Transcript dea6ba587b5ac9e

Dental Cariology I
DR. Khalid AL-Tubaigy
Photos of dental caries
Photos of dental caries
Photos of dental caries
Dental caries can be defined as
1. Chronic progressive deconstructive
disease of hard dental tissues
2. Bacterial infected diseases caused by
specific bacteria
3. A reversible multifactorial process of
tooth demineralization and
remineralization.
Dental caries
4. Dental caries, a bacterial infection, may
be define as; a post-eruptive pathological
process of external origin, involving the
softening of the hard dental tissue and
proceeding to cavity formation.
 In caries active individuals, pH at the tooth surface
remains below the critical pH (5.5) for 20 - 50 minutes
following single exposure to sucrose.
 Below the critical pH (5.5), the tooth mineral acts as a
buffer and loses calcium and phosphate ions into
the plaque.
 At lower pH values, such as 3.0 or 4.0, surface of
enamel is etched and roughened.
 At a pH of 5.0, the surface remains intact while the
subsurface mineral is lost.
Basic pathological changes
• demineralization of inorganic tissues of
tooth
• Disintegration of the organic tissues of
tooth
• involves enamel, dentin, cementum
The carious process
a pathological process of localized destruction of calcified
tooth tissues by acids produced by organisms.
Etiologically caries is considered a multi-factorial disease,
which involves interplay between the host (saliva and teeth)
micro organisms (streptococcus mutans), and the substrate
(dietary carbohydrate, sucrose) and time with the
production of Lactic acid.
Dental plaque (Bio-film) serves as the medium for caries
development.
Epidemiology of dental caries
Prevalence rate：
is the proportion of a population affected by a
disease of a condition at one point time
Incidence rate：
is a measurement of the rate at which a disease
progresses the increase or decrease in the
number of new cases occurring in a population
within the same time period
epidemiological studies
 Caries prevalence is low in populations
adhering to a primitive way of living and
a diet of local products with little sugar
 A drastic increase in caries is invariably
seen when these population “improve”
their standard of living and adopt a
modern “civilized” diet with high sugar
content
Why has caries prevalence decreased
in modern population?
The is possibly attributable to:
1. The fluoridation of drinking water, use of
fluoride toothpastes and improved oral
health
2. A changing pattern of sugar consumption
3. A decrease in virulence of the organisms
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Prevalence of dental caries (1995)，special
for 12-18Y age groups is increased
significantly（20-40%）
•
In recent 10 years ( 2005), prevalence of
dental caries in primary dentition is
increased significantly than the permanent
Frequency distribution of dental caries
according to various tooth location
permanent dentition
Deciduous dentition
 A strong correlation between caries
development and sugar consumption
 Sucrose-----called the arch-criminal in dental
caries
 Mono-saccharides, di-saccharides and of the
poly-saccharide starch can be fermented to acid
by the plaque bacteria
 Sorbitol, xylitol-----sugar substitutes used in
sugar-free chewing-gums
distribution of dental caries
according to tooth surface
(1) Pits and fissures.
(2) Smooth enamel surfaces (gingival to the proximal
contacts and in the gingival one third of the facial and
lingual surfaces of the clinical crown).
(3) Root surfaces, particularly near the cervical line.
(4) Subgingival areas .
The termination of pits and
fissures :
a. shallow groove
b. Complete penetration of
enamel
c. may end blindly
d. open into an irregular
chamber
Measuring caries activity
DMF index
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D the mean number of decayed teeth with untreated
carious lesions
M the mean number of teeth which have been
extracted and are therefore missing
F the mean number of filled teeth
DMF(T) to denote decayed, missing, and filled teeth
DMF(S) to denote decayed, missing, and filled surfaces
in permanent teeth
dmf(t) dmf(s) similar indices for the primary dentition
Etiology of dental caries
four factors is essential for the
initiation of dental caries:
1. Micro-organism
( Initial microbial colonization )
① mutans streptococci
② Lactobacilli
③ Actinomyces
Mutans Streptococci (MS)
S.mutans
• Is a group of bacteria have significant potential to cause caries,
consists of 8 S.mutans serotypes.
• The serotypes have been labeled a through h.
1. S.cricetus (serotype a),
2. S.rattus (serotype b),
3. S.ferus (serotype c), and
4. S.sobrinus (serotypes d, g, and h).
Why we should refer to it as MS not S.mutans ?
(MS) as a collective term for all the serotypes.
MS & Lactobacilli
• Cariogenic: Organisms that cause caries .
• Acidogenic: can produce great amounts of acids
• Aciduric: are tolerant of acidic environments .
MS are present as a pandemic infection in humans:
1. That is MS are found in everyone regardless of race, ethnic
background, or geographic origin.
2. Normally MS exist in the mouth as an insignificantly small
component of the oral flora.
3. In patients with multiple active carious lesions, MS have become
a dominant member of the plaque flora.
4. MS are most strongly associated with the onset of caries while
lactobacilli are associated with progression of caries.
Cariogenic properties
1. they are able to produce acid rapidly from
fermentable carbohydrates (acidogenic).
