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Types of Stains
Extrinsic stains
are stains on the exterior of the tooth surface or, at most, penetrating
microcracks and fissures, and can thus be removed by dental
polishing.
Many extrinsic stains are pigments embedded in the
calculus or plaque that has become colored from interaction with
food debris, tobacco smoke, wine or other sources. It should be
emphasized that, although coffee, tea, wine, fruit juice, and tobacco
are all well known for their ability to cause staining, the color that
develops is from a chemical reactions occurring in the plaque and does
not necessarily imply anything about the color of the food
itself.
Most common are yellow-brown
to dark brown stains that probably caused by an accumulation of dental plaque, food stain and poor oral
hygiene. Aging or inherit discoloration usually occurs in 9
out of 10 people. These stains usually
bleach quite readily as due yellowish discoloration, whether due to
aging or tobacco smoke, likewise responds well to bleaching.
Staining from aging takes about 1-6 weeks to whiten.
Nicotine staining takes 1-3 months to whitening through
nightly use.
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Black line stain, most frequently found on the
lingual surfaces one millimeter above the gingival (gum) margin. It is a
metabolic stain and is frequently found in clean mouths.
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Green stain is often
found on the cervical surface of the anterior teeth of children and is a
remnant of Nasmyth's membrane and accumulated food debris. Green stain
may also be the result of exposure to some metals, including copper and
nickel. Metallic stains can be absorbed into plaque by inhaling the
fumes of metallic salts. The color varies from green to bluish-green
to brown according to the metal the individual was exposed to. Green
stains can also be the result of decomposed hemoglobin and inorganic
elements like calcium, potassium, sodium, silicon, magnesium,
phosphorous and other elements in small amounts. This type of stain
often overlies demineralized tooth structure.
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Orange and red
stains are usually found on
the cervical third of anterior teeth, and are caused by chromogenic
bacteria.
Repeated use of stannous fluorides can result in a
light brown or yellowish stain. Chlorhexidine and alexidine are also
problematic in this regard, forming a browning stain as well.
Once extrinsic stains are removed, oral hygiene
techniques will be reinforced to minimize extrinsic stain reoccurrence.
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Intrinsic Stains
or stains located within the tooth anatomy, can be of varied
origin. Intrinsic stains may result from pre-eruptive or post-eruptive causes.
Hereditary
conditions
Hereditary conditions such as porphyria and phenylketonuria (if
untreated, which is rare these days) can also result in a deposition of
colored materials in the teeth.
Other pre-eruptive staining resulting from hereditary
conditions include amelogenesis imperfecta and dentinogenesis
imperfecta. These both affect tooth structure in ways that can alter the
color, but that also lead to rapid loss of enamel from the tooth
surface. Enamel hypoplasia is hereditary condition that may contribute
to extrinsic staining. The teeth erupt with whit spots or pits that may
discolor or pick up food pigments over time.
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Tetracycline
Staining
Use of tetracycline during the period of tooth formation - including the
last half of in utero development - leads to its incorporation into the
tooth structure. The resulting appearance depends both on intensity of
use and the type of tetracycline employed. Tetracycline can be
transferred through the placenta and enter fetal circulation. Often,
however, the outcome is a bluish-gray stain affecting only the part
of the tooth that was being formed during the period of use. After
eruption these teeth may fluoresce under UV light, but this is a
property that is generally lost with age and exposure. The
discoloration may be generalized or limited to a specific part of the
individual teeth that were developing.
Tetracycline stains are difficult to bleach, but
will usually respond to prolonged treatment. When only part of the
tooth is affected, however, patients are often disappointed with the results: While the
tooth is lightened overall, and the difference in shade between the
stained and unstained regions is diminished, the difference never
entirely disappears. It was
thought staining of the teeth from tetracycline was only an issue while
teeth were being formed, but many have noticed that the
tetracyclines (minocycline in particular) will stain the erupted tooth
due to salivary concentrations & crevicular fluid too.IDF
Rick Be patient when
whitening these teeth, because good results will take some time, and
your teeth may initially look worse, as their more normal enamel
lightens more quickly than the discolored areas.
