In today’s world, there is a strong focus on perfect physical appearance. (Didier Dietsch, 2008).
Different esthetic dental procedures have been developed since many patients are very dissatisfied with their appearance. Discolored teeth affected by fluorosis, due to the fluoridation of drinking water, are frequently seen in our population.
This kind of pathology leads to the whitish, opaque, unpleasant appearance of enamel which is often visible at speaking distance. Proposed treatments, depending on fluorosis severity, range from expensive ceramic veneers to free hand bonding restorations and abrasive chemical treatments. (S.Ardu et al, 2009)
Bleaching is considered before porcelain veneer placement to either eliminate the need for veneers, reduce the amount of opacifiers needed to mask discoloration, or to give the patient the option of attempting a less expensive/ invasive treatment before committing to veneers. (Van B. Haywood, 2003)
The aim of this article is to describe an easy technique for managing enamel discoloration via microabrasion followed by in-office dental bleaching.
Key words: Dental fluorosis, Microabrasion, in-office bleaching
The intrinsic discoloration is incorporated into the structure of enamel or dentine and can’t be eliminated by simple prophylaxis using pumice or tooth paste. 
Dental fluorosis which is an intrinsic discoloration is defined as hypomineralization of enamel resulting from excessive ingestion of fluoride during tooth development. It is characterized by diffuse opacities on the enamel surface. These are differentiated from other conditions by the characteristic bilaterally symmetric distribution of the enamel defects. (Howard E. Strassler and al, 2011)
Current research suggests that superfluous amounts of fluoride cause retention of amelogenin proteins in the developing tooth structure, there by inhibiting enamel maturation. This interference results in porosities in the enamel at the time of tooth eruption. (Howard E. Strassler and al, 2011)
The enamel affected by fluorosis contains higher levels of protein content than normal enamel. When normal enamel protein content ranges from 0.07 to 0.14 per cent, fluorosed enamel content ranges from 0.03 to 0.56 per cent.  he safe level for daily fluoride intake is 0.05 to 0.07 mg F/Kg/day. Above this level, the risk of developing fluorosis due to chronic fluoride consumption will be evident. Dental fluorosis has been categorized under various grades as follows: (Naveen Chhabra et al, 2010).
Grade 0: Normal, translucent, smooth, and glossy teeth;
Grade I: White opacities, faint yellow line;
Grade II:Changes as in Grade I and brown stains;
Grade III: Brown line, pitting, and chipped off edges;
Grade IV: Brown, black and/or loss of teeth
The severity of dental fluorosis depends on when and for how long the overexposure to fluoride occurs, the individual response, weight, degree of physical activity, nutritional factors and bone growth, suggesting that similar dose of fluoride may lead to different levels of dental fluorosis. (Jenny Abanto Alvarez et al, 2009)
It is very difficult to correct deeper enamel fluorosis via only Microabrasion. For this reason, a combination of different techniques such as microabrasion/in-office bleaching is recommended to mask deeper defects since they are conservative, provide highly satisfactory results, without excessive wear of sound dental. 
Examination for bleaching
We should undertake a standard extra-oral and intra-oral examination. 
The initial examination and diagnosis are very important before starting the treatment. And of course they cannot be performed without the patient consulted the dentist. 
Proper examination and diagnosis, including radiographs, are needed to rule out pathology that will require completely different treatment from bleaching. (Van B. Haywood, 2003)
The differential diagnosis between fluorosis and non-fluoride-induced opacities needs to establish differences between symmetrical and asymmetrical and/or discrete patterns of opaque defects. These criteria imply that all symmetrically distributed and non-discrete opaque conditions of enamel are fluorosis. (Jenny Abanto Alvarez et al, 2009)
A history of eventual tooth sensitivity should be investigated.  No bleaching procedure should be initiated without appropriate dental examination.
Microabrasion is a procedure developed by Dr. Theodore Croll 
Helping in removing superficial stains related to discrete or moderate fluorosis. 
It is composed of a mixture of hydrochloric acid and pumice that is rubbed onto the surface of the tooth repetitively until the outer layers of the enamel containing the stains are abraded away. The stains in the outer layers of enamel can be removed, leaving a smooth, glassy enamel surface. 
It is recommended to use a rubber dam so as to protect the gums from the acid.
After that, the pumice-acid slurry is then applied to the teeth and rubbed with a very slow speed rubber cup. After a few layers of enamel are removed, the slurry is rinsed with water and the result is evaluated. This process is repeated until the stain is gone or the process must be stopped for other reasons such as enamel getting too thin or tooth getting sensitive.  At the end, it is recommended to bath teeth with a fluoride gel so as to reduce eventual post-operative sensitivity.  This technique is simple to perform and the depth of enamel removed in 10 applications is approximately 100 μm. (0.1 mm.).  Microabrasion is a time-proven technique that is safe and effective for the
atraumatic removal of superficial enamel defects. (HO Heymann, 1997)
In Office bleaching
In-office vital tooth bleaching has been used for many years in dentistry and is known to be a reliable technique for quickly lightening discolored teeth. (Ruta Zekonis et al, 2003)
For this technique, we use higher concentration of hydrogen peroxide (35%) than we can use at-home bleaching and for this reason, the bleaching agent will penetrate the tooth more rapidly with in-office bleaching.  In general, the in-office bleaching procedure for vital teeth involves several necessary and important steps: (M. S. Gutmann and J. L. Gutmann, 2001)
• Place a rubber dam or use a light-cured paint-on dam along with a petroleum
jelly to protect the gingival tissues.
