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Inside Dentistry

April 2006, Volume 2, Issue 3
Published by AEGIS Communications


Brushing with a potassium nitrate dentifrice to reduce bleaching sensitivity

Howard E. Strassler, DMD

Haywood VB, Cordero R, Wright K, et al. J Clin Dent. 2005;16(1):17-22.

Abstract

OBJECTIVE: This research systematically evaluated the use of a clinically proven desensitizing dentifrice before a bleaching regimen in a randomized, multicenter, parallel group, open label clinical study following Good Clinical Practice guidelines. METHODOLOGY: Fourteen dental offices in West Palm Beach, Florida participated in the study during April/May 2004. Fourteen days before bleaching, impressions and oral soft tissue assessments were performed, and patients were randomized to either a KNO3 plus fluoride dentifrice (Sensodyne Fresh Mint), or a standard fluoride dentifrice (Crest Regular), brushing 2X per day. On Day 14, patients returned to the dental office for their custom tray and the dispensation of a bleaching kit (Day White Excel 3; 9.5% hydrogen peroxide and KNO3). This was used daily according to the manufacturer’s instructions for 30 minutes, and normal oral hygiene continued to be performed using the assigned toothbrush and dentifrice, brushing 2X per day. At the end of each bleaching day, patients answered diary questions about the occurrence and intensity of sensitivity. At the conclusion of the 14-day bleaching period (Day 28), patients returned to their dental office for re-examination, returning all products and diaries. Within 7 days of completing the study, patients answered a telephone patient satisfaction survey. RESULTS: A total of 202 patients in 14 dental offices completed all aspects of the study and were used for the analysis. The professionally dispensed bleaching product provided an improvement of approximately 4.4 Vita shades, regardless of whether it was used with the KNO3 plus fluoride (Sensodyne) or a standard fluoride (Crest) dentifrice. The patient perception of increased sensitivity caused by the bleaching treatment was low but measurable. In the first week of the bleaching, significantly more patients using the KNO3 plus fluoride dentifrice were free from sensitivity (58%) than the standard fluoride dentifrice group (42%). During the 14-day bleaching treatment period, the KNO3 dentifrice patients experienced significantly more “sensitivity free days” (average = 10.1) compared to the standard fluoride dentifrice group (average = 8.6). CONCLUSION: The use of the KNO3 plus fluoride dentifrice (Sensodyne), two weeks prior to and throughout bleaching, may be a useful adjunct for the management of sensitivity caused by professionally dispensed bleaching products. With the bleaching-induced tooth sensitivity, those patients in the KNO3 plus fluoride toothpaste group were significantly more satisfied with their whitening experience and willing to repeat the bleaching treatment.

COMMENTARY

Sensitivity during vital bleaching is a commonly reported adverse reaction. Studies with both whitening strips and trays have reported sensitivity during treatment as a common occurrence. In some clinical trials as many as 55% to 75% of the patients experience sensitivity from using either the carbamide peroxide or hydrogen peroxide at-home whitening systems. Increased levels of sensitivity with whitening appear to be associated with increased time wearing the trays and higher concentrations of peroxide. In some studies, patients have dropped out during treatment because of sensitivity. Recommendations to patients by practitioners include reducing the time wearing whitening trays, reducing the concentration of the whitening agent, using whitening agents with fluorides and/or desensitizing agents, using desensitizing toothpastes with potassium nitrate, and using desensitizing agents with either potassium nitrate or amorphous calcium phosphate in the tray before and during whitening treatment.

This study evaluated brushing with a 5% potassium nitrate plus fluoride dentifrice to reduce whitening sensitivity compared to brushing with a standard fluoride toothpaste. The mode of action of potassium nitrate has been described as a penetration of the potassium ions through the tubules to the A-fibers of the nerves of the pulp where repolarization of these fibers is prevented after initial depolarization. The potassium levels act to block the action potential generated in the intradental nerves. If elevated levels of potassium nitrate are maintained, the depolarized state decreases the perception of pain. It can almost be described as a numbing effect on dentin hypersensitivity. The treatment regimen for whitening in this study used a high concentration whitening agent (9.5% hydrogen peroxide) that contained potassium nitrate in a custom bleaching tray for 30 minutes once daily. When compared to the standard fluoride toothpaste, the desensitizing toothpaste with potassium nitrate was not statistically significant in decreasing patient-reported sensitivity, but the rate of sensitivity reported by the potassium nitrate toothpaste group was both directionally and consistently lower. This study demonstrated that the patients brushing twice daily for 2 weeks with a desensitizing toothpaste before whitening were significantly more satisfied with their whitening experience and were willing to whiten their teeth again with the same tray techniques. In this study the overall intensity of tooth sensitivity as measured by visual analogue score for tooth desensitizing during the 14 days of whitening treatment (0 = no sensitivity, 100 = extreme desensitizing) was low and not considered bothersome by the subjects. Also, this study used a KNO3 high-concentration hydrogen peroxide whitening gel that had a low rate of sensitivity. A better study design might have been to use patients who had previously dropped out of at-home tray whitening treatment because of sensitivity. In my experience, patients with a past history of whitening sensitivity have been able to complete tray whitening using a KNO3 toothpaste for 2 weeks before and during whitening treatment.

This study provides a strategy for clinicians to recommend to patients when whitening teeth with an at-home tray technique. It is important to understand that potassium nitrate desensitizing toothpastes need to be started before initiating whitening treatment. It is impossible to predict who will experience sensitivity during whitening unless the patient has a history of sensitivity during past whitening experiences. For those patients with a past history of tooth sensitivity while whitening, placing them on a regimen of desensitizing toothpaste use before whitening is a good clinical recommendation.

About the Author

Howard E. Strassler, DMD
Professor and Director of Operative Dentistry
Department of Endodontics, Prosthodontics and Operative Dentistry
University of Maryland Dental School, Baltimore, Maryland


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