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Home Treatment for Dentinal Hypersensitivity: A Comparative Study
A R T IC L E S
Home treatment for dentinal hypersensitivity: a comparative study
W illard J. Tarbet, DD8, PhD Gerald Silverman, DMD, MSc Peter A. Fratarcangelo, PhD Joseph A. Kanapka, PhD
Reliable quantitating methods w ere used to evaluate the effects of fo u r com m ercially available toothpastes on dentinal hypersensitivity.
w
hen the cementum and dentin on the in situ root surface of teeth come in contact with externally introduced tactile, thermal, and chemical stimuli, painful sensations can arise. This con dition is known as dentinal hypersen sitivity or sensitive teeth. Most teeth, when in their ideal anatomical posi tion in the m outh, have only the enamel surface exposed to the oral en vironment. Even in this natural condi tion, discomfort may accompany pro longed exposure of the enamel surface to some stimuli, especially heat or cold. However, dentinal hypersensiti vity is characterized by more severe pain responses to stimulus levels that may not cause discomfort in the nor mal tooth. Root surface exposure al lowing contact with these stimuli may be caused by gingival recession or may be a consequence of some types of periodontal treatment. The mecha nism by which these stimuli elicit pain is not yet clearly understood, although some theories have been advanced.1*3
Various desensitizing agents have been used empirically for the home treatment of the hypersensitive condi tion. Recently, potassium nitrate has been cited as an effective therapeutic agent.4'6 However, there are no pub lished reports containing objective data as to the relative effectiveness of the several available agents. This re port provides data from a study of athome use of four toothpaste products containing the following active ingre dients; 5% potassium nitrate (Denquel), 10% strontium chloride (Sensodyne), 2% dibasic sodium citrate in a pleuronic gel (Protect), and 1.4% for maldehyde (Thermodent).
Materials and methods Eighty male subjects, four groups of 20 each, with an age range of 23 to 57 years and an average age of 37 years, participated in this double-blind par allel study. Each subject selected for study claimed to have one or more hy
persensitive teeth, the presence of which was confirmed clinically with a dental explorer. Associated root sur face exposure caused by gingival re cession was confirmed in each in stance. The affected teeth were other wise clinically normal, having no caries, no fillings, and showing no evidence of enamel cracks on the facial surface. Subjects were assigned to one of four treatment groups on the basis of a best-fit balancing randomization computer program using baseline scores of hypersensitivity as deter mined by the three methods outlined here. Subjects also were best balanced by age and number of hypersensitive teeth. Subjects in each treatment group were given their test product in a plain coded tube by a disinterested third party. They were instructed to brush twice daily with the new brush pro vided, using the test product in place of their regular toothpaste. Sensitivity evaluations were conducted after 7, 12, 21, and 28 days of product use.
D eterm in in g sensitivity lev els Tooth sensitivity levels were quanti tated by electrical stimulus,7'8 by cold air blast,8 and by subjective assessJADA, Vo!. 105, August 1982 i 227
A R T IC L E S
ment based on responses to a ques tionnaire. The electrical stimulus was used as described by Tarbet and as sociates.8In brief, a controlled variable voltage was delivered to a probe tip positioned on the midgingival third of the facial enamel surface of each test tooth. The voltage to the probe tip was gradually increased until the subject felt a sensation of tingling or warmth, whereupon he activated a handheld print-command switch that recorded the perceived threshold stimulus volt age on a printout recorder. The cold air stim ulus was also used.8 It consists of a one-second blast of cold air from a dental unit syringe standardized for pressure and temper ature (60 psi, 70 ± 3 F). Test teeth were isolated from their nearest neighbors mesially and distally by the inves tigator’s fingers or by cotton rolls. Subjective responses were obtained at baseline and before objective mea surements at each evaluation period. At these times, subjects were asked to score their perceived reactions to tac tile, thermal, and chemical stimuli as encountered in their daily routine. The rating scale used for both the cold air response and the subjective evaluation was 0, no significant discomfort or awareness of stimuli; 1, discomfort but no severe pain; 2, severe pain during stimulus; and 3, severe pain during and after stimulus. Each subject served as his own control and changes in mean hypersensitivity level from group baseline means were used to as sess product effect.
Range test was used to make in d i vidual treatment comparisons when the overall P value was less than 0.1. The correlation coefficients among the three evaluation methods were deter mined using Spearman’s Rank Corre lation analysis.
