口腔学英文课件：Etiology_and_pathogenesis
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Protective functions: a. Reservoir of ions eg., calcium, phosphate and
fluoride ions b. Acts as a semi-permeable membrane.
(imp in demineralisation- remineralisation, allows ion exchange) c. Restricts diffusion of acids - protects enamel from minor acid attack d. Lubricant - can protect tooth from wear e. Antibacterial factors – IgA, Lysozyme
What is the ‘white stuff’ present on the labial surfaces of the lower anterior eeth?
How does the white stuff form ?
Why are the labial surfaces of the teeth partly brown ?
the majority of oral bacteria) Mucosa (K, non-K) teeth (non-shedding area) gingival crevice, saliva (contains up to 108 bacteria/ml), tonsils. Prosthodontic and orthodontic appliances
Periodontology
Etiology of periodontal diseases
Bacteria exist in different shapes
Rods Cocci
Curved rods
Spiral (spirochaetes)
Arrangement
Bacteria arrange themselves as: Pairs (diplococci) Chains (streptococci) Grape-like clusters (staphylococci)
(important by use of dental adhesive materials) d. Difficult to remove with toothbrushing, professional
cleaning needed
Streptococci
Capnocytophaga species
clinical appearance - translucent & colorless, invisible to naked eye
Formation of pellicle
Spontaneous Bacteria not necessary (forms in germ free
animals) Forms from salivary glycoproteins by
Oral flora on the child’s first birthday usually consist of streptococci, staphylococci, lactobacillus, less frequently isolated actinomyces, prevotella, fusobacterium species
Origin of normal oral flora
The pioneer species are usually streptococci which bind to mucosal epithelium and remain throughout life
The metabolic activity of the pioneer community then alters the oral environment to facilitate colonization by other bacterial species.
Dental plaque
1mg of plaque contains about 108 bacteria
Dental plaque is now commonly called a dental biofilm….
600 species of commensal (resident) bacteria an estimated 415 species present in subgingival
plaque. Fungi (yeasts) such as Candida albicans, Viruses eg herpes, Epstein-Barr.
Veillonella species
Porphyromonas Gingivalis
Fusobacterium species
Streptococci
Other gram-positive rods
Motile gram-negative rods and spirochetes
Streptococci
Transient flora – of little significance as long as the normal resident flora remains in place.
The oral ecosystem
Diverse habitats for bacteria: tongue (provides the home for
Origin of normal oral flora
The next change in this community occurs during and after tooth eruption: Hard tissue surface of enamel (s. mutans) Gingival crevice (prevotella gingivalis)
Commensal (resident) flora – fixed types of microbes regularly found in a given area at a given age;
Disease occurs when this relationship is broken
The oral ecosystem
Does the white deposit cause any problems for the gums or teeth ?
Dental Deposits
1. Acquired pellicle 2. Dental plaque/biofilm 3. Dental calculus 4. Food debris 5. Materia Alba
The oral ecosystem
The nature of the site determines the type of bacteria.
ie. interproximal, occlusal, supragingival, subgingival
The oral ecosystem
Transient flora – non-pathogenic or potentially pathogenic flora on skin or mucous membranes; derived from the environment & does not establish permanently.
Origin of normal oral flora
Sterile until birth, bacteria acquired from birth canal from mother
Infant exposed to flora of mother, other people and organisms in the environment
Actinomyces species
Early colonizers
Prevotella intermedia
Late colonizers
2. Dental plaque/Dental Biofilms
Definition: It is a soft, non-mineralised microbial deposit which forms on the hard tissue surfaces of the mouth (and dental prostheses), comprising living and dead bacteria and their products together with the host compounds mainly derived from saliva.
selective adsorption Reforms very rapidly on the clean tooth
surface within seconds Takes 1 week to mature
Function & Clinical significance of pellicle
Function & Clinical significance of pellicle
Damaging functions a. Influence while bacteria colonise the tooth (plays a
role in the formation of Dental Plaque) b. Nutrient supply for some bacteria in dental plaque c. Presence of pellicle alters surface energy of tooth
The oral ecosystem
The mouth has a natural microflora (commensal, indigenous, or resident) which exists in a harmony with the host, (like skin, Nasopharynx, Gastro-intestinal tract including oral cavity)
Gram-staining characteristics
Classified into two major subgroups: Gram-positive (purple) Gram-negative (pink)
What for? Bacteria identification Therapy of bacterial infection
A second childhood is reached if all teeth are lost. Bacteria are very similar to those in a child before tooth eruption.
Introduction of a prosthetic appliance at this stage changes the microbial composition once again. Acrylic denture (Candida) Over 70 y (Staphylococcus aureus, lactobacilli)
1. Acquired pellicle
composed of - salivary glycoproteins (mucins) - No cells, no minerals, no bacteria
structure - surface layer & sub-surface layer - homogenous - very thin 1-10um
fluoride ions b. Acts as a semi-permeable membrane.
