Year : 2010 | Volume
: 21 | Issue : 2 | Page : 207--212
Comparative evaluation of different strengths of electrical current in the management of dentinal hypersensitivity
Sharn Pal Sandhu1, Roshan Lal Sharma2, Vipin Bharti3,
1 Department of Periodontics, S.G.T Dental College, Hospital and Research Institute, Budhera, Gurgaon, Haryana, India
2 Surendera Dental College and Research Institute, Sri Ganganagar, Rajasthan, India
3 Government Dental College, Patiala, Punjab, India
Sharn Pal Sandhu
Department of Periodontics, S.G.T Dental College, Hospital and Research Institute, Budhera, Gurgaon, Haryana
Background : Dentinal hypersensitivity is a commonly occurring but less understood and poorly managed problem of the teeth. Iontophoresis is a technique wherein desensitizing agents can be transferred under electrical pressure into the tooth structure to manage hypersensitivity.
Aim : The purpose of present study is to compare the effect of different strengths of electrical current used for varying lengths of time, keeping the electrical dosage constant with the iontophoretic unit in the management of dentinal hypersensitivity.
Materials and Methods : This study was conducted among the patients attending the Periodontal Department of the Government Dental College and Hospital, Patiala, Punjab, specifically complaining of tooth hypersensitivity. The Verbal Rating Scale (VRS) was used to record scores pre-, during, and post-treatment. Ten percent SrCl2 solution was applied with an iontophoretic unit. Three applications were performed at weekly intervals, up to the second week, using the same electric current dosage. The data compiled was statistically analyzed.
Results : A remarkable reduction in dentinal hypersensitivity to both air blast and cold water stimuli was noted at the end of two months after iontophoresis with each current group / method, namely, I (0.25 mA for 4 minutes), II (0.5 mA for 2 minutes), and III (1 mA for 1 minute). However, the differences in effectiveness / improvement within the three current groups during the entire duration of the study were found to be statistically insignificant.
Conclusion : Within the limits of this study, it could be implied that for relieving hypersensitivity, iontophoresis for all three current groups was almost equally effective, and it was found that repeated applications (up to three) gave good relief. Iontophoresis was found to be effective and safe.
|How to cite this article:|
Sandhu SP, Sharma RL, Bharti V. Comparative evaluation of different strengths of electrical current in the management of dentinal hypersensitivity.Indian J Dent Res 2010;21:207-212
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Sandhu SP, Sharma RL, Bharti V. Comparative evaluation of different strengths of electrical current in the management of dentinal hypersensitivity. Indian J Dent Res [serial online] 2010 [cited 2021 May 8 ];21:207-212
Available from: https://www.ijdr.in/text.asp?2010/21/2/207/66643
Dentin hypersensitivity is characterized by short, sharp pain arising from exposed dentin in response to external stimuli, which cannot be ascribed to any other form of dental defect or disease. The sensory stimuli usually considered are thermal by the application of a burst of air to the tooth and tactile by running a metal instrument across the hypersensitive region of the tooth. 
Dentinal hypersensitivity is a commonly occurring but less understood and poorly managed problem of the teeth.  It is viewed as originating from the underlying exposed dentin after the enamel or the cementum of the root surface has been lost.  Dentin exposure can occur as a result of erosion, abrasion, attrition, hypoplastic enamel, gingival recession,  defective restoration, improperly formed cemento-enamel junctions (CEJs), occlusal wear, caries, cracking, trauma, and iatrogenic reasons, that is, induction of dentine exposure by the dentist.  It occurs as a result of periodontal therapy, in tooth restoration, in occlusal equilibration and so on. Thus, it is perhaps more of a symptom complex than a true disease. 
Dentinal hypersensitivity is different from dentinal and pulpal pain, in that, the patient's ability to locate the site of pain is very good. In the vast majority of cases (89.3%) cold is the major stimulus for pain, other commonly reported causes are tooth brushing (38.6%) and hot (37.9%) and sweet (25%) stimuli.  It is a response from a non-noxious stimulus and a chronic condition with acute episodes. 
The condition generally involves the facial surfaces of teeth near the cervical aspect and is very common in premolars and canines. 
Three major theories currently exist, to explain the mechanism of dentinal hypersensitivity. The Hydrodynamic theory proposes that the stimuli cause a displacement of the fluid that exists within the dentinal tubules. The displacement occurs either in an inward or outward direction, and this mechanical disturbance activates the nerve endings in the dentin or pulp. 
