We are all aware of Teeth Whitening Methods but we are always inquisite about reasons as to why we should consider them. Dentists have been perplexed by the problem of tooth discoloration for the last 200 years and have tried numerous chemicals and methods to remove various types of discoloration. Many of the early attempts, though highly innovative in their time, were not successful and bleaching techniques were considered to be experimental and unpredictable. Attempts to bleach teeth started in earnest in the nineteenth century and have continued successful bleaching techniques could found. However, the technique of using 35% hydrogen peroxide to bleach vital teeth has been available for nearly 100 years.

History of Teeth Whitening

Most of the attempts to bleach teeth in the nineteenth century were tried on non-vital but later dentists attempted to bleach vital teeth. Several oxidizing agents were used directly or indirectly to act upon the organic part of the tooth such as aluminium chloride, oxalic acid, pyrozone (ether peroxide), sodium peroxide, hydrogen peroxide etc. These materials were used for non-vital teeth. Most of these materials were quite caustic and dangerous and had to be used with great caution. From the 1860s, one of the most effective early techniques for bleaching non-vital teeth was using chlorine produced from a solution of calcium hydrochloride and acetic acid; the commercial derivative was called Labarraque’s solution which was liquid chloride of soda. But now the effective materials considered were pyrozone, superoxol and sodium dioxide (Haywood 1992).

Intercoronal / Internal Bleaching

In the original technique to treat non-vital teeth, the bleaching agent was applied to the outside buccal surface of the tooth and was expected to penetrate through the enamel. This had limited success: it was only after the bleach was placed inside the tooth, making use of the pulp chamber, that the technique produced better results. Spasser (1961) described a method of sealing a mixture of sodium perborate with water into the pulp chamber and leaving it in situ for 1 week. This technique became known as the ‘Walking bleach Technique’.

Nutting and Poe (1963, 1967) described a modified version using a combination of 30% hydrogen peroxide and sodium perborate sealed into the pulp chamber for a week. The two materials used in combination had a synergistic effect. This was known as the ‘Combination walking Bleach technique’.

The ‘Thermocatalytic Technique’ (Stewart 1965) involves the placement of an oxidizing chemical into the pulp chamber. This is followed by the application of a heating instrument either directly into the pulp chamber or the buccal surface of the tooth. The heat generated, in combination with the high concentration of hydrogen peroxide is thought to contribute to the possibility of developing cervical resorption and nowadays this technique is not used as frequently.

A new technique, using the open pulp chamber and 10% carbamide peroxide in a custom tray, has been recommended. This is called the ‘Inside/Outside Technique’ (Settembrini et al 1997, carrillo et al 1998). The patient applies the bleaching material directly into the pulp chamberwith a syringe and then the bleaching tray is seated into the mouth. This way the tooth is bleached from the inside as well as the outside at the same time.

Home Bleaching / Teeth Whitening Materials

It was an incidental finding and a chance discovery in the 1960s that led to the successful technique of home bleaching as we know it today. In this technique, the bleaching material, which is usually 10% carbamide peroxide, is placed in a custom-fitted tray. The patient places the tray with the material in the mouth and wears the tray for several hours or overnight while the teeth lighten within a few days, weeks or months, depending on the nature of the discoloration. Dr Van Haywood and Dr Harald Heymann published the original technique, called Nightguard Vital Bleaching, in an article in 1989.

The American Dental Association (ADA) in 1994 established safety and efficacy guidelines for tooth bleaching agents under ‘seal of approval’ Acceptance program. The ADA recognized 3 types of dental products containing hydrogen peroxide and intended for home use:

1.     Oral antiseptic agents available over the counter and intended for short term use.

2.  Whiteners or bleaching agents containing 10% carbamide peroxide (3% hydrogen Peroxide) which may be prescribed by a dentist for home use or may be available over the counter.

3.     The over the counter (OTC) dentrifices with low concentrations of Hydrogen Peroxide or calcium Peroxide (Dunn 1998)

 

In-Office Power Bleaching / Teeth Whitening

There were numerous attempts to discover a material that was powerful enough to bleach teeth at the dentist’s chairside. The first attempt was in 1918 when Abbot discovered that a high intensity light would produce a rapid increase in temperature to increase the efficiency. It involves the patient sitting for many hours with a rubber dam on the teeth to protect the mucosa and gingival, with 35% hydrogen peroxide bleaching material on the teeth, under a heated bleaching lamp (Zack and Cohen 1965). This was very laborious for the patient and dentist. However the introduction of the faster and safer light-activated units for power bleaching has popularized this in-office technique. Many light units do not generate heat: the halogen curing light, plasma arc or Xenon power arc light activates the bleach on teeth. This power bleaching material is more concentrated (35% hydrogen peroxide or 35% carbamide peroxide) than the home bleach material. LASERS have also been advocated for chairside bleaching technique, but ADA does not approve their use yet.

Why Should You Consider Teeth Whitening

BEAUTY is an abstract and subjective concept, but an essential and incredible part of human nature (Etcoff 1999). What makes a beautiful smile…? One definition is one in which the size, position and color of the teeth are in harmony, proportion and relative symmetry to each other and with the elements that frame them. The ideal smile is considered to be:

a)        Bright

b)        Vigorous

c)        Youthful, regardless of age ( Mokowitz and Nayyar 1995)

d)        Symmetrical teeth

e)        Showing natural teeth

f)          Light tooth shade (Dunn et al 1996)

g)        Healthy gingival color, harmony and form ( Garber and Salama 1996)

Tooth shade was the most important factor in a study conducted by Dunn et al (1996) to assess the patients’ perceptions of dental attractiveness. This was followed by natural (unrestored) tooth appearance and the number of tooth showing. Each year millions of individuals change tooth paste, purchase ineffective preparations, and even change their dentists in their quest for whiter teeth. Many an attractive smile is marred by some discoloration or stain. Generally stains can be divided into EXTRINSIC (located on the outside of the tooth) and INTRINSIC (located within the tooth). Moreover extrinsic stains can become intrinsic over time. A number of treatment options should be considered , in order of INCREASING AGGRESSIVENESS:

Treatment options for stained teeth

 

TREATMENT OPTION
 
INTRINSIC
EXTRINSIC
Prophylaxis
 
Air polisher
 
Y
Bleaching external with 10% or more CP
Bleaching external with 35% hydrogen peroxide
 
Bleaching internal with 10% CP
Y
 
Bleaching internal with 35% HP
Y
 
Sealant or preventive resin
Y
 
Macroabrasion: hand piece, burs and disks
 
Y
Microabrasion: rubber dam and acids
 
Y
Resurface and seal restoration
 
Replace restoration
Veneer (partial or complete, composite or ceramic)
 
Crown ( PFM, porcelain butt, all ceramic)
Y
 

CP= carbamide peroxide, HP= hydrogen peroxide, PFM= porcelain fused to metal

Bleaching is thus such an attractive simple option to lighten the appearance of natural teeth. Although bleaching teeth as a dental treatment is now more predictable than ever, there is still no guarantee that the teeth will bleach to a lighter shade. The only way of knowing whether teeth will respond is to endeavor to undertake the treatment. Further treatment may be required to achieve an excellent smile such as composite bonding, porcelain laminates or full crowns. Not all teeth are responsive to the treatment, and not all teeth respond at the same rate. Some patients’ teeth can whiten to the lightest shade on the shade guide, while others respond to a slight degree of lightening. The patients’ smile definitely appears brighter after the treatment and this is the final benefit. 

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