Year : 2006 | Volume
: 17 | Issue : 4 | Page : 178--184
Dentinal hypersensitivity?-Can this agent be the solution?
Madhu SS Pretha, Swati Setty, S Ravindra
Department of Periodontics, SDMCDS, Sattur, Dharwad-580009, India
Madhu SS Pretha
Department of Periodontics, SDMCDS, Sattur, Dharwad-580009
AIM : To test the efficacy of desensitizing tooth paste containing EMS salts in alleviating dentinal hypersensitivity, reducing plaque accumulation, and reducing gingivitis. METHODS : A randomised, single blind, parallel placebo controlled study was conducted in 40 cases. The cases were randomly assigned to test and control groups. The test group was instructed to use the test tooth paste (containing EMS salts) and control group a placebo tooth paste (without any therapeutic agents) for a period of 6 weeks. The hypersensitivity levels were measured with scratchometer and verbal rating scale. Student t test and wilcoxon«SQ»s Mann-Whitney test were used to compare the test and control groups. RESULTS AND CONCLUSION : The results indicated that both the test as well as the control toothpastes were effective in alleviating dentinal hypersensitivity as well as reducing gingivitis. However, the test toothpaste was superior in alleviation of dentinal hypersensitivity.
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Pretha MS, Setty S, Ravindra S. Dentinal hypersensitivity?-Can this agent be the solution?.Indian J Dent Res 2006;17:178-184
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Pretha MS, Setty S, Ravindra S. Dentinal hypersensitivity?-Can this agent be the solution?. Indian J Dent Res [serial online] 2006 [cited 2017 Apr 28 ];17:178-184
Available from: http://www.ijdr.in/text.asp?2006/17/4/178/29867
Dababneh et al (1999)  described dentinal hypersensitivity (DH) as, "An exaggerated response to non-noxious stimuli. It is characterized by pain of short duration arising from exposed dentin in response to stimuli, typically thermal, evaporative, tactile, osmotic, or chemical and which cannot be ascribed to any other dental defect or pathology".
The reported incidence of hypersensitive dentin in the dental population ranges from 8.7% to 30% and occurs equally in males and females 
For dentin to be sensitive, it must first be exposed to the oral environment. This exposure may occur by either removal of enamel or denudation of the root surface by loss of the overlying cementum and periodontal tissues. Removal of enamel may occur as a result of attrition, abrasion or erosion while exposure of the root may be due to chronic trauma from faulty tooth brushing and habits, acute and chronic inflammatory gingival and periodontal diseases, or surgical periodontal treatment.
Dentinal hypersensitivity poses a major problem as many patients are unable to perform adequate oral hygiene in hypersensitive areas thus leading to further plaque accumulation and degradation in gingival or periodontal health.
Several theories have been proposed to explain the mechanism of dentinal hypersensitivity.
Pashley and Parsons in 1987  suggested 3 mechanisms of dentinal sensitivity:
Nerve endings or nociceptors that respond directly when dentin is stimulated, located throughout dentin.Odontoblasts, being chemically or electrically related to nerves, function when depolarized as receptors generating nerve impulses.Stimuli applied to dentin producing displacement of dentinal tubule contents which could excite mechanosensitive nerve endings near the pulpal end of the tubules (hydrodynamic mechanism).
Current, evidence favours the hydrodynamic theory originally postulated in the 19th century and later developed by Brannstrom in 1963 .
This theory suggested that dentinal tubules act as capillary tubes and the fluid within them obeys the laws of fluid movement. The rapid movement of fluid in the dentinal tubules in response to certain stimuli may cause distortion of intradental nerves and generate a response.
Hypersensitivity at microscopic level
At microscopic level, dentine is made up of a large number of dentinal tubules. The tubule contains dentinal fluid which when disturbed, pass ripples of stimuli to the nerve endings situated in the pulp.
The sensory nerve cell in its inner membrane has a negative charge all over and a positive charge surrounding it. The positive charge around the membrane is maintained by a pool of sodium and potassium ions. In a normal condition the ion balance is maintained and there is no flow of signals through nerves.
The dentinal sensitivity has been a complex phenomenon of disturbance of the dentinal fluid in tubules that cause irritation of the nerve endings in the pulp. The external stimuli disturb the ion balance and potassium diffuses out of the cells and the sensory nerves get irritated and leading to the feeling of pain.
Among the various agents used for treating dentinal hypersensitivity, potassium nitrate in dentifrices appears to be quite effective . The addition of EMS salts (alkaline salts) to such toothpastes appears to have an added benefit on the gingival health.
AIM OF THE STUDY
To evaluate the efficacy of commercially available desensitizing toothpaste containing EMS salts in:
a) Decreasing the dentinal hypersensitivity
b) Reducing gingival inflammation
c) Reducing plaque accumulation and
d) To evaluate if the toothpaste had any continued effect even after cessation of the use of the toothpaste.
