Source: Salute e Beauty, magazine, 2007, pgs. 64-66, by Vivì Zizzo
A sparkling
s m i l e
Over the years, teeth tend to become stained, even discolored, losing their natural
brightness. And as everyone knows, the smile plays a very important role in a
person’s facial aesthetics. Nowadays, remedies to bring enamel back to its natural
white abound; yet despite this, the best advice is to check that what is being used
does not actually damage it.
To shed some light on teeth bleaching as well
as on techniques that can make our smile
sparkle again, we spoke with Dr. Domenico
Monda from Naples who, in addition to
specializing in Dentistry and Dental Implants,
Oral Implantology and Posturology, teaches
Laser Light in the Craniofacial Region at the
University of Genoa (Laser Surgery in the
Craniofacial Region Department). Below are
some questions we asked him.
brightness. “Chrome”, instead, refers to the
color’s saturation or, that is to say, its intensity
level.
How come over time, besides becoming
stained, tooth coloring changes?
Over time, the natural abrasion of the dental
tissue thins the layer of enamel and leads to
the development of secondary as well as of
tertiary protective dentin underneath the
areas that have been abraded most. These
conditions entail a variation in color because
reparative dentin is usually a darker brown
than the original dentin. The consequences of
these changes are a variation towards a
yellow that is stronger and more saturatedlooking in an aged tooth. Extrinsic color
changes are classified in three groups: direct
dyschromias of N1 or N2 type, or indirect
dyschromias of N3 type.
What is “teeth bleaching” exactly?
It is a procedure to bring teeth back to their
natural color. Teeth bleaching has to be
identified as part of preventive rather than
cosmetic odontology; bringing a tooth, that
has undergone alterations, back to its natural
state, in fact, does not involve changes to its
condition or appearance. This concept is
particularly significant for it is at the basis of
the transparent information that has to be
relayed to the patient about the results that What is the difference amongst these three
can actually be obtained.
groups?
In the N1 type dyschromias, the discolored
Can this system get rid of all kinds of stains?
tooth takes on the same color as the
Stains are amongst the causes of alteration of chromogen causing it. This type of dyschromia
teeth’s natural color and we can distinguish includes discoloration caused by foods,
two types. Stains of extrinsic origin are on the especially those with color properties such as
outer surface. Those of intrinsic origin are coffee, tea and red wine. The type N2
beneath the enamel’s surface; at times, dyschromia, instead, is produced by dental
intrinsic stains can be embedded in the plaque which in causing protein decay, turns
enamel, between it and the dentin, or even the pigment into a much darker shade. The
within dentin itself. Dyschromias of intrinsic type N3 dyschromias are caused by
origin are classified as pre-eruptive and post- chlorhexidine which can actually provoke,
eruptive. In the pre-eruptive forms, color when hydroxymethylfurfurals are present, a
alterations can already be noted when the rearranging process between carbohydrates
tooth first appears in the arch. In the post- and amino acids, and this is at the basis of
eruptive forms, instead, the tooth’s elements black stains not only of teeth but also of the
do not show alterations in the color’s shades mucous membrane.
which appear at a later time. As a general
rule, the conditions that cause post-eruptive What can be done to bring teeth back to their
dental discoloration occur when hemoglobin natural color?
is detected in the pulp chamber. This can Techniques as a whole focusing at bringing
happen subsequent to dental traumas of a teeth back to their natural color utilize
degree that is such that it causes vascular mechanical as well as chemical means.
and/or pulp lesions, pulp necrosis or during Mechanical means refer to procedures that
endodontic treatments when necrotic pulp aim at physically removing substances that,
debris is left in situ.
once settled on the tooth, cause its
dyschromia. This is possible thanks to
Is tooth color hereditary?
ultrasounds which via implosion removes supra
Natural teeth color is genetically determined. and subgingival tartar, followed by air
In forming it, the contribution comes from microabrasion. To achieve this, the device
dentin which gives it the shade, or color as used releases a spray of lukewarm water, air
genetically intended and by enamel which, and very fine bicarbonate dust and performs
with its opalescent translucency, provides
its cleansing action through the bicarbonate’s
abrasive particles. Chemical bleaching,
instead, utilizes two types of peroxides to
achieve its scope.
The first is hydrogen
peroxide which is a 35% solution mixed with
oxygenating agent at 100% volume. The
second is carbamide peroxide or rather the
combination of hydrogen peroxide and urea.
