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Table of Contents   
ORIGINAL ARTICLE  
Year : 2022  |  Volume : 25  |  Issue : 5  |  Page : 526-530
Comparison of pulp sensibility test responses in normotensive and hypertensive individuals: A clinical study


Department of Conservative Dentistry and Endodontics, K. M. Shah Dental College and Hospital, Vadodara, Gujarat, India

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Date of Submission16-Feb-2022
Date of Decision20-May-2022
Date of Acceptance06-Jun-2022
Date of Web Publication12-Sep-2022
 

   Abstract 

Background: Pulp sensibility testing is an essential part of the diagnostic process in the assessment of pulpal health. Several lines of evidence suggest an interaction between control of blood pressure and pain regulatory mechanisms.
Aim: The aim of the study is to compare pulp sensibility test responses in normotensive and hypertensive individuals.
Materials and Methods: Ninety-eight patients participated in the study, with 49 individuals each in the hypertensive and normotensive groups. A minimum of 4 and maximum of 8 sound teeth were included in the study each from the anterior, premolar, and molar, i.e., 4 teeth from either arch. A total of 832 teeth were tested. The value and time when the responses evoked for electric pulp test (EPT) and cold test were recorded respectively.
Statistical Analysis: For intergroup and intragroup analyses, independent t-test and paired t-test were utilized.
Results: A statistically significant difference was noted in values for EPT as well as cold test responses when both the groups were compared (P < 0.01). Higher values were obtained with the hypertensive group.
Conclusion: Patients with established hypertension showed an increased threshold to electric pulp testing and cold stimulus as compared to normal healthy individuals.

Keywords: Electric pulp test; hypertension; pulp sensibility test

How to cite this article:
Saklecha P, Kishan KV, Shroff MG. Comparison of pulp sensibility test responses in normotensive and hypertensive individuals: A clinical study. J Conserv Dent 2022;25:526-30

How to cite this URL:
Saklecha P, Kishan KV, Shroff MG. Comparison of pulp sensibility test responses in normotensive and hypertensive individuals: A clinical study. J Conserv Dent [serial online] 2022 [cited 2022 Sep 25];25:526-30. Available from: https://www.jcd.org.in/text.asp?2022/25/5/526/355897

   Introduction Top


Identifying the pulpal status of the teeth is of paramount importance while establishing a diagnosis and treatment for oral rehabilitation.[1] Pulse oximetry and laser Doppler flowmetry, two diagnostic techniques that monitor pulpal blood flow, have shown encouraging results in the assessment of pulp vitality. These technologies, on the other hand, come with some drawbacks and significant costs. Thermal and electric tests are the most commonly used pulp sensibility tests to assess pulp status via the sensory response. Those tests have been shown to be efficient and comprehensive for distinguishing between vital and nonvital pulps;[2] however, there may be some uncertainty in determining pulpal disease/health. The accuracy of diagnostic tests and how they are used can be influenced by a number of variables.[3],[4],[5],[6]

Systemic conditions such as diabetes and hypertension are few of them which can have an influence of pulp sensibility tests. Several lines of evidence suggest an interaction between control of blood pressure and pain regulatory mechanisms.[7],[8] The same brain stem nuclei are associated with both functions; drugs that affect blood pressure, e.g., clonidine, also modify response to pain.[9],[10],[11],[12] In addition, the same neurotransmitters, such as endorphins and monoamines, are involved in both the roles.

The link between pain and hypertension has the potential to be of considerable pathophysiological and therapeutic importance, but it is still little understood. The relationship between hypoalgesic behavior (delayed reaction to noxious stimuli such as a hot plate, an electric shock, or a mechanical force given to a limb) and arterial hypertension has been proven in rat studies.[13],[14] Human studies, however less comprehensive than animal studies, appear to show a relationship between hypoalgesia and high blood pressure. Increased arterial blood pressure has been linked to a reduced feeling of pain in various studies.[13],[15] In hypertensive humans, an increased tolerance to pain, as assessed by the measurement of the pain threshold to graded electrical tooth pulp stimulation, has been reported in some preliminary studies.[16],[17]

Because of its simplicity, noninvasiveness, and acceptability, tooth pulp stimulation is a convenient test to investigate pain mechanisms. The dental pulp is primarily a sensory system, and researchers have found a good correlation between intradental nerve activity and pain perception in regard to graded stimulation of the teeth.[13],[18],[19]

It has been thought that pulp sensibility responses in hypertensive patients might differ from that of normotensive patients. Although it is concluded in studies conducted in medical field, no such studies have been found in dental field. Currently, pulp sensibility responses in hypertensive and normotensive individuals are measured at the same scale; however, this might result in incorrect interpretation of pulp sensibility response, further rendering of wrong treatment. Hence, adequate knowledge about these differences might help us in formulating appropriate scale for hypertensive patients, which will further aid in the treatment planning. Null hypothesis considered was that there would be no difference in the pulp sensibility test responses among the normotensive and hypertensive individuals.


   Materials and Methods Top


Institutional ethical clearance was obtained (SVIEC/ON/Dent/SRP/W129), following which the study was registered with Clinical Trials Registry-India (CTRI/2021/03/032002).