MATERIALS AND METHODS
Forty patients visiting the department of Periodontics, SDMCDS, Dharwad were selected. A randomised, single blind, parallel placebo controlled study over a period of 10 weeks was designed. The mean age of the selected subjects was 46 years (range 27-65 years). Eighty percent (32) were males and twenty percent  were females. Patients in good general health who exhibited cervical dentinal hypersensitivity, as demonstrated by pain elicited by 2 stimuli in relation to at least 1 or more teeth associated with gingival inflammation were selected.
Criteria for selection of teeth
Patients of either gender over 18 years of age.DH in at least one tooth, with a degree > 2 on the verbal rating scale (VRS), after stimulation of a blast of air, and scratchometer reading The mean gingival index score for the tooth with dentinal hypersensitivity was to be > 1.5.The mean plaque index score for the tooth with dentinal hypersensitivity was to be > or equal to 2.0.
The presence of dental pathology which caused pain similar to cervical dentinal hypersensitivity (teeth with caries).The presence of orthodontic appliances, restorations (crowns, cervical restorations, bridgework) that interfered with the evaluation or was a possible cause of pain.The presence of occlusal overload or occlusal adjustment recently made in the tooth to be studied..Periodontal surgery in the area of the tooth to be studied during the previous 3 months.Treatment with any product that could influence the dentinal hypersensitivity of the patient in the 30 days prior to baseline.Previous history of hypersensitivity reactions or specific oral allergy to any of the components of the medications to be evaluated.Treatment with any of the medications to be evaluated in the 30 days prior to baseline.Pregnancy or lactation.Systemic diseases.
All patients who met the inclusion criteria were randomly assigned to one of the two treatment groups: Test toothpaste (containing EMS salts) and a placebo paste (containing no therapeutic agents; control group). Patients were instructed to apply the toothpaste for a period of 5 mins followed by brushing their teeth twice a day with no other change in their brushing habits. This was carried out for 6 weeks following which the patients were advised to discontinue the use of the toothpaste and use their original toothpaste for a period of4 weeks.
Test desensitizing toothpaste containing EMS salts
The test toothpaste used in this study as compared to other desensitizing pastes containing only 5% KNO, has EMS salts (Inorganic Salts) i.e., NaCl, Na 2 SO 4 , NaHCO,, K z SO 4 that have added benefit on recession and gingival inflammation. These salts help in reducing bleeding and inflammation by their osmotic effect and thus, tone and firm up the gums. The alkaline pH (8.6) neutralizes demineralizing acids to prevent caries.
The variables that were measured are as follows
The degree hypersensitivity as per the scratchometer value.
A scratchometer is a hand held scratch device (devised by Dr. Israel Kleinberg, University of Stony Brook, New York) and consists of a tension gauge and a sharp explorer like probe that can be passed easily across a sensitive tooth. It has an indicator that is displaced by the arm of the explorer tine that records the force of displacement in centi Newtons. The scratch process was reported with successively greater force in increments of 5 centi Newtons (cN) until pain was felt. That force was considered the pain threshold for the teeth under test and was noted in centi NewtonThe Gingival Index (Loe and S ilness 1963)The Plaque Index (Turesky Gilmore's modification of QuigleyHein Index)The verbal rating scale (VRS) as given by the patient after applying a cold blast of air as well as after scratching the surface of the tooth. (Gillam et al) (Tarbet et al 1979, Collins et al 1984). A VRS of 1-10 was used. (0 = no pain, and 10= excruciating pain).
These variables were measured at baseline, 6 weeks after the use of the toothpaste and 4 weeks following the discontinuance of the toothpaste.
Students t test and Wilcoxon's Mann-Whitney Test were used to compare the various parameters between the test and the control groups.
With regard to the scratchometer readings, it was found that in the control group the hypersensitivity levels decreased from baseline to 6 weeks p at 5% was statistically significant followed by a marginal increase at 10 weeks, yet it was less sensitive than the baseline levels. Thus `p' was statistically not significant. In the test group the hypersensitivity levels fell from baseline to 6 weeks followed by further decrease at 10 weeks. Thus 'p'at 1% was statistically significant. However, when intergroup comparisons were made there was a statistically significant improvement in hypersensitivity levels in the test group when compared to the control group at 10 weeks.
The gingival index scores in the control group decreased from baseline to 6 weeks (p is statistically significant at 1 %) followed by an increase from 6 weeks to 10 weeks which was not statistically significant. However, there was a marginal decrease in gingivitis scores from baseline to 10 weeks and `p' was statistically significant at 1%. In the test group, the gingival index decreased from baseline to 6 weeks (`p' statistically significant at 1 %) followed by a further decrease from 6 weeks to 10 weeks, 'p'at 5% was statistically significant. There was a decrease in gingivitis scores from baseline to 10 weeks and 'p' is statistically significant at 1%.
The plaque index scores in the control group decreased from baseline to 6 weeks ('p' statistically significant at 1%) followed by an increase from 6 weeks to 10 weeks ('p' statistically sign at 1%). However there was a decrease in plaque index scores from baseline to 10 weeks and `p' at 1 % was statistically significant. In the test group the plaque index decreased from baseline to 6 weeks ('p' is statistically significant at 1%) followed by a marginal decrease from 6 weeks to 10 weeks. There was a decrease in plaque index scores from baseline to 10 weeks and `p' at 1 % was statistically significant. When intergroup comparisons were made there was a statistically significant improvement in gingival index as well as plaque index scores in the test group when compared to the control group at 10 weeks.