Results Baseline data values for the four treat ment groups were comparable in their level of hypersensitivity as evaluated by all three methods.
Comparisons to baseline All four treatment groups showed sig nificant increase (less sensitivity) in electrical stimulus scores at all four evaluation periods when compared with baseline values (Fig 1,P < .005). For cold air evaluations, the potas sium nitrate and the dibasic sodium citrate groups both showed signifi cantly lower scores than baseline (less sensitive) at all weekly evaluation periods (P < .05). The strontium chloride and formaldehyde group scores were each significantly lower
20 19
Time on product (weeks) Fig 1 ■ Effects of four desensitizers on sensitivity levels of hypersensitive teeth as measured by electrical stimulus. Higher scores (volts) indicate greater reduction in sensitivity levels.
Statistical methods A comparison of each product group mean at each evaluation period was made w ith corresponding group baseline values. For the electrical stimulus scores, paired t-tests were used. For the cold air and subjective evaluations, a Wilcoxon MatchedPairs test was used. For treatment ef fect comparisons, analysis of electrical stimulus scores was accomplished by a one-way analysis of variance on changes from baseline at each time point. Whenever the overall P value was less than 0.1, the Duncan Multiple Range test was used to make indi vidual treatment comparisons. For the cold air and subjective response data, a Kruskal-Wallis procedure was used to test for differences in change from baseline. Again, the Duncan Multiple 228 ■ JADA, Vol. 105, August 1982
Time on product (weeks) Fig 2 ■ Effects of four desensitizers on sensitivity levels of hypersensitive teeth as measured by stimulus with cold air. Lower numerical scores indicate greater reduction in sensitivity levels.
A R T IC L E S
than baseline at weeks 2, 3, and 4 (Fig 2, P < .05). The subjective response scores re flect the same effect pattern for the potassium nitrate group, that is, sig nificance at all periods (P < .01). The strontium chloride group achieved significant differences from baseline at weeks 2, 3, and 4 (P < .05); the for maldehyde group at weeks 3 and 4 (P < .05); and the dibasic sodium citrate achieved the P < .05 level only at the four-week evaluation (Fig 3).
C om parative analysis The scores for the potassium nitrate group showed significantly greater re ductions (P < .05) in sensitivity than the scores for all the other treatment groups at weeks 1,2,3, and 4 as deter mined by both the electrical stimulus and cold air methods. Subjective re sponses also showed potassium nitrate providing significantly greater score reductions than all other treatments at weeks 2, 3, and 4 (P < .05).
For cold air and subjective response, there were no significant differences am ong the re m a in in g treatm ent groups at any time period. For the elec trical stimulus scores, there were no significant differences among the strontium chloride, dibasic sodium citrate, or formaldehyde groups at week 2. However, at weeks 3 and 4, the s tro n tiu m c h lo rid e an d d ib a sic sodium citrate group scores were sig nificantly higher (less sensitivity) than those of the formaldehyde group.
D e g re e o f r e l i e f An additional measure of product ef fect can be obtained by tabulating the number of subjects who perceived im provement or total relief during prod uct use. Improvement occurs when the subject’s degree of discomfort or pain is less than at initiation of product use. Total relief occurs when a subject who had discomfort or pain at baseline re ports absence of pain at subsequent evaluations. Figure 4 shows the results of such a tabulation for these study data. Time on product (weeks)
Fig 3 ■ Effects of four desensitizers on sensitivity levels of hypersensitive teeth as de termined subjectively (questionnaire). Lower numerical scores indicate greater reduc tions in sensitivity levels.
100
I I Definite improvement ■ Total relief 80
Strontium chloride Dibasic sodium citrate Formaldehyde
40
20
1234
Overall, the three scoring methods are statistically correlated for hypersensi tive teeth (Table). Those correlation coefficients that are negative result be cause electrical stimulus scores in crease as sensitivity decreases.
N onhyp ersensitive teeth
Potassium nitrate
1234
Correlation o f th ree evaluation m ethods
II
1234
There were no significant changes in either electrical stimulus scores or cold air scores in any of the treatment groups at any time period for the teeth indicated as nonhypersensitive. The e le c t r ic a l s t im u lu s sco re fo r nonhypersensitive teeth was approx imately 25 volts, and the cold air score was very close to zero, indicating the nonresponsiveness of these teeth to the standard stimuli. The electrical stimulus score for sensitive teeth was approximately nine volts.
