Claudia Hoffman, D.D.S.
Internal Bleaching Techniques and Cervical Resorption
Claudia Hoffman

Claudia Hoffman

TOOTH DISCOLORATION is a challenge that many dentists face, and internal bleaching is a practical treatment option. Internal bleaching is used to lighten a discolored tooth that has had root canal therapy. It involves placing a chemical oxidizing agent within the coronal portion of a tooth to remove discoloration.  The etiology of tooth discoloration can be intrinsic, extrinsic, or both; it can involve dentin, enamel, or pulp; it may be brought on by diet, age, or habits; it may be local or systemic; and in some cases it may be iatrogenic.  Discoloration can be caused by endodontic filling materials or medications that the patient is taking.  Discoloration associated with pulpal involvement can be caused by intrapulpal hemorrhage (in which case it is pink or brown), necrotic pulpal tissue, secondary dentin formation (in which case it is yellowish), and internal resorption (in which case it is a pink spot). 
    Most bleaching agents are oxidizers that act on organic structures of the hard tissues and degrade them into smaller molecules that are lighter in color, such as C02, 02 and H20. 
    Indications for internal bleaching are discoloration of pulpal origin, dentin stains, and stains not amenable to extra-coronal bleaching. Contraindications to internal bleaching are superficial enamel stains, defective enamel formation, severe dentin loss, presence of caries, and discolored composites.
    There are two techniques for internal bleaching: the chairside technique and the “walking bleach” technique. The chairside technique uses Superoxyl in 30 to 35 percent concentration, H202, and heat. This technique is highly effective, but the oxiding agent is strong and can burn. There is a six-to-eight percent chance of cervical resorption, increasing to 18 to 25 percent when the technique is used in conjunction with heat.  The “walking bleach” technique uses a mixture of sodium perborate and water and may be utilized if the chairside results are inadequate or if you prefer to avoid the possibility of a higher chance of cervical root resorption. The sodium perborate when fresh is 95 percent perborate giving off 9.9 percent of available oxygen. This material is more easily controlled and safer than Superoxyl; therefore, it is the material of choice. 
    The radiograph in Figure 1 shows a tooth that had root canal treatment and internal bleaching ten years earlier. The patient presented to our office with sensitivity in the gingiva in the area around the tooth. The patient presented with a complete history clearly indicating that he had received internal bleaching via the chairside technique. 
    Internal resorption usually occurs at six months after internal bleaching, and after two years the tooth is usually not restorable, so recall accordingly.
Winter 2004
Figure 1

FIGURE 1: Illustrating cervical resorption, number 11, etiology internal bleaching.

Use 17 percent EDTA in the canal to open up the dentinal tubules before using 2 percent Chlorhexidine to disinfect them.

Allan Deutsch

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