♦ Tissue injury can be due to local response to a severe irritant or due to administration of systemic drugs.
♦ Aspirin, sodium perborate, hydrogen peroxide, gasoline, turpentine, rubbing alcohol and battery acid is the
examples.
♦ Various patients many children under psychiatric care
hold medication under their mouth rather swallowing
them. Such medications are potentially caustic when held
in mouth for long duration.
♦ Following are the materials in detail which lead to chemical
injuries of oral cavity:
Chemical Injuries by Materials used Locally in Dentistry
Aspirin
♦ Aspirin tablets or powder are mainly used mistakenly in
oral cavity by patients as local obtundent mainly for relief
of toothache.
♦ Initially there is burning sensation present in oral
mucosa.
♦ Affected surface appear blanched as well as white in appearance.
♦ Epithelial separation and sloughing of epithelium along
with frequent bleeding is seen.
♦ Healing take place under 1 to 2 weeks.
Endodontic Materials
♦ Some of endodontic materials lead to soft tissue damage
causing deep spread of inflammation and necrosis.
♦ Paraformaldehyde is used to devitalize inflamed pulp. It
can leak from pulp chamber in surrounding tissue and
lead to necrosis of gingiva and bone.
♦ Sodium hypochlorite produces same effect as paraformaldehyde when it leaks in surrounding supporting tissue
or injected beyond the apex.
♦ Sodium hypochlorite when come in contact with vital tissue it leads to hemolysis and ulceration.
♦ Microscopically sodium hypochlorite inhibits neutrophil
migration and damage endothelial and fibroblast cells.
Hydrogen Peroxide
♦ This is a caustic agent.
♦ As it comes under the contact with tissues it lead to burning of tissues and release toxic free radicals, perhydroxyl
ion or both.
♦ 30 to 35% of hydrogen peroxide is used with heat for
bleaching teeth. This thermocatalytic process damages the tooth by causing irritation to cementum and
periodontal ligament which also causes cervical root
resorption.
Phenol
♦ It is cavity sterilizing and cauterizing agent.
♦ This is used in treatment of aphthous ulcers.
♦ As extensive necrosis is seen from medicaments consisting
of 0.5% phenol, this product should be used with atmost
care.
Silver Nitrate
♦ It is useful for treatment of aphthous ulcers as chemical
cautery leads to pain relief by destroying the nerve
endings.
♦ Its over usage leads to the painful burn of oral cavity.
Histopathology of Locally Acting Agents Leading to
Chemical Injuries
♦ White slough removed from mucosal chemical burns
shows coagulative necrosis of epithelium. Outline of epithelial cells and nuclei is visible.
♦ Necrosis starts over the surface and moves basally.
♦ Underlying connective tissue consists of mixture of acute
and chronic inflammatory cells.
Chemical Injuries by Materials used Systemically in
Dentistry
Lead
♦ Lead poisoning or plumbism is an occupational hazard.
♦ Lead line or Burtonians line is a grey or blue black line of
sulphide pigmentation present on gingiva.
♦ Ulcerative stomatitis is seen.
♦ Excessive salivation and metallic taste are commonly
present.
Mercury
♦ Mercury poisoning occur when it is used therapeutically.
♦ In this tongue and salivary glands are swollen.
♦ Metallic taste in mouth is present.
♦ Salivary flow is increased.
♦ Ulcerations are present on gingiva, palate and tongue.
♦ Exfoliation of teeth is also present.
♦ Acrodynia occurs due to chronic mercury exposure in
infants and children.
Silver
♦ Subepithelial deposition of silver in mucus membrane
leads to diffuse grayish discoloration.
♦ A blue silver line occurs at gingival margin due to secondary deposition of metallic silver.
♦ Amalgam tattoo is the most common finding. In this particles enter via lacerations which occur during removal of
old amalgam restorations. It appears as raised blue, black
or grey lesion.
Bismuth
♦ It is used by oral surgeons in surgical packs.
♦ Pigmentation of bismuth is seen in gingiva and buccal
mucosa.
♦ Bismuth line, i.e. blue black line is present at marginal
gingiva.
Tetracycline
♦ It lead to the discoloration of permanent or deciduous teeth
due to deposition of tetracycline during prophylactic or
therapeutic regimens in pregnant female or postpartum
in infant.
♦ Affected teeth are yellowish or show brown gray discoloration.
♦ Dentine is more stained than enamel.
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