Teeth whitening

Teeth whitening. Frequently asked questions and answers

albire dentara

How many times have you been impressed by the flawless, white and shiny teeth of the commercials or cinema actors?
You thought it was impossible, and you thought it was a trick, due to lighting, staging or Photoshop.
There’s no pretense! It’s real and possible!
It is just professional dental whitening, an esthetic procedure, usually done by dentists.

What is dental whitening?

The dental whitening process is the most profound way to clean the teeth.
When routine brushing, professional brushing and descaling are insufficient to remove tooth pigmentation, the solution is dental whitening.

The color of your teeth can naturally be darker, yellowish or brown, or we can bring up an artificial cause of pigmentation due to the consumption of coffee, tobacco, tea or excess of drugs (especially antibiotics).

What the patient needs to bear in mind is that through dental whitening, the tooth enamel and the dentin will not be damaged.

Bleaching is carried out with a professional gel, the active substance of which, in the category of peroxides compounds, is hydrogen peroxide. It penetrates the enamel and whitens the dentin.

The result, obtained after the whitening procedure, depends on various factors: The degree and type of pigmentation, the concentration of the whitening agent and its time of action, the frequency of repeated treatment.

What is dental whitening?

Professional gel, based on hydrogen peroxide, cleans the enamel, its integrity remains intact.

Since the organic substance has in its composition a significant amount of water, after the whitening process, a tooth sensitivity can be found, due to dehydration. But this step is not irretrievable. The organic substance of the enamel will regain its water content over time.

During the period of rehydration of enamel, two weeks after the whitening procedure, colored drinks are not recommended. The tooth is exposed to depigmentation.

How is dental whitening done?

Your dentist will isolate your gums with a rubberized protective dam or gel and apply the peroxide-based gel to the outside of your teeth. After which it will project a special light (laser or led), about an hour. A professional dentist will get the desired effects, but even so, there are some consequences, independent of the doctor’s professionalism, such as: dental sensitivity, manifested by uncomfortable reactions, cold or hot, and irritation of the gums.

If you have a dental crown, there is a risk that an uneven color of your teeth will be noticeable as a result of whitening.

Consequences of professional dental whitening

The effect of dental whitening is long and can be done, both on the front teeth and at the level of the premolars and molars. The structure of the teeth, the dental substance or the tooth enamel does not suffer any modification or injury. The whitening gel does not affect your tooth in any way!

Only sensitization, an unpleasant reaction to cold or hot, higher or lower, depending on the strength of your teeth should be considered. However, regardless of the degree of sensitivity, the teeth regain their vitality, over time, or for a quick recovery you can use the fluoridating gels.

We remind you that the integrity of your teeth is guaranteed!

Ways to whiten teeth

Depending on the degree of pigmentation, the desired shades and the speed of achieving the effect, dentists have at their disposal several ways of dental whitening. The decision is yours.

Thus, you can choose:

– dental whitening with whitening accelerators

– dental whitening with professional gel applied with mouth guard

– dental whitening process with baking soda powder.

The whitening accelerator involves the application of a gel, in the presence of a light source, with a spectrum between 460-490 nm that activates hydrogen peroxide.

The gel whitening applied with the go mouth guard involves a personalized print that will be made by the dentist and will be performed in the dental technique laboratory. The obtained mouth guard are stored and used for subsequent bleaching.

Bleaching with baking soda powder is done in the case of teeth that have superficial spots, due to consumption of coffee, tea, red wine, tobacco, etc. bleaching with  baking soda is done if the teeth are white enough and do not require professional gel. For the safety and integrity of your teeth, call your dentist for this procedure.

If your teeth are usually white but have been affected by the above-mentioned excesses, and you want a natural color restoration, baking soda whitening is the process you need to opt for.


The dentist will decide whether the patient can undergo a dental whitening. Thus, pregnant women or those who are breastfeeding are not recommended dental whitening treatment.

Also, people with gum disease or tooth erosion will not be able to endure dental whitening.

Children up to 15 years of age and people with very sensitive teeth, or people allergic to peroxide, are not recommended to have a dental whitening procedure.

Most of us are more and more informed, more interested in maintaining good oral hygiene, but also in the esthetic aspect of dental arches.

Because white and aligned teeth are a benchmark for oral care, more and more patients are opting for a whitening treatment.

But before making this decision, we need to know that teeth whitening is not recommended for everyone and that the results vary from one individual to another.

