The Efficacy of a Newly Designed Toothbrush to Decrease Tooth Sensitivity

Thomas Schiff, DMD; Gerald N. Wachs, MD; Dolores M. Petrone, BA; Pat Chaknis, BS;James H. Kemp, BA; William DeVizio, DMD

Dentinal hypersensitivity is very common, with estimates that up to 30% of the population experiences some tooth sensitivity.^1,2 Dentin hypersensitivity can be defined as a painful or noxious response to thermal, tactile, osmotic, and/or chemical stimuli.³ If no dental decay or pulpal inflammation is present but teeth are sensitive to hot, cold, or sweet foods or drinks or if pain is felt when brushing or flossing, then tooth sensitivity probably is the cause. Tooth sensitivity is mainly caused by the exposure of tooth dentine. The dentine can be abraded by strong brushing force, eroded by the frequent ingestion of highly acidic foods and beverages, or worn by excessive tooth grinding. One way to manage dentinal hypersensitivity is by the use of desensitizing toothpaste. Commercially available desensitizing toothpastes usually contain potassium nitrate, which has been shown to have a depolarizing effect on electrical neural conduction, causing the nerve fibers to be less responsive to stimuli.^4,5 Another way to prevent tooth sensitivity is through proper toothbrushing. Dental professionals commonly recommend that patients use soft-bristled toothbrushes and avoid using excessive force when toothbrushing to prevent tooth abrasion and gum recession, both causes of tooth sensitivity.

In 2004, a new manual toothbrush with a unique design was clinically proven to remove plaque; reduce gingivitis; reduce oral malodor; clean the teeth, tongue, and cheeks; and remove 96% more bacteria in the mouth as compared with brushing with a leading US manual toothbrush.^6-12 The Colgate^® 360°^® toothbrush (Colgate-Palmolive Co, New York, NY) was designed with a unique cheek-and- tongue cleaner, a raised cleaning tip for effectively cleaning the back teeth and between the teeth, and a soft polishing cup to gently remove stains for brighter and whiter teeth.

In an attempt to improve the brush, a new variation of the Colgate 360° toothbrush has been made commercially available. The new Colgate^® 360°^® Sensitive toothbrush (Colgate-Palmolive Co) has the same benefits of the Colgate 360° toothbrush and also was designed to reduce tooth sensitivity. The toothbrush has multifunctional ultrasoft bristles¹³ and unique rubber cups that, together with the soft bristles, result in less wear on exposed root surfaces.¹⁴ The brush also has been shown to affect the morphology of the dental surfaces, thereby helping to decrease dentinal hypersensitivity.¹⁵

The objective of this monadic clinical study was to evaluate the reduction in tooth sensitivity among patients who used the Colgate 360° Sensitive toothbrush (Figure 1) during an 8-week period by using clinically accepted tactile sensitivity and thermal sensitivity scoring procedures. The study protocol was submitted and approved by an Institutional Review Board in compliance with international regulations.

Materials and Methods

This clinical study used a monadic, longitudinal study design. Adult men and women from the northern New Jersey area were enrolled in the study based on the following criteria:

• Subjects had to be between the ages of 18 and 70 years, in generally good health, and have used only a nondesensitizing dentifrice for 3 months before entry into the study.
• Subjects needed to be available for the duration of the study and to sign an informed consent form.
• Subjects were required to present, at baseline, two teeth anterior to the molars that exhibited both tactile and thermal sensitivity (a tactile sensitivity score of at least 50 and a thermal sensitivity score of at least 2) and demonstrated cervical erosion/abrasion or gingival recession.
• Subjects were excluded from the study if they presented any gross oral pathology, chronic disease, or history of allergy to the test products; had advanced periodontal diseases or treatment for periodontal diseases (including surgery) within the past 12 months; presented any sensitive teeth with a mobility score greater than 1; presented teeth with extensive or defective restorations (including prosthetic crowns), suspected pulpitis, caries, cracked enamel, or used as abutments for removable partial dentures; were current users of anticonvulsants, antihistamines, antidepressants, sedatives, tranquilizers, anti-inflammatory drugs, or daily users of analgesics; had participated in a desensitizing dentifrice study or reported regular use of a desensitizing dentifrice within the past 3 months; were current participants in any other clinical study; were pregnant or lactating; or presented any medical condition that prohibited not eating or drinking for 2 hours.
• Subjects with allergies to oral care products, personal care consumer products, or their ingredients also were excluded from the study.