In the control group, there was a decrease in the sensitivity perception (verbal rating scale) of the patients at 6 and 10 weeks instances, which was statistically significant at 1% at 6 weeks and 10 weeks from baseline. In the test group, there was a decrease in the sensitivity perception of the patients at 6 and 10 weeks instances, which was statistically significant at 1%. When intergroup comparisons were made, there was a statistically significant improvement in the verbal rating scale in the test group when compared to the control group at 10 weeks.
Mechanism of action of potassium nitrate
A potential desensitizing agent like potassium nitrate acts in two ways:
Decreasing fluid flow through the tubules by occluding (clogging) them.Decreasing the level of activity of the dental sensory nerves, thus preventing the pain signals to be transmitted to the central nervous system.
Potassium ion of potassium nitrate diffuses through the dentinal tubule and reaches the pulp-sensory complex and forms a region of greatly increased concentration (with K + ions) which subsequently depolarizes the pulpalsensory complex and reduces pain transmission.
EMS salts (alkaline salts) have 2 benefits:
Salts bring about osmotic effect on the gingiva, decreasing the bleeding tendency resulting in resolution of inflammation.They are bacteriostatic to plaque resulting in a decrease in plaque accumulation.
The present study was conducted to test the efficacy of an EMS salts containing desensitizing toothpaste in alleviating dentinal hypersensitivity, reducing plaque accumulation, and reducing gingivitis. The results indicated that the both the test as well as the control toothpastes were effective in alleviating dentinal hypersensitivity, reducing plaque accumulation as well as reducing gingivitis. The control toothpaste too was mildly effective in reducing the dentinal hypersensitivity. However the test toothpaste was superior and statistically significant results were obtained with it when compared to the control toothpaste. Similar findings of both test and control groups showing reduction of their symptoms was in correlation with other studies of Chesters et al  and West et al  who have also found little or no difference between the control and the test products. This could be explained on the basis of the presence of a very large placebo effect of 30-40% (Yates et al) (8) seen in most of these dentinal hypersensitivity studies. Placebo effects are commonly referred to in the dentinal hypersensitivity clinical trial literature but not studied. The placebo effect is a response to medical intervention that results from the intervention itself and not from any particular mechanism of action. (Paquette and Fiorellini 1994) . It consists of a complex mixture of physiologic and psychological interactions depending on the doctor-patient relationship, with both parties needing to believe that the treatment is of value and the desire to obtain relief of symptoms (Trowbridge and Silver 1990) . This does not necessarily rule out a therapeutic effect for the test product but clearly demonstrates that when individuals take part in a clinical trial on dentinal hypersensitivity, they show improvement in symptoms.
Aplacebo effect, observed in our study was also found in other studies of dentinal hypersensitivity by Pearce et al 1994 , Silverman et al 1996 . Such an effect must be justified with the natural tendency toward spontaneous remission of dentinal hypersensitivity (Hodosh 1974) .
Plasma, serum, and whole saliva are also capable of reductions in dentin permeability . Individual plasma protein fractions and several different types of bacteria are also effective in decreasing the ease with which fluid can move across dentin.
It is important to bear in mind that tolerance to the same pain can vary considerably among three different people, and even in the same person depending on the time and circumstances, since the perception of pain depends on individual factors such as personality, psychological factors and educational level (Kanapka 1990) . Pain associated with DH has been difficult to quantify and reproduce (Blong et al 1985) . The threshold of pain can vary by suggestion and by changes in the emotional state of the subject (Hodosh 1982) . A series of norms have been followed throughout the study in order to minimise the possible discrepancies introduced by the above mentioned factors in relation to the results.
Interestingly, the present study appears to show a "Hawthorne effect" common to most home use oral hygiene clinical trials. Subjects or patients who enroll in trials are always informed of the objectives and the nature of the research taking place. It is therefore quite possible that more time and effort are devoted to oral hygiene measures on the day of the visit to the trial unit. It is also possible that in such studies, participants appear to improve their toothcleaning habits and plaque scores decrease irrespective of the therapy provided, such
Hawthorn effects can be of such a magnitude as to hide any therapeutic effect of the active agent or product under test . The test group in the present study also did show a significant improvement in plaque scores. This finding is highly unlikely to be a only a Hawthorn effect in the test group and presumably also reflects the plaque inhibitory action of the EMS salts contained in the test toothpaste.
Desensitizing toothpaste containing EMS salts compared to a placebo indicated a trend for greater improvement in the test group with regard to all three parameters, i.e., dentinal hypersensitivity, gingival index and plaque index and continued to have its effect for four weeks even after discontinuing the toothpaste. However long term clinical trials need to be conducted in order to know the exact duration of its efficacy.
We are extremely grateful to J.L. Morison (INDIA) Ltd for providing us with the EMS salts containing dentifrices (Emoform). We also would like to thank Al Blanc India Ltd for their technical support.
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