Dental caries is caused by an imbalance between tooth minerals and biofilm fluids due to acid production from cariogenic bacteria in dental plaque. It begins as demineralization of enamel and progresses to destruction of dentin and pulp if left untreated. Key factors that influence caries development include the cariogenicity of dental biofilm and bacteria like Streptococcus mutans, diet high in fermentable carbohydrates, low salivary flow and buffering capacity, tooth morphology, and prolonged exposure time. Histopathologically, enamel caries shows irregular fissures and intercrystalline spaces widening while dentin caries exhibits tubular sclerosis and liquifaction necrosis.

1. Anusha Sreedharan
SRM KATTANKULATHUR DENTAL COLLEGE
DENTAL CARIES
PATHOPHYSIOLOGY,
HISTOPATHOLOGY
& INFLUENCING FACTORS

2. SYNOPSIS
• Definition
• Theories by Shafers
• The caries evolution
• Concept of demineralization & remineralization
• Concept of progression by Fejereskov & Kidd
• Current concept by Keyes & Jordan
• Factors influencing caries formation
• Histopathology

3. DEFINITION
• SHAFERS DEFINITION- 1993
Dental caries is an irreversible microbial disease of the calcified tissues of
the teeth, characterized by demineralization of the inorganic portion and
destruction of the organic substance if the tooth, which often leads to
cavitation.
• FEJERSKOV & KIDD DEFINITION- 2004
Dental caries is a complex disease caused by an imbalance in the
physiologic equilibrium between tooth mineral and biofilm fluid.

4. THEORIES
• Early theories- The legend of worms
Dental caries was thought to be caused by
living worms inside the tooth strucutre
• Endogenous theories
Humoral theory- Imbalance between the humors
of body caused tooth decay
Vital theory- Tooth decay originated from within
the tooth itself, like a bone gangrene
• Millers chemico parasitic theory in 1882
1st stage- Decalcification of enamel & destruction of dentin
2nd stage-Dissolution of softened residue of enamel & dentin

5. Theories
• Proteolytic theory by Gottlieb & Gottlieb in 1944
Caries is essentially a proteolytic process in which micro organisms invade the organic
pathways and destroy them while advancing through them by forming acids.
Micro organisms produce proteolytic enzymes which destroy the organic matrix of enamel,
loosening the apetite crystals
• Sucrose chelation theory by Egglers & Lura in 1967
Sucrose itself, and not the acid derived from it can cause dissolution of enamel by
forming an ionised calcium saccharate
• Autoimmune theory
Few odontoblasts within pulp at specific sites are damaged by the autoimmune mechanism.

7. CONCEPT OF DEMINERALIZATION
&REMINERALIZATION

8. CONCEPT OF PROGRESSION
-FEJERESKOV & KIDD
White spot:
Clinically
Shape is determined by the distribution
of microbial deposits and direction of enamel prisms
often in kidney shaped appearance
Histologically
Irregular fissures & small defects– Micro cavities
Widened intercrystalline spaces
Opening of striae of retzius

9. • Progression
It is mainly by:
Acid producing bacteria
Fermentable carbohydrates
Subnormal salivary flow and function
• Dentin reaction
Tubular sclerosis
• Pulpo-dentinal reaction
Tubular sclerosis prevents further
demineralization or invasion of empty tubules
that coalasce to form liquifaction
• Pulpal reaction
Reactionary and reparative dentin formation
• Arrest of caries
 Removal of cariogenic plaque
 Wear & polishing of partly dissolved external microflora
 Promote mineral deposition in exposed porous enamel
 Arrested caries with intact surface layer remains as scar in tissue
Concept of progression

10. SEQUELAE OF DENTAL CARIES
Dental caries in enamel
Dental caries in dentin
Dental caries in pulp
Acute pulpitis Chronic pulpitis
Acute PA periodontitis Chronic PA periodontitis
Acute PA abscess Chronic PA abscess
Cellulitis Dentoalveolar Chronic PA granuloma
abscess PA cyst
Osteomyelitis

