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Is cosmetic teeth whitening safe?

Published by
SmileLabs, LLC
Written by
Zachary Hilgers, DDS (Retired)
November 19th, 2009
© All Rights Reserved


It has often been asked as to whether or not cosmetic teeth whitening procedures done by SmileLABS™ are safe or if the process “hurts the enamel.” A similar question asked is “Does this treatment hurt or effect dental fillings, veneers, or caps?” This paper reviews the scientific literature as regards the safety of using peroxide based whitening agents on dental hard and soft tissues. This is the type of bleaching material that SmileLABS™ uses.


Currently, cosmetic teeth whitening or teeth bleaching is performed, either in a dental office or by an independent entrepreneur, by placing a peroxide-based bleaching gel into direct contact with the dental hard tissues. This contact of bleach to teeth is facilitated either by painting the gel directly onto the teeth or by use of a custom made whitening tray loaded with bleaching gel that is placed into the mouth to carry the gel and keep it held in constant contact with the outer surface of the teeth. The former method is the one that SmileLABS™ uses for its chairside whitening. It has been shown that these two techniques will result in noticeable whitening of the teeth, with the finished degree of whitening being based on both the relative strength and concentration of the peroxide-based gel and the amount of time that the active gel is left in contact with the surface of the teeth. If the concentration was low, a longer amount of time of contact with the teeth bleaching gel was needed to achieve a satisfactory result. This meant that for the patient a number of successive daily treatments were needed either in the dental office or at the patient’s home for the teeth to become satisfactorily white.

Making the teeth bleach concentration stronger, on the other hand, would speed the color change, but would often lead to increasingly painful tooth sensitivity, which was a very non-desirable result for both the patient and practitioner. So, experience showed that a good result could be obtained at home if the patient used either a medium peroxide concentration of bleaching gel coupled with a regimen of spacing the treatments into an hour per day for a number days to a week, or to all-night bleaching with a low peroxide concentration gel every night for a 7-21 day course of treatment. These two variations of the teeth bleaching processes have been used for many years with a good and predictable outcome for the patient who actually correctly completes the treatment regimen.

The only downside was that results were not immediately obtained, but were gained incrementally over a number of days or weeks. Since this type of treatment was done unsupervised at home, strict compliance with treatment guidelines was many times hard, if not impossible to maintain, and results and patient satisfaction with the treatment were many times negative.

Therefore, many a practitioner hoped for a way that could combine the shortest course of treatment, coupled with the ability to be able to supervise the entire treatment to a satisfactory conclusion, that was both easy, safe, and pain free from sensitivity to the patient.

This hope resulted in what is now known as Chairside Power Bleaching, the system used by SmileLABS™. By combining a higher concentration of peroxide gel with the use of a strong, safe wavelength of light as an accelerator or catalyst to the bleaching reaction, a much shorter time of contact between gel and tooth resulted that increased the bleaching efficiency of the gel and shortened treatment time by a very large factor, while keeping the process mostly free from sensitivity and achieved the patient’s desire of whiter teeth in minutes instead of days. Also, SmileLABS™ has recently developed some new very effective take-home cosmetic teeth whitening kits for those that would rather do the procedure themselves at home. The question now is whether any of these processes are safe and do they do any damage to the teeth, gums, or even to any of the various dental restorations that a patient may already have in their teeth prior to any bleaching. The following will show that SmileLABS™ products and procedures are in fact very safe while producing the desired result of beautifully whitened teeth.


In December 2007, a group of dental scientists from China did an experiment that entailed bleaching vital teeth that were scheduled for extraction for orthodontic reasons. After the bleaching process, the treated teeth were extracted either immediately after bleaching or after seven days post-bleaching. These teeth were sectioned and mounted for slides immediately post-surgery and a microscopic examination for pathology was performed. The results indicated that there was no clinical pathology found in any of the slide specimens. All teeth in these two groups “showed normal pulp” (nerve and blood supply) and exhibited no visible pathology (disease).[i]

In a more recent study, Mielczarek et al did an in vitro study on extracted premolars and compared surface changes of the enamel after topical applications of various strengths of peroxide-type teeth bleaching gel was applied to the teeth. The hardness of the enamel was recorded (Vickers Hardness Number) prior to application, after the teeth bleaching treatment regimen was completed, and also 7 days after treatment. The results showed that there was significant lightening or reduction of yellow color and that the hardness of the enamel was unchanged, and they concluded that “the bleaching systems were demonstrated as similarly safe to enamel surfaces.”[ii]

Back in 1998, after examining the previous ten years of the then well accepted practice of both chairside and at-home teeth bleaching, Li et al were convinced that the “overall evidence supports the conclusion that the proper use of peroxide-containing…bleaching agents is safe.”[iii] In a long-term study on the effects and safety of vital bleaching, Leonard found that “since its introduction into dentistry in 1989, … vital bleaching has been proven to be a simple and safe procedure to lighten discolored teeth.” He also noted that “participants report that they are glad they went through the procedure and would recommend the procedure to a friend.”[iv]

