INTRODUCTION:

Diagnosis is critically important in determining the treatment procedures. Exact diagnosis is required for the clinician to identify the correct tooth so that best treatment can be offered to the patient. Always not a single test should be used in determining the status of the pulp. A proper case history, clinical examination, radiographic examination is required^[1,2,3].

Electric pulp tester (EPT) is an instrument which is used to assess the neural response of pulp. It a pulp sensibility testing instrument which operates at both high and low frequency.

Electric pulp testing requires subjective assessment from the patients based on stimulus of sensory nerves. It is the most commonly used and important aid which provides information about the status of vitality of pulp. Electric pulp tester delivers an electric current to stimulate the myelinated A-delta fibers. It directs the neural transmission which confirms the presence of vital nerve fibres. Electric pulp testing is intended to determine the sensitivity of each sensory reaction. For getting better results it needs the proper placement of the electrode on the tooth surface. There are different opinions of authors about the best placement site of the electrode on the tooth surface. Improper location of the tip of the electrode of the electric pulp tester may lead to a false response in a vital tooth. When the instrument is placed on the tooth an action potential is produced due to ionic change in the neural membrane^[4].

It was reported that when electric pulp tester is used properly by keeping in track with the limitations and shortcomings, it can be the best diagnosing aid in evaluating the response of tooth^[5]. It is necessary to have knowledge on the ideal placement site for electric pulp tester on the tooth surface. Various studies have been revealed the ideal placement of electric pulp tester for incisor and molar teeth. The ideal site was determined where there is high concentration of nerve fibers. It was reported that for incisors the ideal site was incisal tip^[6] and for molars it was mesiobuccal cusp tip ^[7]. But with respect to premolar there is no specific literature which discusses about the ideal placement site. The objective of this study was to determine the sensibility of mandibular premolars at the lowest sensory response threshold.

MATERIALS AND METHODS:

The study was carried out on patients reporting to the Department of Conservative dentistry and Endodontics of Saveetha dental college, Chennai, Tamilnadu. Teeth with abrasion, attrition, erosion, abfraction and the teeth with pulpitis, apical infection, pulp necrosis and previously root canal treated teeth were excluded from the study. A sample sizeof 60 teeth from age group 18-50 was included in the study.

All the participants who were involved in the study were informed about the benefits and hazards of the study. The study was carried out after obtaining the informed consent from the patient.

Under proper isolation using rubber dam, the tooth was isolated. To start with, evaluating the response of the tooth, the electrode was coated with the polishing paste which acts as an electrolyte. It is necessary to complete the circuit by placing the participant’s forefinger on the lip clip. Once the patients were able to detect the presence of tingling or pricking sensation, the patients were asked to release the forefinger from the lip clip.

The electrode was placed on three sites on the buccal surface of the tooth namely on the tip of the buccal cusp, middle one third of the buccal surface and cervical one third of the buccal surface. Electric pulp tester was placed on each of these surfaces twice with the time interval of 2 minutes.

RESULTS:

The data were analyzed using SPSS software version 23.0. Frequency and percentage were computed and Chi square test was applied for categorical variables like age and gender. Mean, standard deviation, 95% confidence interval was computed. Variance of ANOVA was used to compare the difference of electric pulp tester between the sites.

Out of the total of 60 participants, most of them were between age group thirty to fifty. 47.50% percentage of the population was between thirty to fifty. 30% of the participant’s age group was less than 30 and 22.50% of the participants age group was above 50. (Figure 1)

Figure 1: Age Distribution

Average response of electric pulp tester on tip of buccal cusp and middle one third of buccal surface were 2.09±0.54 and 2.49±0.53 respectively while average response of electric pulp tester in cervical one third of buccal surface was 5.35±1.03. This shows that the tip of the buccal cusp shows the earliest and lowest response as compared to the middle and cervical third of buccal surface when electric pulp tester is applied to the teeth.

Table 1: Average Response On Mandibular Premolar

Average EPT response	Tip	Middle	Cervical
Mean ± Std dev	2.09±0.54	2.49±0.53	5.35±1.03
95% CI	1.91	2.35	5.02
Median	2.0	2.5	5.0

Bonferroni multiple comparison test applied to compare mean difference between sites which is showing that average response of electric pulp tester was significantly low in cusp tip site as compared to middle site of buccal surface.

Thus it was concluded that placement of electrode on the tip of the buccal cusp elicited low threshold response.

DISCUSSION:

It was found that the buccal surface of mandibular premolar had lowest threshold to stimulation of electric pulp tester. Rubber dam was used to isolate the tooth of interest due to the fact that the current does not flow into the adjacent tooth. Patient’s age was also taken into account to avoid changes in sensitivity response of tooth caused by secondary dentin deposition which cause the reduction in volume of pulp^[8].

False positive and false negative responses have to be taken into consideration in evaluating the response of the tooth. The factors which cause these responses depend on morphology of enamel, dentin, tooth surface conditions such as tooth surface loss and carious lesions ^[9].

