Aetiology, Pathology, Microbiology, Immunology of pulpal and periapical disease

Question 1

Through what routes might micro-orgs enter into the pulp/root canal and cause pulpal/peri-apical disease

Answer 1

• Dental caries
• Cracks
• Trauma
• Resorption
• Perio-related
• Microleakage

Question 2

What is the pulp responsible for

Answer 2

• Sensory response
• Dentine tubule sclerosis
• Tertiary dentine (reparative and reactionary)
• Inflammatory response

Question 3

When might micro-org penetration damage be reversible and how can these cases be treated

Answer 3

• Before they penetrate into pulp/deep into pulp

- Treatment by removing dental caries if present and place an effective and appropriate restoration

Question 4

What can happen to the pulp if the damage is irreversible and how can these cases be treated

Answer 4

• The pulp can become inflamed, and areas of necrotic tissue and abscess formation
• Treatment either RCT or extraction

Question 5

What can the inflammatory response of endodontic origin result in

Answer 5

Eventually can lead to pulp deaths and peri-radicular radiolucency

Question 6

Describe the distribution of bacteria in the root canal

Answer 6

• More micro-organisms coronal
• Facultative anaerobes coronal
• Obligate anaerobes apical
• Micro-organisms are within the root canal and not in the peri-apical lesion

Question 7

What is the function of the periapical lesion

Answer 7

It is an inflammatory lesion that is the first line of defence preventing micro-organisms invading periapical tissues

Question 8

What non specific host defence reactions are elicited by bacteria and their by products in the pulp

Answer 8

• Acute inflammation
• Activation of the kinin and complement systems - release of histamine, plasmins, hangman factor, prostaglandins and leukotrienes
• Chronic inflammation is infection persists

Question 9

What specific host defence reactions are elicited by bacteria and their by products in the pulp

Answer 9

• Cellular and humoral immunity involves T and B lymphocytes, lymphokines, plasma cells and immunoglobulins
• Type 1-4 reaction can be involved

Question 10

What factors will lead to apical periodontitis

Answer 10

• Distribution of different cell populations in the lesion
• Presence of absence of epithelial cells
• Whether the lesion has transformed into a cyst or not
• Relationship of the cyst cavity to the root canal of the infected tooth

Question 11

What can acute apical periodontitis develop into

Answer 11

A primary abscess, maybe from an acute exacerbation of a chronic apical periodontitis (secondary)

Question 12

What are the characteristics of chronic apical periodontitis

Answer 12

Inflammation at the tooth of a long standing nature called a periapical granuloma:
Presence of:
- Granulomatous tissue
- Predominantly lymphocytes, plasma cells and macrophages
- Either epithelialise or non epithelialised

Question 13

What is a periapical true cyst

Answer 13

A classification of apical periodontitis that is a distinct pathological cavity completely enclosed in an epithelial lining so that no communication to the root canal exists

Question 14

What is a periapical pocket cyst

Answer 14

A classification of apical periodontitis that is an apical inflammatory cyst sac like epithelial-lined cavity that is open to and continuous with root canal (responds to root canal treatment)

Question 15

Where in root canal are the majority of infections

Answer 15

Intraradicular

Question 16

What are some common micro-orgs found in necrotic pulp tissue

Answer 16

• Peptostreptococcus
• Eubacterium
• Prevotella
• Fusobacterium
• Streptococcus
• ## Yeasts

Question 17

What do most necrotic pulp cultures contain

Answer 17

• Obligate anaerobes
• Anaerobes, peptide and amino acid degrading bacteria
• Oral yeasts: candida albicans

Question 18

What kinds of bacteria are commonly found in persistent/secondary endodontic infections and give examples

Answer 18

Many +ve gram and many coccoid facultative anaerobes:

• Streptococci
• Enterococci
• Lactobacillus
• Yeasts
• Peptosterptococcus

Question 19

What seems to be the predominant species of bacteria in root filled teeth with unsuccessful outcomes

Answer 19

Enterococcus Faecalis

Yeasts are commonly asccoaited with persistent infections as well

Question 20

When can extra-radicular infections be established

Answer 20

Apical periodontitis lesions are effective barriers to infection, if this barrier is overcome, an extra-radicular infection can be established

Question 21

What makes the root canal an ideal environment for microbe growth

Answer 21

• Warm, moist
• Nutritious
• Anaerobic
• Largely protected from host defences
• Bacteria can communicate each other
• Bacteria can produce virulence factors that create tissue damage

Question 22

What forms do bacteria survive in the pulpal/periapical tissue

Answer 22

• Planktonic state - free floating micro-orgs not attached to a surface (may be single cells or clumped together)
• Biofilms - community of bacteria or micro-organism and their extracellular polymer that is attached to a surface

Question 23

Bacteria in what form are resistant to treatment

Answer 23

Biofilms in root canals -

• exopolysaccharide in which bacteria are embedded may resist diffusion of antibacterial agents
• different layers of bacterial cells may act as barrier to diffusion
• Some bacterial cells maybe dormant and more resistant to killing
• Cell may exhibit specific resistance mechanisms