2. They thrive under acid conditions
(aciduric)
3. able to adhere to the tooth surface because
of their ability to synthesize sticky
extracelluar polysaccharides from dietary
sugars
2. Substrate ( Environmental factors)
① Saliva 1. composition
2. Quantity
3. pH viscosity
4. Antibacterial factors like enzymes
① Diet 1. Physical factors
2. local factors
a. carbohydrate content – presence of refined
cariogenic carbohydrate particles on the tooth surface.
b. Vitamin content
c. fluoride content
d. fat content
2. Substrate
such as: Refined carbohydrates,
sucrose: provide a suitable substrate on which the
cariogenic micro-organisms act to produce the
acids that lead to dissolution of the hard dental
tissues.
Caries experience is influenced by the quantity,
quality and especially frequency of consumption
of the refined carbohydrate
The role of dietary carbohydrate
• Nutrition -----systemic dietary effects
• Diet -----local dietary effects
3. Susceptible teeth ; Tooth ( host )
1. Morphological variation
2. composition
3. position- tooth collection of
plaque due to poor oral hygiene and dietary
habits makes tooth more susceptible.
3. Susceptible teeth
•
Such as : The ingestion of fluorides during tooth
mineralization leads to the formation of fluorapatite in enamel. Its presence in enamel makes
the tooth less susceptible to dental caries because
it is less soluble in acid than the hydroxyapatite
which is normally present in the hard dental
tissues
4. Time
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All the factors should be present for
sufficiently long time for the caries process
to be initiated.
Four factors theories
microorganisms
Host
&
tooth
caries
time
substrate
The four circle diagrammatically
represent the parameters
involved in the carious process.
All four factors must be acting
concurrently (overlapping of the
circles) for caries to occur.
Other factors
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Age
Sex
Geography
Race
Economics status
Nutrition
Health status
Hypotheses and theory relating to
etiology of dental caries
1. Chemico-parasitic theory
• This postulates that oral bacteria act on
sugar to produce acid which demineralizes
the inorganic component of enamel,
resulting in the development of a carious
lesion.
2.
Proteolytic theory
• It is thought that the organic component of
enamel is first broken down by proteolytic
enzymes, opening up path-ways for bacteria
to attack the enamel by other processes such
as by acid or by chelation.
3.
Chelation theory
• This postulates that enamel is
demineralized by chelating agents at neutral
pH.
• Protein breakdown products as well as
lactic acid are some chelating agents known
to exist in nature.
4.
Auto-immunity theory
• In this theory, it is suggested that 'forbidden
clones' of lymphocytes attack target cells
(odontoblasts) rendering the tooth
vulnerable to caries attack.
Early Stages of Plaque Succession
Pellicle
• is formed primarily from the selective precipitation of various components
of saliva.
Functions of the pellicle are believed to be:
• (1) protect the enamel,
• (2) reduce friction between the teeth
• (3) possibly provide a matrix for remineralization.
Pellicle is formed from salivary proteins that have apparently
involved for this function.
• These proteins have many basic groups and consequently adsorb to
the phosphate ions while other acidic proteins adsorb to calcium
ions.
Pellicle formation
– Microorganisms do not attach themselves
directly to the mineralized tooth surface
and the teeth are always covered by an a
cellular proteinaceous film, the pellicle
– Forms on the “naked” tooth surface within
minutes to hours
Major constituents of Pellicle
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Salivary glycoprotein
Carbohydrates
Lipid
a lesser extent components from
the gingival crevicular fluid
Dental plaque
Definition: A gelatinous mass of bacteria
(soft, translucent, and tenaciously
adherent material) accumulating on the
surface of teeth.
Mechanisms of plaque formation
Attachment, growth and reattachment
of bacteria to the tooth surface is a
continuous and dynamic process.
Formation and development of dental plaque
1. Formation of acquired pellicle and
primary aggregation
2. Bacteria growth and development
3. The mature of dental plaque
Composition of Dental plaque
• bacteria which form 50-70% of dental plaque
• glycoprotein together with extracellular
polysaccharides form the plaque matrix
• Muco-poly-saccharides such as glucans and
fructans
• Inorganic components
calcium
phosphorus
fluorides
.
Classification of Dental plaque
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Supra gingival plaque
-----dental caries
Sub gingival plaque
-----periodontal diseases
Structure of Dental Plaque
1. Plaque on smooth surface
Plaque adhere to dental surface
Middle layer condensed microbial layer
(body of plaque)
2. Plaque in pit and fissure
Micro-organism and caries
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Advanced lesions often have a high proportion of
lactobacilli
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dentinal lesions have a diverse micro-flora with many
Gram positive(+), Gram negative(-) bacteria.
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Root surface caries was originally associated with
Actinomyces, but recent studies suggest a similar
etiology to enamel caries
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Rampant caries and early childhood caries can occur in
xerostomic patients and infants fed with high levels of
sugar in pacifiers (nursing bottle caries) the plaque
contains high levels of mutans streptococci and
lactobacilli.
Thank you for your attention!