Week 9 - Pulp Protection - Foundations and Clinical Characteristics

Question 1

Where are pulp horns and the clinical significance of location

Answer 1

• Under the cups the chamber extends into pulp horn which are especially prominent under the buccal cusps of premolar teeth and the mesiobuccally cusp of molar teeth
• Clinical significance: pulp horns must be avoided in dental restoration to prevent exposure of pulp tissue

Question 2

What is primary dentine

Answer 2

• first formed dentine that makes up the most of the tooth structure
• formed before the tooth erupts
• outlines pulp chamber
• included circumpulpal and mantle dentine

Question 3

What is secondary dentine

Answer 3

• Dentine which develops after root formation has been completed
• This dentin is continually produced by odontoblasts throughout life resulting in a gradual reduction in the size of the pulp cavity
• Structure is less regular but mostly similar to primary dentine
• Deposition of secondary dentine is not even and a greater amount is deposited on the floor and root of the pulp chamber – leads to an asymmetrical reduction in size and shape
• Some evidence suggests that the tubules of secondary dentine sclerose (fill with calcified material) more readily than primary dentine – this process tends to reduce the overall permeability of dentine thereby protecting the pulp

Question 4

what is the clinical significance of secondary dentin secretion

Answer 4

Clinical significance: change in the pulp space can be seen in radiographs and are important in determining the form of cavity preparation for some restorative procedures
In a young patient there is a substantial risk of involving the pulp by exposing pulp horn during preparation whereas in the older patient where the pulp horn has receded there is less danger

Question 5

What is tertiary dentine

Answer 5

• Dentine formed in response to various stimuli e.g.. dental caries, tooth wear (attrition, abrasion), fractures, cavity preparation
• Includes reactive and reparative dentine
• Tertiary dentine is produced only by those cells directly affected by the stimulus
• The quality and quantity of tertiary dentine produced are related to the cellular response initiated which depends upon the intensity and duration of the stimuli
• Tertiary dentine may have tubules continuous with those of secondary dentine, sparse and irregularly arranged tubules or no tubules
• The cells forming tertiary dentine line its surface or become included in the dentine (osteodentine)

Question 6

what is reactive/reactionary dentine

Answer 6

dentine deposited by existing odontoblasts

Question 7

What is reparative dentine

Answer 7

dentine deposited by newly differentiated odontoblast like cells

Question 8

What is dental pulp

Answer 8

• Soft connective tissue consisting of cells embedded within a collagenous extracellular matric that supports the dentine

Question 9

What is the composition of dental pulp

Answer 9

• 75% water
• 25% organic matrix (type 1 collage, type 3 collagen ect

Question 10

What are the 4 zones in dental pulp

Answer 10

1. The odontoblastic zone at the pulp periphery
2. A cell free zone of Weil beneath the odontoblasts (prominent in the coronal pulp)
3. A cell rich zone where density is high
4. The pulp core charactertised by the major vessels and nerves of the pulp

Question 11

What are the different types of pulp irritants

Answer 11

If leakage of chemical irritants form biomaterials or bacteria occurs there causes irritation of pulp
- Microbial irritation
- Mechanical irritation
- Thermal irritation
- Chemical irritation
- Radiant irritation

Question 12

What is microbial irritation

Answer 12

• Bacteria that survive drying under the killing material remain viable for many years
• Such dormant bacteria can become active when moisture is reintroduced as a result of marginal percolation of various filling materials, poor marginal seals improper condensation of fillings etc

Question 13

What is mechanical and thermal irritation

Answer 13

Depends on:
- Speed of rotation
- Size and shape of bur
- Amount of moisture/water
- Coolant

Question 14

What are chemical irritants

Answer 14

They are
- Various filling materials
- Various medicaments used for desensitization or dehydration of dentin
- Dentin sterilizing agents such as phenol, silver nitrate, eugenol etc

Question 15

What are radiant irritants

Answer 15

• X ray radiation
• Lazer beam
• Uptake of radium containing water cause radiant irritation

