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Chap3 edited


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Chap3 edited

  2. 2. Definition <ul><li>It is an irreversible microbial disease of the calcified tissues of the inorganic portion and destruction of the organic substance of the tooth, which often leads to cavitations. </li></ul>
  3. 3. ETIOLOGY OF DENTAL CARIES <ul><li>The Early Theories: </li></ul><ul><li>The legend of the worms </li></ul><ul><li>Endogenous theories </li></ul><ul><li>Chemical theories </li></ul><ul><li>Parasitic theories </li></ul><ul><li>The Recent Theories: </li></ul><ul><li>The Acidogenic theory </li></ul><ul><li>The Proteolytic theory </li></ul><ul><li>The Proteolysis-chelation theory </li></ul><ul><li>Sucrose chelation theory </li></ul>
  4. 4. Miller’s Chemico-parasitic Theory or Acidogenic Theory (1882) <ul><li>“ Dental decay is a chemico-parasitic process consisting of two stages: </li></ul><ul><li>the decalcification of enamel, which results in its total destruction and the decalcification of dentin as a preliminary stage </li></ul><ul><li>the second stage is the dissolution of enamel signifying its total destruction.” </li></ul>
  5. 5. Important factors <ul><li>According to Millers’ there are five important factors which can influence the process of tooth destruction: </li></ul><ul><li>Dietary carbohydrates </li></ul><ul><li>Microorganisms </li></ul><ul><li>Acids (Saliva) </li></ul><ul><li>Dental Plaque Bacteria </li></ul><ul><li>Tooth Structure </li></ul>
  6. 6. Role of Dietary carbohydrates <ul><li>Fermentable dietary carbohydrates play an important role in causation of caries: </li></ul><ul><li>Glucose </li></ul><ul><li>Fructose </li></ul><ul><li>Sucrose (most potent) etc. </li></ul><ul><li>These sugars are easily and rapidly fermented by cariogenic bacteria to produce acids at or near the tooth surface & cause dissolution of hydroxyappetite crystals followed by dentin </li></ul>
  7. 7. <ul><li>Rate of caries attack depends on the form of carbohydrate & the frequency of intake of such carbohydrate </li></ul><ul><li>Risk of caries increases if sugar is taken repeatedly in between the two major meals </li></ul><ul><li>Risk of caries increases greatly if the dietary sugar is sticky in nature which can remain adhered to the tooth surface for a long time </li></ul>
  8. 8. <ul><li>Fermentable dietary carbohydrate due to their low molecular weight gets rapidly diffused into the plaque & hence are easily available for fermentation </li></ul><ul><li>Following the ingestion of these sugars the pH of plaque falls to 4.5-5 within 1-3 mins. & it takes another 10-30 mins. To return to neutrality </li></ul><ul><li>The pH alteration can be recorded with the help of graph called “Stephens curve” </li></ul>
  9. 9. <ul><li>Starches produce little or no caries as they are very slowly diffused into the plaque and also require extra cellular amylase to become hydrolyzed before they can be metabolized by plaque bacteria </li></ul><ul><li>When sucrose is replaced by sorbitol or xylitol (non fermentable) caries formation is greatly reduced </li></ul>
  10. 10. Role of micro organisms <ul><li>Streptococcus mutans plays very role to facilitate in caries formation: </li></ul><ul><li>It can readily ferment dietary carbohydrate to produce acid </li></ul><ul><li>It can synthesize dextran from sucrose, the later helps in adhering the bacteria as well as acid on to the tooth surface </li></ul><ul><li>It has ability to adhere & grow even on hard and smooth surfaces of the teeth </li></ul>
  11. 11. <ul><li>Actinomycotic group </li></ul><ul><li>( A.israelii, A.viscosus, A.nasulandii, etc.) </li></ul><ul><li>Produce caries in the root portion of the teeth </li></ul><ul><li>A.viscosus -most active agent to cause root caries </li></ul><ul><li>Lactobacillus acidophilus - </li></ul><ul><li>progression of dentinal caries </li></ul><ul><li>higher lactobacillus counts in saliva indicates the presence of more active carious lesions in the oral cavity. </li></ul>
  12. 12. Role of acids <ul><li>A large variety of acids are produced in the oral cavity during the process of caries formation due to bacterial fermentation of carbohydrates </li></ul><ul><li>Eg. Lactic acid, Aspartic acid, </li></ul><ul><li>Butyric acid, Acetic acid, </li></ul><ul><li> Propionic acid, Glutamic acid </li></ul>
  13. 13. <ul><li>Metabolism of carbohydrate by bacteria produces organic acid which result in highly localized drop in the pH at plaque- tooth interface </li></ul><ul><li>A drop in local pH causes demineralization of tooth surface </li></ul><ul><li>Below the critical pH (5.5) the tooth minerals act as buffers and loose calcium and phosphate ions into the plaque </li></ul>
  14. 14. <ul><li>When the local pH falls to about 5.0 subsurface demineralization is inevitable in the enamel, which results in formation of incipient caries (where the surface of the enamel remains intact but it is demineralized in the area below the surface the process is called subsurface demineralization) </li></ul><ul><li>When the pH is lower further at the level of about 3.0-4.0 the surface of enamel begins to get etched & resorbed </li></ul>
  15. 15. Role of bacterial plaque <ul><li>The plaque is a thin, transparent film produced on tooth surface consisting predominantly of microorganisms suspended in salivary mucins & extra cellular bacterial polysaccharides </li></ul><ul><li>Also presence of desquamated epithelial cells, leukocytes & food debris, etc. </li></ul>