Assuming 0.5 effect size for sensitivity test, minimum 98 (49 per group) patients will be included in the present study considering 95% confidence and 80% power for one-tailed test. The included participants were subdivided into two groups: Group 1: normotensive and Group 2: hypertensive with 49 individuals in each group according to their blood pressure status after obtaining their written consent. The co-investigator assessed the blood pressure of the participants.

Blood pressure was measured from the brachial artery using a sphygmomanometer. The mean of three readings was taken into account for systolic and diastolic blood pressure.

Inclusion criteria

  1. Patients who were 30–70 years old having a minimum of 4 and maximum of 8 sound teeth were included in the study each from the incisor, canine premolar, and molar, i.e., 4 teeth from either arch. A total of 832 teeth were tested
  2. Patients with diagnosed hypertension for at least 1 year. Patients with blood pressure ranging below 140 mmHg systolic and 90 mmHg diastolic were considered in the normotensive group and patients were considered to be hypertensive if their blood pressure was equal to or >140 mmHg systolic or 90 mmHg diastolic as per the 2018 ESC/ESH guidelines for the management of arterial hypertension.[20]


Exclusion criteria

  1. Systemic disease, such as diabetes, or any conditions that may alter the outcomes, such as hyperthyroidism, hyperparathyroidism, chronic renal disease, or hepatic disease, as well as neurological disease
  2. If a patient has any disease that could cause injury to the head-and-neck nervous system (stroke, multiple sclerosis, and so on) as well as other conditions that might affect the results such as cancer; pregnancy; or taking corticosteroids, ibuprofen, opium, or other medications such as gabapentin or phenytoin
  3. History of trauma, severe periodontal disease, orthodontic brackets or a recent history of orthodontic treatment, significant cavities or restorations, apical periodontitis, teeth with root canal treatment, and teeth with crowns are all factors to consider.


A principal investigator who performed the electric pulp test (EPT) and cold test was blinded regarding the blood pressure status of the participants. Electric pulp testing was performed with a pulp tester (Parkell, Brentwood, NY, USA). Each tooth was dried and isolated by cotton rolls. The pulp tester's lip clip was put in the individual's mouth, and a thin amount of toothpaste (Colgate; Colgate-Palmolive, USA) was applied to the incisal/occlusal third of the crown. Following that, the patient was instructed to notify the evaluator if tingling, discomfort, or any other sensation occurred during the activation of the electric pulp tester. Patients' responses were recorded as a number representing the current of the pulp tester.

The sensibility tests were performed with a 1–2-min delay in order to minimize the effect of one test on the other. The cold test was performed with cold spray (Roeko Endofrost, Coltene). The teeth were dried and isolated by cotton rolls. A size 2 cotton pellet was sprayed and positioned on the incisal or occlusal third of each tooth's crown for 10 s or whenever the patient raised his or her hand to indicate pain or a cold sensation. Each pellet was sprayed no more than twice before being replaced with a new pellet for the next tooth/teeth. The information gathered was tabulated and statistical analysis was performed. For intergroup and intragroup analyses, the independent t-test and paired t-test were utilized.


   Results Top


There is a statistically significant difference between the normotensive and hypertensive groups in the current study in terms of pulp sensibility test responses (P < 001) [Table 1].
Table 1: Comparison of electric pulp test and cold test responses between hypertensive and normotensive individuals

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The obtained values for EPT and time required by the individual to respond to cold test were higher in the hypertensive group for incisors, canine, premolar, and molars in both maxillary and mandibular arches. The age of the participants in both the groups was standardized with no statistically significant difference between the two groups.


   Discussion Top


Identifying the state of the pulp tissue is very critical in endodontic treatment.[1] Several approaches for determining pulp sensibility have been proposed and used widely such as thermal test and EPT. Ideally, pulp tests should be simple, reliable, objective, and inexpensive.

Despite being a more accurate indicator of a tooth's pulpal health, vitality tests are not limitation free. The use of vitality tests is difficult and needs strict adherence to optimum application techniques. Further, they are quite expensive as well. This makes the benefits of utilizing these tests in everyday practice questionable. Assessment of the state of pulpal health using pulp sensibility tests, although subject to error, can provide valuable diagnostic information when used as an adjunct along with history and clinical and radiographic examination.[21]

A study done by Villa-Chávez et al.[1] showed that cold test was the most accurate (0.94), and most reproducible followed by the heat (0.86) and the electrical (0.76) tests.

Pulp sensibility tests have been proven to be altered by systemic illnesses.[8],[14],[22],[23] Several systemic disorders have the capability to alter the pulpal response such as hyperparathyroidism, hypothyroidism, and diabetes mellitus to name a few.[7],[8],[14],[22],[23] Patients with hyperparathyroidism may require a double-fold increase in electric current as compared to teeth in healthy people to trigger a response from the pulp. Diabetes mellitus not only causes metabolic alterations in the pulp, but also it has been demonstrated to affect sensory and vascular components.[7],[8],[23],[24],[25]

The majority of animal and human studies using various forms of experimental pain have shown that subjects with high blood pressure have a reduced behavioral response to pain or a lower pain rating.[24] One of the many systemic disorders that can affect pulpal response is hypertension.[8],[14],[16] Individuals with systemic disorders other than hypertension were excluded from the current study to avoid the impact of any of these variables on the study's outcomes. Consumption of anti-inflammatory drugs which has an analgesic effect may alter the outcomes of the pulp sensibility tests.[23],[26],[27] The participants with history of uptake of such medication 1 day prior were excluded from the study.

