Dental Pulp Irritants and Infection

Abrasion

• Abrasion is a type of chronic trauma that causes abnormal tooth surface loss due to direct frictional forces between the teeth and an external object or between contacting teeth in the presence of an abrasive medium.
• Common causes of abrasion include improper brushing, holding a pipe between the teeth, tobacco chewing, and chewing on hard objects such as pens or pencils.
• Tooth brush abrasion is the most common example, typically appearing as a sharp, wedge-shaped notch in the gingival portion of the facial aspect of teeth.

Pulp Response

• The healthy pulp responds to abrasion by depositing a layer of reparative dentine over its pulp surface, walling it off.
• The pulp response is related to the thickness and degree of calcification of the remaining dentine, as dentine permeability can be reduced by dentinal sclerosis and reparative dentine formation.
• If the distance between the caries and the pulp is 1 mm or more, pulp inflammation may be negligible.
• When the caries reaches within 0.5 mm of the pulp, there is a significant increase in the extent of inflammation.

Pulp Inflammation and Necrosis

• If the reparative dentine is invaded by irritants such as bacteria or their toxins, the pulp becomes acutely inflamed.
• After pulp exposure, bacteria colonies persist at the site of necrosis.
• Pulp tissue may remain inflamed for a long period and may undergo eventual or rapid necrosis, depending on factors such as:
  • Virulence of bacteria
  • Host resistance
  • Amount of circulation
  • Lymph drainage

Physical Irritants

• Mechanical irritants, such as tooth preparation (caries removal or crown preparation), can cause pulp trauma.
• Over-cutting during cavity preparation can cause immediate necrosis, regardless of whether the pulp is exposed or not.
• The width of the cavity, as well as its depth, affects the pulp.

Classification of Pulp Irritants

• Pulp irritants can be classified into four categories:
  • Microbial
  • Physical
  • Irradiation
  • Chemical

Microbial Irritants

• Microbial irritants include:
  • Caries
  • Periodontal disease
  • Contamination of an exposure of the pulp by microorganisms
  • Infection through the apical foramen (rare)
  • Bacterial microleakage
• Microorganisms present in dental caries are the main source of irritation of dental pulp and periradicular tissues.
• The response of the pulp to bacteria depends on factors such as the speed of bacterial ingress and the speed of progress of caries.

Erosion

• Erosion is a type of demineralization of superficial hard tissues, typically evident on the facial or lingual surfaces of the tooth structure.
• Causes of erosion include:
  • Extrinsic factors:
    • Industrial acids
    • Food and drink of acidic nature
    • Certain medications
  • Intrinsic factors:
    • Gastric acids
  • Chronic vomiting can affect the palatal surface of the upper teeth.

Filling and Lining Materials

• Certain filling and lining materials can cause irritation of the pulp tissue, such as:
  • Silicate filling material
  • Acrylic filling material
• Silicate filling material is extremely damaging to pulp tissue, especially when used without liners.

Test your knowledge on the different types of pulp irritants that can cause injury and infection, including microbial, physical, irradiation, and chemical factors. Learn how caries, periodontal disease, and other factors can affect the pulp and lead to necrosis.