Discussion
1234
Weeks of treatment
Fig 4 ■ Responses (symptom alleviation) of subjects with dentinal hypersensitivity to four desensitizing agents as determined by daily stimuli during four weeks of treatment.
Although the dentinal hypersensiti vity condition is only partially under stood at present, the recent develop ment of reliable, valid quantitating
Tarbet-Others : HOME TREATMENT FOR DENTINAL HYPERSENSITIVITY ■ 229
A R T IC L E S
Table ■ Correlation coefficients based on all paired observations. No. Hypersensitive teeth Nonhypersensitive teeth
90 90
r (P.c)* -.85 (P < .001) -.14 (P = .18)
r (P.s) -.62 (P < .001) .16 (P = .13)
r(c,s) .64 (P < .001) .04 (P = .71)
The informed consent of all human subjects, who participated in the experimental investiga tion reported was obtained after the nature of the procedures and possible discomforts had been explained fully.
*r = correlation coefficient; p = electrical stimulus score; c = cold air scores; s = subjective response
The authors thank Mr. B. C. Tillery for editorial assistance and Mr. S. V. Colucci for performing the statistical analysis.
methods has allowed comparison of several agents recommended for al leviating the pain associated with this condition. In this study, potassium nitrate was considered as a positive control be cause it has previously been shown to be effective when compared with a placebo treatment.6 The results for potassium nitrate re ported here parallel those reported previously and provide insights into the overall relative effectiveness of the agents tested com p are d w ith a placebo. The 5% potassium nitrate is the most effective of the agents tested. The relative effectiveness of the other agents at the conclusion of the fourweek treatment period are ranked in the following order of effectiveness: strontium chloride, dibasic sodium citrate acid, formaldehyde. It appears from the p re v io u sly established placebo response-level that the latter two products may be difficult to dis tinguish from the placebo effect that has been consistently found in previ ously published studies.
230 ■ JADA, Vol. 105, August 1982
The hypersensitive condition for any specific tooth may be self-limiting in that a diminished or even absent re sponse in some teeth may make a sig nificant contribution to the placebo ef fect. This is analogous to the reduction in thermal sensitivity that occurs with time after placement of a thermally conductive tooth restoration.
Conclusion Until the nature of tooth hypersen sitivity itself is better understood, it is unlikely that the mechanism of action of any of the effective agents used to treat it w ill be ascertained. However, the availability of new, more accurate quantitating methods should stimu late studies leading to a greater under standing of the hypersensitive condi tion and to the evaluation of agents de signed to help control the associated discomfort. f t af'\ Funding was provided by Richardson-Vicks Inc.
Dr. Tarbet (now deceased) was director, clinical research, Vick Oral Sciences Research Center, Richardson-Vicks Inc, One Bradford Rd, Mt. Ver non, NY 10553. Dr. Silverman is in private prac tice, Hartford, Conn. Dr. Fratarcangelo was as sociate director and Dr. Kanapka is assistant di rector, Vick Oral Sciences Research Center. Ad dress requests for reprints to Dr. Kanapka. 1. Avery, J.K., and Rapp, R. Investigation of the mechanisms of neural impulse transmission in human teeth. Oral Surg 12(2):190-198,1959. 2. Brannstrom, M. Dentin sensitivity and aspi ration of odontoblasts. JADA 66(3):366-370,1963. 3. Anderson, D.J.; Matthews, B.; and Shelton, L.E. Variations in the sensitivity to osmotic stimu lation of human teeth. Arch Oral Biol 12(l):43-47, 1967. 4. Hodosh, M. A superior desensitizer— potassium nitrate. JADA 88(4):831-832,1974. 5. Green, B.L.; Green, M.L.; and McFall, W.T., Jr. Calcium hydroxide and potassium nitrate as desensitizing agents for hypersensitive root sur faces. J Periodontol 48(10):667-672, 1977. 6. Tarbet, W.J., and others. Clinical evaluation of a new treatment for dentinal hypersensitivity. J Periodontol 51(9):535-540,1980. 7. Stark, M.M., and others. Rationalization of electric pulp-testing methods. Oral Surg 43(4):598-606, 1977. 8. Tarbet, W.J., and others. An evaluation of two methods for the quantitation of dentinal hy persensitivity. JADA 98(6):914-918,1979.
