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3. Development of Noncavitated Enamel Caries.[Modified from Fejerskov and Clarkson, 1996]
4. Terminology Deposit: something precipitated, delivered, and left, or thrown down, as by a natural process; a natural accumulation
Integument: a natural covering (as skin, shell, or rind); any covering coating, enclosure.
Pellicle: a thin skin or membrane; film, scum
Plaque: a thin flat plate
5. Classification of Surface Coverings: Non-Mineralized Coverings of the Enamel Surface Coverings of embryologic origin
Coverings acquired after eruption of teeth
6. Coverings of Embryologic Origin Primary Enamel Cuticle
Reduced Enamel Epithelium Primary enamel cuticle- Def: Light micorospic term fore an apaprnet organic layer on the enaeml surface fo underupted teeth and sondered to be the final secretory product of the amelolsets. Electorn microspic observations have failed to subbastanitiate the existance of theprimary eneamel cuticle. organic layers that was the final secretory product of the ameloblasts after the formation of enamel was completed, also called the inner cellular and outer cellular layers of the Nasmyth’s membrane. With the electron microscope no organic structure corresponding to a primary enamel cuticle or the dark layer seen between ameloblasets and enamel by phase-co0ntrast microscopy was ever observed. The absence of a primary enamel cuticle in sections studied with electron microscopy suggests that the appearance of a cuticle with light microscopy is probably an artifact due to an optical phenomenon
Reduced Enamel Epithelium and basal lamina. DEF: A few layers of flat cubnnoidfal cells aht are the reamisns of the epitheliala enamel organ afrter the formation of enaeml is complete. The peripheral portion of the reduced enamel epithelium consists of cells derived primarily form the stratum intermedium. Although it is generally agreed that the structures of embryologic origin are lost with or soon after eruption of the teeth, the exact sequence of events accompanying the loss of the embryologic covering of enamel and the acquisition of an acquired coating is not known.
Primary enamel cuticle- Def: Light micorospic term fore an apaprnet organic layer on the enaeml surface fo underupted teeth and sondered to be the final secretory product of the amelolsets. Electorn microspic observations have failed to subbastanitiate the existance of theprimary eneamel cuticle. organic layers that was the final secretory product of the ameloblasts after the formation of enamel was completed, also called the inner cellular and outer cellular layers of the Nasmyth’s membrane. With the electron microscope no organic structure corresponding to a primary enamel cuticle or the dark layer seen between ameloblasets and enamel by phase-co0ntrast microscopy was ever observed. The absence of a primary enamel cuticle in sections studied with electron microscopy suggests that the appearance of a cuticle with light microscopy is probably an artifact due to an optical phenomenon
Reduced Enamel Epithelium and basal lamina. DEF: A few layers of flat cubnnoidfal cells aht are the reamisns of the epitheliala enamel organ afrter the formation of enaeml is complete. The peripheral portion of the reduced enamel epithelium consists of cells derived primarily form the stratum intermedium. Although it is generally agreed that the structures of embryologic origin are lost with or soon after eruption of the teeth, the exact sequence of events accompanying the loss of the embryologic covering of enamel and the acquisition of an acquired coating is not known.
7. Primary Enamel Cuticle Light microscopic term for an apparent organic layer present on the enamel surface of unerupted teeth and considered to be the final secretory product of the ameloblasts. Electron microscopic observations have failed to substantiate the existence of the primary enamel cuticle.
8. Reduced Enamel epithelium A few layers of flat cuboidal cells that are the remains of the epithelial enamel organ after the formation of enamel is complete.
9. Coverings Acquired after Eruption of Teeth
Materia Alba
Food Debris
Dental Plaque
Dental Calculus
10. Materia Alba A soft, white mixture of bacteria, salivary components, desquamated epithelial cells,and disintegrating leukocytes that adheres loosely to the surface of the tooth, dental plaque, or the gingiva.