  16. 16. <ul><li>One hour after formation of acquired pellicle (component of dental plaque) various organisms become attached to it, these organisms are called “pioneering organisms” in dental caries </li></ul><ul><li>These initial organisms lack in caries producing potential since they are mostly aerobic in nature & produce very little amount of acid </li></ul><ul><li>As the plaque matures with time, S.mutuans group becomes more predominant within the plaque & produce organic acids </li></ul>
  17. 17. <ul><li>The dental plaque helps initiation of caries by following ways: </li></ul><ul><li>It harbors the cariogenic bacteria on the tooth surface </li></ul><ul><li>It holds the acids on the tooth surface for a long duration </li></ul><ul><li>It protects the acids produced by the bacteria from getting neutralized </li></ul>
  18. 18. Limitations of acidogenic theory <ul><li>Unable to explain specific areas on the tooth (initiation of smooth surface caries) </li></ul><ul><li>Phenomenon of arrested caries </li></ul><ul><li>Cannot explain subsurface demineralization </li></ul><ul><li>Fails to justify rampant caries </li></ul><ul><li>Cannot explain caries in impacted tooth </li></ul><ul><li>Why some population are caries free? </li></ul>
  19. 19. Classification of dental caries <ul><li>Based on location of the lesion </li></ul><ul><li>Pit and fissure caries </li></ul><ul><li>Smooth surface caries </li></ul><ul><li>Root caries </li></ul><ul><li>Based on the rate of carious progression </li></ul><ul><li>Acute dental caries </li></ul><ul><li>Chronic dental caries </li></ul>
  20. 20. Classification (cont.) <ul><li>Based on virginity of the lesion </li></ul><ul><li>Primary caries </li></ul><ul><li>Secondary caries </li></ul><ul><li>Based on chronology </li></ul><ul><li>Infancy (soother or nursing bottle caries) </li></ul><ul><li>Adolescent caries </li></ul>
  21. 21. Pit & fissure caries <ul><li>This type of lesions occurs in the developmental pit & fissure of the teeth </li></ul>
  22. 22. <ul><li>Pit & fissure caries of the primary type develops in the occlusal surface of molars and premolars, in the buccal; and lingual surface of the molars and in the lingual surface of the maxillary incisors </li></ul><ul><li>This lesion usually appears brown or black, with little softening and opaqueness of the surface when the lesion is examined by a fine explorer tip, a catch point is often felt </li></ul><ul><li>The lesion are smaller in the beginning but become wider as they spread towards the dentin </li></ul>
  23. 23. Smooth surface caries <ul><li>This type of caries develops on the proximal surfaces of the teeth or on the gingival third of the buccal and lingual surfaces </li></ul>
  24. 24. <ul><li>Proximal caries usually begin just below the contact point, and appears in the early stage as a faint white opacity of the enamel without apparent loss of the continuity of the enamel surface and in some cases yellow or brown pigmented area </li></ul><ul><li>As the caries penetrate the enamel, the enamel surrounding the lesion assumes a bluish-white appearance. This is particularly apparent as lateral spread of caries at the DEJ occurs </li></ul>
  25. 25. Root caries <ul><li>Can be defined as ‘a soft, progressive lesion that is found anywhere on the root surface that has lost connective tissue attachment and is exposed to the oral environment’ </li></ul><ul><li>It is predominantly found in dentition of older age groups with significant gingival recession and exposed root surface </li></ul>
  26. 26. <ul><li>Root caries initiates on mineralized cementum and dentin surfaces which have greater organic component then enamel tissue </li></ul><ul><li>Involvement of pulp occurs within a few days (mostly because of the softer nature of the cementum and dentin) </li></ul><ul><li>Enamel may become secondarily involved </li></ul><ul><li>Clinically these lesions are extensive, shallow and saucer shaped, with ill defined margins </li></ul>
  27. 27. Rampant dental caries <ul><li>An acute fulminating type of carious process which is characterized by simultaneous involvement of multiple number of teeth in multiple surfaces </li></ul>
  28. 28. <ul><li>Rapid coronal destruction occurs within a short span of time, causing early involvement of the pulp </li></ul><ul><li>The common age of occurrence of rampant caries is about 4-8 years for the deciduous teeth & 11-19 years for the permanent teeth </li></ul><ul><li>This type of caries attacks those surfaces of teeth, which are otherwise considered immune to the disease </li></ul>
  29. 29. Nursing bottle caries <ul><li>Acute caries lesions which occurs among those children which take milk or fruit juices by the nursing bottle for a considerable longer duration of time preferably during sleep </li></ul>
  30. 30. <ul><li>It commonly occurs in the upper anterior teeth (as these are constantly coming in contact with the sweetened milk) while the lower teeth are not usually affected as they remain under the cover of the tongue </li></ul><ul><li>It causes early pulp involvement because they spread at a very rapid pace and as a result the pulp hardly gets any time to protect itself </li></ul>
  31. 31. Arrested caries <ul><li>It is a lesion whose progression is ceased after the initial development </li></ul><ul><li>It can occur both in enamel and dentin </li></ul>
  32. 32. Recurrent caries <ul><li>It refers to a carious lesion that begins around the margins or at the base of a preexisting defective restoration </li></ul>
  33. 33. Radiation caries <ul><li>Patients receiving large doses of radiation in the head & neck region often develop a specific type of large “caries like lesions” in the cervical of teeth </li></ul><ul><li>They often surround the entire crowns of the affected teeth </li></ul><ul><li>It may be due to the reduced salivary secretions, secondary to the radiotherapy </li></ul>
  34. 34. Thank you The end