A potential desensitizing agent can act by clogging the tubules or by decreasing the activity of the dentinal sensory nerves. 
In the absence of any specific form of therapy, a variety of modalities have been tried with variable success.
The home measures include the use of desensitizing dentifrices with compounds such as, formaldehyde, sodium flouride, monofluorophosphate, potassium chloride, sodium citrate, stannous fluoride, and so on.
The office measures include professional use of ammoniacal silver nitrate, formalin, sodium potassium carbonate, sodium fluoride, Fluoride resin, Durphate, a sodium fluoride varnish, sodium fluoride/Kaoline/glycerine, stannous fluoride, potassium oxalate, prednisolone, Meticortilone, ferric oxalate, strontium chloride, strontium chloride varnish, and so on. It seems prudent to employ therapies that are least likely to cause harm and are reversible.
Besides these chemical agents, other methods of treating hypersensitivity are the use of Laser,  Resin, and Cyanoacrylate.
Iontophoresis is another technique in which desensitizing agents can be transferred under electrical pressure into the tooth structure to manage hypersensitivity. 
The purpose of the present study is to compare the effect of different strengths of electrical current used for varying lengths of time, keeping the electrical dosage constant with an iontophoretic unit, in the management of dentinal hypersensitivity.
Iontophoresis utilizes a low amperage of direct electrical current to introduce ions or ionized drugs into the tissue.  This procedure allows a concentrated application of the drug to the desired localized area. A much higher dose of the drug can be introduced into the area, to be treated without the systemic effects of the conventional oral or parental drug therapy. Normally, ionized drugs will not penetrate the tissue rapidly enough to be of any therapeutic value. By applying appropriately charged direct electrical current, ionized drugs can be driven into the tissue, based on the principle - like charges repel and opposite charges attract. For example, fluoride exists as a negative ion. By applying fluoride under a negatively charged electrode, the fluoride can be driven with a direct electrical current into the tooth structure.
Materials and Methods
This study was conducted among patients attending the Periodontal Department of the Government Dental College and Hospital, Patiala, Punjab, specifically complaining of tooth hypersensitivity. The patients who were excluded were:
Those who had chipped teeth, cracked tooth syndrome, palatogingival groove, and periodontal pockets.Those who had pulpal response to caries or to restorative treatment.Those who were not sufficiently educated and intelligent to be able to respond, or to understand and gauge the discomfort caused by various stimuli on the discomfort scale. (described a little later in the text)Those whose hypersensitive area was not accessible.Those who were taking anti-inflammatory drugs or were using desensitizing pastes or such other remedies.
Patients thus selected were included in the 'probables' and they were asked to undergo diagnostic cum evaluation tests.
Diagnostic cum evaluation tests
The specific tooth was isolated by cotton rolls and operator's fingers and subjected to air blast and cold water tests:
Air blast test: The nozzle tip of an air syringe was kept about 1 - 2 cm away from the isolated tooth and then a blast of air was directed on the tooth for one second.
Cold water test: A disposable syringe was filled with ice-cold water and the water was poured on the suspected isolated tooth surface drop by drop.
VRS (Verbal Rating Scale) was used to record scores:-
0 - No discomfort
1 - Mild discomfort
2 - Moderate discomfort
3 - Severe pain only during application of stimulus
4 - Severe pain persisting after removal of stimulus
Only those subjects who had a discomfort score of two or more were included in the study. The score ascertained was then recorded.
Those scores were designated as pre-treatment scores. Then all teeth included in this study were grouped randomly into groups as given below:
Group I: Those who received 0.25 mA current for four minutes (1.0 mA-minute)
Group II: Those who received 0.5 mA current for two minutes (1.0 mA-minute)
Group III: Those who received 1.0 mA current for one minute (1.0 mA-min)
An apparatus [Figure 1] was designed and fabricated for delivering a measurable amount of direct current for iontophoresis. It consisted of a 9-volt dry cell battery that supplied a direct current of 9 volts; an ammeter with graduations ranging from 0 to 3 milliamperes and at differences of 0.05 mA each; a voltmeter marked from 0 to 10 volts, and a timer; a variable resistance; a polarity selection switch; an on/off switch; an inactive electrode and an active electrode having a head of a No. 7 camel hair brush.