12. Food Debris Large food particles that can be removed with a stream of water or by rigorous mouth rinsing
13. Dental Plaque A tenacious structure formed on tooth surfaces which contains large numbers of closely packed microorganisms surrounded by salivary components and extracellular material of bacterial origin
15. Dental Calculus
16. Acquired Pellicle Histological Appearance
Composition
Function
17. Acquired Pellicle An organic film on tooth enamel surfaces formed by selective adsorption to apatitic surfaces of specific glycoproteins of salivary origin.
18. Histology Acquired Pellicle
Acellular, scalloped surface with bacterial ghosts and debris
2 hour, 100-700 nm
24 hours, 50-1,000 nm
Can be globular, fibrillar, or granular depending on the nature of the surface it adheres to
Sub-surface pellicle
26. Composition Many possible contributors
Saliva
Bacteria
Epithelium
Gingival crevicular fluid
Hemmorrhage from extraction
Exogeneous material such as the diet
Oral hygiene agents
Dental materials and restorations
Also may be affected by the “enamel fluid” that apparently flows from the pulp to the enamel surface
27. Composition of Acquired Pellicle
There is a definite contribution of bacterial cell walls to the composition of natural pellicle
28. Function of the Acquired Pellicle Lubricating medium between opposing surfaces of enamel
Acquired Pellicle in some instances is necessary for plaque formation.
After the formation of pellicle bacteria begin to adhere to the surface of the pellicle
Protective function
Fluoride
Remineralization
29. Composition and Ecology of the Oral Flora Important Concepts about Bacteria
Caries is an infectious disease
Flora of the mouth
Bacterial composition of the mouth
30. Important Concepts About Bacteria Ecology
Biofilms
Structure, morphology, etc.
Bacterial physiology
Virulence factors
31. Ecology A study of the interrelationships of organisms with their environment and the factors in the environment that determine the distribution and abundance of organisms
Niche: Oral cavity
The factors: Water, temperature, food
The organisms: Streptococcus, Lactobacillus, Actinomyces, and hundreds of others
32. Ecology Ecosystem: A community and their environment: Tongue, tooth, gingival crevice, saliva
Community: Groups of species within each ecosystem: Streptococcus, Lactobacillus
Populations: A species present in a community: Streptococcus mutans
Organisms: A bacteria present in a popualation: Streptococcus mutans
33. Biofilms A non-random assembly of microorganisms attached to a surface
Bacteria in environment exist in two states:
Free living
Complex unattached communities=Biofilm
Characteristics:
Slimy(capsule)
Exposed to liquid(but undisturbed)
Has channels for nutrients
Becomes more anaerobic over time
34. Biofilms Advantages
Community formed
Protected form antibacterial agents
Nutrients concentrated
Examples?(besides plaque!)
Good biofilms vs. bad biofilms
How do we control biofilms?
35. Review of Bacterial Structure Morphology(rods=bacillus, spheres=cocci, spirals=spirochetes)
Aggregation(filaments, chains/ bunches)
Classification(gram+, gram-)
Cell wall structure(peptidoglycan, EPS)
Lifestyles(aerobic, anaerobic, acidogenic, aciduric)
36. Bacterial Physiology Nutritional requirements:
Nitrogen, carbon, sugar, amino acid, lipids, phosphate, sulfate, other ions, iron
Energy production: respiration, fermentation
CHO lactic, pyruvic, acetic, butyric acid
Sucrose glucan(glucosyltransferases)
37. Virulence Factors A bacterial product or strategy that contributes to virulence or pathogenicity of the organism.
Types; those that promote colonization, invasion and those that cause damage to the host
Examples: adhesins/fimbriae adhere to host cells
Bacteriocins kill your neighbors
Capsules evade host immune system
Exoenzymes proteases, siderophores, toxin
38. Caries Is an Infectious Disease Koch’s postulates
Pathogenic vs. nonpathogenic
How do we know bacteria cause caries?
