TOOTH WHITENING, THE MICROABRASION TECHNIQUE, AND WHITE SPOT ERADICATION

Linda Greenwall

INTRODUCTION

It has now been 25 years since the introduction of the microabrasion technique. There are many published studies on its 20-year effectiveness as a technique that eradicates and fades white spots, white marks, and white lesions. Microabrasion techniques are used in combination with whitening techniques, and microabrasion is an effective minimally invasive treatment option. It is the intention in this chapter to elaborate on the whitening techniques used for teeth with existing white, brown, and orange spots. The chapter will discuss current whitening techniques, microabrasion, and resin infiltration for the eradication of the white spots.

The small white, brown, or mottled lesions that appear on front teeth can be unsightly, and patients are often concerned about this type of discoloration (see Figure 10.1). Some enamel discolorations, although intrinsic, are confined to the outermost layers of the enamel.

TREATMENT OPTIONS FOR WHITE SPOTS, WHITE MARKS, AND WHITE LESIONS

White spots, marks, and lesions have many possible causes and treatments (Tables 10.1–10.4). There are several treatment options for treating white spots on the labial surfaces of teeth, including the following:

•  Tooth whitening

•  Application of amorphous calcium phosphate directly to the lesion or in a whitening tray (Abreu et al. 2011)

•  Microabrasion using 6.6% hydrochloric acid (Greenwall 2006; Opalustre, Optident, United Kingdom) and 10% hydrochloric acid (Premier Dental Products, Plymouth Meeting, PA)

•  Resin infiltration using 15% hydrochloric acid (Icon, DMG, Germany)

•  Combination therapy using whitening and increasing concentrations of hydrochloric acid

•  Composite bonding directly over the lesion

•  Removing the white mark with a fast handpiece and restoring with composite resin, dentin, enamel, and opaque shades

•  Direct and translucent resin veneer

•  Indirect resin veneer (Edelweiss, Optident)

•  Porcelain laminate over the whole labial surface

WHAT IS MICROABRASION?

Enamel microabrasion is a procedure in which a microscopic layer of enamel is simultaneously eroded and abraded with a special compound, leaving a perfectly intact enamel surface behind (Croll 1991b). It is used to treat enamel discolorations that may be the result of hypermineralization, hypomineralization, or staining. Croll (1991b) called the process “enamel dysmineralization,” which describes the superficial enamel coloration defects resulting from some disturbance of the normal mineralization process. There are advantages in using a combination of chemical and mechanical surface micro-reduction. In successful cases enamel loss is insignificant and unrecognizable and the patient is left with tooth surfaces that appear normal (Greenwall 2009). This technique can be used before, after, or during the whitening treatment.

THE DIFFERENCE BETWEEN WHITENING AND MICROABRASION

Microabrasion improves tooth color by eliminating the superficial discolored enamel. Once the discoloration has been removed, the result is permanent. Microabrasion is preferred when general tooth color changes are not needed, but a defined isolated surface discoloration is present (Haywood 1995).

Whitening treatment improves tooth color by lightening, whitening, and brightening the teeth. Unlike microabrasion, whitening preserves the intact fluoride-rich layer of enamel and the tooth shape. The shade of the teeth over many years may darken slightly, but the teeth never return to their original dark color. Whitening will lighten and whiten the actual tooth color, thus rendering the white spot less noticeable because the background shade is whiter.

The two techniques can be used in conjunction with each other depending on the specific case (see Figure 10.4). Sometimes after microabrasion the tooth appears more yellow or darker. Whitening can thus follow microabrasion to improve tooth color. The best results and improvements are achieved with a combination of both treatments (Croll 1997). Normally whitening is undertaken first when a patient has white spots on the teeth. Many small white spots will fade with whitening and so it may not always be necessary to undertake microabrasion. Because whitening is noninvasive, it is best to undertake whitening first followed by microabrasion if necessary.