There are both good and not so good parts of teeth whitening, the less good ones can only be avoided by following the instructions given by your dentist.

Below we answer the questions we usually receive when it comes to teeth whitening:

Do teeth whitening affect other dental work?

Teeth whitening treatment does not affect other dental work. Thus, fillings, implants or dental crowns will not be affected in any way by the teeth whitening procedure.

How much teeth could be whitened?

First of all, teeth whitening will be done by the patient who has yellowish or brownish stains on the outside of the teeth, caused by the consumption of colored juices, coffee, tea, red wine, tobacco, excess medication or the patient who has naturally stained teeth.

The deeper the pigmentation, from yellow to brown, burgundy or grey, the more gradual the whitening will occur over several dental sessions (usually 3 sessions). The whitening effect can last 2-3 years and can be repeated.

How do I keep my teeth white?

Teeth whitening can persist for a long time. It all depends on you. Thus, avoiding foods and beverages with a high dye content, rigorous oral hygiene and the use of toothpaste are required to keep teeth white.

Can I whiten my teeth?

The best way to get personalized information is to visit your dentist’s office.

The information found on the internet is general, as the characteristics of teeth differ from one patient to another.

In principle, patients with gum recession, young people whose enamel is not fully mineralized and who have a porous surface are not ideal candidates for whitening treatment.

Teeth whitening are not recommended for those with lesions lacking enamel, areas where dentin is exposed, such as patients with bruxism or cuneiform lesions.

They will develop significant sensitivity (discomfort, pain) following this treatment.

How long do the results last?

The patient should be aware that tooth whitening is not a permanent solution.

The results of this treatment will diminish over time.

The effects of whitening normally last between 6 months and 2 years.

Even if the depigmentation process cannot be stopped, it can be slowed down by avoiding smoking and consuming foods and liquids with staining potential.

These include strongly colored tea, coffee, tobacco and red wine.

Does whitening treatment affect my teeth?

There are many studies that say that whitening treatments do not damage the tooth substance as long as calcium and fluoride are applied after treatment to restore the original enamel characteristics.

What are the effects of bleaching on dental fillings, veneers and crowns?

Tooth whitening substances have no effect on pre-existing restorations.

This is why prosthetic work must be replaced after this treatment if the same shade is to be achieved.

Therefore, before the dentist starts the dental treatments, the patient should let the dentist know if he/she wants to opt for teeth whitening.

Teeth whitening treatment is recommended and subsequent to teeth whitening, prosthetic restorations.

What substances are used for whitening? Are they toxic to teeth and body?

Whitening products are based on hydrogen peroxide (H2O2) and carbamide peroxide (CH6N2O3), substances also found in the body’s cells.

The problem is their concentration. Therefore, to avoid overdosing, we do not recommend whitening treatments at home without the guidance of your dentist.

Teeth whitening treatments are one of the most common requests from patients.

However, before opting for this type of treatment, the patient should consult the dentist and agree to temporization if there are pathologies in the oral cavity that require resolution before starting teeth whitening treatments.

What kind of whitening lamp do you use?

The lamp we use for teeth whitening is the Dea Lux from Techno Gas.

How much does it cost, what is the price of the teeth whitening treatment?

Professional tooth whitening is offered in our office for 1000 lei. (apx 200 EUR)

The teeth whitening treatment lasts on average 2h and includes the following steps:

– Scaling

– Professional brushing

– Fluoridation

– Whitening:

  • application of a gum barrier to protect the gums
  • application of peroxide gel
  • activation of the whitening accelerator with LED lamp

General information

Whitening is the process of brightening the color of teeth. Whitening is often desired when teeth yellow over time for a variety of reasons and can be achieved by changing the intrinsic or extrinsic color of tooth enamel. The chemical degradation of chromogens within or on the tooth is referred to as whitening.

Hydrogen peroxide (H2O2) is the most common active ingredient used in whitening products, and is found either under this name or as carbamide peroxide. Hydrogen peroxide is similar to carbamide peroxide and is released when the stable complex is in contact with water.

When it diffuses into the tooth, hydrogen peroxide acts as an oxidizing agent that decomposes to produce unstable free radicals. In the spaces between the inorganic salts in tooth enamel, these unstable free radicals attach to organic pigment molecules resulting in small, less pigmented components.