Prospective study subjects reported to the clinical facility having refrained from all oral hygiene procedures and chewing gum for 4 hours, and having refrained from eating, drinking, and smoking for 2 hours, before their examinations. Prospective subjects who met the inclusion/exclusion criteria received a baseline examination for tactile and thermal tooth sensitivity, along with an oral soft- and hard-tissue assessment. To qualify for further participation in the study, subjects needed to present two teeth that were sensitive to both sensitivity stimuli.

Qualifying subjects were provided with a supply of a nondesensitizing dentifrice (Colgate^® Cavity Protection Great Regular Flavor Fluoride toothpaste, Colgate-Palmolive Co) and the test toothbrush (Colgate 360° Sensitive), which was designed to aid in the relief of tooth sensitivity.

The study toothbrush was supplied in a plain white box with the words Colgate 360° on the toothbrush. The dentifrice was overwrapped in white and labeled with toothbrushing instructions. Patients were instructed to brush their teeth for 1 minute, twice daily (morning and evening) using only the toothbrush and dentifrice provided and to refrain from any other oral hygiene procedures throughout the duration of the study. There were no restrictions regarding diet or smoking habits during the course of the study.

After 4 weeks and again after 8 weeks of product use, patients returned to the dental clinic for follow-up examinations of tactile and thermal sensitivity of the baseline-designated sensitive teeth. Examinations of the oral soft and hard tissues also were performed at these follow-up visits. All examinations were performed by the same dental examiner, with the same procedures used at baseline. At the 4-week and 8-week examinations, patients also were interviewed with respect to the presence of adverse events.

Clinical Scoring Procedures

Tactile Sensitivity
Tactile sensitivity was assessed using a Yeaple Probe (Model 200A Electronic Force Sensing Probe, XiniX Research, Inc, Portsmouth, NH), with a No. 19 explorer tip (Figure 2). The probe was calibrated at least once daily. Teeth that had been identified by the patient as sensitive and had demonstrated accompanying abrasion, erosion, and/or gingival recession were evaluated. Beginning with a preset force of 10 g, the probe tip was held perpendicular to the buccal surface of the tooth and moved over the exposed tooth root at the cementoenamel junction. The procedure was repeated at 10-g increments of applied force until the patient experienced discomfort or until a maximum force of 50 g was applied. Higher scores for this parameter indicate reduced levels of dentinal hypersensitivity.^16,17

For each examination, a subject-wise score for tactile sensitivity was obtained by taking the average of the tactile sensitivity scores obtained from the two baseline-designated sensitive teeth.

Thermal (Air-Blast) Sensitivity
Thermal (air-blast) sensitivity was assessed by delivering a 1-second stream of air perpendicular to the exposed buccal root surface from a distance of approximately 1 cm. The air blast was applied at a pressure of 60 psi (± 5 psi) and a temperature of 70°F (± 3°F), using a standard dental-unit air syringe. The tested tooth was isolated from the adjacent distal and mesial teeth by the placement of the examiner’s fingers over those teeth. The patients’ responses to the air blast were recorded using the Schiff Air Sensitivity Scale and scored as follows¹⁸:

• 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 stimulus.

At each examination for sensitivity, the testing for thermal sensitivity was performed approximately 5 minutes after the testing for tactile sensitivity. For each examination, a subject-wise score for thermal sensitivity was obtained by taking the average of the thermal sensitivity scores obtained from the two baseline-designated sensitive teeth. Lower thermal (air-blast) sensitivity scores indicated reduced dentinal hypersensitivity for this parameter.

Oral Soft- and Hard-Tissue Assessment
The dental examiner visually examined the oral cavity and perioral area using a dental light and dental mirror. These examinations included assessment of the soft and hard palatal mucosa, gingival mucosa, buccal mucosa, mucogingival fold areas, tongue, sublingual area, submandibular area, salivary glands, and tonsilar and pharyngeal areas.

Adverse Events
Adverse events were assessed based on interviews with the patients and dental examinations of the patients by the examining dentist.

Statistical Methods

Statistical analyses were performed separately for the tactile and thermal sensitivity scores. Paired t-tests were used to evaluate the changes in sensitivity scores between the baseline and follow-up examinations. All statistical tests of hypotheses were two-sided and used a level of significance of a = 0.05.

Results

Table 1 presents a summary of the age and gender of the 41 patients who qualified for participation in the study and completed the 8-week examinations. Throughout the study, no adverse effects on the soft or hard tissues of the oral cavity were observed by the dental examiner or reported by the patients when questioned.

