In this article:
When thinking about whitening teeth, (1) it is important to know that what is a normal tooth color – a white smile – is not what was considered normal 10–15 years ago.
Like skin tones, enamel has many shades of normal color with yellow, grey, or red undertones. Also, when your teeth are visible, the perception of color changes.
Fuller lips and a small oral opening add shadowing, resulting in a darker appearance. Darker skin and gums increase the contrast, resulting in a whiter appearance.
Primary teeth are designated as an A1 shade for filling material. Until recently, this shade was never used in restorations on adult teeth except for full dentures, as it was regarded as “Chiclet teeth” or fake.
As people look into improving their appearance and reducing the signs of aging, dental age seems to be one of the quickest and least invasive ways to gain an edge.
Types of Teeth Staining and Their Causes
Teeth stains are typically classified based on how they occur, which can either be due to intrinsic factors or extrinsic ones.
a. Intrinsic staining of the teeth
The most common type of teeth staining that exists in the pediatric and adolescent population falls into the intrinsic category.
As the name suggests, this type of scarring is the result of internal damage to the teeth, usually during the formation stage.
When more than one tooth is affected, it is usually caused by a disruption of the enamel formation or localized bleeding into the tooth. Scarring can occur when actual enamel is being formed for each individual tooth. (2)
The damage occurs within the tooth but shows on the outside in the form of stained enamel.
Here are some of the major intrinsic factors that contribute to teeth staining:
1. Fetal age/infancy
Primary teeth form enamel in utero during the third trimester. If the mother is ill during this time, the mineralization of the enamel matrix can be disrupted, resulting in deformed or stained enamel.
If the assault occurs at birth or the first 3 months of infancy, the teeth present in the early mixed dentition will be affected, which include the primary second molars and perhaps the permanent incisors and first permanent molars.
2. Mineral deposition
Any mineral or compound with ionization similar to hydroxyapatite (calcium) crystals can be incorporated into the enamel. (3) This includes antibiotics (tetracycline) and excessive fluoride (swallowing rather than topical).
Poor matrix formation can also lead to this condition because other compounds are absorbed by this unusual tubular formation.
Bleeding into the tooth and yellowing of a tooth following trauma are also intrinsic stains.
When bleeding occurs within the pulp chamber, the clots often deposit into the matrix and are very hard to be absorbed.
4. Other factors
Yellowing is caused by both erosion of the white enamel and thickening of the dentin to maintain a protective biological width, which is the distance from the oral cavity to the tooth pulp.
When this thickness is decreased, teeth become very sensitive to temperature and chemicals (acids and sweets).
These types of discoloration are usually deeper and require more invasive whitening procedures.
b. Extrinsic staining of the teeth
Extrinsic stains are caused by environmental factors, habits, or a genetic predisposition that damage the outermost surface of the tooth, particularly the crown.
Here are some of the major culprits that can stain your fully developed teeth over time:
Ingested substances darken teeth every day. The most common products that result in staining are tobacco, coffee, black teas, and red wine, although most children do not drink, suck on, chew, or consume these.
Dyed foods, such as sports drinks and soda, also cause staining. However, all these things require time to discolor teeth.
Children and some adults tend to accumulate iron and other minerals in their mouth that stain teeth, (4) but abrasive toothpastes and frequent professional cleanups can help remove these salivary deposits.
Age will darken teeth almost uniformly (5) and is often considered as an extrinsic factor for tooth staining.
Dentinal thickening (yellow infrastructure) with thinning of the enamel (enamel translucent) results in a darker and more brittle tooth.
If a good dental cleaning with scaling and stain removal is not enough to reverse this damage, whitening treatments can deliver the desired results.
Types of Teeth Whitening Procedures
There are basically two types of teeth whitening:
- Local whitening, based on the removal of intrinsic (developmental) staining (6)
- Overall whitening, based on the removal of extrinsic (environmental) staining (6)
Teeth Whitening Treatments
Treating stained teeth entails addressing its root cause. There are both clinical and over-the-counter (OTC) interventions that can help whiten stained teeth.
a. Professional teeth whitening treatments
Intrinsic stains are first treated with whitening procedures, (7) but they are usually incapable of masking the deep-seated discoloration, and the tooth has to be covered or cleaned out.
1. Root canal therapy
The discoloration caused by bleeding is typically treated with root canal therapy, which starts with cleaning out the blood deposits from the dentinal tubules by using bleaches or peroxides and then placing the filling material.
Removing the residual blood clots from the tooth keeps them from breaking down and getting reabsorbed in the body. The blood supply is so small to a tooth that normal healing often cannot fully occur.
When localized staining occurs on specific teeth, bleaching can work to reduce the contrast of the stain with the rest of the enamel and make it more uniform in appearance.
The stained enamel is often softer and prone to developing caries (8) that can spread more readily, which is why restorations are often the treatment of choice in such a case.
3. Blue light/lasers and multiple treatments
Etching of teeth is often accelerated with either blue light or lasers and multiple treatments.
Many practitioners feel that lasers can help remove the intrinsic stains and even out the tonal variations in a more controlled manner.
4. Composite fillings, crowns, or veneers
When all the previously mentioned treatments do not fully work, the dentist may recommend composite fillings, crowns, or veneers to camouflage teeth staining.
