Making the Case for the Abandonment of
Superfluous Overnight Bleaching.
by Rodney Ogrin, DDS
Reservoirs sounded like such a good idea at the time. But, when Clinical Research Associates released the results of their 1997 study of the major bleaching materials, all the products had expired approximately 70% of the active ingredient in the first hour.(1) Dr. Matis' more recent study found a higher retention of the oxidizing agent studied. However, since the CRA study, most of the bleaching suppliers have been running to short-term modality. So why would we continue to use reservoirs?

Reservoirs take unnecessary lab time and may not be in the best interest of our patients. Overnight/multiple-hours bleaching is just not user friendly, making reservoirs the baggage of an outdated bleaching modality.
As pointed out by Rella Christiansen, PhD. of Clinical Research Associates last November at the Loma Linda University, "The State of the Art 2000" panel discussion, an independent CRA study has found no data to support the contention of reservoir effectiveness. An identical conclusion was reached in another clinical study concluding, "...there are no statistically significant differences in those teeth whitened with tray reservoirs versus teeth whitened without tray reservoirs."(2) So, the evidence indicates the desired benefits are simply not realized.

Rodney Ogrin, DDS is a whitening consultant, innovator; and pioneer. Dedicated to whitening for more than a decade, Dr. Ogrin has introduced many whitening products to dentistry.
Other researchers have known it for years. A Haywood 1997 article states: "There is no indication that the presence or absence of a reservoir-type spacer or similar foam insert has any effect on bleaching time."(3)

I believe that reservoirs lack benefits because the extra oxidizing material doesn't reach the tooth surface. The additional material in the reservoir dissipates in the reservoir cavity instead of being absorbed into and activated inside the tooth.

The old-school method of reservoirs and overnight bleaching subject the patient to the swallowing of gel. The reservoirs provide more gel to be swallowed. Overnight bleaching then gives the patient a great deal more time to swallow the extra gel. Swallowing whitening gel is especially a questionable idea when the product contains KNO3.
With no reservoirs, nature's methods are left to work their basic science, and your patients are at lower risk. Van der Waal's forces create a seal between the tray and the tooth that holds the stent in place and helps resist saliva penetration (see left illustration). The minimal amount of gel is used. This way, regardless of how well the patient follows instructions, less gel is at risk of being swallowed. Dosage is .25 cc, the equivalent of 10 to 12 drops placed in the tooth indentations. Less gel equals less patient risk. Therefore, very little material is swallowed and the actual whitening process has the benefit of maximum oxidation per volume of gel. High concentration / short-session bleaching makes whitening teeth amenable to keeping bleaching as a bathroom modality.

Put the gel in the tray, the tray onto the teeth, shower, dry, put on cosmetics/shave, take the tray out, expectorate, rinse, and voilá – timeless patient compliance!

The repeatable data in bleaching science has ushered out overnight modality. We can leave the rest of the overnight reservoir baggage behind, simplify our lab work, and lower the risks for our patients.
Why No Reservoirs?


1. Clinical Research Associates Newsletter, Tooth bleaching, state-of-art '97, 21 :4, 1 :3
2. Bosma M, Bowman J, Dorfman W, and Soil K, Clinical evaluation of a tray fabrication design and effects on vital tooth bleaching. Hill Top Re- search, Inc., Miamiville, OH; 1 :3
3. Haywood V, Extended bleaching of tetracycline-stained teeth. Cont. Esth. & Rest. Practice, Sep. '97, 14:21