Tooth Whitening - what affects tooth color, anyway?!
All That You Need To Know About Tooth Whitening
Welcome back to this exciting series of seminars in dentistry: tooth whitenting. Today we’re going to take a closer look at the etiology of tooth discoloration. This topic may be boring, but actually it is quite an important one. Without identifying the cause of discoloration, the objective of a treatment may be inappropriate, become aimless, wander in a bush, or miss the target altogether. Similar scenario applies to using an antibiotic to treat a viral infection—it simply will NOT work!
Natural Color of Teeth
Before we talk about discoloration problem, let’s review the natural color of the tooth.
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Tooth Anatomy
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Tooth consists of enamel, dentin, cementum (not shown in the figure), and pulp.
Enamel is the outermost layer. It is translucent, thus allowing light to pass through. This property plays an important role in esthetic dentistry. When you look at your anterior teeth closely, the incisal edge (or the cutting edge) of the front teeth is translucent. If this translucency can be simulated while a tooth is restored/fixed, the tooth will have a more natural look.
Dentin lies beneath enamel and is yellowish white in color. Due to the translucent property of enamel, the tooth color that we see comes mainly from the yellowish dentin. Supposed enamel is less translucent, then the underlying dentin will not show through enamel as much, and therefore the tooth will appear whiter. This explains why baby (deciduous) teeth are whiter than adult (permanent) teeth. As well, tooth with thin enamel also appears more yellowish; this condition can be due to a number of factors.
As with enamel covering dentin at the crown portion of a tooth, cememtum covers dentin at the root portion of a tooth. Cementum has similar constituents as dentin and thus also appears yellowish white. You won’t see cementum (or the root of a tooth) unless there is gum recession, which may be esthetically compromised.
Pulp is located in the center of a tooth. It contains nerves and lots of blood vessels and hence it’s pinkish red. Normally we won’t see this color because there is enough thickness of enamel and dentin. In case of trauma where the blood circulation inside the tooth is impaired and microscopic fractures exist, the pulp undergoes necrosis and the tooth will turn purple or black. It’s like a bruise (or hematoma) in the tooth. Basically a puddle of stagnant blood & rotten tissue in the pulp chamber.
Discoloration of Teeth
There are two major types of tooth discoloration: intrinsic versus extrinsic.
Intrinsic Tooth Discoloration
- Intrinsic discoloration is caused by incorporation of chromatogenic (color-producing) material into dentin and enamel during tooth formation or after tooth eruption.
- Exposure to high levels of fluoride leads to a condition called “fluorosis,” characterized by white spots and pits on tooth surface. In severe cases, the pits get stained and become black/brown spots.
- Use of tetracycline, inherited developmental disorders, and trauma to the developing tooth may result in pre-eruptive discoloration.
- After eruption of the tooth, aging, pulp necrosis, and iatrogenesis are main causes of intrinsic discoloration.
Extrinsic Tooth Discoloration
- Coffee, tea, red wine, carrots, oranges, and tobacco give rise to extrinsic stain.
- Wear of the tooth structure (thinning of enamel), deposition of secondary dentin due to aging, or as a consequence of pulp inflammation affect the light-transmitting property of teeth, resulting in gradual darkening of teeth.
Tooth Whitening 1 | 2 | 3 | 4 |
References:
Crit Rev Oral Biol Med: 14(4):292-304 (2003)
Filed under: Health, dentistry