Ten percent SrCI 2 solution was prepared by dissolving 5 mg of 98.1% pure SrCI 2 crystals in distilled water, so as to get 50 ml of solution. The electrolyte solution was prepared by the Biochemistry Department of GMC, Patiala, monthly or before, according to the requirement and was discarded after one month, even if not consumed.
In each group, after recording the pre-treatment scores, the tooth was cleaned, dried, and isolated with cotton rolls / pledgets. The inactive electrode was held firmly, but lightly, in the patient's left hand within water-soaked cotton. The brush of the active electrode of the iontophoretic unit was dipped in 10% SrCI 2 solution, taken in a dappen glass separately from the prepared solution, and placed on the required surface of the tooth [Figure 2]. Then, the timer was adjusted for the time at which the current was to be applied for that group. Then the current was switched on and the resistance knob was slowly turned clockwise till the mA reading was at the strength of electrical current required for that group of teeth. The brush was in place for the length of time required for that group of teeth. There was no movement of the brush during this time, so as to avoid its displacement on the adjacent gingiva. It was removed after hearing the siren of the timer and after the time for which current was to be applied was over.
The score was taken five minutes before and after application of the current. For each tooth, three applications were done at weekly intervals up to the second week, if required, using the same electric current dosage. Scores were taken after two months from the start of the treatment.
The patient was instructed to maintain good oral hygiene and to avoid acidic foods like citrus fruits, pickles, low pH beverages, including wines, curd, and so on, throughout the study.
The improvement was gauged according to the following scale:
All scores were compared with the baseline scores. When in doubt, a lower score was assigned.
Patients showing 'good' improvement after the first application were asked to report after two months and those showing 'no' or 'moderate' improvement were recalled after seven days and put on diagnostic-cum-evaluation tests before the second application. Those who showed 'good' improvement were discharged without any application and called after two months from the start of treatment. However, those who showed 'no' improvement or 'moderate' improvement were given a second application. Again the post-application scores were taken. Those who showed 'good' improvement were called after two months from the start of treatment and those who showed 'no' improvement or 'moderate' improvement were recalled after seven days, that is, 14 days from the start of treatment.
The same considerations were taken into account on the fourteenth day, after the start of treatment, that is, at the time of the third / final application (if needed). The patients were called after two months from the start of treatment.
The data was compiled and put to statistical analysis.
Taking N as the number of teeth and / or percentage of teeth showing good, moderate or no response,
B' N after first application
A1' N before second application
B1' N after second application
A2' N before third application
B2' N after third application
A3' N two months after start of treatment
R Response after and before every iontophoretic application
G Good response
N No response
Dental hypersensitivity probably affects most individuals at some time, and in some instances pain may be so severe and so regular as to constitute a psychic problem for the patient, who believes that his / her dentition has been seriously and perhaps irreversibly affected.  Of greater importance in the maintenance of oral health is the neglect in the oral hygiene of the hypersensitivity areas and in some instances, its total absence. This only increases the basic sensitivity problems. 
Over the years, a wide variety of methods have been used for the treatment of dentin sensitivity. Effective and robust dentin occlusion offers the greatest prospect for instant and lasting relief of dentin hypersensitivity.  Various desensitizing agents have been used, such as, office or home measures, which include sodium fluoride, stannous fluoride, sodium monoflurophosphate, strontium chloride, sodium citrate, potassium oxalate, resins / adhesives, and so on.  Iontophoresis is another office procedure that produces rapid and effective relief in hypersensitivity.
The present study was carried out to study the effect of different strengths of electrical current used for varying lengths of time, keeping the electrical dosage constant with an iontophoretic unit, using 10% strontium chloride, in the management of dentinal hypersensitivity [Figure 3].
In this study, it was found that the iontophoretic application of an electrolyte was very effective in dentinal hypersensitivity. There has been extensive research demonstrating the beneficial effects of iontophoresis with an electrolyte, in desensitizing the hypersensitivity of dentin. Gangarosa and Park  and others ,,,,,,,,,,,,,,,, have reported the effectiveness of iontophoresis application of an electrolyte in the management of dentinal hypersensitivity.
A remarkable reduction in dentinal hypersensitivity to both air blast and cold water stimuli was noted at the end of two months after iontophoresis, with every current group / method, as shown in the [Table 1] and [Table 2].