Reflecting less light, these smaller molecules create a ‘whitening effect’. There are various products available on the market for stain removal. For whitening treatment to be successful, the dentist should correctly diagnose the type, intensity and location of tooth discoloration. The exposure time and the concentration of the whitening compound determine the final whitening point of the teeth.

Natural shade

The perception of tooth color is multi-factorial. The reflection and absorption of light by the tooth can be influenced by a number of factors, including specular transmission of light through the tooth, specular and diffuse reflection of light at the surface, absorption and scattering of light in dental tissues; enamel mineral content, enamel thickness, dentin color, eye strain, type of light incidence and the presence of extrinsic/intrinsic stains. In addition, the prediction of tooth brightness may change depending on the brightness and color of the background.

The combination of intrinsic colors and the presence of extrinsic stains on the tooth surface influence the color and thus the overall appearance of the teeth. Light scattering and absorption in enamel and dentin determine the intrinsic color of the tooth, and since enamel is relatively translucent, the properties of dentin can play an important role in determining the overall tooth color. On the other hand, extrinsic stains and color are a result of colored areas that have formed in the film that appears on the surface of the enamel and can be influenced by certain behaviors or daily habits. For example, eating tannin-rich foods, using incorrect brushing techniques, tobacco products and exposure to iron salts or Chlorhexidine can cause the teeth to darken.

As we age, teeth tend to darken in color. This can be attributed to secondary dentin formation and thinning of the enamel due to tooth wear, which contributes to a significant decrease in brightness and exposure to a yellowish hue. Tooth shade is not influenced by gender or race.

Staining and fading

Discoloration and staining of teeth is primarily due to two sources of discoloration: intrinsic and extrinsic. Essentially, teeth whitening mainly target those intrinsic stains that cannot be removed by mechanical cleaning, such as scaling or certain prophylaxis techniques, in the dentist’s office. The differences between the two sources contributing to such tooth surface discoloration are explained in detail below.

Extrinsic discoloration

Extrinsic discoloration is largely due to environmental factors, including smoking, pigments in beverages and foods, antibiotics and metals such as iron or copper. Colored compounds from these sources are adsorbed into the acquired dental pellicle or directly onto the tooth surface causing staining.

Dental plaque: Dental plaque is a biofilm of bacteria that develops naturally in the oral cavity, especially along the gum line, and occurs due to normal development and defense of the immune system.

Although usually invisible on the tooth surface, plaque can become stained by chromogenic bacteria such as Actinomyces species.

Prolonged accumulation of dental plaque on the tooth surface can lead to demineralization of the enamel and the formation of white spot-like lesions that appear as an opaque lesion. The acidic products of fermentable carbohydrates derived from sugar-rich foods contribute to a higher percentage of bacteria such as Streptococcus mutants and Lactobacillus in dental plaque. Higher consumption of fermentable carbohydrates will accentuate demineralization and increase the risk of developing pre-carious lesions.

Tartar: unremoved plaque will eventually calcify and lead to the formation of a hard deposit on the teeth, especially around the gums. The organic matrix of dental plaque and calcified tissues undergoes a series of chemical and morphological changes that lead to calcification of dental plaque and hence tartar formation. Its color varies from grey, yellow, black or brown, depending on the duration of its presence in the oral cavity. It is usually yellow initially but over time the tartar will begin to change color to a darker color and become harder to remove.

Tobacco: the tar from smoking tobacco products tends to form a yellowish-brown-black stain around the tooth socket above the gum line. Nicotine and tar from tobacco, combined with oxygen, turn yellow and over time will absorb into the pores of the enamel and stain the teeth which will turn yellow. The dark brown to black stains that appear along the gum line of the teeth are the result of the porous nature of tartar, which readily accumulates nicotine and tar pigments.

Betel chewing. Betel chewing produces blood-red saliva that can stain teeth reddish-brown to almost black. The gel extracted from the betel leaf contains tannin, a chromogenic agent that causes discoloration of tooth enamel.

Tannin is also present in coffee, tea and red wine and produces a chromogenic agent that can discolor teeth. Heavy consumption of drinks containing tannin stains tooth enamel brown due to the chromogenic nature.

Certain foods, including curries and tomato-based sauces, can cause staining of the teeth.