Home treatment for dentinal hypersensitivity: a comparative study
W illard J. Tarbet, DD8, PhD Gerald Silverman, DMD, MSc Peter A. Fratarcangelo, PhD Joseph A. Kanapka, PhD
Reliable quantitating methods w ere used to evaluate the effects of fo u r com m ercially available toothpastes on dentinal hypersensitivity.
w
hen the cementum and dentin on the in situ root surface of teeth come in contact with externally introduced tactile, thermal, and chemical stimuli, painful sensations can arise. This con dition is known as dentinal hypersen sitivity or sensitive teeth. Most teeth, when in their ideal anatomical posi tion in the m outh, have only the enamel surface exposed to the oral en vironment. Even in this natural condi tion, discomfort may accompany pro longed exposure of the enamel surface to some stimuli, especially heat or cold. However, dentinal hypersensiti vity is characterized by more severe pain responses to stimulus levels that may not cause discomfort in the nor mal tooth. Root surface exposure al lowing contact with these stimuli may be caused by gingival recession or may be a consequence of some types of periodontal treatment. The mecha nism by which these stimuli elicit pain is not yet clearly understood, although some theories have been advanced.1*3
Various desensitizing agents have been used empirically for the home treatment of the hypersensitive condi tion. Recently, potassium nitrate has been cited as an effective therapeutic agent.4'6 However, there are no pub lished reports containing objective data as to the relative effectiveness of the several available agents. This re port provides data from a study of athome use of four toothpaste products containing the following active ingre dients; 5% potassium nitrate (Denquel), 10% strontium chloride (Sensodyne), 2% dibasic sodium citrate in a pleuronic gel (Protect), and 1.4% for maldehyde (Thermodent).
Materials and methods Eighty male subjects, four groups of 20 each, with an age range of 23 to 57 years and an average age of 37 years, participated in this double-blind par allel study. Each subject selected for study claimed to have one or more hy
persensitive teeth, the presence of which was confirmed clinically with a dental explorer. Associated root sur face exposure caused by gingival re cession was confirmed in each in stance. The affected teeth were other wise clinically normal, having no caries, no fillings, and showing no evidence of enamel cracks on the facial surface. Subjects were assigned to one of four treatment groups on the basis of a best-fit balancing randomization computer program using baseline scores of hypersensitivity as deter mined by the three methods outlined here. Subjects also were best balanced by age and number of hypersensitive teeth. Subjects in each treatment group were given their test product in a plain coded tube by a disinterested third party. They were instructed to brush twice daily with the new brush pro vided, using the test product in place of their regular toothpaste. Sensitivity evaluations were conducted after 7, 12, 21, and 28 days of product use.
D eterm in in g sensitivity lev els Tooth sensitivity levels were quanti tated by electrical stimulus,7'8 by cold air blast,8 and by subjective assessJADA, Vo!. 105, August 1982 i 227
A R T IC L E S
ment based on responses to a ques tionnaire. The electrical stimulus was used as described by Tarbet and as sociates.8In brief, a controlled variable voltage was delivered to a probe tip positioned on the midgingival third of the facial enamel surface of each test tooth. The voltage to the probe tip was gradually increased until the subject felt a sensation of tingling or warmth, whereupon he activated a handheld print-command switch that recorded the perceived threshold stimulus volt age on a printout recorder. The cold air stim ulus was also used.8 It consists of a one-second blast of cold air from a dental unit syringe standardized for pressure and temper ature (60 psi, 70 ± 3 F). Test teeth were isolated from their nearest neighbors mesially and distally by the inves tigator’s fingers or by cotton rolls. Subjective responses were obtained at baseline and before objective mea surements at each evaluation period. At these times, subjects were asked to score their perceived reactions to tac tile, thermal, and chemical stimuli as encountered in their daily routine. The rating scale used for both the cold air response and the subjective evaluation was 0, no significant discomfort or awareness of stimuli; 1, discomfort but no severe pain; 2, severe pain during stimulus; and 3, severe pain during and after stimulus. Each subject served as his own control and changes in mean hypersensitivity level from group baseline means were used to as sess product effect.
Range test was used to make in d i vidual treatment comparisons when the overall P value was less than 0.1. The correlation coefficients among the three evaluation methods were deter mined using Spearman’s Rank Corre lation analysis.