The result of the study shows that with all three methods (i.e., 0.25 mA for 4 minutes, 0.5 mA for 2 minutes, and 1 mA for 1 minute), the electrical dosage kept at a constant value of 1 mA-minute, and was also found to be effective and safe, as no untoward reaction or worsening of scores was seen. Previous studies ,,,,,, have shown that a current up to 1 mA was safe to use, as it had no adverse effect on the pulpal tissue and would not damage the odontoblasts.
Within the limits of this study, it can be implied that for relieving hypersensitivity, to both air blast and cold water, for all three Groups, iontophoresis was almost equally effective; with no statistically significant difference between them. Parr and Brokaw  remarked that more the electricity used, more was the drug delivered and higher was the rate of penetration. They further proposed that to minimize the treatment time, the device used be operated at the maximal current possible. If the patient can tolerate 1 mA current, this amount is applied for one minute. If this current setting is uncomfortable to the patient, 0.5 mA can be used for two minutes or 0.25 mA for four minutes, for the total dosage of 1 mA-minute is generally sufficient in alleviating sensitivity. The results of the present study endorse the above-mentioned views.
One striking finding while comparing the effectiveness of each of the three groups / methods was that after the first application: in Group II, 45% of the teeth showed good improvement and 35% of the teeth showed moderate improvement; in Group I, 30% of the teeth showed moderate improvement and 25% of the teeth showed moderate improvement after the first application; and in Group III, 30% of the teeth showed good improvement and 45% of the teeth showed moderate improvement. The results for 0.5 mA current used for two minutes are consistent with the findings of Carlo et al.,  who found that 87.7% of all lesions had at least 50% relief from the blast of air after an initial treatment. However, at the end of the study, that is, after two months from the start of treatment, 95% of the teeth showed good improvement to air blast, and all (100%) teeth showed good improvement to cold water with 1 mA of current for one minute, which proved to be the most effective current group / methods. Therefore, it is concluded that for better results, initial treatment / first application of 0.5 mA current used for two minutes followed by 1 mA current for one minute at subsequent applications, whenever required, may be given (provided the current setting is comfortable to the patient).
With all the three groups, it was found that repeated applications (up to three applications) gave gradual increase in the percentage of teeth showing good relief. The results of this study are consistent with the earlier studies. ,, Carlo et al.,  found that patients with severe hypersensitivity (a score of at least 3) required a second application, while those with mild-to-moderate sensitivity (a score of 1 or 2) experienced highly significant relief and did not require any additional therapy. Gangarosa  also recommended that if relief was not complete, the procedure could be repeated once or twice, at weekly intervals. Parr and Brokaw  also advocated that if relief was not complete after one iontophoretic application, the procedure could be repeated up to a total of four times, at weekly or [SUPPORTING:1] [SUPPORTING:2]biweekly intervals. Gupta  also concluded that repeated applications, at least upto three applications, resulted in gradual increase in the percentage of teeth showing good improvement.
It was also observed during the study that in some teeth, the post application scores improved on their own, within a few days before the next application. For example, in teeth where moderate improvement was obtained after an application, good improvement was seen before the next application. It may be due to the natural desensitization or due to inducing of rapid secondary dentin formation by iontophoretic application as stated by Lefkowitz et al. Similarly, a few teeth showing moderate improvement after an application changed over to the category of teeth showing no improvement before the next application. Devinder Singh;  Gupta  also reported similar observations. This tendency to revert to original scores has been reported earlier.  No tooth showed worsening of scores from the pretreatment scores throughout the study. No untoward reaction was found in any tooth or patients due to iontophoresis.
During the course of this study, it was found that post-application reduction in sensitivity was almost immediate in a majority of the cases. It was also observed that for all the three methods / groups, the lesions which were easily approachable and effectively insulated, responded better to this mode of treatment. Lesions at or under the gingival margins could not be effectively insulated and allowed for passage of current through the lesser resistance pathways, thereby limiting the effectiveness of the treatment.
After the first iontophoretic application, 0.5 mA current used for two minutes was the most effective. However at the end of the study, that is, after two months, 1.0 mA current used for one minute was found to be most effective to both air blast and cold water tests, followed by 0.5 mA used for two minutes and 0.25 mA used for four minutes. However, the three current groups, during the entire duration of the study, were found to have statistically insignificant differences in effectiveness/improvement.
There was a gradual increase in the percentage of teeth showing good improvement, on repeated applications.
Hypersensitivity to air blast was slightly more effectively and reliably manageable with iontophoresis than hypersensitivity to cold water.
Iontophoresis was a safe and effective treatment for the management of dentinal hypersensitivity.
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