39. Koch’s postulates The bacterium should be found in all people with the disease and the bacterium or its products should be found in parts of the body affected by the disease
The bacterium's should be isolated from the lesions of an infected person and maintained in pure culture
The pure culture, inoculated into a susceptible human volunteer or experimental animal, should produce symptoms of the disease
The same bacterium should be re-isolated in pure culture from the intentionally infected human or animal
40. Problems with Koch’s postulates Implies that virulence is independent of the host
Some bacteria are nonculturable in pure form
Implies that all members of disease-causing species are equally virulent
Implies that one bacterium is responsible for the disease
Ignores human ethics
41. Modified “Koch’s postulates for virulence factors” The gene(s) for the virulence factor should be found and expressed in all strains of the bacteria that cause the disease
Disrupting the gene(s) with a mutation should reduce virulence or introduction of the gene(s) into a bacterial strain that is avirulent now renders it virulent
The gene is expressed during infection
Antibodies to the gene product are protective
42. Pathogenic vs. Nonpathogenic Bacteria are everywhere
Definition of “normal flora”
External factors that upset flora leading to disease
Diet
Host
43. Pathogenic vs. Nonpathogenic Mere presence of S. mutans does not render it “pathogenic”
Capability to cause disease ALWAYS present: It’s all about opportunity!
Colonization sugar, loss of toothbrush, saliva buffering capacity Caries
pH flux, demineralization
44. Virulence Factors of Cariogenic Bacteria Acidogenic (acid production leads to demineralization)
Aciduric (must be able to live in acidic environment)
Adherent (can adhere tightly to surfaces in mouth)
Encapsulated (sticky, prevents neutralization)
Superoxide detoxification (stress defense)
45. Dental Caries Is an Infectious Disease Characteristics of infectious disease:
Transmissible
Treatable with antibiotics(bacterial agent)
Are present at disease site
Early experiments:
Germ-free mice on highly cariogenic diet were caries-free
Transfer of Streptococcus from cariogenic mouse to uninfected mouse resulted in caries
Gnotobiotic mouse infected with the usual suspects on highly cariogenic diet acquired caries
Cohabitation of caries-free mice with cariogenic mice resulted in all cariogenic mice
46. Dental Caries is an Infectious Disease How do we know bacteria cause caries?
Germ free mice do not develop caries
Antibiotics are effective treatment
Oral bacteria can demineralize enamel in vitro
Bacteria are isolatable form the carious lesion
Caries is transmissible from mother to child
Unerupted teeth do not develop caries
47. Etiologic Factors (Summary) Microflora: acidogenic bacteria that colonize the tooth surface
Host: quantity and quality of saliva, the quality of the tooth, etc.
Diet: intake of fermentable carbohydrates, especially sucrose, but also starch
Time: total exposure time to inorganic acids produced by the bacteria of the dental plaque
48. Flora of the mouth Streptococcus mutans
Other Streptococcus spp.
