Periradicular pathology Flashcards
What is the purpose of periapical pathology?
Part of host defence mechanism
Confines bacteria to root canals and prevents spread
What is the cause of endodontic disease?
Bacteria
Which microbes cause endodontic disease?
Mostly anaerobes (9:1 anaerobes to aerobes)
Porphyromonas and prevotella (bacteroides)
Which bacteria is strongly implicated in cases of sinus tracts and strong odours?
Prevotella melaninogenica
Which bacteria are present in extra radicular cluster formations?
Actinomyces israeli, propionibacterium propionicum
Where are the microbes?
In almost all infections, microbes stay in the root canal
The exception is acute apical abscess
What mostly passes apically?
Endotoxins
How do microbes get in?
Pulpal exposure, dentinal tubules, PDL, anachoresis
What are the different ways pulp can be exposed?
Trauma, vertical root fracture, pulp exposures during treatment, caries
What is anachoresis?
Positive attraction of blood borne microorganisms to inflamed or necrotic tissue during bacteraemia
What are perio/endo lesions?
Due to the communications between the pulpal and periodontal tissues
What type of inflammation has evolved to discriminate pathogens from self?
Acute
In acute inflammation, which cell is the first to react?
Neutrophils
How is inflammation achieved in acute inflammation?
TLRs act on immune cells and non-immune cells to recognise pathogen associated molecular patterns (PAMPs) on the bacteria
PAMPs bind to TLR-4 to increase inflammatory mediators
What are the three enzymatic systems involved in acute inflammation?
Kinin system, fibrinolytic system, complement system
When does chronic inflammation occur?
- After acute inflammatory response doesn’t resolve
- Without prior acute response where immune system responds to antigen
- Infectious agent of low toxicity
What characterises chronic inflammation?
Infiltration of injured tissues by leukocytes and proliferative responses
Which lymphocytes are mostly involved in chronic inflammation?
CD4+ T lymphocytes
What type of lymphocytes are the majority of circulating lymphocytes?
T cells
What are the two types of T cells?
CD4 (t helper) and CD8 (cytotoxic/suppressor)
What are the subdivisions of CD4 cells?
T helper 1, T helper 2
What do Th1 cells do?
Produce IL2, interferon and activates macrophages
What do Th2 cells do?
Produce interleukins and regulate production of antibodies from plasma cells
How are macrophages activated?
Activated CD4 cells make interferon which primes macrophages
Primed macrophages are activated by bacterial endotoxin and other mediators
How do activated macrophages differ from non-activated (naïve) macrophages?
Larger, increased chemotaxis, ability to adhere, greater ability to phagocytosis and kill microorganisms, produce bone resorptive mediators
Consequences of chronic inflammation?
Damaged tissue is replaced by fibrous CT, intermittent destruction of normal tissue and healing leads to scar formation
What factors contribute to chronic inflammation?
Inadequate drainage, mobility (e.g., in bony fractures), presence of necrotic tissue acts as an irritant, mechanical irritation
What three things do you need for peri radicular pathology?
Bacteria, pathway to pulp, time
What is apical periodontitis?
Inflammation in the periodontal tissues around apex of tooth
Functions of apical periodontitis?
Defence - confines bacteria, prevents spread into adjacent bone spaces, bone resorption
What are the three different histological presentations of apical periodontitis?
Granuloma, abscess, cyst
How to distinguish between a granuloma, abscess and a cyst?
Cannot distinguish clinically or radiographically (only histologically) except if there is a sinus tract then it is an abscess
What is the most common histology of apical periodontitis?
Granuloma
What is a granuloma?
Inflammatory lesion - lymphocytes, macrophages, plasma, fibroblasts, CT
Can be seen on tooth sometimes when extracted
What happens histologically during abscess formation?
Change in cellular dynamics - dramatic increase in phagocytic activity and number of PMNs
What is a chronic abscess?
Persistent, walled off chronic inflammatory tissue keeps areas of suppuration localised
What are cysts?
Epithelium lined cavities that contain fluid or semi-solid material
Where do apical cysts originate from?
Epithelial cell rests of Malassez
What are the variations in cyst linings?
Continuous, disrupted, missing
What is a pocket/bay cyst?
Inflammatory cyst, sac-like, open to and continuous with the root canal space
What is a true cyst?
Within the apical granuloma, no connection between cavity and root canal surface
Where can cysts of upper teeth originate from?
Maxillary sinus
What can we do with Endodontics?
Reduce bacterial levels to negligible, prevent endotoxins from reaching apical tissues, entomb/incarcerate any surviving bacteria, prevent ingress of fluid
This leads to the active lesion subsiding and bone regeneration
What is the success rate of endodontic treatment in teeth without AP?
83-100%
What is the success rate for endodontic treatment in re-treatment cases without AP?
89-100%
What is the success rate of teeth with Apical periodontitis?
46-93%
What is the success rate for re-treatment cases with AP?
56-84%
