Blankeamiento Dental

Periodontology 2000, Vol. 48, 2008, 148–169
Printed in Singapore. All rights reserved

Ó 2008 The Author.
Journal compilation Ó 2008 Blackwell Munksgaard

PERIODONTOLOGY 2000

An overview of tooth-bleaching
techniques: chemistry, safety and
efficacy
M U N T H E R A.M. S U L I E M A N

Tooth discolouration results from varied and complex causes that are usually classified as being either
intrinsicor extrinsic in nature. Extrinsic discoloration
arises when external chromogens are deposited on
the tooth surface or within the pellicle layer. Intrinsic
discoloration occurs when the chromogens are
deposited within the bulk of the tooth (usually in the
dentine) and are often of systemic or pulpal origin (1,
150). A third category of Ôstain internalizationÕ has
been described to include thosecircumstances where
extrinsic stain enters the tooth through defects in the
tooth structure (1).
Tooth discoloration creates a wide range of cosmetic problems, and, as the dental profession and
the public strive for a more esthetically pleasing
appearance, considerable amounts of time and
money are being invested in attempts to improve the
appearance of discolored teeth. A study assessing the
impactof teeth on personal esthetic satisfaction
found that dental variables (including tooth color)
were more important than orthodontic variables,
suggesting that the appearance of the teeth was a
greater contributing factor to an esthetic smile than
their position within the arch (101). In another study,
of 254 patients, it was found that the appearance of
the dentition was more important to womenthan to
men and that the esthetics of the dentition was more
important to younger patients (147).
The methods available to manage discolored teeth
range from the removal of surface stain, bleaching or
tooth-whitening techniques and surgical techniques
to camouflage of the underlying discoloration, using
veneers and crowns.
The use of a variety of bleaching techniques has
attracted most interest fromthe dental profession
because these techniques are noninvasive and relatively simple to carry out. Contemporary bleaching

148

systems are based primarily on hydrogen peroxide or
one of its precursors, notably carbamide peroxide,
and are often used in combination with an activating
agent such as heat or light. Bleaching agents can be
applied externally to the teeth (vital bleaching), or
internallywithin the pulp chamber (nonvital
bleaching) (41, 54). Both techniques aim to bleach
the chromogens within the dentine, thereby changing
the body color of the tooth.

Tooth discoloration
Natural color of teeth
Teeth are made up of many colors, with a natural
gradation from the darker gingival third to the lighter
incisal third of the tooth. This variation is affected by
the thickness andtranslucency of enamel and dentine, as well as by the reflectance of different colors.
Typically, canine teeth are naturally darker than
central and lateral incisors and teeth become darker
with age, whereas lighter teeth are common in
younger people, especially in the primary dentition.
The color of teeth is primarily determined by the
dentine but is influenced by the color, translucency
and varyingdegrees of calcification of enamel as well
as its thickness, which is notably greatest at the
occlusal or incisal edge. The normal color of teeth is
determined by the blue, green and pink tints of
enamel and is reinforced by the yellow through to
brown shades of the dentine beneath.

Classification of tooth discoloration
The appearance of teeth depends on their absorptive
or reflective properties of lightand is influenced by

An overview of tooth-bleaching techniques

Table 1. Colours produced by various causes of tooth
discolouration
Types of discolouration

Colour produced

Extrinsic (direct stains)
Tea, coffee and other foods
Cigarettes ⁄ cigars
Plaque ⁄ poor oral hygiene

Brown to black
Yellow ⁄ brown to black
Yellow ⁄ brown

Extrinsic (indirect stains)
Polyvalent metal salts and
cationic...