The difference between the two consists in
the fact that by now hydrogen peroxide has
become the only pharmaceutical product
utilized for in-office bleaching whereas
carbamide peroxide is only used in at-home
bleaching procedures. In order to analyze
how peroxide works in the bleaching process,
we have to understand how chromogens
induce color variation in the tooth. In the
bleaching process, in fact, the role of
peroxide is not to eliminate chromogens, but
to split the molecular bonds by transforming
the complex chains of the chromogenic
substances into simple chains which, being
free of double bonds and visually neutral,
they acquire a transparent quality. The action
of hydrogen peroxide can be accelerated
with the help of a diode laser, which operates
in an infrared spectrum between 810 to 830
nm. The hydrogen peroxide that we use is, in
its natural form, a liquid a bit denser than
water; so that it can be applied on teeth, it
needs to be mixed with a carrier, an inert
substance (silicon dust), with which it forms a
gel. We can add, to this carrier, a
chromophore or rather a colored substance;
if light blue, this chromophore will absorb from
the spectrum of electromagnetic waves
striking it, especially those that are red in color
and those of the near infrared where laser is
at work. Through this technique this colored
substance channels the laser ray to the
tooth’s surface, to the precise point where we
want a temperature rise and hydroxyls
formation. The action of hydrogen peroxide
can be increased even through plasma lamp
heat source. Once the aliphatic chains and
the double bonds of the chromogenic
molecules are broken, peroxide is allowed to
react until molecules are even split into
simpler forms. The absence of aliphatic rings
and double bonds alike turn chromogenic
substances into transparent substances. This
explanation makes it clear that the instead of
removing the substance that caused the
dental discoloration, the bleaching process
involves modifying the Characteristics of this
substance, so that it can no longer create
alterations in the tooth’s color.
Can a bleaching procedure be performed on
everyone?
Prior to being carried out, this type of
treatment requires the patient to go through
an accurate evaluation of his/her medical
history as well as through a dental exam to
ensure that there are no lesions to the enamel,
cavities in progress, cracked fillings or for any
other contra-indicated conditions. Before we
start the actual treatment, the patient has to
also go through a teeth cleaning session, at
the end of which we match his/her teeth color
with a shade guide and we take photographs
that are kept in the patient’s file along with
his/her informed consent. After the cleaning
session, we treat the vestibular surface of the
teeth in question with a 70% alcohol solution;
the scope of this part of the procedure is to
remove grease from these surfaces.
Does this degreasing step affect the lips in any
way?
No, because we apply a lip protection to
prevent that they accidentally come in
contact with the peroxide gel; and, by
applying a silicon barrier coating that is
polymerized with a halogen lamp, we protect
the periodontal membranes. This protection is
vitally important to safeguard soft tissues since
the bleaching gel is highly corrosive. Once all
the necessary protections are in place, we mix
liquid hydrogen peroxide at 35% with the
carrier until we obtain a gel that won’t drip
from the dental surface. We then spread
about three mm of this preparation on the
dental surface in a uniform manner. At this
point, all personnel and the patient are
required to put on eye wear to protect
themselves from the laser wavelength (this
prevents damages that the laser light and
halogen lamp alike could cause to the retina).
Once this is done, the gel is activated with the
infrared laser source. Activation is to last 20
seconds per tooth at a 1.5 watt power in
continuous-wave with a circular motion that
ranges between 5 to 6 mm. Once activation is
completed, the mix is left on for an additional
10 minutes with no further laser activation.
After that, the gel is removed through
suctioning and the dental surfaces are
thoroughly cleansed with an air-water spray
FOR FURTHER INFORMATION,
CONTACT:
CENTRO DENTISTICO MONDA
Dr. Domenico Monda
Book a visit, via phone/fax:
+39 081 64-63-78
or via toll-free number:
+39 800 71-97-97;
or visit Dr. Monda’s web site:
www.studiomonda.it
or, send an email to:
info@studiomonda.it
which needs to be lukewarm to prevent
thermal shocks. At this point, a second
application round begins. It starts with
preparing a new batch of gel mix
because the previous batch, due to
spontaneous reaction, has become
partially deactivated by that time. At
the end of the second laser application,
a similar ten-minute waiting period
ensues with no further laser radiation.
Once the gel is suctioned and the
surfaces are thoroughly cleansed again,
we check the teeth color. By this point,
in most cases, the dental surfaces have
regained their natural color. One or two
additional gel application sessions can
be done, if needed, at intervals that
can be bi-weekly or monthly”.
How long does the bleaching treatment
last?
The treatment can last six to 12 months
and its result also depends on the
patient’s correct oral hygiene both at
home and at the dentist’s office.
Can bleaching also be performed on
patients with partial prosthesis?
Bleaching only works on natural teeth; it
does not work on prostheses since these
are made in ceramic and as such they
are not subject to color variation.