Lactobacillus
Actinobacillus, Actinomyces
Others
49. Streptococcus mutans Gram positive cocci
Facultative anaerobe
Cariogenic
Makes extracellular capsule of dextran and / or fructan from sucrose(smooth and rough variants)
Little or no fimbriae
Able to ferment a variety of sugars including mannitol and sorbitol (homofermentative lactic acid former)
Very acid tolerant
Adhesins: P1 (anti-P1 antibodies render S. mutans non-cariogenic)
Binds to S. sanguis, S. oralis and A viscousus, but not to Veillonella
50. Other Streptococcus spp. Includes S. mitior, S. oralis, S. sanguis. S. Gordonii, S. sobrinus(cariogenic)
Most species found in dental plaque
Majority of species make IgA1 protease (human IgA1 prevents binding of bacteria to tooth sucrose
All make extracellular polysaccharides (glucans) from sucrose via glucoysltransferases
S. oralis early colonizer
S. sanguis: can metabolize arginine as sole energy source, early colonizer, less aciduric (produce ammonia to neutralize acid)
S. salivarius, S. sobrinus: bind to other bacteria
51. Lactobacillus spp. Gram-positive rod
Facultative anaerobe
Homo- and heterofermenter
Grows at low pH
Debated role in caries, used in susceptibility tests
L. acidophilus, L. casei, L. salivarius
52. Actinobacillus actinomycetemcomitans Gram positive rod
Facultative anaerobe
Agent of periodontal disease
Makes IgA protease
Makes a leukotoxin which destroys human and monkey neutrophils(PMN’s)
Non-fermenter of carbohydrates
53. Actinomyces viscosous Gram-positive rod
Facultative anaerobe
Early colonizer
Causes root caries in mice
Two types of fimbriae: Type 1 binds to saliva, Type 2 binds to Streptococci
54. Fusobacterium nucleatum Gram-negative rod
Obligate anaerobe
Colony morphology varies with Fusobacterium species
Agent of periodontal disease
55. Veillonella atypica Gram-negative cocci
Obligate anaerobe
Major resident of the human tongue
Non-fermenter of carbohydrates
56. Autogenic Succession The adaptation of microbial populations to change in the environment
Early dominance of streptococci
Shift to anaerobes and filamentous bacteria
Streptococci shifts to Actinomyces, followed by and increase in Veillonella and Fusobacterium
61. Animal models Germ free mouse
Gnotobiotic mouse
Rat, hamster, monkey
62. Bacterial Colonization of the Oral Cavity Flora of tooth
Flora of the tongue and epithelial surfaces
63. Flora of the Tooth Smooth surface: S. mutans-very significant
S. sanguis
Pits and fissures: S. mutans-very significant
S. salivarius
Lactobacillus spp. very significant
Flora of the root surface: Actinomyces spp.
Streptococcus spp
64. Flora of the Tongue and Epithelial Surfaces S. salivarius: present in greatest amounts, minor significance in caries
S. mitior found on mucous membranes
S. Sanquis
Veillonella
65. Microbial Aspects of Dental Caries Plaque biology
Diagnosis
Prevention and treatment
Current research
66. Plaque Biology How plaque forms
Contributions of diet
Contributions of host
67. “…..yet notwithstanding, my teeth are not so cleaned theory (rubbing with rag and salt) but what here sticketh or groweth between my front ones and my grinders a little white matter which is as thick as if twere batter”“…I then most always saw, with great wonder, that in the said matter there were many very little living animalcules, very prettily a-moving…”-Anthony Von Leeuwenhoek(1632-1723)
68. How plaque forms Acquired pellicle formation
Primary colonizers: S. sanguis, S. oralis, S. salivarius, S. mitis, Actinomyces
Secondary colonizers: S. mutans
Plaque composition (diet, hygiene, saliva, host immunological experience)
Bacterial multiplication plaque build-up
69. Adhesion A mechanism through which cells become attached tenaciously to other cells or to surfaces. Adhesion is considered important in the process of bacterial colonization.
70. Agglutination Bacterial Cells under the influence of specific molecules or cell mechanisms adhere together to form clumps and therefore exhibit agglutination behavior
71. Bacteriocins Antibacterial compounds produced by some streptococci against specific bacteria that may inhibit attachment or growth of the organism in the immediacy of the bacteriocinogenic streptococci.
72. Glucosyltransferase
75. Extracellular Polysaccharide Polymers produced extracellularly by plaque bacteria using sucrose or some other sugar as a substrate. Examples of extracellular polysaccharides are glucans and fructans.
