1. Management of Caries

2. Caries Advancement

3. Enamel Covers Anatomical Crown Translucent
Enamel Rods (perpendicular to DEJ and tooth surface)
Requires a base of Dentin to withstand forces
Hardest substance in the human body
Incapable of repairing itself

4. Histology of Enamel Enamel
Composed of very tightly packed hydroxyapatite crystallites organized into long columnar rods (prisms).
Each rod starts at DEJ and extends as a wavy continuous column to the surface of the crown. Unstained, 100x

5. Dentin Formed by Odontoblasts Darker than Enamel, less translucent
Hydroxyapatite crystals and collagen
type I
Harder than bone, softer than enamel
Dentinal tubules

6. Dentinal Tubules Unstained, 400x
Histology of Dentin
Dentinal Tubules Unstained, 400x
Dentinal tubules allow fluid movement, ion transport necessary for remineralization and apposition and perception of pain

7. Chemistry # ENAMEL – 96% Inorganic (Mineral Hydroxyapatite)
2% Organic (Protein)
2% Water
# DENTIN % Inorganic (Mineral Hydroxyapatite)
22% Organic (Collagen)
10% Water

8. Primary Dentin
Type of Dentin formed before and shortly after eruption

9. Secondary Dentin
Continuation of Primary Dentin (forms at slower rate as tooth ages and with structural irregularities)
Circumpulpal Dentin (laid down incrementally every day)
Tubules take different directional pattern

10. Reparative Dentin
Formed in response to irritation (attrition, abrasion, erosion, trauma, caries, operative procedures, other irritants)
Confined to localized irritated area of Pulp Chamber
Defense reaction to an area of injury
Structurally and chemically different from Primary and Secondary Dentin

11. Sclerotic Dentin Results from aging or mild irritation
Tubular content is replaced by calcified material
Tubules are obliterated
Intertubular Dentin is smooth

12. Dead Tracts Regions of empty Tubules
Degeneration of Odontoblastic Processes
Pulp is not stimulated to form replacement Odontoblasts

13. The Pulp
Pulp is the connective tissue situated within the rigid encasement of mineralized dentin
Functions of the Pulp
# Formative
# Repair
# Nutrition
# Sensory
# Protection/Defensive

14. Relationship Pulp - Dentin
Permeability of dentin regulates the rate of diffusion of irritants that initiate pulpal inflammation
Odontoblasts are arranged peripherally in direct contact with dentin matrix
This close relationship between the dentin and pulp create a functional unit called the PULPODENTINAL COMPLEX

15. Dentinal Tubules
Extend through entire thickness of dentin from DEJ to the pulp
S-shaped in the crown, less S-shaped in the root, almost straight in the cervical aspect
Inverted cone shape with smallest dimensions at the DEJ and largest dimensions at the pulp

16. Dentinal Tubules
Number of tubules increases from DEJ to pulp ( vs /sq mm)
Because both the density and diameter of the tubules increase with dentin depth from the DEJ, the permeability of dentin is lowest at the DEJ and highest at the pulp
Axial dentin is more permeable than occlusal dentin

17. Enamel Caries
Demineralization results in pores enlargement # roughness + loss of shine
Demineralization progresses # pores increase in size
Through large pores bacteria may invade subsurface

18. Enamel Caries ENAMEL CARIES
This shows enamel prisms which have been extensively demineralized revealing the microanatomy of the prisms and the interprismatic substance.
This represents initial surface breakdown of enamel and is the next stage after the white spot lesion.

19. Enamel Caries – clinical characteristics of „white spot” lesion
# loss of normal translucency of enamel with a chalky white apperance, particularly when dehydrated
# a fragile surface layer susceptible to damage from probing particularly in pits and fissures
# increased porosity particularly of the subsurface, with increased potential for uptake of stain

20. Enamel Caries – clinical characteristics of white spot lesion
# reduced density of the subsurface that may be detectable radiographically or with transillumination
# a potential for remineralization with an increased resistance to further acid challenge
# the reversed lesion will either regain normal translucency or the chalky appearance may remain and take up stain

21. Microscopically, several zones have been identified.
1. Translucent Zone
2. Dark Zone
3. Body of the Lesion
4. Surface Zone

22. Zones of Incipient Lesion

23. Zones of Incipient Lesion
# Translucent Zone
The deepest, structureless appearance (quinoline + polarized light)
# Dark Zone
doesn’t transmit polarized light (pores too small to absorb quinoline)