Certain topical medicines: Chlorhexidine (antiseptic mouthwash) binds to tannin molecules, which means that prolonged use in people who drink coffee, tea or red wine is associated with extrinsic staining of teeth. Chlorhexidine mouthwash has a natural affinity for sulphate groups and acids that are commonly found in areas where plaque accumulates, such as along the gum line, on the dorsal side of the tongue and in carious lesions. Chlorhexidine is retained in these areas and turns brownish-yellow. The stains are not permanent and can be removed with proper brushing.

Metal compounds. Exposure to such metal compounds can be in the form of medication or through occupational exposure. Examples include iron (black stain), iodine (black), copper (green), nickel (green) and cadmium (yellow-brown). Sources of metal exposure include insertion of metal into the oral cavity, inhaling metal-containing dust or taking oral medication. Metals can penetrate the tooth structure, causing permanent discoloration, or can bind to dental plaque causing surface staining.

Removing extrinsic discoloration

Extrinsic discoloration can be removed by various treatment methods:

Prophylaxis: dental prophylaxis includes the removal of extrinsic stains using a rotating hand piece at low speed and a rubber cup with abrasive paste, which contains mostly fluoride.

Unfortunately, the action of the rubber cup together with the abrasive nature of the paste removes around one micron of enamel from the tooth surface each time such a prophylactic action is performed. This method of stain removal can only take place in the dentist’s office.

Air-flow: allows a dentist to use an instrument that emits a powder, water and compressed air to remove biofilm and extrinsic stains. This method of stain removal can only be performed in a dental office, not at home.

Toothpaste: there are many variants available on the market that contain both peroxide and abrasive particles, such as silica gel, to help remove extrinsic stains, while peroxide works on intrinsic discoloration. This method of stain removal can be performed both at home and in a dental practice.

Intrinsic discoloration

Intrinsic discoloration mainly occurs during tooth development, either before birth or in early childhood. Intrinsic stains are those that cannot be removed by mechanical methods such as scaling or by prophylactic methods. As we age, teeth may appear yellower. Listed below are a number of examples that are the source of these discolorations:

Abrasion and ageing teeth: abrasion is a progressive loss of enamel and dentin due to erosion and attrition of the teeth. As the enamel wears away, the dentin becomes more obvious and chromogens penetrate the tooth more easily. The natural production of secondary dentin contributes to the changing color of teeth as they age.

Tooth decay: The evidence for dyschromia caused by tooth decay is inconclusive, however it is suggested that cavity lesions allow exogenous agents to penetrate the dentin and therefore the increased absorption of chromogens causes tooth color change.

Restorative materials: Materials used during endodontic treatments, such as eugenol and phenolic compounds, contain pigments that stain dentin. Restorations using amalgam also penetrate the dentinal tubules which over time, cause tooth color darkening.

Dental trauma can cause staining as a result of pulp necrosis or internal resorption.

Enamel hypoplasia: Enamel hypoplasia causes enamel thickness and strength to decrease. It causes yellow-brown discoloration and can also cause the smooth enamel surface to be rough and porous, making the tooth susceptible to extrinsic discoloration, tooth sensitivity, malocclusion and dental caries.

The evidence for enamel hypoplasia is inconclusive; however, the most likely cause is infection or trauma to the primary dentition. Developing tooth germ disorders during the neonatal and early childhood stages, such as maternal vitamin D deficiency, infection and drug administration can cause enamel hypoplasia.

Pulpal hyperemia: Pulpal hyperemia refers to inflammation of a traumatized tooth that can be caused by stimuli such as trauma, heat shock or dental cavities. Pulpal hyperemia is reversible and produces a red tinge initially seen after trauma that has the ability to disappear if the tooth is revascularized.

Fluorosis: Dental fluorosis causes the enamel to become dull, chalky white and porous.

The enamel can break down and cause the layer under the exposed enamel to become marbled and lead to the appearance of extrinsic dark brown to black stains. Dental fluorosis occurs as a result of excessive fluoride ingestion or overexposure to fluoride during enamel development, usually occurring between the ages of one and four.

Fluoridated drinking water, fluoride supplements, topical fluoride (fluoride toothpaste) and formula prescribed to children can increase the risk of dental fluorosis. Fluoride is considered an important factor in the management and prevention of dental caries, the optimal level for daily intake is 0.05 to 0.07 mg/kg/day.