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Minocycline Staining
Minocycline is a semi-synthetic derivative of tetracycline often
prescribed for the treatment of acne or rheumatoid arthritis. Unlike
tetracycline, however, it can stain teeth even after tooth eruption.
Although the mechanism of action is not well understood, there is some
evidence that a corresponding protocol of Vitamin C may help prevent
this discoloration from occurring. Predicted whitening results are
similar to those for tetracycline: Prolonged bleaching is usually
successful, but may be less than satisfactory when banding is
severe.
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Ingestion of
fluoride
Ingestion of excessive amounts of fluoride during tooth formation can lead to areas of lighter appearing enamel. These spots are chalky white
in appearance and, obviously, cannot be bleached to match the
surrounding enamel. It is often referred to as 'mottled enamel'. Whitening
does not remove the white spots but lightens background so they are less
noticeable. Secondary stains that occur around these white areas are readily
bleached to produce an appearance that, while not normal, may be less
noticeable. Sometimes fluorosis is accompanied by pitting and other
surface defects that may suggest veneering or bonding, perhaps following
an initial bleach.
Whitening use takes 1-6 weeks.
Brown Fluorosis will take 1-6 weeks to whiten. About 80% will
respond to this procedure while the rest may need polishing and composite
restoration to follow.
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Natural
Tooth Color Variation
In addition to acquired discolorations, teeth naturally vary in color.
Enamel is more or less translucent, allowing the underlying dentin color
to show through. Normal variations in dentin structure can result in
more or less light being reflected. Variations in dentin structure can
also, to a small extent, affect the color of the reflected light, as can
materials that may be incorporated into the tooth structure. These
natural variations can make teeth look old. The teeth may yellow over
time due to pulp recession. Aging teeth develop secondary dentin over time which also makes the teeth appear
darker.
Prolonged jaundice early in life can impact a yellow
or greenish discoloration to the teeth. Erythroblastosis fetalis (Rh
incompatibiity) can leave a green, brown, or blue hue to the teeth.
Post-eruptive intrinsic staining to some extent
reflects the process of enamel and dentin maturation. This includes
tubule mineralization and secondary dentin formation. A variety of
stains present either in the systemic circulation or locally in the
tooth, can become incorporated during these processes.
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Trauma
Perhaps the most common cause of post-eruptive intrinsic staining is
trauma. Trauma is usually accompanied by hemorrhage, producing a rise in
pressure within the pulp cavity that forces the extravasated blood into
the dentinal tubules. This will initially produce a pink color. As the
hemoglobin breaks down, however, it is converted to black iron sulfide.
Even though this is an inorganic pigment, it responds well to
bleaching.
Trauma may also produce necrosis of the pulp, with or
without accompanying hemorrhage. Various by-products of protein
degradation will migrate into the tubules, producing a grayish-brown color that is
less intense than that due to hemorrhage. The stain will be lighter when
the necrotic material is removed promptly. This stain will usually
respond well to non-vital bleaching techniques. Note however that not
all pulpless teeth will discolor. It will take 1-6 week to whiten.
Discoloration
due to trauma responds to 10% carbamide peroxide bleaching in 47
hours.***
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Iatrogenic
discoloration.
Dental materials can also result in tooth discoloration. Sometimes this
can be as simple as the color of the restorative material showing
through the translucent enamel. It is possible for restorations to
discolor adjacent tooth surfaces as they deteriorate and release various
metal ions. The presence of recurrent decay beneath the old or leaking
restoration can also result in a darkening of the tooth. Once the
defective restorations are replaced, any remaining stains should respond well to bleaching. Various other
materials used in dentistry, such as amalgam (gray/black); silver
nitrates (black stain), iodine (brown); essential oils (yellow/brown);
aureomycin (yellow), and silver-containing root canal sealer (black) can
also cause stains under some circumstances.
[phdservices] Digest Number 80, 6 Dec 2001
10:26:28 -0000