24. Zones of Incipient Lesion
# Body of the Lesion
- The largest portion, the largest pore volume varying from 5% to 25% at the center
Bacteria may be present
# Surface Zone
- Relatively unaffected (saliva, fluoride), serves as a barrier to bacterial invasion

26. Dentinal Caries
# Caries produces a variety of responses in dentin: i) pain, ii) demineralization, iii) remineralization, iv) apposition
# The level of dentinal reaction to caries can vary depending on clinical advancement (slowly-, moderate-, rapidly advancing lesions) and acid level.
# The dentin can react to low and moderate intensity caries attacks as long as the pulp remains vital and has an adequate blood circulation

27. Dentinal Caries
Caries advancement in dentin proceeds through three changes:
# Demineralization by weak organic acids
# The organic material of the dentin, particularly collagen, degenerates and dissolves
# The loss of structural integrity is followed by invasion of bacteria

28. Dentinal Caries
"Dentinal sclerosis" and "reparative dentin" slow down microbial invasion.
# In the earliest stages of exposure to the microorganisms of dental caries, there is an effort to seal off the tubules, increased calcification
# The result is a visible change known as „transparent dentin” or, better, "dentinal sclerosis."
# In addition to this pulpal odontoblasts, stimulated by the advancing carious lesion, will rapidly deposit dentin.

29. Dentinal Caries
# The dentinal tubules in this new dentin are irregular, an arrangement that makes it less permeable to microorganisms.
# Histologists cannot seem to decide what to call this newly-formed dentin; the terms "irregular dentin," "reparative dentin," "secondary dentin," and "tertiary dentin" all have been used.

30. Dentinal Caries
# Dentinal sclerosis and reparative dentin may be a successful deterrents if the carious lesion progresses slowly.
# Usually, however, the dentinal tubules are invaded and the occupant odontoblast is killed in the process.

31. Destruction of dentin exposes the pulp to bacterial invasion.
Dentinal Caries
Destruction of dentin exposes the pulp to bacterial invasion.
# As microbial invasion progresses along the dentinal tubules, acid production decalcifies surrounding dentin causing a fusion of them.
# As decalcification continues, clefts appear; they are oriented perpendicular to dentinal tubules and cross a number of them.

32. Dentinal Caries
# These clefts are responsible for the flaking observed by dentists as carious dentin is removed during cavity preparation.
# At this point it is important to realize that carious dentin is loaded with microorganisms and that when the pulp chamber is finally reached, bacterial invasion of the dental pulp will ensue

33. Dentinal Caries Dentin Caries
Horizontal clefting is revealed here and this occurs at right angles to the dentinal tubules.
The process of beading, coalescence, and clefting typifies the mode of progression of dentinal caries.

34. Dentinal Caries

35. Zones of Dentinal Caries
Zone 1 Normal Dentin
# The deepest area
# Tubules with odontoblastic processes
# No bacteria or crystals found

36. Zones of Dentinal Caries
Zone 2 Subtransparent Dentin
Demineralization of the intertubular dentin
Damage of the odontoblastic processes
Crystals in the tubule lumen
Remineralization is possible
Zone 3 Transparent Dentin
Carious dentin – softer
Loss of mineral from the intertubular dentin, many crystals in the lumen of the dentinal tubules
No bacteria, collagen remains intact
Affected dentin
-Softened
-Demineralized
-No bacteria
-Repair is possible

37. Zones of Dentinal Caries
Zone 4 Turbid Dentin
Zone of bacterial invasion
Widening and distortion of the dentinal t
Dentinal tubules filled out with bacteria
Collagen is irreversibly denatured
Zone 5 Infected Dentin
Great numbers of bacteria filling the t
Granular material in the intertubular spa
Infected dentin
-Softened
-Demineralized
-Contaminated w/bacteria
-Requires removal

38. Zones of Dentinal Caries
Sclerotic dentin (s.d.)
# Result of remineralization of transparent dentin
# In slowly advancing lesions
# Shiny, dark, hard (hypermineralized)
# Function – to wall off a lesion by sealing the tubules
# S.d. shows ideal final excavation depth (natural barrier that blocks penetration of toxins and acids)

39. Pathology of Dentin
Dentin Caries
This is a zone of infected tubules.

40. Pathology of Dentin Dentine Caries
In these frames, bacteria in the dentinal tubules are demonstrated by special stains.