| Abstract|| |
Background: Dentin hypersensitivity is a recurrent condition causing discomfort and sometimes pain to the patient, which also deters him from maintaining adequate oral hygiene. Home care and office measures are used for treatment of this malady.
Aim: To evaluate and compare the efficacy of 2 treatment modalities for dentinal hypersensitivity, iontophoresis with acidulated phosphate gel (APF) gel, and dentin-bonding agent application.
Materials and Methods: This split mouth randomized clinical study recruited subjects with a history of hypersensitivity with at least 2 teeth, verified by a light stroke with a dental explorer along the cervical third of the teeth. The patients were subjected to a 1-s air blast and cold water stimuli and their responses were recorded on a verbal rating scale. A total of 30 sites from 15 patients were divided into Group A-1.23% APF gel iontophoresis; and Group B-aqueous solution of hydroxyl-ethyl-methacrylate and glutaraldehyde. The teeth were evaluated immediately after the treatment and at the end of 2 weeks. In case of failure, the tooth was retreated with the same agent as before.
Results: The results were statistically analyzed using Kruskal-Wallis analysis of variance and Mann-Whitney U tests. There was no statistically significant difference between the groups at the end of 2 weeks. However, Group A was more effective clinically, with fewer number of failures compared with Group B.
Conclusion: Both the agents showed a statistically significant reduction in sensitivity compared with baseline; however, APF gel iontophoresis was more effective in reducing hypersensitivity over a longer time period.
Keywords: Dentine hypersensitivity, APF gel iontophoresis, dentine bonding agent
|How to cite this article:|
Aparna S, Setty S, Thakur S. Comparative efficacy of two treatment modalities for dentinal hypersensitivity: A clinical trial. Indian J Dent Res 2010;21:544-8
Dentin hypersensitivity is one of the most common painful conditions affecting oral comfort and function. With regard to the etiology, dentin hypersensitivity represents a symptom of presumably multifactorial pathology.
|How to cite this URL:|
Aparna S, Setty S, Thakur S. Comparative efficacy of two treatment modalities for dentinal hypersensitivity: A clinical trial. Indian J Dent Res [serial online] 2010 [cited 2013 May 20];21:544-8. Available from: http://www.ijdr.in/text.asp?2010/21/4/544/74213
It could be defined as a short, sharp pain arising from exposed dentin in response to stimuli typically thermal, evaporative, tactile, osmotic, or chemical and which cannot be ascribed to any other form of dental defect or pathology. 
Primary treatment strategies should undoubtedly aim at eliminating these predisposing factors, such as abfraction, abrasive, or erosive components, thus preventing recurrence. For ready alleviation of mild to moderate symptoms, occlusion of dentinal tubules can be noninvasively achieved by using desensitizing tooth pastes containing strontium salts and/or highly concentrated fluoride lacquers or varnishes. A second approach is to use potassium salt formulation modulating intradental nerve excitability. In case of pronounced severity, a semi-invasive treatment by blocking the tubules in the form of application of a bonding agent or an adhesive restorative material can be used. These different modalities have shown varied results over time. Hence the primary aim of this clinical study was to compare the efficacy of iontophoresis using acidulated phosphate gel (APF) gel and dentin-bonding agent (DBA) in providing short-term relief from hypersensitivity.
| Materials and Methods|| |
This randomized, split mouth design trial for comparison of two treatment modalities, namely, iontophoresis using APF gel and DBA was conducted in the Department of Periodontology of S.D.M. College of Dental Sciences and Hospital, Dharwad, India, with the ethical approval of the Joint Ethics Committee of the college.
Thirty sites were identified and randomly divided into the 2 treatment groups. Inclusion criteria were as follows: signed informed consent, subjects above 18 years of age, presence of hypersensitivity to thermal, mechanical, sweet, or sour stimuli on at least 2 teeth, and systemically healthy. Exclusion criteria were as follows: fractured or restored teeth, carious teeth, subjects undergoing orthodontic treatment, subjects on analgesics, antibiotics, or desensitizing agents, history of periodontal therapy in the last 6 months, pregnant women or lactating mothers, and subjects with unshielded cardiac pace maker.
Study design and treatment
Suitability for recruitment was assessed at the screening visit. The potential target sites were identified and informed consent was obtained. The tooth to be tested was isolated using cotton rolls and the 3 stimulus tests were performed in order, with the least painful, that is, tactile test first followed by the air blast and finally the cold water test. Each of these tests was performed with an interval of 5 min separating them.
Tactile test: An explorer was gently run across the affected surface of the tooth [Figure 1].
Air blast test: A blast of air at a pressure of 45-60 psi from a 3-way dental syringe for 1 s [Figure 2].
Cold water test: Ice cold water in a disposable 1-cc syringe was slowly expelled onto the tooth surface [Figure 3].
The subjects were asked to score based on the Voluntary Report Scale  of 0-5 with 1 being no discomfort or pain to 5 being severe pain, which does not subside even after removal of stimulus. Subjects scoring greater than 2 on the measured VRS were subjected to therapy. Target sites were randomly assigned (left side/right side) to each one of the 2 treatment groups; Group A: iontophoresis and Group B: dentin bonding agent (DBA).
Application of agents
Group A: Iontophoresis-the tooth was isolated with cotton rolls, dried, and a thin layer of APF gel was applied with a brush (one stroke of the brush). The iontophoresis unit was switched on with the circuit being completed and a progressively increasing current was applied to the tooth until the patient complained of pain or sensitivity. Once this threshold was reached, the APF gel was reapplied and the procedure was repeated at a lower ampere current (Desensitron® using APF gel, 1.23% w/w + phosphoric acid, 0.3%) [Figure 4] and [Figure 5].
