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.

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

Epidemiology of dental caries

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

epidemiological studies

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 consumption3. A decrease in virulence of the organisms

• 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

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

A strong correlation between caries development and sugar consumption

(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 .

distribution of dental caries according to tooth surface

The termination of pits and fissures :

a.shallow groove b.Complete penetration of enamel c.may end blindly d.open into an irregular chamber

DMF index• 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

Measuring caries activity

four factors is essential for the initiation of dental caries:

1.Micro-organism

①mutans streptococci

②Lactobacilli

③Actinomyces

Etiology of dental caries

( Initial microbial colonization )

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 fluor-apatite 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

• All the factors should be present for sufficiently long time for the caries process to be initiated.

Four factors theories

microorganisms

Host &

toothsubstrate

time

caries

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

•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

• Salivary glycoprotein

• Carbohydrates

• Lipid

• a lesser extent components from the gingival crevicular fluid

Major constituents of Pellicle

Definition: A gelatinous mass of bacteria (soft, translucent, and tenaciously adherent material) accumulating on the surface of teeth.

Dental plaque

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

• 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

• Advanced lesions often have a high proportion of lactobacilli

• dentinal lesions have a diverse micro-flora with many Gram positive(+), Gram negative(-) bacteria.

• Root surface caries was originally associated with Actinomyces, but recent studies suggest a similar etiology to enamel caries

• 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.

Micro-organism and caries

Thank you for your attention!