Question 16

pulpal irritation leads to what

Answer 16

pulpal inflammation

Question 17

What is used in case of exposure of pulp

Answer 17

• pulp capping
• pulpotomy
• liners

Question 18

What is pulp capping

Answer 18

A procedure that places a protective material (usually the same as liners) directly on the pulp to preserve it vitality

Question 19

What are the different types of pulp capping

Answer 19

direct pulp capping
indirect pulp capping

Question 20

what is direct pulp capping

Answer 20

• Placement of the agent directly on the exposed pulp
• Used when accidental exposure of pulp when excavating deep caries
• pulp should be healthy and uninfected to use capping
• Area of exposure should not be more than 0.5mm
• After exposure isolate the tooth immediately to prevent contamination

Question 21

What is indirect pulp capping

Answer 21

• Used when pulp isn’t exposed but decay is very close to the pulp
• A protective material is placed over it to allow healing and remineralization
• Indication – deep carious lesion close to pulp, excessive crown preparation, traumatic tooth fraction

Question 22

What is pulpotomy

Answer 22

Procedure when the coronal portion of the tooth’s pulp (nerve tissue) is removed while the radicular (root) pulps left intact.
- Used when pulp of young teeth have been exposed by dentinal caries
- Involves removal of infected coronal pulp tissue
- It is safe for patients with history of rheumatic fever
- This procedure is more preferable in deciduous teeth with chronic pulpitis
- MTA have proof of this being effective to induce dentinal bridge

Question 23

What are dentine liners

Answer 23

A liner for dentin is a thin protective layer of dental material placed on the exposed dentin surface before placing a permanent filling or restoration
- Creates a barrier against the passage of irritants from cements or other restorative material and to reduce the sensitivity of freshy cut dentin
- Made of a suspension of CaOH in an organic liquid such as methyl ethyl ketone or ethyl alcohol

Question 24

What are dentine liners made of

Answer 24

Made of a suspension of CaOH in an organic liquid such as methyl ethyl ketone or ethyl alcohol

Question 25

What is a cavity varnish

Answer 25

- thin protective coating applied to the walls and floor of a cavity preparation before placing a restoration - serves as a barrier between the restorations and the dentinal tubules - varnish is confined to the dentin - prevents microleakage (fluid moving under the filling) - applied using a brush, wire loop or a small pledge of cotton

Question 26

When do you need to use cavity varnish

Answer 26

in silicate or silico phosphate restoration – varnish confined to dentin

Question 27

When do you not need to use a cavity varnish

Answer 27

when using - Composite resins - Glass ionomer - Therapeutic action from overlying cement

Question 28

What are dentin bases

Answer 28

- a layer of cement on the floor of a deep cavity preparation often over a liner to replace missing dentin and protect the pulp A base is a layer of cement placed beneath the permanent restoration to encourage recovery of the injured pulp and to protect it against numerous types of insults to which it may be subjected. The insults may be thermal or chemical or galvanic.

Question 29

What is a high strength base

Answer 29

- Provides thermal protection of pulp and mechanical support for the restorations - E.g. Zn phosphate, Zn poly carboxylate, GIC, RMGI - Applied as a thick layer - Provides mechanical support under large restorations – often used in deep cavities with significant dentin loss

Question 30

What is a low strength base

Answer 30

- Has minimal strength and rigidity - Acts as a barrier to irritating chemicals and to provide therapeutic effect to pulp - E.g. Ca hydroxide, ZnOE - In case of deep excavation its necessary to overlay CaOH with RMGI or a strong base - Applied in a thin layer - Provides pulpal protection but not structural support

Question 31

What are patient level risk factors ascertained by patient history

Answer 31

- head and neck radiation treatment - uses medication - social background - dental attendance - fluoride exposure - oral hygiene practice - dietary intake

Question 32

What are clinical level risk factors determined through introral soft and hard tissue examination and diagnostic testing

Answer 32

- salivary glands reducing the production of sufficient amount and quality of saliva that have a direct impact in development and progression of caries - absence of professional follow up in patient difficult early detection of caries increasing morbidity - decrease/absence concentration of fluoride decrease the remineralization process (replacement of hydroxyapatite by fluorapatite) - increase of digestible carbohydrates with high fermentable capacity (refine sugars) decrease the pH and trigger enamel demineralisation)