Surface Receptors
76. Formation and Development of Dental Plaque Initial Colonization
first eight hours
rapid, selective
Rapid Bacterial growth
8 hours - 2 days after prophylaxis
Remodeling
2 days and continues indefinitely, organisms remain constant, with increasing organization
77. Contributions of Diet Sugar
Simple sugars diffuse acid into plaque
Bacteria produce acid from sugar
Brief sugar exposure leads to rapid decrease in plaque pH
Repeated sugar consumption leads to demineralization of tooth
78. Roles of Saliva(Host) Attachment (PRPs)
Nutrition (alpha amylase)
Aggregation and clearance
Antibacterial (sIgA, lysozyme, lactoferrin)
Buffering agent (demineralization)
79. Major antimicrobial proteins of human whole saliva Immunoglobulins
Secretory immunoglobulin A
Immunoglobulin G
Immunoglobulin M Nonimmunoglobulin proteins
Lysozyme
Lactoferrin
Salivary peroxidase system (enzyme: SCNŻ-H2O2)
Myeloperoxidase system (enzyme: SCNŻ/halide-H2O2)
Agglutinins
Parotid saliva glycoproteins
Mucins
Secretory immunoglobulin A
Beta-microglobulin
Fibronectic
Histidine-rich proteins (histatins)
Proline-rich proteins
81. Microbial Composition of Plaque Supragingival
plaque/tooth interface
condensed microbial layer
body of the plaque
plaque surface
Fissure
gram+ cocci and short rods
microorganisms and food particles
fewer morphological types
Subgingival
84. Chemical Composition of Plaque 80% water, 20% solids
Protein 40-50% by weight of plaque, carbohydrates 13-18%, lipids 10-14%
Similar to washed streptococcal cells, but higher in protein and lipid components, due to intracellular matrix, higher lipid content is from accumulation of gram- organisms
85. Carbohydrates Glucose predominates
Arabinose, ribose, galactose, fucose
Extracellular polymers(glucans, fructans) or heteropolysacharrides......all produced by microorganisms
reservoir of fermentable carbohydrate for plaque metabolism, function in adherence and coherence
glucans(dextrans, mutans, amylose type)
mutans skeletal link
fructans(levans, inulin type)
86. Proteins From saliva, bacteria or gingival fluid
amylase
lysozyme
IgA(from gingival crevicular fluid)
IgG(from gingival crevicular fluid)
albumin
Glucosyltransferase, glucan hydrolase, hyaluronidase, phosphatases, proteases
87. Inorganic Components Calcium, phosphate, fluoride in higher concentration than in saliva
fluoride 14-20ppm(in saliva .01ppm)
88. Metabolism of Dental Plaques Glycolysis
Concept of Critical pH
Clinical Data on Plaque pH in Relation to Caries
Properties of Cariogenic Plaque
89. Stephan’s Curve Response
90. Diagnosis Bacterial identification methods
Caries activity tests
91. Procedures Obtain plaque sample (high variability)
Preservation and dispersion
Transport
Culture
92. Bacterial identification methods DNA probes
RFLP (restriction fragment length polymorphism)
PCR (polymerase chain reaction)
Ribotyping
Bacteriocin typing
Fluorescent antibodies
93. Requirements for Caries Activity Tests Accurate
Simple
Inexpensive
Quick
Experimentally valid
94. Caries Activity tests Lactobacillus count
Streptococcus count
Buffer capacity test (pH of saliva)
Do they predict future caries activity?
