WHITENING TREATMENTS FOR TETRACYCLINE DISCOLORATION

Linda Greenwall and Bruce Matis

INTRODUCTION

Home whitening techniques have been shown to be effective in treating basic, intermediate, and advanced discoloration problems. Tetracycline discoloration can be classified as advanced discoloration because of its depth and complexity. There are several forms of tetracycline discoloration—a diverse range of discolorations that result from the ingestion of the antibiotic tetracycline (Watts et al. 2001). It is the intention of this chapter to discuss the methods of treating tetracycline discoloration and their effectiveness, to help with treatment planning and sequencing of staging of appointments for a patient with this condition.

Tetracycline discoloration has been the most tenacious type of staining to remove with whitening techniques. Initially it was thought that use of whitening techniques would not be successful. When the treatment times were extended initially from 2 weeks to 6 weeks, it was discovered that the treatments could be successful, with success being time dependent. This is because the tetracycline discoloration molecule is embedded in the dentin, and so the whitening gel needs to travel deep into the tooth to be able to effect whitening and to lift the stain out of the tooth. The antibiotic tetracycline belongs to a category of broad-spectrum antibiotics that are capable of staining teeth. Staining can be generalized or localized, with banding or without banding. The onset of staining can vary from 1 month to many years after the start of therapy (Tredwin et al. 2005).

Some tetracycline antibiotics, such as minocycline, a semisynthetic antibiotic (also known as Minocin) that is prescribed after tooth eruption to treat acne in teens and adults, can cause severe gray discoloration. There are reports that ingestion of this antibiotic also causes staining of the bones, and it has been shown to cause pigmentation of a variety of tissues, including skin, thyroid, nails, sclera, teeth, and conjunctivae (Dodd et al. 1998). Adult-onset tooth discoloration after long-term treatment with minocycline has also been reported. Minocycline is prescribed as a long-term medication; some patients may take the drug for 1–2 years. Recent reports in the medical literature have recommended that this medication be used as a second-line drug and that there be greater disclosure of the harmful effects on the teeth by medical doctors who are prescribing such antibiotics to their patients (Raymond and Cook 2015).

Three mechanisms can cause staining of the teeth after minocycline ingestion (Raymond and Cook 2015):

1.  The intrinsic theory proposes that discoloration occurs with absorption. The minocycline molecule becomes highly protein bound and then preferentially binds to higher collagen-containing tissue (i.e., teeth and bone), resulting in discoloration (Sanchez et al. 2004, Good and Hussey 2003).

2.  The extrinsic theory is based on the high concentration of minocycline excreted in the gingival fluid. The drug stains by etching into the enamel, where the minocycline becomes oxidized (i.e., turns black in color) either by exposure to oxygen or from bacterial activity (Dodd et al. 1998, Good and Hussey 2003, Sanchez et al. 2004, Kugel et al. 2011).

3.  The chelation of hemosiderin (a breakdown product of minocycline) with iron ions forms an insoluble complex within the teeth.

Raymond and Cook (2015) also recommend strategies to avoid minocycline staining as follows:

1.  Avoid prescription of minocycline until all crowns are complete (16 years + 2–3 years).

2.  Avoid long-term use of minocycline.

3.  Decrease the dose of minocycline from 100 mg/day to 50 mg/day for long-term treatment, provided the indication allows.

4.  Decrease the dose of minocycline from 100 mg/day to 50 mg/day in patients being treated for acne (Bernier and Dréno 2001).

5.  Administer vitamin C with minocycline because it has been shown to decrease the formation of the degradation product (the quinine ring structure) that is a component of the actual stain (Bowles 1998).

Tetracycline staining may be classified as in Table 13.1. For several reasons, incisors are affected more than molars:

1.  Time of ingestion of medication normally occurs earlier during the child’s growth, so the anterior teeth are affected first.

2.  Exposure of the teeth to sunlight and radiation causes these teeth to become more yellow and to darken as the teeth erupt (Cohen et al. 2002).

3.  Posteruption staining may occur on wisdom teeth when minocycline is administered during the teenage years to treat acne (Raymond and Cook 2015).

Table 13.2 lists whitening methods to consider for tetracycline staining.

PROGNOSIS OF WHITENING FOR TEETH AFFECTED BY TETRACYCLINE

The study of tetracycline-stained teeth by Haywood et al. (1997) led to a prognosis assessment, which can benefit the clinician when planning whitening treatment of teeth stained by tetracycline (Table 13.3).

FACTORS TO CONSIDER FOR TETRACYCLINE STAINING DURING WHITENING

Once the diagnosis of tetracycline staining has been made, the next important factor to discuss is the sequence of the treatment timing. It is well known that the whitening treatment may take an extended period of time; it is important to discuss the time commitment with the patient so that he or she is fully aware of the extended duration. The patient should be aware that there are no guarantees as to the amount of whitening that can be achieved, but the time factor is essential. The patient should be recalled at extended intervals.

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