Dentine genesis imperfecta: Dentinogenesis imperfecta is an inherited defect of dentin, associated with osteogenesis imperfecta, which causes the tooth to change color, usually to blue or brown and translucent, giving teeth an opalescent lustre. The condition is autosomal dominant, meaning it runs in families.

Amelogenesis imperfecta: The appearances of amelogenesis imperfecta depends on the type, there are 14 different subtypes and can range from the appearance of hypoplasia to hypomineralisation, which can produce different enamel appearances from white to a yellowish brown appearance.

Tetracycline and minocycline. Tetracycline is a broad-spectrum antibiotic and its derivative, minocycline, is commonly used in the treatment of acne. The drug is able to bind calcium ions by being incorporated into teeth, cartilage and bone.

Ingestion during the developmental years of teeth causes yellow-green discoloration of dentin visible through enamel that fluoresces under ultraviolet light. Over time, tetracycline is oxidized and the staining becomes browner and no longer fluoresces under UV light.

Porphyria: A rare metabolic disorder in which the body fails to adequately metabolize porphyrins, resulting in the accumulation or excretion of porphyrins in the teeth. These porphyrins produce red-purple pigmentation in the teeth.

Hemolytic disease of the newborn: This disease occurs when a newborn’s red blood cells are attacked by antibodies from the mother as a result of an incompatibility between the mother’s blood and that of the fetus. This condition can cause green staining of the teeth due to jaundice, which refers to the inability to properly excrete bilirubin.

Root resorption: Root resorption is clinically asymptomatic, but may produce a pink appearance at the amelocemental junction.

Alkaptonuria: Metabolic disorder that favors the accumulation of homogentisic acid in the body and can cause brown pigmentation of the teeth, gums and oral mucosa.

Bleaching methods

Before proceeding with teeth whitening alternatives, it is recommended that the patient visit the dentist’s office for a complete oral examination consisting of a full medical and dental history. This will allow the doctor to note if there are any treatments that need to be performed, such as crown restorations after caries removal, and to assess whether or not the patient will be a good candidate to recommend whitening.

The doctor would then perform ultrasonic loop scaling, hand instruments and possibly brushing with a special paste to remove extrinsic stains as mentioned above.

This will allow a clean surface to achieve the maximum benefits of whichever teeth whitening method the patient chooses. Below we will discuss the different types of teeth whitening methods, including internal application of whitening product and external application using whitening agents.


Before treatment, the doctor should examine the patient: take a medical and dental history (including allergies and sensitivities), observe hard and soft tissues, the quality of restorations, and sometimes x-rays to determine the nature and depth of possible problems. If these things are not completed before whitening agents are applied to the tooth surface, excessive sensitivity and other complications can occur.

Color keys are used to determine the color of teeth. These shades determine the effectiveness of the whitening procedure, which can range from two to seven shades. These shades can be achieved after a single in-office procedure or may take longer, depending on the individual.

The effects of whitening can last for several months, but can vary depending on the patient’s lifestyle. Eating foods or drinking beverages that stain teeth can compromise the effectiveness of the treatment. These include foods and drinks containing tannin such as; coffee, tea, red wine and curry.

In-office whitening procedures generally use a light-curing protective coating that is carefully applied to the gums and papillae to reduce the risk of chemical soft tissue burns. The bleaching agent is either carbamide peroxide, which breaks down in the oral cavity to form hydrogen peroxide, or hydrogen peroxide itself. Bleaching gel usually contains between 10% and 44% carbamide peroxide, which is roughly equivalent to a 3% to 16% concentration of hydrogen peroxide. The legal percentage of hydrogen peroxide allowed to be administered is 0.1-6%. Bleaching agents can only be administered by dentists.

Whitening is least effective when the natural color of the teeth is grey and may require personalized whitening treatments. Whitening is most effective on yellow teeth.

If strong staining or tetracycline damage is present on the patient’s teeth and whitening is ineffective (tetracycline discolorations may require prolonged whitening because the whitening agent has a harder time reaching the dentin layer), there are other methods of covering the pigmentation. Fillings, which also mask dental stains, are made when a thin layer of composite material is applied to the front of a person’s teeth, followed by light-curing. Veneers can also mask tooth discoloration.

In-office whitening is faster and more effective compared to at-home whitening options. Some doctors also perform custom whitening guards, which can take up to a week to achieve. After the whitening treatment is complete, the patient can use these mouth guards for maintenance whitening with at-home kits or for use with desensitizing products.

