Pulpal and Periapical Pathology

Question 1

What are the steps of biofilm formation?

Answer 1

1. Deposition of a conditioning film.
2. Adhesion and colonization of planktonic microorganisms in an extracellular amorphous matrix (EPS).
3. Co-adhesion of other organisms.
4. Detachment into surroundings.

Question 2

What is a prerequisite for establishment of primary endodontic infections?

Answer 2

Pulpal necrosis.

Question 3

Does dentinal exposure present a significant route of infection?

Answer 3

No UNLESS:
- dentinal thickness is reduce.
- dentinal permeability is increased.

Question 4

Name 3 chronic inflammatory cells.

Answer 4

macrophages, plasma cells, lymphocytes.

Question 5

What are the two types of host respone?

Answer 5

Inflammatory and immunological response.

Question 6

Which part of the canal has less microorganisms? Why? What nutrients predominate in the area.

Answer 6

APICAL region:
- lower oxygen levels.
- nutrients: proteins and glycoproteins from periradicular tissues.
LOWER BACTERIAL COUNTS.

Question 7

What are the two fates of a pulp that has become inflamed? What does this depend on (5)?

Answer 7

• stay inflamed for a long time.
• undergo necrosis slowly or rapidly.

Depends on: host resistance, bacterial virulence, inflammatory response, amount of circulation, lymphatic drainage.

Question 8

What are 4 ways in which a vital pulp offers protection?

Answer 8

1. outward flow of dentinal fluid.
2. tubule contents.
3. host defense molecules.
4. tertiary dentine.

Question 9

What is the inflammatory response?

Answer 9

NON specific response.
- inflammatory mediators: bradykinin, histamine, arachinoid acid, neuropeptides.

Question 10

How do caries lead to pulpal inflammation?

Answer 10

o Allows bacterial penetration of tubules and destruction of dentine.
- Microbial irritants include TOXINS and BY PRODUCTS.
- These cause the pulp to be INFILTRATED at the base of the carious tubule by CHRONIC INFLAMMATORY CELLS (macrophages, lymphocytes, plasma cells).

Question 11

What is the immunological response?

Answer 11

SPECIFIC response.
- immunocompetent cells: T and B lymphocytes, macrophages, dendritic cells.
- potential antigens: bacterial toxins.

Question 12

How are microbes distributed in the root canal system?

Answer 12

• most located in SUSPENSION (planktonic bacteria) within the canal.
• some live in biofilms on canal walls, dentinal tubules, accessory/lateral canals, isthmi, apical delta.

Question 13

How can dental factors cause pulpal inflammation? (6)

Answer 13

o Crown/ bridge preparation.
o Accidental exposure.
o Inadequate water spray on high-speed drill.
o Over drying exposed dentine.
o Inadequate isolation of teeth from saliva.
o Failure to adequately protect and seal tubules.

Question 14

What happens once the pulp is exposed?

Answer 14

• Pulp becomes infiltrated by PMNs to form an area of liquefaction necrosis at the site.
• Microbes can then colonize and persist at the site of necrosis.

Question 15

Does micorbial colonization become easier as the microbes reach closer to the pulp? Why/why not?

Answer 15

YES, because dentinal tubules are largest closest to the pulp (2.5μm), giving space for microbial colonization (microbial diameter 0.2-0.7 μm).

Question 16

What is REQUIRED to cause periapical periodontitis?

Answer 16

microbes.

Question 17

What is a biofilm?

Answer 17

a sessile, multi-cellular microbial community characterized by cells that are firmly attached to a surface and enmeshed in a self-produced matrix of extracellular polymeric substances (EPS).

Question 18

Why does the body form apical lesions upon root canal infection?

Answer 18

apical lesions are PROTECTIVE, PREVENT HIGHLY PATHOGENIC BACTERIA from SPREADING TO ADJACENT BONE AND REMOTE SITES IN THE BODY.

Question 19

What are two requirements to develop apical periodontitis?

Answer 19

Necrotic pulp AND microbial infection

Question 20

How can traumatic accident cause pulpal inflammation? (2 types).

Answer 20

1. Impact injury (crown remains intact, microcracks in enamel allow bacteria to reach the pulp. Blood flow is damaged).
2. fracture of crown (can result in pulpal exposure).

Question 21

does pulpal necrosis cause periapical periodontitis?

Answer 21

• Pulpal necrosis DOES NOT cause periapical periodontist. HOWEVER with pulpal necrosis the pulp has LOST its ability to DEFEND ITSELF, it will become infected with bacteria. The microbes will colonize the root canal system and end up producing their toxins which cause destruction of the adjacent bony tissue.

Question 22

How can orthodontic procedures cause pulpal inflammation?

Answer 22

if a tooth is moved through bone too quickly, that may disrupt its blood supply and cause damage

Question 23

What are 5 types of mechanical injury to the pulp which can cause pulpal inflammation?

Answer 23

1. traumatic accident.
2. iatrogenic damage (ex. tooth preparation).
3. excessive orthodontic procedures.
4. sub-gingival scaling.
5. abrasion/ attrition.

Question 24

Why is bacterial invasion of dentinal tubules easier in necrotic pulp?

Answer 24

• no host defenses, no tertiary dentine, no outward flow of dentinal fluid.

Question 25

Which part of the canal has most microorganisms? Why? What nutrients predominate in the area.

Answer 25

CORONAL region:
- higher oxygen levels.
- nutrients: carbohydrates.
HIGHER BACTERIAL COUNTS

Question 26

What distance away does bacteria have to be to cause pulpal inflammation?

Answer 26

0.5mm

Question 27

What causes pulpal necrosis? (physiological process)

Answer 27

1. lesion progression.
2. increased tissue pressure, inability of pulpal tissue to expand —> lack of collateral circulation.
3. pulpal necrosis + microbes.
4. periapical periodontitis

Question 28

How many species of endodontic microbes are there?

Answer 28

1-12.

Question 29

What are the three main types of microorganisms in the infected root canal system?

Answer 29

• Gram negative obligately anaerobic bacteria.
• viruses and fungi.

Question 30

How can chemical factors cause pulpal inflammation? (2)

Answer 30

o Erosion
o Inappropriate use of acidic dental materials (acid etch and certain unbound components of resin materials)

Question 31

Are planktonic bacteria or biofilm more difficult to treat in a root canal?

Answer 31

 Biofilms PROTECT microorganisms from adverse ENVIRONMENTAL CHANGES and EFFECTS OF BIOCIDES more than 1000 TIMES in comparison with the same bacteria in planktonic suspension.
 Hence much more difficult to remove from the root canal system.

Question 32

Different species dominate at different stages or root canal infection. What does this depend on?

Answer 32

• Availability of nutrition and oxygen level.
• local pH

Question 33

What are 3 causes of pulpal inflammation?

Answer 33

• micro-organism (most common). (ex. caries)
• mechanical trauma (ex. mechanical injury or dental factors)
• chemical irritation.

Question 34

Name some common bacteria found in infected root canals (9)

Answer 34

• prevotella, porphyromonas, peptostreptococcus, streptococcus, fusobacterium, eubacterium, veillonella, actinomyces, lactobacillus.

Question 35

What is apical periodontitis?

Answer 35

An inflammatory disease of microbial etiology caused by infection of the root canal system which results in bone resorption around the root(s).