Tactile Sensitivity
Table 2 presents a summary of the tactile sensitivity scores measured at each of the three study examinations and also provides a summary of the analysis of the changes in scores between the baseline and follow-up examinations. The mean tactile sensitivity score at baseline was 10, indicating that all teeth in each patient responded to the probing at the lowest level of applied force (10 g), therefore, the highest level of sensitivity. At the 4-week examinations, the mean tactile sensitivity score was 15.49, which represented a statistically significant 5.49-unit increase from baseline, indicative of an improvement in tooth sensitivity. At the 8-week examinations, the mean tactile sensitivity score was 23.78, which represented a statistically significant 13.78-unit increase from baseline, again indicative of an improvement in tooth sensitivity.

Thermal Sensitivity
Table 3 presents a summary of the thermal sensitivity scores measured at each of the three study examinations and also provides a summary of the analysis of the changes in scores between the baseline and follow-up examinations. The mean thermal sensitivity score at baseline was 2.67. At the 4-week examinations, the mean thermal sensitivity score was 1.90, which represented a statistically significant 0.77-unit decrease from baseline, indicative of an improvement in tooth sensitivity. At the 8-week examinations, the mean thermal sensitivity score was 0.82, which represented a statistically significant 1.85-unit decrease from baseline, again indicative of an improvement in tooth sensitivity.

Adverse Events
No adverse events were noted during this study.

Discussion and Conclusion

It is estimated that up to 30% of the population experiences some tooth sensitivity, which is characterized by a painful or noxious response to thermal, tactile, osmotic, and/or chemical stimuli. Tooth sensitivity mainly is caused by exposure of tooth dentine, which can be from brushing teeth using a strong brushing force, causing the dentine to abrade. Proper toothbrushing can alleviate the pain associated with tooth sensitivity. Dental professionals commonly recommend that patients use soft-bristled toothbrushes and avoid using excessive force when toothbrushing to prevent possible tooth abrasion and gum recession.¹⁹

The Colgate 360° manual toothbrush’s unique design has been proven clinically to remove plaque; reduce gingivitis; reduce oral malodor; clean the teeth, tongue, cheeks; and remove 96% more bacteria in the mouth.^6-12 The new Colgate 360° Sensitive toothbrush has the same benefits of the Colgate 360° toothbrush and, in addition, was designed to reduce tooth sensitivity. The toothbrush has ultrasoft tapered bristles (one laboratory test showing 48% softer bristles when compared with a leading soft manual toothbrush) and unique rubber cups that, together, result in less wear on exposed root surface. The brush also has been clinically proven to remove up to 38% more plaque than a leading soft manual toothbrush, has been shown to affect the surface morphology of dentin, and has been shown in a similar in vivo clinical study to reduce tactile and thermal tooth sensitivity.²⁰

The objective of this monadic clinical study was to evaluate the reduction in tooth sensitivity in vivo among patients who used the Colgate 360° Sensitive toothbrush during an 8-week period by using clinically accepted tactile sensitivity and thermal sensitivity scoring procedures.

The data generated from this clinical study showed that after 4 weeks of brushing with the Colgate 360° Sensitive toothbrush, there was a statistically significant 5.49-unit increase in tactile sensitivity scores and a statistically significant 13.78-unit increase in tactile sensitivity scores after 8 weeks of brushing with the toothbrush. The data also demonstrated a statistically significant 0.77 decrease in thermal (air-blast) sensitivity scores after 4 weeks of brushing with the Colgate 360° Sensitive toothbrush and a statistically significant 1.85 decrease after 8 weeks of brushing with the toothbrush. It can therefore be concluded that brushing with Colgate 360° Sensitive toothbrush can help reduce the painful effects of tooth sensitivity.

Disclosure

Dr. DeVizio and Ms. Chaknis are employees of Colgate-Palmolive Company. Dr. Wachs and Ms. Petrone have received research support from Colgate-Palmolive Company.

References

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About the Authors

Thomas Schiff, DMD
Professor Emeritus, Director of Maxillofacial Radiology
Scottsdale Center for Dentistry
San Francisco, California

Gerald N. Wachs, MD
Concordia Clinical Research
Cedar Knolls, New Jersey

Dolores M. Petrone, BA
Concordia Clinical Research
Cedar Knolls, New Jersey

Pat Chaknis, BS
Colgate-Palmolive Technology Center
Piscataway, New Jersey

James H. Kemp, BA
Colgate-Palmolive Technology Center
Piscataway, New Jersey

William DeVizio, DMD
Colgate-Palmolive Technology Center
Piscataway, New Jersey