95. Caries Activity Tests
96. Current Research Methods
Physical models
Animal models
97. Fields of Study Bacterial composition of plaque, biofilm characteristics
Sugar, fluoride, pH effects on plaque formation and composition
Bacterial adherence
98. Physical models Mice culture chemostat
Artificial mouth
In vitro model
Intra-oral
99. Animal Models Dental characteristics similar to humans(rat, monkey)
Success depends on animal’s susceptibility, applicable results to humans
Diet, animal care important
Procedures: illicit immune response with vaccine, infect with specific bacteria, alter diet etc., standard scoring methods
100. Control of Dental Plaque Agents that act against the microflora
Agents interfering with bacterial attachment
attacking plaque matrix components
altering the tooth surface
Mechanical removal of plaque
101. Prevention and Treatment Vaccines
Antibiotics/ Antimicrobials
Other
102. Immunology Humoral: IgG
Blood (serum)
Mucosal Immunity: IgA
Location: salivary glands, gut(Peyer’s patches), breast milk, tears, secretions
Types IgA1(CH0), IgA2(lipids)
Mode of action: neutralization of enzymes or toxins by agglutination, inhibition of attachment or colonization
The immune system remembers
103. Use of Antibiotics/ antimicrobials in Dental Caries Safe for intraoral use (safe if swallowed)
Active over range of pH, buffered saliva
Acceptable taste
Able to penetrate and be retained in plaque
Mouthrinse, gel, dentifrice, topical varnish
104. Antibiotics/ Antimicrobials Bacteriostatic vs. Bactericidal
MIC=minimum inhibitory concentration
Testing a possible agent
Absorption characteristics? Mechanism
Goal: control rather than eliminate plaque
105. Concerns with Antibiotics Abuse (doctors, patient)
Antibiotic resistant bacteria
Disrupt flora- opportunistic infections
Decrease efficiency of other producers
Schedule of delivery
Substantivity
106. Other Antibiotics/ Antimicrobials Chlorhexidine (bis biguanides)
Triclosan (phenolics)
Others (phosphates, iodine)
Fluoride
Combination therapy
Oxygenating agents
peroxide
perborate
Quaternary ammonium compounds
107. Prevention of Caries by Plaque Control: The Use of Chlorhexidine in the Control of Caries Indications
Mechanism of action, dosage and delivery
Side effects
staining
parotid gland swelling
desquamation of gingiva
long-term effects
Methods of application
108. Other preventatives/ treatments Lower plaque pH
Interfere with attachment
Attack plaque matrix
Sugar substitutes (Xylitol)
109. Oral Hygiene and Dental Caries Effect of Toothbrushing on Dental Caries
Effect of Flossing on Dental Caries
Professional Prophylaxis
110. Control of Dental Plaque Mechanical removal
toothpick
toothbrush (1498)
commercial development of toothbrushes 18th century little change in design
111. Plaque Detection FD & C no. 3 (erythrosine)
tablet, gel or solution
Two tone dye (erythrosine and malachite green)
Fluorescein sodium
112. Toothbrush Design Lateral profile
Cross-sectional profile
Bristle shape
Bristle firmness
Nylon versus natural
Bristle actions
Handle design
Powered toothbrushes
113. Toothbrushing and Toothbrushing Techniques Is there an ideal toothbrush
Natural vs. Nylon
Handle, head profile and shape
Manual vs. Powered in effectiveness and motions used during brushing
Methods for use
Why are different amounts of time needed by different individuals for toothbrushing?
Modification of toothbrushing techniques applicable to special patient care, patients using prostheses and those under orthodontic care
114. Toothbrushing Methods Horizontal
Fones
Leonard
Stillman
Charters
Bass
The Rolling Stroke
115. Toothbrushing Frequency Time
Frequency
116. Supplemental Brushing Tongue brushing
Special needs
Abutment teeth
Orthodontic appliances
117. Prevention of Caries by Plaque Control: Does a Clean Tooth Decay Advice to Patients
118. Auxiliary Measures Dental floss
Dental floss holder
Dental floss threader
Knitting yarn
Pipe cleaner
Gauze strip
Interdental tip stimulator
119. Dental Floss Remove plaque and debris that adhere to teeth, restorations, orthodontic appliances, fixed prostheses and pontics, gingiva and the interproximal embrasures and around implants
Polishes the surfaces as it removes the debris
Massages the interdental papillae
120. Dental Floss Aides in identifying the presence of subgingival calculus deposits, over hanging restorations, or interproximal carious lesions
May be used as a vehicle for the application of polishing or chemotherapeutic agents to interproximal and subgingival areas
Reduces gingival bleeding
121. Interproximal Plaque Removal Interproximal brushes
Dental floss
Water jets
Toothpicks