Results Baseline data values for the four treat ment groups were comparable in their level of hypersensitivity as evaluated by all three methods.
Comparisons to baseline All four treatment groups showed sig nificant increase (less sensitivity) in electrical stimulus scores at all four evaluation periods when compared with baseline values (Fig 1,P < .005). For cold air evaluations, the potas sium nitrate and the dibasic sodium citrate groups both showed signifi cantly lower scores than baseline (less sensitive) at all weekly evaluation periods (P < .05). The strontium chloride and formaldehyde group scores were each significantly lower
20 19
Time on product (weeks) Fig 1 ■ Effects of four desensitizers on sensitivity levels of hypersensitive teeth as measured by electrical stimulus. Higher scores (volts) indicate greater reduction in sensitivity levels.
Statistical methods A comparison of each product group mean at each evaluation period was made w ith corresponding group baseline values. For the electrical stimulus scores, paired t-tests were used. For the cold air and subjective evaluations, a Wilcoxon MatchedPairs test was used. For treatment ef fect comparisons, analysis of electrical stimulus scores was accomplished by a one-way analysis of variance on changes from baseline at each time point. Whenever the overall P value was less than 0.1, the Duncan Multiple Range test was used to make indi vidual treatment comparisons. For the cold air and subjective response data, a Kruskal-Wallis procedure was used to test for differences in change from baseline. Again, the Duncan Multiple 228 ■ JADA, Vol. 105, August 1982
Time on product (weeks) Fig 2 ■ Effects of four desensitizers on sensitivity levels of hypersensitive teeth as measured by stimulus with cold air. Lower numerical scores indicate greater reduction in sensitivity levels.
A R T IC L E S
than baseline at weeks 2, 3, and 4 (Fig 2, P < .05). The subjective response scores re flect the same effect pattern for the potassium nitrate group, that is, sig nificance at all periods (P < .01). The strontium chloride group achieved significant differences from baseline at weeks 2, 3, and 4 (P < .05); the for maldehyde group at weeks 3 and 4 (P < .05); and the dibasic sodium citrate achieved the P < .05 level only at the four-week evaluation (Fig 3).
C om parative analysis The scores for the potassium nitrate group showed significantly greater re ductions (P < .05) in sensitivity than the scores for all the other treatment groups at weeks 1,2,3, and 4 as deter mined by both the electrical stimulus and cold air methods. Subjective re sponses also showed potassium nitrate providing significantly greater score reductions than all other treatments at weeks 2, 3, and 4 (P < .05).
For cold air and subjective response, there were no significant differences am ong the re m a in in g treatm ent groups at any time period. For the elec trical stimulus scores, there were no significant differences among the strontium chloride, dibasic sodium citrate, or formaldehyde groups at week 2. However, at weeks 3 and 4, the s tro n tiu m c h lo rid e an d d ib a sic sodium citrate group scores were sig nificantly higher (less sensitivity) than those of the formaldehyde group.
D e g re e o f r e l i e f An additional measure of product ef fect can be obtained by tabulating the number of subjects who perceived im provement or total relief during prod uct use. Improvement occurs when the subject’s degree of discomfort or pain is less than at initiation of product use. Total relief occurs when a subject who had discomfort or pain at baseline re ports absence of pain at subsequent evaluations. Figure 4 shows the results of such a tabulation for these study data. Time on product (weeks)
Fig 3 ■ Effects of four desensitizers on sensitivity levels of hypersensitive teeth as de termined subjectively (questionnaire). Lower numerical scores indicate greater reduc tions in sensitivity levels.
100
I I Definite improvement ■ Total relief 80
Strontium chloride Dibasic sodium citrate Formaldehyde
40
20
1234
Overall, the three scoring methods are statistically correlated for hypersensi tive teeth (Table). Those correlation coefficients that are negative result be cause electrical stimulus scores in crease as sensitivity decreases.
N onhyp ersensitive teeth
Potassium nitrate
1234
Correlation o f th ree evaluation m ethods
II
1234
There were no significant changes in either electrical stimulus scores or cold air scores in any of the treatment groups at any time period for the teeth indicated as nonhypersensitive. The e le c t r ic a l s t im u lu s sco re fo r nonhypersensitive teeth was approx imately 25 volts, and the cold air score was very close to zero, indicating the nonresponsiveness of these teeth to the standard stimuli. The electrical stimulus score for sensitive teeth was approximately nine volts.
