Comparative Investigation of the Desensitizing Efficacy of a New Dentifrice Containing 5.5% Potassium Citrate : An Eight-Week Clinical Study

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1 Comparative Investigation of the Desensitizing Efficacy of a New Dentifrice Containing 5.5% Potassium Citrate : An Eight-Week Clinical Study Deyu Hu, DDS College of Stomatology West China University of Medical Sciences Chengdu, China Yun Po Zhang, PhD Patricia Chaknis, BS Margaret E. Petrone, JD Anthony R. Volpe, DDS William De Vizio, DMD Colgate-Palmolive Technology Center Piscataway, New Jersey, USA ABSTRACT The objective of this double-blind clinical study was to investigate the relative effectiveness provided by a commercially-available desensitizing test dentifrice containing 5.5% potassium citrate, 1.14% sodium monofluorophosphate (MFP) and 10% high cleaning silica (HCS) in a silica base (Test Dentifrice, Colgate-Palmolive Company, New York, NY) for reducing dentinal hypersensitivity over an eight week period, as compared to that provided by a commercially-available desensitizing control dentifrice containing 3.75% potassium chloride, 0.32% sodium fluoride and 0.3% triclosan in a silica base (Positive Control Dentifrice, Sensodyne F Total Care Toothpaste, GlaxoSmithKline, UK). A total of eighty subjects were entered into the study, and stratified into two balanced groups according to their baseline mean thermal (air blast) and baseline mean tactile (Yeaple Probe) sensitivity scores. The two groups were randomly assigned to use either the test dentifrice containing potassium citrate/mfp/hcs or the positive control dentifrice containing potassium chloride/sodium fluoride/triclosan. The two groups were well balanced with regard to their mean baseline thermal and tactile sensitivity scores, sex and age. Subjects were instructed to brush their teeth twice daily (morning and evening) for one minute with their assigned dentifrice and a commercially available soft bristled toothbrush. Dentinal hypersensitivity examinations, which included tactile sensitivity and thermal sensitivity (cold air blast) were conducted at baseline, four weeks, 转载

2 and eight weeks. Examinations were conducted by the same dental examiner on the subjects at each examination. After four weeks' use of their assigned products, those subjects in the test dentifrice group demonstrated no statistically significant difference for reducing dentinal hypersensitivity as compared to the positive control dentifrice group, in tactile and cold air blast. After eight weeks use of their assigned products, those subjects in the test dentifrice group again demonstrated no statistically significant difference, in tactile and cold air blast sensitivity, as compared to the positive control dentifrice group. Thus, the results of this double-blind clinical study support the conclusion that the commercially-available test dentifrice containing 5.5% potassium citrate, 1.14% sodium monofluorophosphate and 10% high cleaning silica in a silica base demonstrates no statistically significant difference in tactile and air blast sensitivity as compared to the commercially-available desensitizing control dentifrice containing 3.75% potassium chloride, 0.32 % sodium fluoride and 0.3% triclosan in a silica base. INTRODUCTION Dental hypersensitivity, as typically encountered clinically, can be characterized as a painful, sometimes exaggerated, response to tactile, thermal, chemical, or osmotic stimuli applied to susceptible tooth surfaces. Varying degrees of abrasion or erosion of tooth structure coupled with gingival recession and the consequent exposure of dentinal tubules are clinical events commonly associated with increased dentinal hypersensitivity. The prevailing theory explaining this phenomenon is the hydrodynamic theory 1, which has subsequently been modified 2. This theory proposes that a noxious stimulus at the tooth surface causes fluid movement within the dentinal tubules leading to deformation of mechanoreceptors in the pulp tissue and the resultant painful sensation 3. Various therapeutic agents have been recommended for the relief or control of dentinal hypersensitivity. Previous studies have demonstrated that potassium salt, i.e. potassium nitrate, is an efficacious desensitizing agent 4. Potassium ion has a depolarizing effect on electrical nerve conduction, causing nerve fibers to be less responsive to stimuli 5. Incorporation of potassium salt, i.e. potassium nitrate or potassium citrate or potassium chloride, into dentifrices can be shown to significantly reduce dentinal hypersensitivity 6-8. The objective of the present 8-week clinical investigation was to compare the dentinal hypersensitivity-reducing effect of a new dentifrice formulation containing 5.5% potassium citrate, 1.14% sodium monofluorophosphate and 10% high cleaning silica in a silica base to a commercially available desensitizing dentifrice containing 3.75% potassium chloride, 0.32% sodium fluoride and 0.3% triclosan in a silica base (positive control, Sensodyne F Total Care Toothpaste, GlaxoSmithKline Company, UK).