If the discolored tooth or teeth are very visible such as the maxillary anterior teeth, recommendations will usually include covering 6–8 teeth so that the appearance is consistent for all adjacent teeth when you smile.
The number of teeth involved in this cosmetic procedure will depend on your smile width, tooth, and bite.
Note: In children with primary, mixed, and early permanent dentition, only composite resin materials and crowns that will not impinge on the gum tissue are used. Teeth are still forming and growing longer until the age of about 15–16.
If the procedure is performed before full tooth formation on the affected tooth or any adjacent teeth, the root and attachment might not properly mature.
b. Bleaching treatments
When thinking of teeth whitening, people generally think of bleaching treatments. (9) These can be done using chairside, prescribed, or OTC bleaching kits.
Chairside bleaching uses acids or peroxides to break down the mineral deposits in the enamel tubules. This is performed in a chemical reaction that is often accelerated and strengthened using a light or laser source of energy.
Enamel is eroded away with the laser in the same way as a white lesion is removed, which forms on the teeth prior to a cavity. This stage of enamel erosion is reversible.
Many bleaching treatments are now recommending the use of fluoride mouthwashes to further whiten and harden the enamel following its erosion.
These treatments work more rapidly because they contain a more concentrated form of peroxide compounds at 15%–43%.
Treatments usually last for 2 hours and are done in one long or several short appointments. You have to follow up with your dentist thereafter, who will monitor you for any subsequent sensitivity or soft tissue irritation.
Note: These treatments only work on the tooth enamel and will not lighten any artificial dental restoration placed on your teeth. If a crown, filling, tooth replacement, or veneer is needed, the bleaching should be performed before the final placement.
If gingival lesions or gum disease are present, they should be identified and treated before the application of any bleaching product, which can otherwise trickle into any infected area or cavities to trigger tooth sensitivity.
Also, remember that any prosthetic does not absorb colorants in the same way as a natural tooth structure, so if you bleach to a very light color and match the shade of the dental prosthesis to overly white, it will appear whiter until the bleaching treatment can be repeated, usually every 2 years for complete treatment regimens.
c. OTC products for home-based teeth whitening treatment
With most people leading very busy lives, take-home procedures have become extremely popular. These procedures often require only one office visit to customize gel holding trays.
These are thin shells that adapt closely to an individual bite so that one does not slip or spill the bleaching compound.
The home treatment has to be done daily for 2 weeks. The length of time for daily treatment can last from 30 minutes to overnight, depending on the concentration of peroxide agent, which is generally between 3% and 20%.
When OTC carry systems are used without dental supervision, the concentration tends to be toward the low side for peroxide and acid concentration.
OTC products come in strips, trays, or brushes. (9) These offer less predictable results and must be applied one to several times daily and often up to 4 weeks.
Toothpastes that claim to be whitening often have chemicals or abrasive products that help to remove stains and clean teeth better than regular dentifrices.
They usually contain a fluoride compound as it is more readily incorporated into the enamel (faster uptake), so it can help harden and whiten the tooth after erosion of the enamel has occurred.
Note: Always check to see if your OTC teeth whitening product carries the American Dental Association’s seal, and consult your dentist before using it to understand how to safely apply it.
Side Effects of Teeth Whitening Procedures
Teeth whitening procedures don’t always work as well as they should and can result in the following adverse outcomes:
- Uneven distribution of the product can lighten some teeth more than others.
- Different types of staining result in better or poorer outcomes and different stains might exist throughout the oral cavity and sometimes within a single tooth.
- Tooth sensitivity from thinning enamel and hypertrophy of the pulp tissue can occur.
- Ingestion of the chemicals has to occur because you swallow your saliva even in a short span, and suction is generally not used for part or total treatment.
- Chemical burns, irritation, and an allergic reaction of the gums can occur.
- Increased likelihood of developing tooth decay may also result.
- The combination of enamel erosion and reduction of salivary flow against the teeth results in potentially higher bacterial colonization. The acidic environment also mimics bacterial by-product that leads to cavities.
Cost of Teeth Whitening Treatment
The cost of treatment will vary depending on the product used. In-office procedures can run from $500 to $1,500 depending on the desired outcome and condition of the teeth.
Tray-based systems usually are priced at $150–$800. Strips and gels are the least expensive but need to be repeated more frequently and have less predictable results.
Note: Always remember that all forms of teeth whitening are temporary, and the appearance will revert to a darker shade over time. The lighter the result, the longer the cosmetic effect will last. Avoiding vices that darken teeth and maintaining faultless oral hygiene can help prolong the whiter appearance.
Caution: Teeth whitening is not recommended for children, teens, and pregnant or lactating women. If teeth are stained, consult with your dentist if dental restoration can be done to maintain the tooth until other treatments could be used. OTC mouthwashes and toothpastes can be used to remove stains, but stain removal usually leads to thinning of the enamel.
Teeth whitening is temporary and needs to be repeated over time. It is safe in moderation, but it can trigger problems such as burns, sensitivity, and other unpredictable complications when used in excess.
Teeth whitening appeals to adults largely for cosmetic reasons, as it helps them look better and younger, thus bolstering their confidence.
But this has to be weighed against cost, time, and potential long-term effects on your teeth, which all increase with the age at which you start and the length you use it.