• Teeth may or may not be etched prior to placement of the bleaching agent. A gel or liquid bleaching agent, usually 35% hydrogen peroxide, is then applied to the enamel surface. If the liquid form is used, gauze squares saturated with the bleaching agent are placed on the facial surfaces. Allow the bleaching agent to remain on the teeth for 20- 30 minutes. Apply a heat source, usually a visible light curing lamp or a laser, to accelerate the chemical reaction
• Do not use local anesthesia during bleaching and monitor patient discomfort to avoid tissue burns or excess heat build-up in the pulp. Analgesics, such as ibuprofen, acetaminophen, or aspirin, may be recommended for the first 24 hours if any tooth sensitivity is noted.
• At the end of the procedure the excess bleaching agent should be removed with water before removing the rubber dam.
Different studies reveal that, 2-6 visits with about 45 minutes application per time in- office bleaching are necessary to obtain acceptable results.  We also should take into account the possible appearance of tooth sensitivity that is why we must wait at least one week between visits.  The use of bleaching light may lead to the augmentation of pulpal temperature which depend on the exposure time and the light source.  In addition to that, tooth sensitivity and pulpal irritation may be higher with the use of bleaching light or even heat application. [9,15] One of the most safety advantages of the in-office dental bleaching is that it is under dentist’s control.  The disadvantages are: the cost which can be considered as expensive for some patients, the duration of the treatment and the unpredictable results.  Some dangerous features may be the post-treatment sensitivity, the increasing temperature of the pulp and eventual discomfort concerning the gingival barrier. 
A 30-year old male patient with complaints of dissatisfaction about the discolored teeth (Figure 1) came to the department of conservative dentistry. Patient gave history of discoloration from his childhood. No other relevant medical history was reported by the patient. His oral hygiene was good.
Diagnosis: Dental fluorosis (Grade III: Brown line, pitting, and chipped off edges)
Treatment plan: Microabrasion followed by in-office dental bleaching.
A 47-year old female patient was insatisfied with the discolored upper front teeth (Figure 5) came to the department of conservative dentistry. Patient gave history of discoloration since her childhood. Good oral hygiene.
Diagnosis: Dental fluorosis (Grade III: Brown line, pitting, and chipped off edges)
Treatment proposed was Microabrasion followed by in-office dental bleaching.
Due to the recent increase in dental fluorosis, extensive research has been performed to understand the aetiology and pathogenesis of this systemic disease. (S.Ardu et al, 2009)
The aetiology is well established and based on the excessive consumption of fluoride during specific critical ages.  Browne indicated that this critical period is 15 to 24 months of age for males and 21 to 30 months of age for females.  Bleaching may represent a conservative first approach for many cosmetic conditions. (Kevin J. Donly et al, 2002)
Conservative treatment options such as microabrasion and/or tooth whitening can produce dramatic improvements in brown and yellow discoloration, providing a satisfactory interim result before more invasive procedures are considered, if necessary.(F Ng et al, 2007)
The microabrasion procedure is considered as safe and simple. It allows us to obtain excellent results when treating superficial enamel stains.  It doest not require the use of anesthesia that is why dentist can have a better relationship with patients.  The Opalustre™ microabrasion slurry (Ultradent Products Inc, Utah, USA) is composed of 6.6% hydrochloric acid and silicon carbide microparticles.  According to (F Ng et al, 2007), the Hydrogen peroxide (HP) is an oxidizing agent which breaks down into free radicals that will combine to create oxygen and water. And that the HP oxidizes, carboxylates and lightens chromophores, particularly within the dentine.
Most current in-office whitening systems are based on HP solutions of 25 to 35 per cent.
Higher peroxide concentrations also have been shown to be effective in tooth whitening; however, these are professionally supervised to a greater extent. (Kevin J. Donly et al, 2002)
The higher concentrations of proxide lead to faster rate of bleaching, but added to that a possible higher incidence of dental sensibility.  hile the higher concentrations may reach the end point sooner, they also “overshoot” the color and have a greater relapse, and a longer time for the color to become stable. (Van B. Haywood, 2003)
One of the common adverses of vital bleaching is dental sensitivity because the peroxide can penetrate the enamel, dentine and even the pulp chamber.  Other side effects such as irreversible pulpitis and pulp necrosis can occur with the uses of 35% of hydrogen peroxide.  When the concentration of PH increase, the degree of penetration in dental structure will increase, also we can note a greater penetration in hypomineralized enamel.  The patient in the second case reported sensitivity with the in-office whitening system containing 35% of HP that is why we opted for desensitizing gel Flor Opal ®.
This may have been because of the relatively higher concentration of HP used (35%).
According to (HO Heymann, 1997), we must wait a minimum of one week after bleaching procedure before placing any resin-bonded restoration on tooth structure because the strength of resin bonds to freshly bleached enamel and dentine are reduced.
A study of (Christian Hannig et al, 2006) showed that bleaching procedure has an impact not only on surface micro-hardness of composites but also for deeper layers of adhesive filling materials.
Bleaching versus Porcelain venners?
entists should make a choice for their patients between teeth whitening or venners.
If there is any regression in whitening after esthetic translucent veneers are placed, the teeth can be relightened from the lingual. (Van B. Haywood, 2003).
In cases when teeth bleaching didn’t produce the expected result, the patient is confident since the most conservative options have been attempted first, and that porcelain veneers are the best option they have for an esthetic smile.  We shouldn’t also ignore the minor cost of bleaching compared with the expensive cost of dental veneers that is why the bleaching procedure is usually the first choice for patients to retrieve better smile. 
This combined approach (Micro abrasion and in office bleaching) may be considered an interesting alternative to more invasive prosthetic techniques such as ceramic veneers.
In addition to that, this minimal invasive technique allows acceptable aesthetic results and even a possible cost reduction for these patients.
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