3 MATERIALS AND METHODS This eight-week clinical study employed a double-blind, stratified, two treatment design, and was conducted in accordance with the recommendations for the evaluation of agents for the reduction of dentinal hypersensitivity developed by the Ad Hoc Advisory Committee on Dentinal Hypersensitivity for the Council on Dental Therapeutics of the American Dental Association Adult male and female subjects from the Chengdu, China area reported to the clinical facility for a baseline examination to determine whether they qualified for entry into the study. They were asked to refrain from all oral hygiene procedures and from chewing gum for eight hours and from eating or drinking for two hours prior to this examination. Possible inclusion into the study was based upon the following criteria: (i) (ii) (iii) (iv) (v) Subjects had to be between 18 and 70 years of age, in generally good health, with no history of allergies or idiosyncrasies to dentifrice ingredients. Subjects needed to possess at least two sensitive teeth other than molars, displaying cervical erosion or abrasion, or gingival recession. Sensitivity was determined by a positive response to stimulation of the denuded root surface just apical to the cemento-enamel junction employing either a dental explorer, or a one-second air blast from a dental air/water syringe. Subjects needed to be available for the duration of the study, and to sign an Informed Consent Form. Teeth exhibiting extensive or defective restorations, caries, cracked enamel, excess mobility, or suspicion of pulpitis were disqualified from the study, as were teeth used as abutments for partial dentures. Subjects were excluded from the study if they had orthodontic appliances, more than one incisor with a prosthetic crown or veneer, tumors of the soft or hard oral tissues, moderate or advanced periodontal disease, or five or more carious lesions. Further, subjects were excluded if they were concurrently using medications, including analgesics with a potential to mask pain sensation, or who had employed commercially-available desensitizing agents within the three-month time frame prior to the study. Additionally, pregnant or lactating women, and individuals who were participating in any other clinical study or test panel were excluded.

4 Qualifying subjects were stratified according to gender, age, and baseline Tactile and Air Blast Sensitivity scores, and were randomly assigned within strata to one of the following two study treatments: New Dentifrice A new dentifrice containing 5.5% potassium citrate, 1.14% sodium monofluorophosphate and 10% high cleaning silica in a silica base (Colgate-Palmolive Company, New York, NY). Positive Control Dentifrice A commercially-available desensitizing dentifrice containing 3.75% potassium chloride, 0.32% sodium fluoride and 0.3% triclosan in a silica base (Sensodyne F Total Care Toothpaste, GlaxoSmithKline, UK). The New Dentifrice and the Positive Control Dentifrice were provided in tubes overwrapped with opaque white paper to ensure double blind design. Subjects were provided with a supply of their assigned dentifrice and a commercially-available softbristled toothbrush, and instructed to brush their teeth employing their usual oral hygiene practice, twice each day (morning and evening) for one minute. All clinical supplies were refurnished on a regular basis. After four weeks use of the assigned dentifrices, and again after eight weeks use, subjects were again evaluated for the presence of sensitivity using the same criteria applied at baseline. All examinations were performed by the same investigator throughout the study. At each examination time point, all subjects in the clinical study received a thorough oral examination of their hard and soft tissues. There were no adverse effects reported or observed which could be attributed to the use of the study dentifrice. CLINICAL SCORING PROCEDURE Evaluation of Tactile Sensitivity Tactile sensitivity was assessed using a calibrated Model 200A Yeaple Electronic Pressure Sensitive Probe (Yeaple Research, Pittsford, NY). Scores were recorded in terms of a quantified, reproducible force (grams) 11, 12, 13.

5 To test for tactile sensitivity, the probe tip was passed over the exposed dentin on the buccal surface of the designated tooth, just apical to the cemento-enamel junction. After an initial pass was made with a preset force of 10 grams applied to the probe, subsequent passes were made, each time with the applied force increased by 10 grams, until the subject indicated that he/she was experiencing discomfort, or until the maximum force of 50 grams had been applied. It is noted that higher scores on this index correspond to lower levels of dentinal sensitivity. Evaluation of Air Blast Sensitivity Air blast sensitivity was measured by directing a one-second blast of air onto the exposed buccal root surface of the sensitive tooth from a distance of approximately one centimeter, using a dental air syringe. The air blast was applied with a pressure of 60 p.s.i. (± 5 p.s.i.), and temperature of 70 F (± 3 F). Adjacent proximal teeth were shielded from the blast through placement of the examining dentist s fingers. Sensitivity was recorded in accordance with the air sensitivity scale described by Schiff 13, and scored as follows: 0 = Tooth/Subject does not respond to air stimulus 1 = Tooth/Subject responds to air stimulus, but does not request discontinuation of stimulus 2 = Tooth/Subject responds to air stimulus, and requests discontinuation or moves from stimulus 3 = Tooth/Subject responds to air stimulus, considers stimulus to be painful, and requests discontinuation of the stimulus. For this parameter, lower scores are indicative of reduced sensitivity. STATISTICAL METHODS T-tests were employed to compare the treatment groups with respect to the mean scores for the sensitivity parameters. All statistical tests of hypotheses were two-sided, and employed a level of significance of p = RESULTS