(imp in demineralisation- remineralisation, allows ion exchange) c. Restricts diffusion of acids - protects enamel from minor acid attack d. Lubricant - can protect tooth from wear e. Antibacterial factors – IgA, Lysozyme
What is the ‘white stuff’ present on the labial surfaces of the lower anterior eeth?
How does the white stuff form ?
Why are the labial surfaces of the teeth partly brown ?
the majority of oral bacteria) Mucosa (K, non-K) teeth (non-shedding area) gingival crevice, saliva (contains up to 108 bacteria/ml), tonsils. Prosthodontic and orthodontic appliances
Periodontology
Etiology of periodontal diseases
Bacteria exist in different shapes
Rods Cocci
Curved rods
Spiral (spirochaetes)
Arrangement
Bacteria arrange themselves as: Pairs (diplococci) Chains (streptococci) Grape-like clusters (staphylococci)
(important by use of dental adhesive materials) d. Difficult to remove with toothbrushing, professional
cleaning needed
Streptococci
Capnocytophaga species
clinical appearance - translucent & colorless, invisible to naked eye
Formation of pellicle
Spontaneous Bacteria not necessary (forms in germ free
animals) Forms from salivary glycoproteins by
Oral flora on the child’s first birthday usually consist of streptococci, staphylococci, lactobacillus, less frequently isolated actinomyces, prevotella, fusobacterium species
Origin of normal oral flora
The pioneer species are usually streptococci which bind to mucosal epithelium and remain throughout life
The metabolic activity of the pioneer community then alters the oral environment to facilitate colonization by other bacterial species.
Dental plaque
1mg of plaque contains about 108 bacteria
Dental plaque is now commonly called a dental biofilm….
600 species of commensal (resident) bacteria an estimated 415 species present in subgingival
plaque. Fungi (yeasts) such as Candida albicans, Viruses eg herpes, Epstein-Barr.
Veillonella species
Porphyromonas Gingivalis
Fusobacterium species
Streptococci
Other gram-positive rods
Motile gram-negative rods and spirochetes
Streptococci
Transient flora – of little significance as long as the normal resident flora remains in place.
The oral ecosystem
Diverse habitats for bacteria: tongue (provides the home for
Origin of normal oral flora
The next change in this community occurs during and after tooth eruption: Hard tissue surface of enamel (s. mutans) Gingival crevice (prevotella gingivalis)
Commensal (resident) flora – fixed types of microbes regularly found in a given area at a given age;
Disease occurs when this relationship is broken
The oral ecosystem
Does the white deposit cause any problems for the gums or teeth ?
Dental Deposits
1. Acquired pellicle 2. Dental plaque/biofilm 3. Dental calculus 4. Food debris 5. Materia Alba
The oral ecosystem
The nature of the site determines the type of bacteria.
ie. interproximal, occlusal, supragingival, subgingival
The oral ecosystem
Transient flora – non-pathogenic or potentially pathogenic flora on skin or mucous membranes; derived from the environment & does not establish permanently.
Origin of normal oral flora
Sterile until birth, bacteria acquired from birth canal from mother
Infant exposed to flora of mother, other people and organisms in the environment
Actinomyces species
Early colonizers
Prevotella intermedia
Late colonizers
2. Dental plaque/Dental Biofilms
Definition: It is a soft, non-mineralised microbial deposit which forms on the hard tissue surfaces of the mouth (and dental prostheses), comprising living and dead bacteria and their products together with the host compounds mainly derived from saliva.
selective adsorption Reforms very rapidly on the clean tooth
surface within seconds Takes 1 week to mature
Function & Clinical significance of pellicle
Function & Clinical significance of pellicle
Damaging functions a. Influence while bacteria colonise the tooth (plays a
role in the formation of Dental Plaque) b. Nutrient supply for some bacteria in dental plaque c. Presence of pellicle alters surface energy of tooth
The oral ecosystem
The mouth has a natural microflora (commensal, indigenous, or resident) which exists in a harmony with the host, (like skin, Nasopharynx, Gastro-intestinal tract including oral cavity)
Gram-staining characteristics
Classified into two major subgroups: Gram-positive (purple) Gram-negative (pink)
What for? Bacteria identification Therapy of bacterial infection
A second childhood is reached if all teeth are lost. Bacteria are very similar to those in a child before tooth eruption.
Introduction of a prosthetic appliance at this stage changes the microbial composition once again. Acrylic denture (Candida) Over 70 y (Staphylococcus aureus, lactobacilli)
1. Acquired pellicle
composed of - salivary glycoproteins (mucins) - No cells, no minerals, no bacteria
structure - surface layer & sub-surface layer - homogenous - very thin 1-10um