HYDROCHLORIC ACID

The use of hydrochloric acid to whiten teeth and remove stains from teeth has been advocated for many years. Hydrochloric acid and pumice are the main ingredients used for the technique. The use of hydrochloric acid depends on the decalcification of enamel, that is, softening and dissolving the enamel to remove the stain. It should be selectively applied and well controlled (McEvoy 1998). Normally less than 200 mm of enamel in total is removed, but it may be much less. Use of the correct concentration, procedure, and application can allow careful control of the degree of enamel loss (Touati et al. 1999). The effects of hydrochloric acid are nonselective and superficial. The technique may be enhanced by adding an abrasive (pumice, as advocated by Croll 1986), heat, or chemicals such as hydrogen peroxide and ether (Touati et al. 1999). Which concentration of hydrochloric acid is used first depends on the case. A higher concentration of hydrochloric acid is used in the resin infiltration technique (Greenwall 2013). This technique allows for the placement of 15% hydrochloric acid directly onto the white lesion for 2 minutes. This is followed by an alcohol preparation to assess the likelihood of the white lesion disappearing. This preparation is called Icon-Dry. This is then followed by the Icon resin, which infiltrates the white lesion. The Icon resin is placed onto the tooth for approximately 3 minutes and then the resin is light cured for 40 seconds. This resin is then applied again and allowed to set, followed by further light curing. If the area does not fade, the technique can be repeated again, this time using a microetcher to sandblast (see Figure 10.4G) the white lesion first to obtain deeper penetration (Greenwall 2013). The resin infiltration technique was first used to treat interstitial lesions showing changes in the enamel causing demineralization interstitially.

WHAT IS THE BEST AGE FOR TREATMENT OF THE WHITE SPOTS?

Although the white spots can sometimes be treated at the time of eruption of the permanent tooth, it is best to wait until full eruption of the tooth to understand the nature of the white spot or lesion. Teenagers are at an ideal age to undertake this treatment because this is the age at which individuals become aware of their appearance, especially the appearance of their teeth.

Normally it is best to undertake whitening first because home whitening treatment may eradicate the lesion completely. Once the whitening treatment is completed, then microabrasion can be undertaken. Less treatment may be required because the lesion is smaller. Sometimes despite all available treatment options, the white spot is too large to respond to whitening, microabrasion, and resin infiltration treatment; the only option may be to place a composite bond directly over the white spot area. This can result in a satisfactory outcome as well. Normally the tooth is whitened first to lighten the background shade and then the white patch is surveyed for the results, after which a simple mega-abrasion technique may be used whereby a microscopic layer of the surface enamel is removed and a direct composite resin is placed over the white lesion. Before treatment is begun, the area is cleaned with a mixture of pumice and chlorhexidine soap (Hibiscrub soap; see Figure 10.7E). The tooth is prepared and then the restoration is layered segmentally for a beautiful esthetic result (see Figure 10.7G). The tooth can also be prepared by air abrasion with the Aquacut machine using bioglass for cleaning (Aquacut and Sylc bioglass [Velopex International, London]).

Microabrasion of the enamel surface can be undertaken in patients of all ages: adolescents, adults, and the elderly.

In a study using a split-mouth study design (Sheoran et al. 2014) 37% phosphoric acid and 18% hydrochloric acid were used for removal of visually unesthetic developmental enamel opacities of young permanent maxillary anterior teeth from 25 patients (11–13 years old) by two microabrasion techniques for 10 and 5 seconds. This procedure was repeated four to six times during each clinical appointment. The patients were evaluated about their satisfaction with the treatment. Two blinded evaluators appraised both sides of the mouth using a visual analog scale. The records were analyzed using the Wilcoxon test. The results showed that the majority of the patients (approximately 97%) reported satisfaction at the end of the treatment (P = .001). Statistically significant reduction in enamel opacities was observed by evaluators immediately after microabrasion technique in group 1 (81.75%) and in group 2 (81.4%) (P < .002). Reduction was increased to 97.2% in group 1 and 96.7% in group 2 after 1 month.

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