Accelerated light whitening

Light/laser whitening uses light energy which is intended to accelerate the whitening process in a dental practice. Different types of energy can be used in this procedure, the most common being halogen, LED or plasma arc. The use of light during whitening increases the risk of tooth sensitivity and may not be more effective than whitening without light when high concentrations of hydrogen peroxide are used.

A 2015 study showed that the use of a light activator does not improve whitening, has no measurable effect, and rather is likely to increase the temperature of associated tissues, resulting in damage.

The ideal energy source should be one of high intensity to displace peroxide molecules without overheating the tooth pulp. Light is usually in the blue light spectrum, as this has been found to contain the most effective wavelengths for initiating the hydrogen peroxide reaction.

A light whitening treatment usually involves isolating the soft tissues with a protective barrier, which can be fixed by light curing, applying a professional hydrogen peroxide whitening gel (25-38% hydrogen peroxide) and exposing to the light source for 6- 15 minutes. Recent technical advances have minimized heat and UV emissions, allowing for a shorter patient preparation procedure.

For any whitening treatment, a thorough examination of the patient is recommended, including the use of radiographs to help diagnose the current condition of the oral cavity, including any allergies that may be present. The patient will need to have healthy teeth free of periodontal disease or decay and have had a scaling/cleaning to remove any tartar or plaque build-up.

It is advisable to avoid smoking, drinking red wine, and intensely colored foods as teeth can stain quickly immediately after treatment.

Nanoparticle catalysts for low hydrogen peroxide concentration

A recent launch in this field are new accelerated light bleaching agents containing lower concentrations of hydrogen peroxide with a titanium oxide nanoparticle catalyst.

Lower concentrations of hydrogen peroxide result in lower incidences of hypersensitivity of teeth. The nanoparticles act as photocatalysts and their size prevents them from diffusing deeply into the tooth.

When exposed to light, the catalysts produce a rapid and localized breakdown of hydrogen peroxide into highly reactive radicals. Due to the extremely short lifetime of free radicals, they are able to produce whitening effects similar to much higher concentration products, no deeper than the outer layers of the teeth in which the nanoparticle catalysts are located.

This ensures effective teeth whitening while reducing the required concentration of hydrogen peroxide and other reactive side effects in the dental pulp.

Internal whitening

Internal whitening is a process that takes place after a tooth has been endodontically treated. This means that the tooth has had the nerve excised (removed) through a root canal treatment by the dentist or an endodontic specialist. Internal bleaching is often indicated in teeth that have been treated endodontically, as tooth discoloration becomes a problem due to lack of innervation.

It is normal to perform this internal whitening on an anteriorly located tooth (a front tooth that is visible when you smile and speak).

One method by which this can be achieved is by applying the whitening agent inside the tooth and replacing it every few weeks until the desired shade is achieved. The time between appointments varies from patient to patient and according to preference until the desired shade is achieved.

While this is an excellent option, the downside of this treatment is the risk of internal resorption of the root of the tooth that is internally whitened. This may not occur in every patient or every tooth, and its existence is difficult to determine before treatment is completed.

Bleaching at home

Home teeth whitening products are available from dentists or pharmacies without a prescription. Home whitening methods include strips and gels, whitening mouthwashes, whitening toothpastes and mouth guards. These products can be used for milder cases of tooth discoloration. Home whitening (following the manufacturer’s instructions) results in less sensitive teeth than in-office whitening.

Strips and gels

Plastic whitening strips contain a thin layer of peroxide gel and are shaped to fit the oral/lip surfaces of the teeth. Many different types of whitening strips are available on the market, having been introduced in the late 1980s. Each whitening strip product has its own set of instructions, but the strips are usually applied twice a day for 30 minutes over 14 days. Within a few days, the color of teeth can change by 1 or 2 shades. Achieving the teeth whitening goal depends on the frequency of use and the ingredients of the product. Whitening gels are applied to the surface of the teeth with a small brush.


Whitening mouthwash works by the reaction between oxygen sources such as hydrogen peroxide in the water and chromogens on or in the tooth. It is recommended to use twice a day, rinsing for one minute. It can take up to three months to see an improvement in tooth color.


Whitening toothpastes differ from regular toothpastes in that they contain higher amounts of abrasives and detergents to be more effective at removing more stubborn stains. Some whitening toothpastes contain low concentrations of carbamide peroxide or hydrogen peroxide which help to open up the color of teeth, however they do not contain sodium hypochlorite. With continued use over a longer period, the color of teeth may change by one or two shades.

