Teeth Bleaching
Libyan International Medical University
Common causes of tooth sensitivity
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Root caries
Tooth brush abrasion
Bruxism
Scaling and root planning
Leakage restoration
Periodontal problems….recession
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Desensitizing agents
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Tooth pastes……e.g. Sensodyne
Fluoride Gel
Inorganic salts….Sensodyne sealent
Desensitizer resin agents
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Teeth Bleaching
• A desire by patients for brighter, whiter
smiles has caused an explosion in the
demand for cosmetic services.
• Office bleaching (whitening).
• Home or out side office bleaching (1989).
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Composition
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Office bleaching….30 to 35 % hydrogen
peroxide. One system mixes 35% hydrogen
peroxide with silica to form a gel.
Another system contains calcium,
phosphate, and fluoride ions to allow
remineralization during treatment.
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Home bleaching…10 – 22% carbamide
peroxide or 1.5 to 6% hydrogen peroxide.
Bleaching agent do not affect gold alloys,
amalgam, porcelain. Composite, hybrid
ionomer, and GIC have been roughened
slightly by bleaching gel.
Bleaching should not contact the dentine
because could cause hypersensitivity.
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How Bleaching works?
• Teeth bleaching occurs when the hydrogen
peroxide or nonperoxide bleaching material
passes through the enamel to the dentine
and oxidizes pigments in the dentine,
resulting in a lighter colour.
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Bleaching products are:
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Hydrogen peroxide
Carbamide peroxide
Urea peroxide
Non-hydrogen peroxide system that
contains sodium chloride, oxygen, and
natrium fluoride.
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Types of stains
1. Extrinsic stain:
Poor oral hygiene, coffee, tea, foods, tobacco
products.
2. Intrinsic stain:
Tetracycline, fluoride, trauma, pulp necrosis,
endodontic materials and aging.
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Techniques
 Three
major methods of in-office bleaching
involve the use of heat, light, and gels….laser?
 Gel technique is a more conservative chairside
approach. The gel is place in 2 mm thickness
for 20 to 30 min.
 Gel technique works faster if combined with
the use of a light curing unit for 10 min.
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Home bleaching, required use of a tray for 3
to 4 hours once or several times a day.
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Rubber dam, eye wear and gloves
protection, no anesthesia, and constant
patient monitoring.
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Side effects of bleaching!
1. Hypersensitivity
2. Irritation of the gingiva, mucosa, and
throat from excess bleaching material
coming out of trays.
3. Reduced bond strength…wait 2 weeks
after bleaching before placing adhesive
restorations.
4. TMJ problem due to trays.
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Abrasion, polishing and cleansing
materials
• Abrasion is the process of wear on the surface of
one material by another material, such as a
sandpaper, disc, or chiseling.
• The material that causes the wear is called an
ABRASIVE; the material being abraded is called
the SUBSTRATE.
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Verities of cutting, finishing, and polishing tools. Top, rage wheel and
Bendick polish. Bottom, left to right, silicon carbide disc, aluminum oxide
disc, rubber polisher, greenstone, white stone, diamond bur and carbide bur.
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• Types of Abrasives…..Three types of
abrasives used in dentistry
• Finishing, polishing and cleansing abrasives
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• Polishing is the process of making a rough surface
smooth to touch and glossy.
• Polishing is performed with very small particle size abrasive.
• Surface roughness Ra is measure of the irregularity of the
finished and polished surface and is measured in Micrometers.
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A smooth surface Ra less than 0.2 Micrometer)
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• Gloss is a measure of reflection of light
from a surface. A totally non reflected
surface has zero gloss unit (GU).
• An ideal restorative material would have
high gloss after polishing and would retain
its gloss during function in the mouth.
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• Cleansing…
• Cleansing techniques are meant to remove
food and other debris from a surface
without damaging it.
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Factors affecting rate of abrasion
1- A large difference in hardness between the
abrasive and substrate. e.g. enamel, dentin,
amalgam, and composite.
2- The particle size of an abrasive may be
expressed in micrometers.
Fine…..0 to 10 Micron
Medium ….10 to 100 M
Coarse…..100 to 500 M
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3- The particle shape….
Sharp, irregularly shaped particles.
4- The greater the speed at which the abrasive
travels across the surface of the substrate
the greater the rate of abrasion.
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5- The greater the pressure applied, the more
rapid will be the abrasion for a given
abrasive.
6- Lubricants (silicone, grease, water spray).
Applications of abrasive dental prophylaxis
pastes are: Pumice, silica, zirconium,
silicate, sodium fluoride.
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Type of denture cleanser for use at home
are?
1. Abrasive creams.
2. Alkaline hypochlorites.
3. Sodium perborate to releases peroxide.
4. Dilutes acids e.g. Citric acid.
5. Enzymes e.g. Papin
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We finished the Biomaterials course
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Wish you all the best
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