11. CURRENT CONCEPT
-KEYS & JORDAN
Older concept Modified concept
Keyes Triad in
1960 Newburn in 1982

12. HISTOPATHOLOGY

13. ENAMEL CARIES

14. DENTINAL CARIES

15. FACTORS INFLUENCING CARIES
FORMATION
• Biofilm and flora
• Saliva
• Diet
• Tooth
• Time
• Systemic conditions

16. DENTAL BIOFILM
Community of micro organisms growing on a surface
Development of dental biofilms
• Pellicle formation
• Attachment of single bacterial cells( 0- 24h)
• Formation of distict microcolonies (4-24 h)
• Microbial succession & coadhesion (1-7 days)
• Mature biofilm

17. • Cariogenic features of dental biofilm
 Rapid ability to transport fermentable sugars & its conversion to acids
 Ability to maintain sugar metabolism under extreme environmental condition
like low pH
 Production of extracellular (glucans & fructans) & intracellular
polysaccharides( glycogen like storage compounds)
Dental Biofilm

18. FLORA
Pioneer species in enamel decay- Streptococcus (S.mutans,
S.sobrinus, S.sanguinis), Lactobacilus spp.(L.acidoplilus, L.casei, L.
fermentum, L.salivarius)
Progressing species in dentinal decay- Actinomyces,
Bifidobacterium, Prevotella, Selenomonas, Veilonella, Propionibacterium

19. SALIVA
 Oral clearance
Clearance time: Time saliva takes to reach certain detectable low level of sugar
concentration
Clearance rate varies greatly with individuals
Depends mainly on the salivary flow rate & sugar exposure
 Quantity & Quality
Individuals with unstimulated salivary flow rate <0.2ml/min have higher risk of
developing caries.
Patient is evaluated for salivary gland hypofuntion, any chronic diseases,
medication & previous radiation therapy
Inorganic composition of saliva- Immune & non- immune proteins

20. Saliva
 Buffer capacity
Ability of saliva to maintain p H & counteract acid production
Saliva buffer capacity = Increase in saliva acid conc.
Change in saliva pH
o Phosphate buffer system
o Bicarbonate buffer system
o Protein buffer system
 Antibacterial properties
Lysozyme
Salivary peroxidase
Immunoglobulins

21. DIET
• Frequency
A positive co relation b/n frequency of consumption of confectionary & sugar
containing gum & DMF rate was found.
• Sequence
The sequence of eating cariogenic food product during a meal/ snack can alter its
cariogenic properties.
 Cheese & peanuts- Reduce cariogenic properties of sugar
 Starch- Increase cariogenic properties of sugar
adding to its sticky nature increasing retention time
• Cariogenicity of different carbohydrates
• High caries potential- Fruit, vegetables, table sugar brown sugar, grains
 Low caries potential- Cow’s milk, Artificial sweeteners
Saccharin Sweet

22. DIET
• Protective factors in food
 Fluorides
 Cow’s milk compared to breast milk
 Cheese
 Fibre rich food
 Unrefined plant food
 Sugar free chewing gum for 20 mins following a meal or snack
accelerate pH rise

23. TOOTH
• Morphologic characteristics:
Deep, narrow occlusal fissure
Buccal/ Lingual pits
• Variation in surfaces:
Eg: In mand molars, decay is found in occlusal, buccal, mesial & distal
In max lateral incisors, lingual surface is more susceptible than labial surface
• Position
Malaligned, rotated, out of position

24. • Time
Time is a significant factor in the development of dental caries
If the tooth surface has been exposed to the acid produced by the bacteria of the
dental plaque for a long period, acid will harm & demineralize tooth surface

25. • Systemic Conditions
• Vitamin deficiency
• Decreased immunity
• Cancer therapy
• Pregnancy
• Obesity

26. REFERENCES
• Dental caries by Fejereskov & Kidd
• Shafers textbook of Oral Pathology
• J DentvRes 83 2004 by Kidd & Fejereskov