Mouth guards

Teeth whitening can be achieved by wearing an individual mouth guard containing carbamide peroxide whitening gel overnight or for two to four hours a day. If the manufacturer’s instructions are followed, teeth whitening can take place within three days and open up the color of teeth by one or two shades. This type of teeth whitening is available without a prescription.

Baking soda

Baking soda is safe, mildly abrasive and effective toothpaste for stain removal and teeth whitening. Toothpaste that has excessive abrasiveness is harmful to tooth tissue; therefore baking soda is a desirable alternative. To date, clinical studies on sodium bicarbonate have reported that no adverse effects have been identified. It also contains acid-neutralizing components that make sodium bicarbonate biologically antibacterial at high concentrations and capable of preventing the growth of Streptococcus mutants. Sodium bicarbonate could be useful for both patients with cavities and those who want whiter teeth.


– Teeth whitening can be performed for a variety of reasons, but may also be recommended by medical professionals.

– Intrinsic tooth discolorations

– Aesthetic

– Dental fluorosis

– Endodontic treatment

– Tetracycline dyschromia


– Certain categories of people are advised to take care when choosing to whiten their teeth, as they are in certain risk groups and there is a possibility of adverse effects.

– Patients with unrealistic expectations

– Allergies to peroxide

– Pre-existing tooth sensitivity

– Cracks or exposed dentin

– Developmental enamel abnormalities

– Acid erosion

– Gingival retractions

– Sensitive gums

– Non-compliant dental restorations

– Tooth decay. White chalky stains from decalcification may be evident after a tooth whitening process, but with repeated sessions, other areas of the teeth become whiter and the stains less obvious.

– Periapical pathologies

– Untreated periodontal disease

– Pregnant or breastfeeding women

– Children under 16 years of age. Because the pulp chamber is enlarged at this age, bleaching under these conditions can irritate the pulp of the tooth, causing sensitivity. Young people are also more likely to abuse whitening.

– People with visible white fillings/crowns. Tooth whitening does not change the color of fillings or other restorative materials and does not affect porcelain, ceramic or gold. However, it may slightly affect composite restorations, cements and amalgam. Tooth whitening will not restore the color of fillings, porcelain or ceramics when they become stained by food, drink and smoking, as these whitening products are only effective on the natural tooth structure. Thus, a shade mismatch can occur as the natural tooth structure whitens and restorations remain the same color. Other options for such situations are porcelain veneers or restorations.

– Patients with poor oral hygiene.


Some of the common side effects involved in teeth whitening are increased tooth sensitivity, gum irritation and extrinsic discoloration.


The use of bleaching agent with extremely low pH levels in the teeth whitening procedure can lead to dentin hypersensitivity, as it causes the dentinal tubules to open. Exposure to cold, warm or sweet stimuli can further exacerbate the intensity of the hypersensitive response. Of those who receive in-office whitening treatment, between 67-78% of individuals experience sensitivity after the procedure using hydrogen peroxide and heat. Although it varies from person to person, sensitivity after whitening treatment can last up to 4-39 days.

Potassium nitrate and sodium fluoride in toothpastes are used to decrease discomfort after whitening, however, there is no evidence to suggest that this is a permanent method of eliminating the problem of hypersensitivity.

Irritation of mucous membranes

Hydrogen peroxide is irritating and cytotoxic. Hydrogen peroxide at a concentration of 10% or more can cause tissue damage, be corrosive to mucous membranes and cause burning sensations on the skin. Chemical burns may occur as a matter of course, while bleaching, irritation and discoloration of mucous membranes may occur if a high concentration of oxidizing agent comes into contact with unprotected tissue. Improperly bleaching guards are among the most common causes of chemical burns. Transient burns induced by bleaching treatments can be reduced by using individual plastic or night guards made by the dentist. This prevents the solution from leaking onto the surrounding mucosa.

Unstable results

Unstable results are quite common after whitening. Moderate consumption of foods and drinks that cause staining of the tooth surface can contribute to a favorable and lasting result after teeth whitening.

Returning teeth to their original color

Nearly half of the original tooth color changes that occur after intensive in-office treatment (i.e. one hour of treatment) can be lost within seven days. This return is experienced when much of the whitening of teeth comes from dehydration (also a significant factor in causing sensitivity). As the tooth rehydrates, the color of the tooth returns back to where the whitening treatment started.


