Pathology of Pulpitis

• Learning objectives:

  
• What is acute inflammation?

  -An immediate response to insult

  
  

  -There is dilation & an increased permeability of microvasculature

  
  

  -Exudation of fluid

  
  

  -Emigration of leukocytes (particularly neutrophils)
• What are the outcomes of acute inflammation?

  -Complete resolution occurs with regeneration of native cells and restoration to normalcy

  
  

  -Healing by connective tissue replacement (fibrosis) occurs after substantial tissue destruction and in non-regenerating tissues

  
  

  -Progresses to chronic inflammation
• What is chronic inflammation?

  -Prolonged response to persistent stimuli

  
  

  -Involves lymphocytes, plasma cells & macrophages

  
  

  -Co-existing injury, inflammation and repair
• What is pulpitis?

  Inflammation of the pulp
• Describe the aetiology of pulpitis.

  The most common cause is microbial

  
  

  Can also be caused by thermal insult: insufficient cooling of dental hand piece

  
  

  Chemical insult
• How can bacteria damage the pulp?

  They can damage the pulp through toxins or directly after extension

  
  

  They gain access through:

  
  

  Carious cavitation

  Attrition/Abrasion/Erosion

  Fracture, cracked tooth

  Perio-endo lesion

  Iatrogenic
• How can you classify pulpitis?

  Acute or chronic (from clinical & histological findings)

  
  

  Reversible or irreversible (from clinical findings)

  
  

  Open or closed

  
  

  Subtotal or generalised

  
  

  Sterile or infected
• Why does pulpitis usually result in pulp necrosis with periapical periodontitis as an outcome?

  -Because the pulp chamber is enclosed in dental hard tissue with limited blood supply through narrow opening of mature apical foramen

  
  

  -So an increase in pulpal pressure due to oedema can result in venous stasis which can lead to ischaemia which can lead to necrosis

  
• Which local & systemic factors affect healing?

  Local:blood supplydegree of infectionpersistent irritationmobility

  Systemic:agenutritionpre-existing medical condition
• What factors influence the progress of pulpitis?

  Host factors:

  pulpal anatomyapical blood flowpre-existing state of pulp

  Irritant:

  natureseverityduration
• What happens when there's acute inflammation of the pulp?

  - Initial constriction and then dilation of vessels

  
  

  -Increased blood flow

  
  

  -Formation of exudate

  
  

  -Neutrophils (moving from blood vessels to surrounding tissues)

  
  

  -Oedema

  
  

  -Destruction of odontoblasts and adjacent pulpal tissue

  
  

  -Variable necrosis

  
  

  -Variable abscess formation (look at pic for more info)

  
• What happens when there is chronic inflammation of the pulp?

  - Lymphocytes, plasma cells, macrophages

  
  

  - Variable necrosis
• What does an inflamed pulp look like histologically:

  - Dense acute inflammatory infiltrate of neutrophils

  
  

  - Presence of chronic inflammatory cells such as : plasma cells and lymphocytes

  
• What does a necrotic pulp look like histologically?


  The pulp is dead

  
• What is the main symptom of pulpitis?

  -Pain

  -Pulps of individual teeth are not precisely represented in the sensory cortex, therefore pain can be poorly localised.

  -Can be felt in the upper or lower jaw or more rarely distant sites such as the ear

  -Pain is not provoked by pressure to surface of tooth (biting, percussion) as infection/inflammation not spread to periapical tissues
• What are the symptoms of reversible pulpitis?

  Hypersensitive to hot and cold

  
  

  Pain subsides on removal of the stimulus

  
  

  Positive response to vitality testing
• What are the symptoms of irreversible pulpitis?

  As inflammation progresses, pain becomes persistent and spontaneous

  
  

  Reduced or no response to vitality testing
• What's is Vitality testing?

  technique that is uses either thermal or electrical stimulation to determine where there a tooth is vital or nonvital
• What would you see in reversible pulpitis?

  -Hyperaemia

  
  

  -Oedema

  
  

  -Chronic inflammatory cells underlying the area of affected dentinal tubules

  
  

  -Scattered acute inflammatory cells are found occasionally

  
  

  -Can see reparative secondary dentine

  
• What would you see in irreversible pulpitis?

  -Often congestion of venules that results in focal necrosis

  
  

  -Surrounding pulp tissue can show fibrosis

  
  

  -Mixture of neutrophils, plasma cells, lymphocytes and macrophages

  
• How would you treat reversible & irreversible pulpitis?

  Reversible pulpitis is treated by removal of the local irritant

  
  

  Irreversible pulpitis treated by tooth extraction or root canal treatment
• Is pulpitis usually open or closed?


  The vast majority is usually closed
• What is open pulpitis and where might you see it?

  In open pulpitis, pulp survives chronically inflamed beneath a large exposure despite heavy infection

  
  

  Often associated with open apices (see in children) giving a good blood supply
• What is chronic hyperplastic pulpitis (pulpal polyp)?

  -Deciduous molars or first permanent molars in children (have large pulp chambers)

  
  

  -Large carious exposures of the pulp in which entire dentinal roof often missing.

  
  

  -Chronic inflammation produces hyper plastic granulation tissue that extrudes from the pulp chamber

  
  

  -The apex may be open and reduces the chance of pulpal necrosis

  
  

  -Tooth is asymptomatic except for a possible feeling of pressure when it is placed into masticatory function.