Group B: Dentin bonding agent (Scotchbond® Bis-glycidylmethacrylate (GMA) and hydroxyethylmethacrylate (HEMA)-The tooth was isolated, dried, and acid etched for 10 s  and a thin layer of DBA was applied. It was then cured for a period of 20s.
Teeth were evaluated at baseline and again at 2 weeks. In case of recurrence the affected teeth were retreated.
Data and statistical analysis
Data were analyzed on an intention-to-treat basis with the subject as the unit of statistical analysis. The protocol-defined primary outcome variable was the reduction in the VRS scores from baseline. Statistical analysis was done using the Wilcoxon matched pairs test, Kruskal-Wallis analysis of variance and Mann-Whitney U test. At the end of 2 weeks, there was a marked reduction in the VRS scores in both the groups, as shown by the intragroup analysis, which was statistically significant [Table 1] and [Table 2], [Graph 1] [Additional file 1] and [Graph 2] [Additional file 2] . The intergroup analysis presented a statistical significance in favor of the iontophoresis group with respect to the air blast test [Table 3], [Graph 3] [Additional file 3] . Both the groups showed a statistically significant reduction in the VRS scores at the end of 2 weeks suggesting that they were equally effective measures for treating hypersensitivity. However, there were 6 sites requiring a repeat application of DBA as compared with one site in the iontophoresis group.
|Table 1: Comparison of pre and post values in groups 1, 2, and 3 of fluorides by Wilcoxon matched pairs test|
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|Table 2: Comparison of pre and post values in groups 1, 2, and 3 of DBA by Wilcoxon matched pairs test|
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|Table 3: Comparison of fluoride (APF) and DBA groups by Mann-Whitney U test|
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| Discussion|| |
In light of the hydrodynamic theory,  many of the treatment modalities aim to reduce sensitivity by blocking the dentinal tubules. The method of iontophoresis was described by Pivati in 1747. Galvani and Volta, two well-known scientists working in the 18th century, combined the knowledge that electricity can move different metal ions, and that movements of ions produce electricity. The method of administrating pharmacologic drugs by iontophoresis became popular at the beginning of the 20 th century due to the work of Leduc (1900) who introduced the word iontotherapy and formulated the laws for this process.  Iontophoresis was first used in the early 1960s to treat dentin hypersensitivity. Gangarosa and Hill  have provided extensive evidence that iontophoresis is effective in the treatment of aphthous ulcer, lichen planus, herpes labialis, and so on. Iontophoresis uses a low amperage direct electrical current to introduce ions or ionized drugs into tissues. This procedure allows a concentrated application of the drug in a desired localized area. By applying the appropriately charged electrical current, ionized drugs can be driven into tissue based on the principle that like charges repel and opposite charges attract. The exact mechanism of this desensitization is not yet clearly understood. Several hypotheses have been proposed to explain the desensitization by iontophoresis. One, involves the formation of reparative dentin following application of current to dentin, which results in dead tracts. The second mechanism proposed is that electrical current produces paresthesia by altering the sensory mechanism of pain conduction and the third is that iontophoresis probably causes microprecipitation of calcium fluoride that may block the hydrodynamically mediated stimuli that induce pain.  McBride et al  demonstrated that iontophoretically treated teeth had a fluoride concentration twice that of topically applied and 20 times that of control teeth. Previous studies have been conducted using sodium fluoride (NaF) for iontophoresis and DBA alone.  APF gel, when applied on dentin forms calcium fluoride, fluorhydroxyapatite, and phosphate ions.  The phosphoric acid provides for a low pH, which favors the formation of fluorhydroxyapatite and prevents loss of phosphate ions from the enamel surface. The use of bonding resin or adhesive material for sealing dentinal tubules has also been suggested. One such product, HEMA, is said to have desensitizing property.  It blocks the tubules by coagulation of dentinal fluid proteins within the tubules, thereby counteracting the hydrodynamic theory. The bonding agent used in this study was composed of Bis-GMA, HEMA, and dimethacrylates, which is a fifth generation DBA (single-bond adhesive; 3M ESPE). HEMA is said to be water soluble, thus permitting the resin to better penetrate into the dentinal tubules. In the present study, both the agents, that is, iontophoresis using APF gel and DBA provided immediate relief from tooth hypersensitivity. However, there were a larger number of patients who required a repeat application of DBA as compared with the iontophoresis group. Within the 1 st week of follow-up, 6 of the 15 sites in the DBA group needed repeat application, whereas only 1 in the iontophoresis group required reapplication. Thus it would seem that iontophoresis using APF gel is an effective method to treat hypersensitivity. This is in accordance with previous studies using NaF, wherein there was a significant reduction in the sensitivity with one application of NaF.  The present study also showed a statistically significant reduction in the response to air blast posttreatment with APF iontophoresis. The effectiveness of DBA was statistically no different from iontophoresis. However, there was a definite clinical difference. Immediately after the application, DBA did provide relief but the effects were short lived compared with iontophoresis, probably as a result of the wearing away of the bonding agent layer. APF iontophoresis probably has a better penetration of fluoride ions into the tubules, thus providing relief for a longer time.
| Conclusion|| |
Both the treatment modalities, iontophoresis with APF gel and DBA application provide immediate relief from dentinal hypersensitivity. Iontophoresis was more effective in providing long-term relief from hypersensitivity compared with DBA application.
| Acknowledgment|| |
Mr. Javali, Biostatistician, SDM College of Dental Sciences and Hospital,Dharwad, for his support with the statistical analysis.
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Department of Periodontics and Implantology, S.D.M. College of Dental Sciences and Hospital, Dharwad, Karnataka
[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5]
[Table 1], [Table 2], [Table 3]