Bacteriocidal toxin is found in:
Correct Answer: Zone of infection
Description: The reaction of the periradicular tissues to noxious products of tissue necrosis, bacterial products and antigenic agents from the root canal has been described by Fish.
The four zones
Zone of infection
Zone of contamination
Zone of irritation
Zone of stimulation
Zone of Infection:
This is present in the center of the lesion.
It is characterized by PMNL's.
The bacterial toxins are found in this zone.
Zone of Contamination:
It is characterized by round cell infiltration.
It demonstrates cellular destruction due to toxins from the central zone or zone of infection. Because of autolysis and death of bone cells, the lacunae were empty.
Lymphocytes are prevalent everywhere.
Zone of Irritation:
This zone is characterized by macrophages and osteoclasts.
The collagen framework was digested by phagocytic cells, the macrophages, while osteoclasts attacked the bone tissue. This opens a gap in the bone all around the center of lesion. That space becomes filled with PMNL's. It contains cholesterol crystals.
This zone demonstrates much activity preparatory to repair.
Zone of Stimulation: (Peripheral zone)
This zone is characterized by fibroblasts and osteoblasts.
In this zone, the effects of toxins were mild enough to be stimulant which results in laying down of collagen fibers around the zone of irritation that acts both as a wall of defense and as a scaffolding on which the osteoblasts built new bone.
This new bone was built in an irregular fashion.
Category:
Dental
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