Dental Caries Short Essays

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Dental Caries

Question 1. Zinc polycarboxylate cement.
Answer:

Composition:

1. Powder:

  • Zinc oxide Basic ingredient
  • Magnesium oxide
    • Modifier
    • Aids in sintering
  • Bismuth and aluminum oxide occur in small amounts
  • Stannous fluoride
    • Increase strength
    • Modifies setting time
    • Imparts anti-cariogenic properties

2. Liquid:

  • Polyacrylic acid
  • The copolymer of acrylic acid with other unsaturated carboxylic acids

Properties:

1. Physical properties:

Dental Caries Zinc polycarboxylate cement Physical properties

2. Biocompatibility:

  • Mild pulpal response

3. Adhesion:

  • Excellent adhesion
  • Polyacrylic acid reacts with calcium ions via car¬boxyl groups on the surface of enamel and dentin
  • The bond strength of enamel is greater

4. Optical properties:

  • It is very opaque

5. Thermal properties:

  • It is a thermal insulator

Uses:

  • Cementation of restoration
  • As bases and liners
  • As intermediate restoration
  • Luting of permanent restoration
  • In orthodontics cementation of bands
  • In endodontics as root canal filling material

Question 2. Define and classify caries. Add a note on the diagnosis of caries.

Answer:

Caries Definition:

  • Dental caries is defined as a multifactorial, transmissible, infectious oral disease caused primarily by the complex interaction of cariogenic oral flora with fermentable dietary carbohydrates on the tooth surface over time

Caries Classification:

1. According to location

  • Primary caries
    • Pit and fissure caries
    • Smooth surface caries
    • Root caries
  • Secondary caries

2. According to the direction

  • Forward caries
  • Backward caries

3. According to the extent

  • Incipient caries
  • Cavitated caries

4. According to rate

  • Acute caries
  • Chronic caries

5. According to a histological depth of penetration

  • Enamel caries
  • Dentinal caries

Diagnosis Of Caries

1. Visual Tactile Examination:

  • Visual method:
    • Cavitation
    • Opacification
    • Discoloration
    • Surface roughness
  • Tactile method:
    • Softness of enamel
    • Catch obtained by an explorer
  • Illumination:
    • UV light creates decreased fluorescent in carious lesions as compared to healthy tissue
    • Cavitation produces echoes of higher amplitude

2. Caries detecting dyes:

  • Dyes for enamel caries:
    • Procion Staining is irreversible
    • Reacts with nitrogen and hydroxyl groups
    • Calcein Bounds with calcium
    • Zyglo ZL22 Visible by UV illumination
  • Dyes for dentin caries:
    • Infected and affected dentin layers are present
    • Basic Fuschia in propylene glycol stains only the infected dentin
  • Radiographic methods:
    • Requires 50% tooth destruction
    • Seen as a radiolucent lesion

Caries Types

1. Conventional:

  • IOPA
  • Bitewing For proximal caries
  • Occlusal
  • Xeroradiography
  • Edge enhancement

2. Advanced:

  • Digital radiography
  • Subtraction radiography
  • RVG

3. Electrical Conductance:

  • Electrical conductivity is directly proportional to the amount of demineralization

4. Lasers:

Question 3. Methods of Diagnosis of proximal caries.

Answer:

1. Bitewing Radiograph:

  • It includes occlusal surfaces of both arches in the same radiograph
  • It must be differentiated from cervical bum out
  • It describes the extent of the carious lesion
    • 0 Normal
    • 1 – Only enamel is involved
    • 2-  Caries extends upto DEJ/Dentinoenamel junction
    • 3 – Caries involve the whole of the enamel and the outer half of the dentin
    • 4 – Caries involve complete enamel and dentin

2. – Separation of Teeth:

  • With the help of separators, teeth are moved apart and viewed for carious lesions

3. Dental Floss:

  • Dental floss is used through the proximal surface
  • Fraying of it indicates the presence of a lesion

4. Transillumination:

  • It is based on the refractory index between the carious and sound tooth
  • Carious tooth appears as a dark shadow when compared to normal tooth

Question 4. Pit and fissure Caries.

Answer:

  • The shape of pit and fissure make it more susceptible to caries

Pit and fissure Caries Features:

  • Initial Brown/Black in color
  • Catch with an explorer
  • DecalciFication of enamel
  • Enamel involvement in the direction of the rod
  • Shape Triangular, base towards DE
  • Progress to the involvement of dentinal tubules
  • Result in cavitation
  • Undermining of enamel

Dental Caries Magnified schematic presentation of smooth surface caries

Question 5. Root Caries/Cemental Caries.

