Smiling is an important aspect of a person's appearance as it can enhance a person's facial features and convey positive emotions like friendliness and approachability. It makes a person look more attractive and youthful by enhancing their facial features, thereby uplifting their confidence and self-esteem. When someone smiles, their teeth are often visible and healthy teeth significantly improve the overall appearance of the smile. With increasing awareness, more people are opting for cosmetic dental whitening products and treatments to enhance the aesthetic appeal of their smile, furthering the demand for over-the-counter (OTC) teeth-whitening products.
‘Teeth whitening’ is only the desired outcome which is achieved by altering the shade of the tooth internally or externally via ‘bleaching’. Therefore, it is important to understand that success lies in the accurate diagnosis of whether the staining or discoloration is internal or external called Intrinsic or Extrinsic staining respectively. Whitening dentifrices (toothpaste), mouth rinses, strips, and paint-on gels/varnishes among others are the most popular categories of available whitening products in the global market; and OTC use involves independent purchase followed by unsupervised use and application by the patient. In this segment of our series, we shall explore some of the OTC products available.
Dr Meghana Pasala - an orthodontist- explains the science of teeth whitening in a bound at MedBound:
https://www.medbound.com/public/public-post/c2ba6a78-9437-46e8-b50b-7357cacf379a
Whitening Dentifrices:
These kinds of toothpaste occupy the majority of the market and are the most common and cost-effective OTC whitening products used by people. Most whitening dentifrices consist of greater proportions of detergent and abrasives as opposed to regular dentifrices. They primarily intensify extrinsic stain removal and dislodge the deposits from tooth surfaces; having a no impact on intrinsic staining. Various brands contain various types of abrasive agents like hydrated silica, calcium carbonate, sodium bicarbonate, nanohydroxyapatite, etc and more recently charcoal as a vegan alternative; but the abrasiveness increases with increased size and quantity/concentration of this component. Additionally, the type, shape, pH, and detergent components also influence the abrasive potential of these products. A possible risk highlighted with the use of whitening dentifrices is regarding increased chances of erosion of the tooth surfaces (enamel and dentin) especially in susceptible people, subsequently leading to sensitivity; and irritation of soft tissues.
According to research data, sodium bicarbonate-based whitening dentifrices have demonstrated better efficacy as compared to conventional dentifrices due to reduced hardness and its ability to buffer acidity. Some whitening effects may be expected from products containing low concentrations of bleaching agents like hydrogen peroxide or carbamide peroxide, but their ‘whitening’ effect remains controversial as it may be attributed to stain removal alone and not an actual ‘bleaching’ effect. Recently, blue covarin dye-based dentifrices have been launched where an optical effect tends to reduce the yellowish appearance of teeth due to light scattering. An illusion of white lustrous teeth is noted which was found to be unstable even after a twice-daily application for two weeks. Many products do not accurately disclose the contents and therefore it is difficult to predict their effect; however, no significant colour change has been documented with the use of any dentifrice so far and they all primarily prevent extrinsic staining to keep the tooth surfaces free of deposits.
Mouth rinses:
Conventional mouth rinses are swished vigorously in the oral cavity and are typically used in dilution. Whitening mouth rinses can contain low concentrations of bleaching agents like hydrogen peroxide, up to 4%, which breaks down the superficial chromogenic stains leaving a clean tooth surface. They may also contain pyrophosphate which has an affinity for calcium in the tooth surface and therefore inhibits chromogenic deposition and stain formation. Alternatively, hexametaphosphate may also be present, which also prevents extrinsic stain formation.
Mouth rinses are indicated for use in short spells, therefore their overall efficacy is relatively inconsistent resulting from a limited contact period and penetration into the tooth surface. Due to their acidic pH, it may not be advisable to use them for an extended period as they can increase the risk of tooth erosion. Tooth sensitivity and mild irritation, particularly in susceptible individuals, have also been observed.
Some concerns regarding carcinogenic risks were expressed due to the presence of hydrogen peroxide in combination with alcohol, but this was not adequately proven; subsequently, alcohol consumption and smoking are mostly discouraged during bleaching treatments. While the whitening effect may be debatable, based on the available research data, mouth rinses are relatively safe as they do not cause damage to soft tissues and fewer long-term adverse effects were noted.
