A BRIEF DESCRIPTION TO THE PROCESS OF ENAMEL FORMATION.

1. AMELOGENESIS
PROCESS BY WHICH ENAMEL
IS LAID DOWN BY
AMELOBALSTS
DR.VIGNESH R, BDS

2. AMELOGENESIS
➢ CONSISTS MAINLY OF 3 STEPS:
➢ FORMATION OF ENAMEL MATRIX
➢ MINERALIZATION OF THE FORMED
MATRIX
➢ MATURATION OF MINERALIZED
MATRIX.
➢ BEGINS BY THE LATE BELL STAGE
OF TOOTH FORMATION.

6. AMELOGENESIS
□ REQUIRES A SMALL AMOUNT OF
DENTIN TO BE LAID DOWN FIRST
□ THIS PREDENTIN LAYER INDUCES
AMELOBLASTS TO SECRETE THE
FIRST LAYER OF ENAMEL
□ EACH ROD IS FORMED FROM 4
AMELOBLAST CELLS

10. AMELOGENESIS
□ At the late bell stage, the inner
enamel epithelium has already
differentiated into ameloblasts
□ When the first layer of dentin is
secreted by odontoblasts, the
ameloblasts secrete the first layer
of enamel

11. AMELOGENESIS
□ THIS INITIAL LAYER OF ENAMEL DOES
NOT CONTAIN RODS (PRISMS).
CALLED RODLESS / APRISMATIC ENAMEL
□ AS EACH INCREMENT OF ENAMEL IS
FORMED, THE AMELOBLASTS MOVE
AWAY FROM THE DENTIN SURFACE.
□ THIS IS TO ACCOMMODATE
SUBSEQUENT INCREMENTS OF ENAMEL.

13. AMELOGENESIS
□ THE SURFACE OF THE AMELOBLASTS
FACING THE DENTIN IS NOT SMOOTH
□ CERTAIN FINGER LIKE THIN
EXTENSIONS APPEAR ON THIS BORDER
OF THE CELLS
□ TOME’S PROCESSES / FIBERS
□ INTERDIGITATE WITH THE ENAMEL
RODS WHICH ARE BEING PRODUCED.

15. AMELOGENESIS
□ TOME’S FIBERS HELP THE ENAMEL
TO BE LAID DOWN PRECISELY AT
THE REQUIRED POINT.
□ THIS ARRANGEMENT OF TOME’S
FIBERS ALONG THE SECRETORY
BORDER GIVES A “PICKET FENCE”
ARRANGEMENT.

17. AMELOGENESIS
□ IN THE INITIAL STAGES OF TOOTH
FORMATION, THE DENTAL PAPILLA
SUPPLIES NUTRITION TO THE ENAMEL
ORGAN.
□ AS ENAMEL & DENTIN ARE FORMED, THE
AMELOBLAST CELLS MOVE AWAY FROM
THE DENTAL PAPILLA
□ THE BLOOD SUPPLY IS THEN DERIVED
FROM THE VESSELS INVAGINATING
THROUGH THE OUTER E. E.

18. AMELOGENESIS
□ ENAMEL FORMATION FIRST
BEGINS IN THE TIP OF THE CUSPS
□ THEN IT SLOPES DOWNWARDS
GRADUALLY TO THE CERVICAL
LOOP AREA.
□ THIS AREA FORMS THE FUTURE
CEJ.

19. LIFE CYCLE OF AMELOBLASTS
□ DURING AMELOGENESIS, THE
AMELOBLASTS UNDERGO CHANGES
IN THEIR MORPHOLOGY, STARTING
FROM PRE-SECRETORY STAGE TO
POST-SECRETION PERIOD.
□ AT EACH STAGE, THE CELL
REARRANGES ITSELF TO SUIT THE
FUNCTIONAL REQUIREMENTS.

20. LIFE CYCLE OF AMELOBLASTS
BROADLY CLASSIFIED INTO 3
STAGES:
■ PRE-SECRETORY STAGE
■ SECRETORY STAGE
■ POST-SECRETORY STAGE.

21. LIFE CYCLE OF AMELOBLASTS
EACH IS AGAIN SUBCLASSIFIED:
PRE-SECRETORY
■ MORPHOGENETIC PHASE
■ ORGANIZING / DIFFERENTIATING
SECRETORY
■ FORMATIVE PHASE
POST- SECRETORY
■ MATURATIVE PHASE
■ PROTECTIVE PHASE
■ DESMOLYTIC PHASE.

22. MORPHOGENETIC PHASE
□ COINCIDES WITH EARLY BELL STAGE
□ SHAPE OF THE TOOTH DETERMINED AT THIS STAGE
□ CELLS OF THE DENTAL PAPILLA SEPARATED FROM IEE
BY A BASEMENT MEMBRANE
□ CELLS OF IEE SHORT COLUMNAR
□ OTHER ORGANELLES ARE NOT FULLY DEVELOPED.

23. DIFFERENTIATING PHASE
□ CELLS OF THE IEE BECOME TALL
COLUMNAR
□ HYPERCHROMATIC NUCLEUS SHIFTS TO
PROXIMAL END (TOWARDS SI)
□ ORGANELLES MOVE DISTALLY.
□ THIS CELL IS “POLARIZED”, CALLED
“PREAMELOBLASTS”

24. FORMATIVE STAGE
□ ACTIVE SECRETION OF ENAMEL MATRIX
TAKES PLACE
□ TOME’S PROCESSES DEVELOPS FROM THE
DISTAL END OF THE CELL
□ ENAMEL FORMATION MOVES DOWN FROM
THE CUSP TIP TO THE CERVICAL AREA.
□ ORGANELLES ACTIVITY INTENSE.

25. MATURATION PHASE
□ FULL MINERALIZATION (MATURATION)
OCCURS AFTER FULL THICKNESS OF ENAMEL
MATRIX HAS BEEN LAID DOWN IN THE
OCCLUSAL / INCISAL AREA.
□ WHEN MATURATION TAKES PLACE IN THE
CUSP TIP, FORMATION OF MATRIX WILL STILL
BE ON IN THE CERVICAL LOOP AREA.
□ CELLS OF SI TAKE A SPINDLE SHAPE

26. PROTECTIVE PHASE
□ WHEN ENAMEL HAS FULLY CALCIFIED,
AMELOBLST LAYER LOOSES IDENTITY.
□ CANNOT BE DIFFERENTIATED FROM SI & OEE.
□ THESE CELLS OF THE OEE & IEE (AMELOBLSTS)
TOGETHER FORM A EPITHELIAL COVERING OVER
NEWLY FORMED ENAMEL  REDUCED ENAMEL
EPITHELIUM. (REE)
□ PROTECTS ENAMEL BY SEPARATING IT FROM
CONNECTIVE TISSUE TILL IT ERUPTS.

27. DESMOLYTIC PHASE
□ CELLS OF THE REE ELABORATE SOME
ENZYMES WHICH CAUSE LYSIS OF
THE CONNECTIVE TISSUE
□ SO THAT THE TOOTH CAN ERUPT
INTO THE ORAL CAVITY.
□ THIS IS CALLED “DESMOLYSIS”.