In 1996 Curtis et al examined the effects of carbamide peroxide teeth bleaching gel on the oral soft tissue, or gum tissue. (Carbamide peroxide is the specific type of peroxide bleach that SmileLABS™ uses in their take home kit.) The researchers found that after conducting a double-blind, placebo-controlled clinical investigation, the data collected did not indicate that any soft tissue damage had occurred as a result of the teeth bleaching regimen.[v]

In a scanning electron microscopy study of dental enamel surface exposed to 35% hydrogen peroxide some very interesting and undeniable results were found. 35% hydrogen peroxide is a very strong concentration of bleach, much higher than used by most teeth whitening systems or over-the-counter products available today. It was shown by examining the post-bleaching electron microscopic data that “considering the morphologic features of the tooth surface, bleaching can be considered safe for enamel.”[vi]

Lastly, I cite a study regarding the effects of bleaching with peroxide on dental restorations, such as tooth-colored composite fillings and on porcelain veneers and crowns. Polydorou et al conducted an in vitro study of teeth bleaching products on the microhardness of six restorative materials used today by dentists. Four of these were resin-based composite materials used in so-called “white fillings,” and on two types of porcelain ceramics used for veneers and crowns or caps. The authors measured the microhardness of the samples before bleaching, after 8 hours and 56 hours of bleaching, and 24 hours and one month post treatment with the bleaching agents. The statistical analysis showed that there was not any “effect on the micro-hardness of any of the restorative materials tested.” 7


Research has shown us undeniably that bleaching teeth with a peroxide-based gel, such as the gel that SmileLABS™ uses, is a safe procedure. The procedure causes no damage to the pulp, that is, the interior nerve and blood supply of the tooth. This prevents a condition known as pulpitis from occurring. Pulpitis is an inflammation of the nerve, which in the minimum causes tooth sensitivity or pain. If the pulpitis is severe enough, it can result in nerve death and necrosis, which leads to the patient having to get root canal therapy and a crown to correct the condition. Not having any pulpal damage is one of the most important indications of safety when bleaching.

The scientific literature also shows that bleaching teeth does not damage the enamel crystalline structure so that no morphological (shape) changes occur. Also, the hardness of the enamel is unaffected by cosmetic teeth whitening with peroxide gel. Enamel is the hardest structure in the human body, and not having it become weaker by bleaching is very important so that chipping and fracture problems won’t occur that would necessitate the patient to have fillings or full coverage crowns to be placed to repair the damage. This again is a very important safety feature of teeth bleaching.

Soft tissues, such as the gingiva (gums) and the buccal and labial mucosa (inner cheek and lip) tissues could also potentially be effected by teeth bleaching gel, however, studies again have shown that proper techniques and lower strength bleaching gel concentrations have resulted in no observable damage or trauma to these tissues. This is a real benefit, as it wouldn’t do to have nice white teeth at the expense of raw gum, cheek, and lip tissues. And lastly, it has been proven that peroxide-based teeth bleaching does not damage in the least any of the current anterior cosmetic restorative materials such as tooth colored composite fillings or porcelain veneers, which are becoming increasingly popular, as well as porcelain crowns (caps.) Not having to replace these restorations because of damage caused by bleaching is a definite boon to the teeth whitening procedures available today. So, a prospective client interested in having a SmileLABS™ teeth whitening procedure performed, whether in one of our Authorized Dealer's retail locations as a chairside power bleaching (with accelerator light) or as a home whitening with one of SmileLABS™ take home kits, can rest assured that the materials and procedures used by SmileLABS™ to whiten their teeth are perfectly safe and efficacious, resulting in beautifully whitened teeth with no undesirable or potentially harmful side effects whatsoever.

Cited References

[i] Zhao Q, Qang JX, Feng ZH. A pathological study of bleaching technique on vital tooth pulp. Chinese Journal of Stomatology. 2007 Dec; 42 (12): 718-19

[ii] Mielczarek A, Klukowska M, Ganowicz M, Kwiatkowska A, Kwasny M. The effects of strip, tray and office peroxide bleaching systems on enamel surfaces in vitro. Dent Mater 2008 Nov; 24 (11): 1495-500

[iii] Li Y. Tooth bleaching using peroxide-containing agents: current status of safety issues. Compend Contin Educ Dent 1998 Aug; 19 (8) 783-6, 788, 790, quiz 79

[iv] Leonard RH Jr. Long term results with nightguard vital bleaching. Compend Contin Educ Dent 2003 Apr; 24 (4A) 364-74

[v] Curtis JW, Dickinson GL, Downey MC, Russell CM, Haywood VB, Myers ML, Johnson MH. Assessing the effects of 10 percent carbamide peroxide on oral soft tissues. J Am Dent Assoc 1996 Aug; 127 (8) 1218-122

[vi] Spaulding M, Taveira LA, de Assis GF. Scanning electron microscopy study of dental enamel surface exposed to 35% hydrogen peroxide: alone, with saliva, and with 10% carbamide peroxide. J Esthet Restor Dent 2003 Mar; 15 (3) 154-64

7 Polydorou O, Hellwig E, Auschill TM. The effect of at-home bleaching on the microhardness of six esthetic restorative materials. J Am Dent Assoc 2007 July; 138 (7) 978-984

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