Whitening strips:
These are adhesive strips containing active ingredients like hydrogen peroxide in moderate (5-14%) concentrations. They are adhesive and can be applied on the front teeth for 5-60 minutes, once or twice a day depending on the desired outcome. Their ability to provide "whiter teeth" can be attributed to both, an extended contact period and the presence of a barrier that prevents dilution of the active agent, resulting in favorable outcomes. The majority of relevant research studies found whitening strips to be the most effective option available on the market, and that patients preferred them over all other options. In addition to the adverse effect on existing fillings, the severity of tooth sensitivity and gum irritation was greater and therefore cautious use is advised.
Paint-on varnish and gels:
These are OTC barrier-free whitening products containing bleaching agents in suspension form. They are applied on the enamel surface using a brush or cotton-based applicator and may be left to dry for 30 seconds. Studies suggest that the apparent shade change is inferior to whitening strips, but they are easy to use and cost-effective. Accidental swallowing puts the patient at risk for adverse experiences and therefore their safety is questionable. They are best used under a dentist's supervision, hence their OTC availability is often subject to the regulations of the respective authorities.
Other products:
Another popular OTC product is a universal tray used with bleaching gel and activated using LED light, but there is a lack of clarity regarding the active agent used and its concentration. Furthermore, the universal tray may not adapt correctly to every dentition, leading to soft-tissue damage, adverse effects, and irritation or bite problems. Chewing gums are becoming widely popular and often contain sodium hexametaphosphate (4-7.5%) as the active ingredient. They prevent the accumulation of stains and plaque resulting in a superficial action. While they may be effective in the removal of tea or coffee-based stains, their efficacy against other OTC products is not proven. Whitening dental flosses and toothbrushes are also available but their effect is strictly superficial resulting in extrinsic stain removal.
Charcoal-based products are trending because of successful marketing as vegan and natural alternatives, but their mode of action is purely abrasive and their abrasive potential depends on the source like, nutshells, bamboo, peat or wood, etc. Charcoal is frequently incorporated in toothpaste, but due to its high absorption capacity, it inactivates fluoride and other active ions; thereby diminishing the crucial benefits like remineralization and anti-caries effects. There is a lack of scientific evidence to support any whitening effect attributed to charcoal, and its use increases the risk of caries in individuals who are susceptible to them.
To summarize, the abundance of OTC products has created a potentially hazardous and perplexing situation for patients. In order to prevent allergic reactions and negative experiences, there is a need for greater transparency in product descriptions regarding the composition and concentration of active ingredients. Although OTC services and products offer patients the freedom to make their own decisions, a trained dentist's expertise in observation, diagnosis, and treatment recommendations far exceeds that of patients in evaluating their condition or detecting any abnormalities.
References:
Mazilu Moldovan A, Popescu V, Ionescu CV, Cuc S, Craciun A, Moldovan M, Dudea D, Mesaros AS. Various Aspects Involved in the Study of Tooth Bleaching Procedure: A Questionnaire-Based Study. Int J Environ Res Public Health. 2022 Mar 27;19(7):3977.
de Freitas MR, de Carvalho MM, Liporoni PCS, Fort ACB, Moura RM and Zanatta RF. Effectiveness and Adverse Effects of Over-the-Counter Whitening Products on Dental Tissues. Front. Dent. Med. 2021;2:687507.
Blanchard D, van Wissen K. Home-based chemically induced whitening (bleaching) of teeth in adults: A summary of a systematic review. Public Health Nurs. 2020 Jul;37(4):626-627.
Omar F, Ab-Ghani Z, Rahman NA, Halim MS. Nonprescription Bleaching versus Home Bleaching with Professional Prescriptions: Which One is Safer? A Comprehensive Review of Color Changes and Their Side Effects on Human Enamel. Eur J Dent. 2019 Oct;13(4):589-598.
Naidu AS, Bennani V, Brunton JMAP, Brunton P. Over-the-Counter Tooth Whitening Agents: A Review of Literature. Braz Dent J. 2020 Jun;31(3):221-235. Demarco FF, Meireles SS, Masotti AS. Over-the-counter whitening agents: a concise review. Braz Oral Res. 2009;23 Suppl 1:64-70.
