Oral Pathology I Third Year

1. By
Dr. Wael Mohamed Swelam

2. ? Dental Caries
Dental caries is a demineralization/ not decalcification of the tooth surface
caused by bacteria.
Caries= Carious process?
Monday, January 20, 2014Dr. Wael Swelam
Caries= Carious lesion?

3. Dental caries
major concepts
Definition: It is a microbial diseasenotthedisease tissues of the teeth,
Caries is a process, of a calcified
characterized by demineralization of the inorganic portion and destruction
Driven by biofilm, but initiated by the host –
of the organic substance of the tooth.
Closely linked to specific microenvironments –
The process is dynamic and reversible
Oral ecological shifts are normal and cyclical
–
Many factors influence the outcome
Microbes are necessary, but not sufficient
Monday, January 20, 2014Dr. Wael Swelam
–

4. , It is the most prevalent disease affecting the human race •
Some isolated populations like Eskimos, some African natives, and •
inhabitants of rural India are “immune” to dental caries because they
.are not exposed to western food habits
Affects both sexes and all races, all socio-economic strata and people •
,of all ages
.Starts soon after teeth erupt into the oral cavity •
Monday, January 20, 2014Dr. Wael Swelam

5. Carbohydrates
Microorganisms
Caries
Monday, January 20, 2014Dr. Wael Swelam

6. What is Dental Caries?
The word ‘caries’ is derived from the Latin word ‘rot’.
It is a microbial disease of the calcified tissues of the teeth, characterized by
demineralization of the inorganic portion and destruction of the organic substance
of the tooth.
Monday, January 20, 2014Dr. Wael Swelam

7. Carbohydrates
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When sucrose is hydrolyzed it forms a 1:1 mixture of glucose and fructose
It promote colonization of S. mutans
Rapidly diffuse into dental plaque and converted to acids
If Sucrose is injected by oesophageal tube = No caries = Its effect is directly local
Fructan is essential in formation of adhesive insoluble plaque polysaccharide
SUGAR
6-carbon
5-carbon
POLYMER
Glucose
Glucan
Dextrose
Dextran
Fructose
Fructan
Levulose
Levan
Monday, January 20, 2014Dr. Wael Swelam

8. Microbiology of caries:
1. Specific plaque hypothesis (Loesche, 1976)Out of the diverse collection of micro-organisms that constitute the plaque
microflora, only a very limited number are actively involved in causing disease.
Specific cariogens- Streptococcus mutans and Lactobacillus Acidophilus
2. Non-Specific plaque hypothesis(Theilade,1986)Heterogenous mixture of organisms in plaque could play a role in disease, and that
disease is a result of the overall interaction of the plaque microflora with the host.
-“low pH non-mutans streptococci”
3. Ecological plaque hypothesis (Marsh,1991)-A change in a key environmental factor (or factors) will trigger a shift in the
balance of the resident plaque microflora, and this might predispose a site to disease.
Monday, January 20, 2014Dr. Wael Swelam

9. Bacteria Commonly Isolated
from the Oral Cavity
Gram positive bacteria Gram Negative Bacteria
Actinomyces
Arachnia
Bifidobacterium
Lactobacillus
Micrococcus
Neisseria
Propionibacterium
Rothia
Streptococcus
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Actinobacillus
Bacteroides
Branhanelia
Capnocytophaga
Eldenella
Fusobacterium
Peptostreptococcus
Haemophilus
Leptotrichia
Selenomonas
Simonsiella
Treponema
Veilonella
Wolinella
Monday, January 20, 2014Dr. Wael Swelam

10. Dental Plaque Composition
Pellicle ♦
Salivary proteins, 500-100nm thick ♦
(Matrix (20-30% ♦
Host and microbial substances −
Salivary materials −
Gingival exudate −
(Bacteria (70-80% ♦
Monday, January 20, 2014Dr. Wael Swelam

11. Demineralization/ remineralization
Human teeth are made from biological apatite. It can dissociate slightly in
water, especially in low pH situation. For example Coca-cola, which has a pH
2.5-4.2.
However, you teeth will not be gone after a can of soda because the
enamel pellicle shields the surface of teeth from oral environment.
Monday, January 20, 2014Dr. Wael Swelam