Answer:

  • It is a soft, progressive lesion that is found anywhere on the root surface that has lost its connective tissue attachment and is exposed to the environment

Root Caries Features:

  • Periodontal attachment loss
  • Soft, irregular lesion
  • Round or oval in shape
  • Irregular outline
  • Common in males
  • Common in mandibular molars

Etiology:

  • Streptococcus mutants
  • Lactobacillus
  • Actinobacillus

Root Caries Prevention:

  • Plaque removal
  • Diet modification
  • Use of topical fluoride
  • Soft tissue management
  • Use of xylitol-containing chewing gum

Question 6. Roles of fluoride in caries prevention

Answer:

1. Increased enamel resistance/ reduction in enamel solubility

  • Dental caries involves the dissolution of enamel by acid formation
  • This dissolution is inhibited by fluoride as the fluoride forms fluorapatite which reduces enamel solubility
  • Fluoride reduces enamel solubility also by promoting the precipitation of hydroxyapatite and phosphate mineral
  • Fluoride inhibits demineralization by
  • Reducing bacterial acid production
  • Reducing equilibrium solubility of apatite
  • By fluoridation of apatite crystal

2. Increased rate of post-eruptive maturation

  • Newly erupted teeth have hypomineralised areas and the enamel surface is also prone to dental caries
  • Fluoride increases the rate of mineralization of these areas
  • Organic material is also deposited over the enamel surface which increases its resistance to dental caries

3. Remineralization of incipient lesions

  • Fluoride enhances remineralization by the deposition of minerals into the damaged areas
  • This reduces enamel solubility through the growth of crystals which are more resistant to acid
  • Fluoride enhances remineralization from calcium phosphate solution by the formation of calcium fluoride which prevents hydroxyapatite crystal growth

4. Interference with microorganisms

In two ways

  • In high-concentration bacteriocidal
    • By reducing plaque
  • In low-concentration bacteriostatic
    • Inhibits enzymes responsible for acid metabolism

5. Modification in tooth morphology

  • If fluoride is ingested during tooth development it results in the formation of
  • More caries-resistant tooth
  • A tooth with smaller and shallow fissures
  • Smaller diameter and cusp depth
  • All these make them more self-cleansing

Question 7. Zones of enamel caries

Answer:

1. Zone 1 Translucent zone

  • It is the deepest zone
  • It is slightly more porous
  • Contains 1% by volume
  • Pores are larger than usual pores seen in normal enamel
  • Dissolution of mineral occurs at the junction of prismatic and interprismatic enamel

2. Zone 2 Dark zone

  • Located superficial to the translucent zone
  • Excessive demineralization of enamel occurs
  • It is narrow in rapidly advancing caries and wide in slowly advancing caries
  • Contains 24% pore volume
  • Pores are smaller than that of the translucent zone
  • There is some degree of remineralization

3. Zone 3 body of the lesion

  • Present between dark zone and surface zone
  • Represents the area of greatest demineralization
  • Pore volume is between 525%
  • Contains larger apatite crystals
  • Reprecipitation of minerals occurs
  • Dissolution of minerals occurs
  • Lost minerals are replaced by unbound water and organic matters

4. Zone 4 Surface zone

  • It remains unaffected
  • It is 40 pm thick
  • Surface remineralization occurs due to the active precipitation of mineral ions

Question 8. Zones of dentinal caries.

Answer:

  • Zone 1: Normal dentin
    • Zone of fatty degeneration of odontoblast
    • Represents thinner most layer of carious dentin
    • No crystals are present in the lumen of tubules
    • No bacteria present in tubules
    • Intertubular dentin has normal collagen

Zone 2: Subtransparent dentin

    • Zone of dentinal sclerosis characterized by deposition of calcium salts in dentinal tubules
    • The superficial layer shows areas of demineralization and damage of odontoblastic processes
    • It is capable of remineralization
    • No bacteria is present in tubules

Zone 3: Transparent dentin

  • Zone of decalcification of dentin, a narrow zone preceding bacterial invasion
  • It is softer than normal dentin
  • Large crystals are present within the lumen of dentinal tubules
  • No bacteria is present in tubules
  • It is capable of self-repair and remineralization

Zone 4: Turbid dentin

  • Zone of bacteria] invasion of decalcified but intact dentin
  • Widening and distortion of dentinal tubules
  • Cannot undergo self-repair or remineralization
  • Must be removed before restorative treatment

Zone 5: Infected dentin

  • Zone of decomposed dentin
  • It is the outermost zone of carious dentin
  • Characterized by complete destruction of dentinal tubules
  • Areas of decomposition of dentin occur along the direction of dentinal tubules called liquefaction foci of Miller
  • Transverse clefts are seen due to the decomposition of dentin
  • Bacteria invade and destroy peri and intertubular dentin

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