6 All of the eighty (80) subjects initially enrolled at baseline complied with the protocol, and completed the eight-week clinical study. A summary of the age and sex of the study population is presented in Table 1. The treatment groups did not differ significantly with respect to either of these characteristics. Tactile Sensitivity Table 2 presents a summary of the Tactile Sensitivity scores measured at each study examination. At baseline, the mean scores were and for the New Dentifrice and the Positive Control Dentifrice groups, respectively. No statistically significant difference was indicated at baseline. After four weeks, the mean Tactile Sensitivity scores were for the New Dentifrice group, and for the Positive Control Dentifrice group. Relative to the Positive Control Dentifrice group, the New Dentifrice group exhibited no statistically significant difference in Tactile Sensitivity scores after four weeks use. After eight weeks, the mean Tactile Sensitivity scores were for the New Dentifrice group, and for the Positive Control Dentifrice group. Relative to the Positive Control Dentifrice group, the New Dentifrice group exhibited no statistically significant difference in Tactile Sensitivity scores after eight weeks use. A further illustration of the Tactile Sensitivity scores observed across the entire study is provided in Figure 1. Air Blast Sensitivity Table 3 presents a summary of the Air Blast Sensitivity scores measured at each study examination. At baseline, the mean baseline scores were 2.53 for the New Dentifrice group and, 2.50 for the Positive Control Dentifrice group. No statistically significant difference was indicated at baseline. After four weeks, the mean Air Blast Sensitivity scores were 1.80 for the New Dentifrice group, and 1.74 for the Positive Control Dentifrice group. Relative to the Positive Control Dentifrice group, the New Dentifrice group exhibited no statistically significant difference in Air Blast Sensitivity scores after four weeks use. After eight weeks, the mean Air Blast Sensitivity scores were 1.33 for the New Dentifrice group, and 1.31 for the Positive Control Dentifrice group. Relative to the Positive Control Dentifrice group, the New Dentifrice group exhibited no statistically significant difference in Air Blast Sensitivity scores after eight weeks use. A further illustration of the Air Blast Sensitivity scores observed across the entire study is provided in Figure 2.

7 DISCUSSION AND CONCLUSION This eight-week clinical study was conducted to assess the effect of the new dentifrice, a commercially-available desensitizing dentifrice containing 5.5% potassium citrate, 1.14 % sodium monofluorophosphate and 10% HCS in a silica base on dentinal hypersensitivity, as compared to the positive control dentifrice, a commercially-available desensitizing dentifrice containing 3.75% potassium chloride, 0.32% sodium fluoride and 0.3% triclosan in a silica base. The new dentifrice formulation in this clinical study contains an agent to reduce dentinal hypersensitivity (potassium citrate). This dentifrice also provides protection against dental caries, since it contains sodium monofluorophosphate, a clinically proven anticaries agent. The results of this independent, double-blind and controlled clinical study demonstrate that the twice daily use of the new dentifrice, a commercially-available desensitizing dentifrice containing 5.5% potassium citrate, 1.14 % sodium monofluorophosphate and 10% HCS in a silica base over an eight-week period provides no statistically significant difference in reduction of dentinal hypersensitivity, measured as tactile and thermal, as compared to the positive control dentifrice, a commercially-available desensitizing dentifrice containing 3.75% potassium chloride, 0.32% sodium fluoride and 0.3% triclosan in a silica base. REFERENCES 1. Gysi A: An attempt to explain the sensitiveness of dentine. Br. J. Dent. Res. 43: 865, Brannstrom M: Dentin sensitivity and aspiration of odontoblasts. JADA 66:366, Pashley DH: Mechanisms of dentin sensitivity. Dent. Clin. of N. Amer. 34, 3: , Hodosh M: A superior desensitizer: potassium nitrate. JADA 88: , Kim S: Hypersensitive teeth; Desensitization of pulpal sensory nerves. J. Endodont. 12: , Tarbet WJ, Silverman G, Stolman JM, Fratarcangelo PA: Clinical evaluation of a new treatment for dentinal hypersensitivity. J. Periodontol. pp , Sept., 1980.

8 7. Tarbet WJ, Silverman G: Home treatment for dentinal hypersensitivity: A comparative study. JADA 105: , Silverman G.: The sensitivity-reducing effect of brushing with a potassium nitrate-sodium monofluorophosphate dentifrice. Compend. Contin. Educ. Dent. 6: , 136, Ad Hoc Advisory Committee on dentinal hypersensitivity, ADA Council on Dental Therapeutics. Recommendations for evaluating agents for the reduction of dentinal hypersensitivity. JADA 112: , Council on Scientific Affairs, American Dental Association: Proposed American Dental Association Acceptance Program Guidelines for Products for the Treatment of Dentinal Hypersensitivity, January, Clark GE, Troullos ES: Designing hypersensitivity studies. Dent. Clin. of N. Amer. 34, 3: , Gillam DG, Dulman JS, Jackson RJ, Newman HN: Efficacy of a potassium nitrate mouthwash in alleviating cervical dentine, J Clin Periodontol 23: , Schiff T et al.: Efficacy of a dentifrice containing potassium nitrate, soluble pyrophosphate, PVM/MA copolymer, and sodium fluoride on dentifrice hypersensitivity: A twelve-week clinical study. J Clin Dent 5(Spec Iss): 87-92, 1994.