12. Dental Plaque is a biofilm
Monday, January 20, 2014Dr. Wael Swelam

13. Equilibrium at normal pH
Remineralization
Demineralization
Dietary CHO + biofilm CHO; salivarydiffusion into enamel normal pH drop
Saliva flow clears = lactic acid; HCO3 returns pH to = local
Saliva is supersaturated with respect to enamel
Saliva
Ca+statherin [HCO3] Ca+aPRP [HCO3]
& [PO ]
[Ca] [PO4] [Ca] [PO4] [Ca] to saliva
exit
[Ca], & [PO4]
move into enamel
4
Enamel
Enamel becomes
Less soluble
CHO
Demineralization
Demineralization
[H+]
Remineralization
Remineralization
CHO
CHO
[H+]
[H+] Ca (PO ) OH
10
4 6
2
Monday, January 20, 2014Dr. Wael Swelam
[H+]
[H+]
Enamel
solubility
increases

14. Stephan Curve
Monday, January 20, 2014Dr. Wael Swelam

15. Extracellular Glucan/ Dextran
1. Attachment of Bacteria to tooth
surface
Intracellular Fructan/ Levan
1.Bacteria Utilize it to gain energy in
absence of substrates
2. Bacteria use it to produce acids
Streptococcus ……………
Lactobacillus Acidophilus
Streptococcus mutans +IC fructan+ EC Glucan
Dextran
First stage
Second stage
Third stage
Initial transport of B. to tooth surface
Reversible adsorption
Firm attachment
Monday, January 20, 2014Dr. Wael Swelam
Demineralization
Fourth stage
Surface colonization

16. Extracellular Glucan/ Dextran
1. Attachment of Bacteria to tooth
surface
Intracellular Fructan/ Levan
1.Bacteria Utilize it to gain energy in
absence of substrates
2. Bacteria use it to produce acids
Streptococcus ……………
Lactobacillus Acidophilus
Streptococcus mutans +IC fructan+ EC Glucan
First stage
Initial B. transport to tooth surface
Second stage
Reversible adsorption
Third stage
Firm attachment
Fourth stage
Surface colonization
Dextran
Demineralization
Monday, January 20, 2014Dr. Wael Swelam

17. Dental plaque
Every time we eat or drink
A layer of dental plaque
accumulate on the surfaces of
our teeth
Saliva can reduce acid attack
towards our teeth but it must
have enough time to work
If we are eating and drinking
frequently, saliva will not have
enough time to work
Monday, January 20, 2014Dr. Wael Swelam

18. FACTOR
HIGH RISK
LOW RISK
Amount of plaque
Large amount of plaque on the
teeth, meaning many bacteria
that can produce acids (low pH,
(demineralization
Few bacteria = "good" oral
hygiene
Type of bacteria
Large proportion of "cariogenic"
types of bacteria, resulting in
lower pH and sticky plaque and
also prolonged acid production
Low proportion of "cariogenic"
types
Type of diet
High in carbohydrates, in
particular sucrose; "sticky" diet
leading to low pH longer time
Low sugar content; non- "sticky"
type of diet
Frequency of carbohydrates
High sugar frequency resulting
in longer time per day with low
pH
Low sugar frequency
Saliva secretion
Reduced saliva flow leading to
prolonged sugar clearance time
and to a reduced amount of
other saliva protective systems
Optimal, helps to wash out
sugars and acids
Saliva buffer capacity
Low buffer capacity resulting in
prolonged time with low pH
Optimal, time with low pH
shorter
Fluorides
Absent: reduced
remineralization
Available: increased
remineralization
Monday, January 20, 2014Dr. Wael Swelam

19. Acidogenic Theory (Miller, 1882)
Most believe bacterial acids decalcify enamel first then remove enamel proteins.
Miller, recognized two stages in the carious process:
1( decalcification of enamel,
2( dissolution of protein enamel matrix.
Decalcification of enamel, the first step in the process, was, Miller believed, caused by
metabolism of carbohydrate food residues by microorganisms.
Proteolytic Theory
A few believe that bacteria first attack enamel proteins then decalcify enamel.
The idea here is that Keratinolytic bacterial first invade malformations commonly found
in enamel. The most common of these are incompletely calcified occlusal grooves and
protein lamellae that extend through the entire enamel thickness in some teeth. As
bacterial acids accumulate in these sites, surrounding protein is destroyed exposing
calcified enamel to bacterial acids.
Proteolysis-Chelation Theory (Schatz and Martin, 1962)
They suggested that. Proteolytic breakdown of the protein of enamel releases chelating
agents that dissolve the mineral content of Enamel
Monday, January 20, 2014Dr. Wael Swelam

20. Dental Caries
Enamel Caries
Smooth surface caries
Dentin Caries
Cementum Caries
(Root caries)
Pit and fissure caries
Monday, January 20, 2014Dr. Wael Swelam