Over-whitening occurs among treatments that promise a big change over a short period of time, for example, within a few hours. Excessive whitening can result in a translucent and brittle appearance of the tooth.

Enamel damage

Tooth enamel can be adversely affected by whitening treatment. Studies shows that carbamide peroxide in bleaching gels can damage the enamel surface.

Although this effect is not as damaging as etched phosphoric acid, the irregularly extended surface of teeth makes them more susceptible to extrinsic discoloration, thus having an intensely damaging effect on aesthetics.

Increased porosity and changes in surface roughness can have an impact on supra- and sub gingival plaque formation, thereby increasing the adhesion of bacterial species such as Streptococcus mutans and Streptococcus sobrinus, which contribute significantly to dental cavities.

Fragile dentin

Internal Bleaching (intracoronal bleaching) is a method of teeth whitening that uses 30% more hydrogen peroxide. Such tooth whitening methods can decrease the mechanical properties of dentin and could lead to severe tooth sensitivity.

Effects on existing restorations

Dental restorations are susceptible to unacceptable color changes even when using at-home bleaching.

Ceramic crowns – aggressive bleaching can chemically react with ceramic crowns and reduce their stability.

Dental amalgam – exposure to carbamide peroxide solutions increases the release of mercury for one to two days. The release of amalgam components is said to be due to active oxidation. This increase in mercury release from amalgam is proportional to the concentration of carbamide peroxide.

Composite resin- the bond between the enamel and composite fillings loses strength. Many studies have found that dental bleaching gels with 10-16% carbamide peroxide (containing approximately 3.6-5.76% hydrogen peroxide) lead to an increase in surface roughness and porosity of composite resins. However, saliva can exert a protective effect. In addition, changes in the composite material were analyzed after bleaching with high concentration (30-35%) hydrogen peroxide. This suggests that tooth bleaching has a negative impact on composite resin restorations.

Glass ionomers and other cements – studies suggest that the solubility of these materials may increase.

Bleaching dependency

“Bleachorexia” is the term used to describe a person who develops an unhealthy obsession with teeth whitening. This condition is similar to body dysmorphic disorder. The characteristics of this addiction are the continued use of whitening products, even though the teeth may not become whiter despite repeated treatment. A person diagnosed as such will continuously seek different whitening products, therefore it is recommended to set a target shade before starting the treatment procedure to eliminate this problem.

Risks of teeth whitening at home

The use of custom home whitening guards is a patient administered therapy that is prescribed and administered by a dentist. Patients must actively participate in their treatment and follow the directions given by the dentist precisely. Incorrect or inaccurate use of whitening guards could cause damage to the patient, such as canker sores or sensitivity of the teeth and surrounding soft tissues.

Inconsistent use of whitening guides can lead to a slow and irregular whitening process. Some patients with gag reflex may not be able to tolerate the mouth guard and should consider other methods of teeth whitening.

Other risks

Evidence suggests that hydrogen peroxide may act in favor of tumors development. Although root resorption at the cervical level is more obviously seen in thermocatalytic bleaching methods, intracoronal internal bleaching can also lead to this resorption process. Furthermore, severe intracoronal dentin lesions and dental crown fractures may occur due to this bleaching method.

However, the International Agency for Research on Cancer (IARC) has concluded that there is insufficient evidence to show that hydrogen peroxide is carcinogenic to humans. Recently, the genotoxic potential of hydrogen peroxide has been evaluated. The results indicated that oral health products containing or releasing hydrogen peroxide up to 3.6% will not increase a person’s risk of cancer, therefore it is safe to use in moderation.


Despite achieving the desired results from treatment, stains may reappear several months after whitening. Several methods can be adopted to prolong the whiteness of teeth, such as:

Brushing or rinsing the mouth with water after every meal or drink consumed

Floss to remove plaque and biofilm between teeth

Pay special attention to your teeth during the first 2 days after whitening – the first 24-48 hours after the procedure are seen as the crucial time when teeth need to be protected. So it is vital to consume non-staining foods and drinks during this time, as enamel is prone to absorb any pigment.

Depending on the method used to whiten teeth, retreatment every 6 months or after a year may be indicated. If a patient is a smoker or consumes foods with the ability to stain, regular treatments are preferable.