A perfect pearly white smile is a priority for many patients, and that usually means a dose of at-home or in-office bleaching. But what about situations in which bleaching is not an option?
One possible treatment in such cases is "tooth lightening." Developed in 2000 at the University of Queensland in Brisbane, Australia, this technique avoids peroxide altogether, instead relying on remineralization to change tooth color.
Basically, a dentist or hygienist polishes and smoothes the tooth surface, making it reflect more light and appear brighter. This is followed by at-home remineralization therapy to strengthen enamel.
"There is no oxidation chemistry at work; rather, it is remineralization chemistry, so the enamel and dentin color is not changed dramatically," said Laurence J. Walsh, Ph.D., D.D.Sc., the head of dentistry at the University of Queensland and an inventor of the technique, in an interview with DrBicuspid.com. "It's a partner to whitening, not an alternative."
The concept exploits the optical properties of the tooth, particularly the enamel, and the influence of water present in the enamel.
"The scientific foundations of the tooth-lightening concept rest largely on altering the short wavelength (blue) scatter of enamel and reducing its transmission of yellow light," Dr. Walsh wrote in Australasian Dental Practice (March/April 2008, Vol. 192, pp. 48-50). "The more porous the enamel, the less it scatters short (blue) wavelengths of light. The more the enamel scatters blue light, the lighter it appears."
During the procedure, the patient first receives a gentle microabrasion procedure using 37% phosphoric acid etching for 20 seconds, followed by gentle application of flour of pumice or graded abrasive pastes at low rotational speeds. This process enhances not only the scatter of the shorter wavelengths but also the subsequent subsurface mineral changes, Dr. Walsh explained in the article.
The patient then uses MI Paste each night immediately before bed for at least two weeks. This process results in a reduced yellow transmission and increased backscatter of blue light from the enamel, making teeth appear brighter, he explained furthur in the article.
MI paste contains Recaldent, which is touted by makers to have remineralization qualities -- a claim that has been refuted by many researchers but upheld by others.
Where did the idea for tooth lightening come from?
"When we began working with topical preparations of Recaldent about eight years ago, we realized that several changes in the optical properties of enamel occurred," Dr. Walsh said. "We were interested in applications of this material for altering enamel, and when we started to analyze before/after images of patients we had treated to reverse their enamel demineralization, it became clear that there were other effects as well as reducing the areas of opacity."
The tooth-lightening procedure can be used on patients with minor enamel opacities prior to whitening to achieve a consistent enamel shade, explained Dr. Walsh.
"We also use the lightening method on patients with very light baseline shades, such as A1 or B1, to maximize the reflective light appearance of their teeth -- since there would be limited benefit in attempting whitening in such patients," he said.
According to Dr. Walsh, likely candidates for tooth lightening include:
- Patients with mild fluorosis
- Patients who have small enamel opacities from previous whitening treatments that have caused overbleaching
- Patients who have just been debanded after fixed orthodontic treatment
- Pediatric patients, who you would not consider for bleaching treatment
The technique was developed in Australia and has been in clinical use there for many years. It is also popular in Southeast Asia and New Zealand, Dr. Walsh explained. However, it has yet to garner much attention in the U.S.
Edward J. Swift Jr., D.M.D., M.S., professor and chair of the department of operative dentistry at University of North Carolina at Chapel Hill and associate editor of the Journal of Esthetic and Restorative Dentistry, told DrBicuspid.com that he had not heard of tooth lightening and so could not comment on it.
Lynn Ramer, L.D.H., president-elect of the American Dental Hygienists' Association, said that patients should ask their oral healthcare professional about all whitening options and whether they are an ideal candidate for this procedure.
"Experts agree that peroxide is usually the way to go," she added.
