPOPLASIA OF RENAL RICKETS

71. MOTTLED ENAMELMOTTLED ENAMEL

72. CONGENITAL SYPHILISCONGENITAL SYPHILIS

73. TURNERS TOOTHTURNERS TOOTH

74. LINEAR ENAMEL HYPOPLASIA : THE HORIZONTALLINEAR ENAMEL HYPOPLASIA : THE HORIZONTAL
GROOVES AND PITS ACROSS THE LABIALGROOVES AND PITS ACROSS THE LABIAL
ENAMEL CORRESPONDS TO CESSATION OFENAMEL CORRESPONDS TO CESSATION OF
ENAMEL FORMATION AT ABOUT THE AGE OF 10ENAMEL FORMATION AT ABOUT THE AGE OF 10
MONTHS AS A RESULT OF TEMPORARY METABOLICMONTHS AS A RESULT OF TEMPORARY METABOLIC
DISTURBANCEDISTURBANCE

75. HYPOCALCIFICATION AND INCIPIENT CARIESHYPOCALCIFICATION AND INCIPIENT CARIES
• USUALLY INCIPIENT CARIES IS CONFUSED WITHUSUALLY INCIPIENT CARIES IS CONFUSED WITH
HYPOCALCIFICATION.HYPOCALCIFICATION.
• INCIPIENT CARIES OCCURS WITH INTACTINCIPIENT CARIES OCCURS WITH INTACT
ENAMEL SURFACE ,WITH ENAMEL DESTRUCTIONENAMEL SURFACE ,WITH ENAMEL DESTRUCTION
UNDERNEATH .UNDERNEATH .
• IT LOOKS AS WHITE CHALKY SPOT JUST LIKEIT LOOKS AS WHITE CHALKY SPOT JUST LIKE
LOCALIZED HYPOCALCIFICATION.LOCALIZED HYPOCALCIFICATION.
• IF THE LESION APPEARS IN DRIED TOOTH ANDIF THE LESION APPEARS IN DRIED TOOTH AND
DISAPPEARS IN WET TOOTH- INCIPIENT CARIESDISAPPEARS IN WET TOOTH- INCIPIENT CARIES
• WHEREAS HYPOCALCIFIED SEEN EVEN IN WETWHEREAS HYPOCALCIFIED SEEN EVEN IN WET
TOOTH.TOOTH.

76. ECTOPIC ENAMEL/ ENAMEL PEARLECTOPIC ENAMEL/ ENAMEL PEARL
• PRESENCE OF ENAMEL IN UNUSUAL LOCATIONPRESENCE OF ENAMEL IN UNUSUAL LOCATION
MAINLY ROOTMAINLY ROOT
• MAY CONSIST ENTIRELY OF ENAMEL OR MAYMAY CONSIST ENTIRELY OF ENAMEL OR MAY
CONTAIN UNDERLYING DENTIN & PULP TISSUE.CONTAIN UNDERLYING DENTIN & PULP TISSUE.
• SIGNIFICANCESIGNIFICANCE
PREDISPOSE TO PLAQUE ACCRETION FOLLOWINGPREDISPOSE TO PLAQUE ACCRETION FOLLOWING
GINGIVAL RECESSIONGINGIVAL RECESSION

77. CERVICAL ENAMEL PROJECTIONSCERVICAL ENAMEL PROJECTIONS
 LOCATED ON THE BUCCALLOCATED ON THE BUCCAL
SURFACE OF THE ROOTSURFACE OF THE ROOT
OVERLYING THE BIFURCATIONOVERLYING THE BIFURCATION
 USUALLY PRESENT ON MOLARSUSUALLY PRESENT ON MOLARS
, LEADING FURCATION, LEADING FURCATION
INVOLVEMENT.INVOLVEMENT.

78. AGE CHANGES IN ENAMELAGE CHANGES IN ENAMEL
• ATTRITIONATTRITION
• DISCOLORATIONDISCOLORATION
• PERMEABLILITYPERMEABLILITY
• MODIFICATION OF SURFACE LAYERMODIFICATION OF SURFACE LAYER

79. ATTRITION:ATTRITION:
• WEAR FACETS INCREASINGLY PRONOUNCED IN OLDERWEAR FACETS INCREASINGLY PRONOUNCED IN OLDER
PEOPLE.PEOPLE.
• EVIDENCED BY LOSS OF VERTICAL DIMENSION OF THEEVIDENCED BY LOSS OF VERTICAL DIMENSION OF THE
CROWN AND BY FLATTENING OF PROXIMAL CONTOUR.CROWN AND BY FLATTENING OF PROXIMAL CONTOUR.

80. DISCOLORATIONDISCOLORATION
• TEETH DARKEN WITH AGETEETH DARKEN WITH AGE
• WHY….?WHY….?
• ADDITION OF ORGANIC MATERIAL OR DEEPENING OFADDITION OF ORGANIC MATERIAL OR DEEPENING OF
DENTINE COLORDENTINE COLOR

81. PERMEABILITYPERMEABILITY
• BECOMES LESS PERMEABLEBECOMES LESS PERMEABLE
• WITH AGE THE PORES DIMINISH AS THE CRYSTALWITH AGE THE PORES DIMINISH AS THE CRYSTAL
ACQUIRE MORE IONS.ACQUIRE MORE IONS.

