cariology second part.pptxcariology second part.

cariology second part.

1. Dental Cariology Part 2 ILOS: 1- I dentify different characteristics of dental caries . 2- Describe histological features of enamel and dentin caries. 3- Outline t he different reactions of the pulp dentin complex to dental caries. 4- Define Caries risk assessment.

2. Clinical Characteristics &Histopathology of dental caries

3. Enamel is composed of hydroxyapatite crystals which arranged in long columnar rods (prisms) and inter-rod enamel. These enamel rods are formed by the activity of the ameloblasts . Enamel caries

4. - Mineralization process is characterized by alternating phases of high activity & low activity. ( Striae of Retzius ) - Crystals are separated by i ntercrystalline spaces filled with water and organic content. Both allow for movement of water and ions .

5. The movement of ions through carious enamel leads to acid dissolution of dentin before actual cavitation of the enamel surface . These acids attack dentinal tubules initiating a pulpal response .

6. Appears as an inverted V-shaped with a wide area of involvement at the dentino - enamel junction (D.E.J.) as the caries progresses parallel to the direction of the enamel rods . Pits and fissures surface caries :

7. It have a broad area of origin and a conical or pointed extension towards DEJ as the path of ingress of caries parallel to the long axis of enamel rods. Smooth surface caries:

8. It is U-shaped in cross section with its base on the surface of the root progress more rapidly than coronal caries lesions because of the lack of protection from an enamel covering. Root caries:

9. - Progression of dental caries in dentin is different from progression in enamel because of the structural differences of dentin. Dentin caries Producing the characteristic second cone of caries activity in dentin Rapid lateral expansion of the caries lesion along the DEJ

10. Histological Structure of enamel caries:

11. Histological Structure of enamel caries: Enamel caries is formed of 4 zones 1-Translucent zone: - The deepest zone is the translucent zone. The name refers to its structurless appearance. - Pore volume is 1 %

12. 2- Dark zone: Located adjacent & superficial to translucent zone. Contains small pores , Pore volume 2- 4%

13. 3- The body of the Lesion: - It is the largest portion. The striae of Ritzius are well demarcated indicating preferential dissolution along the areas of high organic contents . - Pore volume 5%

14. 4- The surface zone: (Intact zone) It is relatively unaffected by caries with minimal demineralization. Pore volume less than 5%.

15. Zones of dentin caries: 5 different zones have been described in carious dentin:

16. Zone 1: Normal dentin: It is the inner most layer. There are no bacteria in the tubules. Zone 2: Transparent dentin:(affected dentin) It is the zone of carious dentin . There are no bacteria present (affected dentinal tubules is obliterated by minerals precipetate . Zone 3: Sub transparent dentin: (affected dentin, demineralized) It is the zone of demineralization and damage of odontoblastic processes. There are no bacteria in this zone . It Can be repaired and remineralized .

17. Zone 4: Turbid dentin ( Contaminated) - It is the zone of bacterial invasion. - The collagen is irreversibly denatured. - Canꞌt be remineralized . - Canꞌt be repaired. Zone 5 : Infected dentin (Necrotic) - It is the outermost zone. - Great number of bacteria is found - Canꞌt be remineralized & canꞌt be repaired.

18. Three levels of dentin reaction to caries can be recognized: Reaction of dentin-pulp complex to caries attack: (1) Reaction to mild attack (2) Reaction to moderate intensity attack (3) Reaction to severe irritation

19. (1) Reaction to mild attack - Demineralized dentin can repaired by remineralization of the intertubular dentin and apposition of peri -tubular dentin . As long as the pulp remains vital with adequate blood circulation

20. This peritubular dentin is called sclerotic dentin : Which is characterized by :- Has more mineral content ii. Shiny iii. Darker color and hard to the explorer tip.

21. iv. Less permeable due to decrease in the tubule lumen diameter. v. There are crystalline precipitates in the lumen of the dentinal tubules in front of a demineralization zone (affected dentin).

22. 2) Reaction to moderate intensity attack: More intense caries activity results in bacterial invasion of the dentin . - The infected dentin contains pathogenic materials leading to degeneration and death of odontoblast forming dead tracts .

23. (3) Reaction to severe irritation: Acute rapidly advancing caries with very high levels of acid production overpowers dentinal defenses and results in infection, abscess and death of the pulp.

24. Caries risk assessment

25. “ Caries risk defined as The probability that a specific number of new lesions will develop and/or a specific number of existing lesions will progress.

26. Caries risk assessment could be performed using: the cariogram model

27. or by testing saliva for cariogenic microorganism , flow and its buffering capacity.

28. Some systems permit monitoring the lesion severity (depth) over time, one of these systems : E0= no lesion, E1=lesion confined to the outer half of enamel, E2= lesion confined to the inner half of enamel, D1=lesion extends to the outer third of dentin, D2= lesion extends to the middle third of dentin, D3= lesion extends to the inner third of dentin.

29. Also, as ICDAS system Do you remember it

30. Mount’s classification: (the Si/ Sta concept) • A new classification of cavity based on specifying the size of the lesion. Site-size • The sites include: Site 1 : Pits and fissures on the occlusal surfaces of posterior teeth. Site 2: Contact areas between any pair of teeth, anteriors or posteriors. Site 3: Cervical areas related to gingival tissues including exposed root surfaces.

31. • The sizes that can be readily identified include: Size 0 : Initial lesion at any site but not yet resulted in surface cavitation. It can possibly be healed by remineralization. Size 1: Smallest minimal lesion requiring operative intervention. The cavity is into dentin just beyond healing by remineralization.

32. Size 2: Moderate-sized cavity. There is still sufficient sound tooth structure. Size 3: The cavity needs to be modified to provide some protection for the remaining tooth tissues. Size 4: The cavity is extensive, following the loss of cusp from a posterior teeth or an incisal edge from an anterior. (Bulk loss)

33. Finally ,the patient could be classified according to caries risk assessments into: 1. No care advised :( NCA) low caries risk values. 2. Preventive care advised : ( PCA) patient is at risk and has initial lesions that could be treated by non-surgical model ( biological/medical model) 3. Operative care advised : ( OCA) the lesions are irreversible and must be treated operatively .

34. Caries Risk Assessment guides the clinician to: 1- Control preventive measures. 2- Timing of recall appointments. 3- Types of restorative procedures and materials. 4- Prediction of prognosis.