Internal vs. External Tooth Bleaching: Two Completely Different Processes

External bleaching, the standard whitening most people are familiar with, applies a bleaching agent to the outer surface of the teeth, addressing surface and near-surface staining across all treated teeth simultaneously.

Internal bleaching is a specific technique used on a single tooth that's darkened from the inside, typically following trauma or a root canal, where a bleaching agent is placed inside the tooth's hollow pulp chamber, accessing discoloration that standard external whitening can't reach.

When a tooth darkens due to internal factors, such as blood breakdown products following trauma, or changes related to root canal treatment, the discoloration originates from within the tooth structure itself, meaning external whitening, which only affects the outer surface, generally can't adequately address this specific type of staining.

Internal bleaching is typically performed on teeth that have already had root canal treatment, since access to the pulp chamber, which is empty and sealed following a root canal, is what makes this specific technique possible.

Your dentist accesses the pulp chamber through a small opening, places a bleaching agent inside, and seals it temporarily, sometimes repeating this process over one or more appointments until the desired shade change is achieved, after which the tooth is permanently sealed.

This varies by the severity of discoloration and the specific technique used, sometimes achieved within a single office visit using a more concentrated approach, or sometimes involving the bleaching agent being left inside the tooth for several days between appointments for a more gradual technique.

Effectiveness varies based on the specific cause and severity of the internal discoloration, with your dentist evaluating your specific case to determine whether this technique is likely to achieve a satisfactory result, or whether an alternative approach, like a veneer or crown, might be more appropriate.

In rare cases, this technique has been associated with a specific complication involving resorption of the tooth root, which is part of why proper technique and appropriate case selection by an experienced provider matter, along with follow-up monitoring after treatment.

Results are generally considered long-lasting, though as with external whitening, some gradual relapse of color over many years is possible, and the technique doesn't prevent new external staining from developing on the tooth's outer surface over time from normal factors like diet.

Yes, in some cases, particularly if a patient wants both to address a specific internally discolored tooth and to lighten their overall smile shade, both techniques might be used together as part of a comprehensive treatment plan.

A veneer or crown can cover a discolored tooth entirely, providing a more immediate and predictable cosmetic result compared to bleaching, though these options involve more significant, permanent alteration to the tooth compared to the more conservative internal bleaching approach.