82. MODIFICATION IN SURFACE LAYERMODIFICATION IN SURFACE LAYER::
• SURFACE OF UNERUPTED AND RECENTLYSURFACE OF UNERUPTED AND RECENTLY
ERUPTED TEETH COVERED WITH PRONOUNCEDERUPTED TEETH COVERED WITH PRONOUNCED
ROD ENDS AND PERIKYMATA.ROD ENDS AND PERIKYMATA.
• GENERALIZED LOSS OF ROD ENDS, SLOWERGENERALIZED LOSS OF ROD ENDS, SLOWER
FLATTENING OF PERIKYMATA LATERFLATTENING OF PERIKYMATA LATER
DISAPPEAR COMPLETELYDISAPPEAR COMPLETELY

83. CLINICAL CONSIDERATIONSCLINICAL CONSIDERATIONS
•DENTAL CARIESDENTAL CARIES
•FLUORIDATIONFLUORIDATION
•ACID ETCHING TECHNIQUESACID ETCHING TECHNIQUES
•BLEACHINGBLEACHING

84. ENAMEL CARIESENAMEL CARIES
• DESTRUCTION OF THE ENAMEL SURFACE WITHDESTRUCTION OF THE ENAMEL SURFACE WITH
ACID LEAD TO THE DISSOLUTION OF THEACID LEAD TO THE DISSOLUTION OF THE
ENAMEL MATRIX, FOLLOWING IS THE CARIOUSENAMEL MATRIX, FOLLOWING IS THE CARIOUS
ATTACK.ATTACK.
• CARIES PREFERENTIALLY ATTACK CORES OFCARIES PREFERENTIALLY ATTACK CORES OF
RODS AND MORE PERMEABLE STRIAE OFRODS AND MORE PERMEABLE STRIAE OF
RETZIUS , WHICH PROMOTE LATERAL SPREADINGRETZIUS , WHICH PROMOTE LATERAL SPREADING
AND UNDERMINING ADJACENT ENAMEL.AND UNDERMINING ADJACENT ENAMEL.

85. FLUORIDATIONFLUORIDATION
• INCORPORATION OF FL IONS MAKES HYDROXYAPATITEINCORPORATION OF FL IONS MAKES HYDROXYAPATITE
CRYSTALS MORE RESISTANT TO ACID DISSOLUTIONCRYSTALS MORE RESISTANT TO ACID DISSOLUTION
• DECREASING RATE OF DEMINERALIZATION ANDDECREASING RATE OF DEMINERALIZATION AND
INCREASING RATE OF REMINERALIZATION.INCREASING RATE OF REMINERALIZATION.

86. ACID ETCHINGACID ETCHING
• REMOVES PLAQUE , DEBRIS & THIN LAYER OFREMOVES PLAQUE , DEBRIS & THIN LAYER OF
ENAMELENAMEL
• BY DISSOLVING MINERALS IN ENAMEL,BY DISSOLVING MINERALS IN ENAMEL,
ETCHANTS REMOVE THE OUTER 10 MICROMETERSETCHANTS REMOVE THE OUTER 10 MICROMETERS
ON THE ENAMEL SURFACE AND MAKES A POROUSON THE ENAMEL SURFACE AND MAKES A POROUS
LAYER 5–50 MICROMETERS DEEPLAYER 5–50 MICROMETERS DEEP
• IT INCREASES POROSITY THROUGH DISSOLUTIONIT INCREASES POROSITY THROUGH DISSOLUTION
OF CRYSTALSOF CRYSTALS

87. TYPES OF ETCHING PATTERN-TYPES OF ETCHING PATTERN-SILVERSTONE,1975SILVERSTONE,1975
• TYPE-1 PREFERENTIALTYPE-1 PREFERENTIAL
REMOVAL OF RODREMOVAL OF ROD
CORES.CORES.
• TYPE-2 PERIPHERYTYPE-2 PERIPHERY
OF RODS REMOVEDOF RODS REMOVED
• TYPE-3 IRREGULAR,TYPE-3 IRREGULAR,
INDISCRIMINATEINDISCRIMINATE
REMOVAL.REMOVAL.

88. BLEACHINGBLEACHING
• LIGHTENING OF COLOR OF A TOOTH THROUGHLIGHTENING OF COLOR OF A TOOTH THROUGH
THE APPLICATION OF A CHEMICAL AGENT TOTHE APPLICATION OF A CHEMICAL AGENT TO
OXIDIZE THE ORGANIC PIGMENTATION IN THEOXIDIZE THE ORGANIC PIGMENTATION IN THE
TOOTH.TOOTH.
• TRANSITORY DECREASE IN THE POTENTIAL BONDTRANSITORY DECREASE IN THE POTENTIAL BOND
STRENGTH OF COMPOSITE WHEN APPLIED TOSTRENGTH OF COMPOSITE WHEN APPLIED TO
BLEACHED SURFACEBLEACHED SURFACE
• NO LOSS IF COMPOSITE IS APPLIED 1 WEEK AFTERNO LOSS IF COMPOSITE IS APPLIED 1 WEEK AFTER
THE CESSATION OF THE THERAPYTHE CESSATION OF THE THERAPY

89. REFERENCESREFERENCES
• ORBAN’S ORAL HISTOLOGY & EMBRYOLOGYORBAN’S ORAL HISTOLOGY & EMBRYOLOGY
• TENCATE’S ORAL HISTOLOGYTENCATE’S ORAL HISTOLOGY
• SHAFER’S ORAL PATHOLOGYSHAFER’S ORAL PATHOLOGY
• BERKOVIT’S ORAL HISTOLOGYBERKOVIT’S ORAL HISTOLOGY

90. THANK YOU