Discussion
1234
Weeks of treatment
Fig 4 ■ Responses (symptom alleviation) of subjects with dentinal hypersensitivity to four desensitizing agents as determined by daily stimuli during four weeks of treatment.
Although the dentinal hypersensiti vity condition is only partially under stood at present, the recent develop ment of reliable, valid quantitating
Tarbet-Others : HOME TREATMENT FOR DENTINAL HYPERSENSITIVITY ■ 229
A R T IC L E S
Table ■ Correlation coefficients based on all paired observations. No. Hypersensitive teeth Nonhypersensitive teeth
90 90
r (P.c)* -.85 (P < .001) -.14 (P = .18)
r (P.s) -.62 (P < .001) .16 (P = .13)
r(c,s) .64 (P < .001) .04 (P = .71)
The informed consent of all human subjects, who participated in the experimental investiga tion reported was obtained after the nature of the procedures and possible discomforts had been explained fully.
*r = correlation coefficient; p = electrical stimulus score; c = cold air scores; s = subjective response
The authors thank Mr. B. C. Tillery for editorial assistance and Mr. S. V. Colucci for performing the statistical analysis.
methods has allowed comparison of several agents recommended for al leviating the pain associated with this condition. In this study, potassium nitrate was considered as a positive control be cause it has previously been shown to be effective when compared with a placebo treatment.6 The results for potassium nitrate re ported here parallel those reported previously and provide insights into the overall relative effectiveness of the agents tested com p are d w ith a placebo. The 5% potassium nitrate is the most effective of the agents tested. The relative effectiveness of the other agents at the conclusion of the fourweek treatment period are ranked in the following order of effectiveness: strontium chloride, dibasic sodium citrate acid, formaldehyde. It appears from the p re v io u sly established placebo response-level that the latter two products may be difficult to dis tinguish from the placebo effect that has been consistently found in previ ously published studies.
230 ■ JADA, Vol. 105, August 1982
The hypersensitive condition for any specific tooth may be self-limiting in that a diminished or even absent re sponse in some teeth may make a sig nificant contribution to the placebo ef fect. This is analogous to the reduction in thermal sensitivity that occurs with time after placement of a thermally conductive tooth restoration.
Conclusion Until the nature of tooth hypersen sitivity itself is better understood, it is unlikely that the mechanism of action of any of the effective agents used to treat it w ill be ascertained. However, the availability of new, more accurate quantitating methods should stimu late studies leading to a greater under standing of the hypersensitive condi tion and to the evaluation of agents de signed to help control the associated discomfort. f t af'\ Funding was provided by Richardson-Vicks Inc.
Dr. Tarbet (now deceased) was director, clinical research, Vick Oral Sciences Research Center, Richardson-Vicks Inc, One Bradford Rd, Mt. Ver non, NY 10553. Dr. Silverman is in private prac tice, Hartford, Conn. Dr. Fratarcangelo was as sociate director and Dr. Kanapka is assistant di rector, Vick Oral Sciences Research Center. Ad dress requests for reprints to Dr. Kanapka. 1. Avery, J.K., and Rapp, R. Investigation of the mechanisms of neural impulse transmission in human teeth. Oral Surg 12(2):190-198,1959. 2. Brannstrom, M. Dentin sensitivity and aspi ration of odontoblasts. JADA 66(3):366-370,1963. 3. Anderson, D.J.; Matthews, B.; and Shelton, L.E. Variations in the sensitivity to osmotic stimu lation of human teeth. Arch Oral Biol 12(l):43-47, 1967. 4. Hodosh, M. A superior desensitizer— potassium nitrate. JADA 88(4):831-832,1974. 5. Green, B.L.; Green, M.L.; and McFall, W.T., Jr. Calcium hydroxide and potassium nitrate as desensitizing agents for hypersensitive root sur faces. J Periodontol 48(10):667-672, 1977. 6. Tarbet, W.J., and others. Clinical evaluation of a new treatment for dentinal hypersensitivity. J Periodontol 51(9):535-540,1980. 7. Stark, M.M., and others. Rationalization of electric pulp-testing methods. Oral Surg 43(4):598-606, 1977. 8. Tarbet, W.J., and others. An evaluation of two methods for the quantitation of dentinal hy persensitivity. JADA 98(6):914-918,1979.