Dental caries22

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Oral Pathology I
Third Year

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Dental caries22

  1. 1. By Dr. Wael Mohamed Swelam
  2. 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. 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. 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. 5. Carbohydrates Microorganisms Caries Monday, January 20, 2014Dr. Wael Swelam
  6. 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. 7. Carbohydrates      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. 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. 9. Bacteria Commonly Isolated from the Oral Cavity Gram positive bacteria Gram Negative Bacteria Actinomyces Arachnia Bifidobacterium Lactobacillus Micrococcus Neisseria Propionibacterium Rothia Streptococcus • • • • • • • • • • • • • • Actinobacillus Bacteroides Branhanelia Capnocytophaga Eldenella Fusobacterium Peptostreptococcus Haemophilus Leptotrichia Selenomonas Simonsiella Treponema Veilonella Wolinella Monday, January 20, 2014Dr. Wael Swelam
  10. 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. 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. 12. Dental Plaque is a biofilm Monday, January 20, 2014Dr. Wael Swelam
  13. 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. 14. Stephan Curve Monday, January 20, 2014Dr. Wael Swelam
  15. 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. 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. 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. 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. 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. 20. Dental Caries Enamel Caries Smooth surface caries Dentin Caries Cementum Caries (Root caries) Pit and fissure caries Monday, January 20, 2014Dr. Wael Swelam

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