A total of 98 individuals, with a sample size of 832 teeth, were considered in the present study. All of the people in the hypertensive group had essential hypertension. Every patient underwent a clinical evaluation prior to testing, and none of the hypertensive participants had any evidence that their hypertension was secondary to any other disease.

A-delta fibers are present mainly at the pulp dentin border zone toward the pulp periphery. Their free nerve terminals travel 150–200 pm into the dentinal tubules. The majority of A-delta fibres are found in the coronal section of the pulp, with the pulp horns having the highest nerve density.[23] The pulp horns in permanent teeth have the highest concentration of neural components, with fewer in the cervical and radicular areas of the pulp. Hence, the pulp sensibility test was carried out at incisal third in maxillary as well as mandibular incisors, whereas it was carried out in buccal cusp tip in premolars and mesiobuccal cusp tip in molars.[28] Furthermore, EPT studies show that there are regional variations in dentinal pain. The least threshold exists at the incisal edge or incisal third of the facial surface.[23],[29]

Several authors have shown that EPTs produce the most consistent results when the probe tip is placed on the incisal edge or on the cusp tip of teeth.[3]

To avoid bias regarding the age related changes, individuals with 30–70 years were considered. There was no statistically significant difference in age between the two groups in this study (P > 0.05).

The results of this study showed that there was a significant correlation between hypertensive status of the patients and reduction in the pulp sensibility to EPT and cold test. The values for EPT as well as the time within which individuals responded to cold test for incisors, canine, premolar, and molar in both maxillary and mandibular arches were higher in the hypertensive group as compared to the normotensive group (P < 0.001). The pain thresholds of hypertensive participants were substantially higher than those of normotensive controls which is in accordance with the study done by Zamir and Shuber.[8]

Probable reason for the obtained results is a possible link between blood pressure and pain regulation mechanisms. Both functions are connected with the same brain stem nuclei.[8] The current findings substantiate the evidence of a strong link between blood pressure and pain perception. Few participants in the present study were on antihypertensive medications. However, studies have shown that hypoalgesia is not influenced significantly by antihypertensive medications.[30]

An increase in pain threshold and decreased perception of painful stimuli may occur in hypertensive individuals. This may be because of increase in the inhibitory descending pathways, which might be further associated with increase in arterial hypertension. Anatomical and physiological research studies have revealed that the brain stem areas involved in blood pressure regulation and those that are involved in the modulation of pain transmission are closely related or even partially overlapping.[13]

Guasti et al.[24] in their study on relationship between dental pain perception and 24-h ambulatory blood pressure demonstrated that pain perception was modulated by an experimentally produced baroreceptor manipulation, with the lowest baroreceptor activity linked with more intense pain.

Pulp vitality assessment is one of the criteria for a successful restoration which includes cold, heat, electrical pulp test for pulp vitality confirmation.[31] The current study has clearly demonstrated that there is an increased threshold to pain in patients with hypertension as compared to normotensive healthy individuals. However, there is no such scale for pulp sensibility responses for hypertensive individuals. Hence, we should always be cautious while carrying out pulp sensibility testing in hypertensive individuals, as higher values do not infer degenerative changes in hypertensive subjects. Rather, it is their higher pain threshold which results in higher values. The values obtained from the present study were used in formation of a scale (Kishan and Saklecha's scale for pulp sensibility test in hypertensive individuals) for EPT and cold test responses in hypertensive individuals.

Further studies with increased sample size and also evaluating the long-term effect of antihypertensive medications on pain perception need to be carried out. A combination of pulp sensibility tests will provide more reliable results for pulpal vitality evaluation.[32]


   Conclusion Top


Within the limitations of this study, it can be concluded that there is a statistically significant difference in the pulp sensibility test responses between the normotensive and hypertensive groups in the current study (P < 001). There is an increased pain threshold in hypertensive individuals. As a result of this, the tooth requires a longer duration or increased intensity of stimulus for it to respond when compared to normotensive individuals. The scale derived from the present study can be used as a guide for future studies.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
   References Top

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  [Full text]  
32.
Salgar AR, Singh SH, Podar RS, Kulkarni GP, Babel SN. Determining predictability and accuracy of thermal and electrical dental pulp tests: An in vivo study. J Conserv Dent 2017;20:46-9.  Back to cited text no. 32
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Correspondence Address:
Dr. Karkala Venkappa Kishan
Department of Conservative Dentistry and Endodontics, K. M. Shah Dental College and Hospital, Sumandeep Vidyapeeth, Pipariya, Waghodia, Vadodara - 391 760, Gujarat
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/jcd.jcd_105_22

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