Therefore it is very critical to analyze the ideal site for placement of electrode especially on the posterior teeth such as premolar and molar^[10]. Summation effect^[11] is the phenomenon wherein the area with abundant nerve fibers gives a powerful response when least electric current is applied on to the tooth compared to the areas with least nerve fibres. Therefore it is concluded that the response depends on how close the nerve fibers are present to the stimulus area^{[12, 13]}.

A laboratory study was done by Jacobson^[14]where he used an oscilloscope to assess the optimal site for the placement of electrode. The study was carried out on an extracted tooth on incisors and premolars. It was concluded that incisal third was the ideal placement site for the incisor teeth and occlusal third of the labial surface of the premolar teeth. But the study results cannot be completely correlated with the clinical situations as the study was done in vitro.

Another study by Christopher I, Udoye^[15] and Bender ^[16]reported that low threshold values are obtained when electrode tip is placed on the buccal cusps and highest threshold is obtained when the electrode tip is placed on the cervical third aspect^[17-19].

From the previous study it was concluded that gender difference do not have a role in impact of perception of threshold during pulp testing^[20-22]. The present study also concludes that there is no statistical significance between males and females in response to pulp testing. In a study by Lin J et al, reported that there was no significant difference found between males and females ^[23,
24].

The age of the patient was also discussed with respect to response to electric pulp tester and was reported that patient’s age does not have any impact on the level of threshold perception. In the present study the subjects were aged between 18-50. When comparing with literature studies done by Christopher I, Udoye, Bender and Lin J et al it was found to be the same. Thus all the above studies have concluded that age does not have any impact on level of threshold perception.

In the literature it was also stated that different medium of electrolyte produce different tooth response. In a laboratory study by Martin et al^[25,26]. it was reported that there was no significant response found with respect to different medium. On the contrary by another study it was concluded that there is a difference in response of the tooth when the electrolytic medium was changed^[27].

CONCLUSION:

It was concluded that as the placement of electrode tip move more apically the response of threshold is also said to increase from buccal to cervical third. Thus it was concluded that the appropriate site for placement of electrode for lower premolar is on the buccal cusp tip.

REFERENCES:

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2. Gopikrishna, V., Tinagupta, K. and Kandaswamy, D., 2007. Comparison of electrical, thermal, and pulse oximetry methods for assessing pulp vitality in recently traumatized teeth. Journal of endodontics, 33(5), pp.531-535.

3. Mickel, A.K., Lindquist, K.A., Chogle, S., Jones, J.J. and Curd, F., 2006. Electric pulp tester conductance through various interface media. Journal of endodontics, 32(12), pp.1178-1180.

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7. Pitt Ford, T.R. and Patel, S., 2004. Technical equipment for assessment of dental pulp status. Endodontic Topics, 7(1), pp.2-13.

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15. Udoye, C.I., Jafarzadeh, H., Okechi, U.C. and Aguwa, E.N., 2010. Appropriate electrode placement site for electric pulp testing of anterior teeth in Nigerian adults: a clinical study. Journal of oral science, 52(2), pp.287-292.

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17. Martin, H., Ferris, C. and Mazzella, W., 1969. An evaluation of media used in electric pulp testing. Oral Surgery, Oral Medicine, Oral Pathology, 27(3), pp.374-378.

18. Rowe, A.H.R. and Ford, T.P., 1990. The assessment of pulpal vitality. International Endodontic Journal, 23(2), pp.77-83.

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22. Robinson, H.B., 1963, January. NATURE OF DIAGNOSTIC PROCESS. In Dental Clinics of North America (No. MAR, pp. 3-+). 1600 JOHN F KENNEDY BOULEVARD, STE 1800, PHILADELPHIA, PA 19103-2899 USA: WB SAUNDERS CO-ELSEVIER INC.

23. Jafarzadeh, H. and Abbott, P.V., 2010. Review of pulp sensibility tests. Part I: general information and thermal tests. International endodontic journal, 43(9), pp.738-762.

24. Pitt Ford, T.R. and Patel, S., 2004. Technical equipment for assessment of dental pulp status. Endodontic Topics, 7(1), pp.2-13.

25. Sigurdsson, A., 2003. Pulpal diagnosis. Endodontic Topics, 5(1), pp.12-25.

26. Schnettler, J.M. and Wallace, J.A., 1991. Pulse oximetry as a diagnostic tool of pulpal vitality. Journal of endodontics, 17(10), pp.488-490.

27. Krishna, V.G., Kandaswamy, D. and Gupta, T., 2006. Assessment of the efficacy of an indigeniously developed pulse oximeter dental sensor holder for pulp vitality testing. Indian Journal of Dental Research, 17(3), p.111.

Received on 29.07.2018 Modified on 27.09.2018

Research J. Pharm. and Tech 2018; 11(12): 5382-5384.

DOI: 10.5958/0974-360X.2018.00982.4