Comparative clinical evaluation of transcutaneous electrical nerve stimulator over conventional local anesthesia in children seeking dental procedures: A clinical study.

AIM: The aim of this study to evaluate the effectiveness of pain control by employing transcutaneous electrical nerve stimulator (TENS) over conventional injectable local anesthesia for children requiring restorative procedures under rubber dam.
MATERIALS AND METHODS: The study design considered was the split mouth design, in experiment (right) side, dental procedures under rubber dam was performed under TENS and in control (left) side, dental procedures under rubber dam was performed under conventional injectable local anesthetic (LA). The level of comfort and discomfort experienced during TENS and conventional LA was determined using visual analog scale (VAS) and heart rate. RESULT: Increase in mean heart rate associated with TENS (0.78%) was significantly less compared to increase in heart rate with administration of conventional local anesthesia (11.78%). In VAS, the mean values for pain indicate that minimum pain was felt with TENS, which was closely followed by LA.
CONCLUSION: TENS can offer many safer and psychological advantages and is a valuable alternative to conventional LA for children.

The most distressing aspect of dentistry for the average dental patient is the fear and anxiety caused by the dental environment, particularly to the dental injection referred to as “needle-phobia” or “blenophobia.”[1] Reducing this fear in children may help to provide overall comfort and well-being during the entire dental experience. Pediatric dentists are constantly searching for tools, which may provide a more comfortable dental procedure.[2] Electronic dental anesthesia (EDA) is one of the nondrug techniques that is available for the management of pain. Several EDA devices are currently being advertised and used for the control of chronic pain (myofascial pain dysfunction) and acute pain (associated with surgical procedures).[3] The concept is not new, known also as transcutaneous electronic nerve stimulation (TENS) is the application of electrical stimulation of varying frequency, intensity, and pulse duration to the skin for pain relief. It is noninvasive, safe and a viable mode of pain control during some dental procedures in pediatric dentistry and it appears to be a substantial alternative to the other conventional injectable local anesthetic (LA) technique.[4] So to provide a feasible alternative in pediatric pain control armamentarium the present study is intended clinically to evaluate the effectiveness of pain control by employing EDA (TENS) over conventional injectable local anesthesia for children requiring restorative procedures under rubber dam.

Materials and Methods

Materials

The apparatus used was TENS [Figure 1]. It has control unit and electrode pad. The control pad consists of two separate galvanic channels. Each channel has individual amplitude control and single frequency control knob. It generates current through 6V battery capable of producing current at amplitude ranging from 1 to 20 mA at the frequency between 2 and 50 Hz and it has a fixed pulse width of 400 μs. The pulse oximeter was used to monitor heart rate of the patient during the experiment.

Figure 1

Transcutaneous electrical nerve stimulator

Methods

Prior to starting the treatment under EDA, the procedure was explained to the parents/guardians in local language and an informed written consent was obtained. The ethical clearance for this study was obtained from the Institutional Ethical Clearance Committee before starting the study.

Sample

Children aged between 6 and 12 years who were attending the Department of Pedodontics and Preventive Dentistry, M. R. Ambedkar Dental College and Hospital, Bengaluru were considered for the study.

Sample size

A total 62 subjects (32 males and 30 females) requiring restoration were selected randomly for the study upon fulfilling the following criteria.

Inclusion criteria

Never exposed to TENS

Requiring restorative procedures in both lower right and left molars

Patients who volunteered.

Exclusion criteria

Immaturity (inability to understand the concept of pain control) such as very young patient, physically and mentally handicapped children

Medically compromised children such as history of epilepsy, transient ischemic attacks, and status post cerebrovascular accidents.

Study design

The study design considered for the study was the split mouth design [Figure 2], in which the same subject served as his/her control.

Figure 2

Study design

At the start of the experiment, baseline valves of heart rate were recorded. For standardization, the procedures on the right side was performed under TENS (experimental group) and on the left side was performed under conventional injectable LA technique (control group).

Experimental side (under transcutaneous electrical nerve stimulator)

The site of electrode pad was gently swabbed with surgical spirit to remove any skin oils or substances that may interfere with the flow of current. Electrode gel was applied on the electrode pad before placement. The patient was instructed to open the mouth wide as done during the treatment and then the electrode pad was secured in place using surgical tape to minimize displacement [Figure 3]. The system was switched on, and the investigator controlled the level of electronic anesthesia by gradually raising the amplitude dial until the patient felt a significant sensation. For the patient to acclimatize to the new sensation of electronic anesthesia, this amplitude level was maintained for an initial duration of 20 s. The amplitude is raised to the next level and the cycle was repeated, until the fasciculation was noted on the lower lip in case of mandibular arch. Muscle fasciculation is the sign of reaching the “minimal therapeutic level” at which the procedure can began. The heart rate using a pulse oximeter of the subject was recorded after the stimulation was begun, rubber dam was placed and restorative procedure was carried out. The subject was instructed to indicate the level of comfort or discomfort felt by him/her using a visual analog scale (VAS) [Figure 4].

Figure 3

Experiment group (transcutaneous electrical nerve stimulator)

Figure 4

Visual analog scale

Control side (under local anesthetic)

On the left side, conventional injectable local anesthesia using 27 gauge needle was administered; heart rate of the subject was recorded. Then, the rubber dam was placed and restorative procedure was carried out [Figure 5]. The subject was instructed to indicate the level of comfort or discomfort on a VAS.

Figure 5

Control group (local anesthetic)

Result

The values were subjected for the statistical analysis in which Mann-Whitney U test was performed. In VAS, the mean values for pain indicate that minimum pain was felt with TENS, which was closely followed by LA. Though it shows a difference, it is not statistically significant [Table 1 and Bar diagram 1]. Increase in mean heart rate associated with TENS (0.78%) was significantly less compared to increase in heart rate with administration of conventional local anesthesia (11.78%) [Table 2 and Bar diagram 2].

Table 1

Visual analogue score with respect to TENS and Infiltration

Bar diagram 1

Visual analog score w.r.t transcutaneous electrical nerve stimulator and infiltration (local anesthetic)

Table 2

Increase in heart rate with respect to TENS and Infiltration (LA)

Bar diagram 2

Increase in heart rate w.r.t transcutaneous electrical nerve stimulator and infiltration (local anesthetic)

Discussion

The idea of using electricity to reduce pain is not a new concept. The use of electricity in medicine and dentistry has a long and fascinating history, dating back to the year 46 AD when Scribonius Largus claimed to cure headache and arthritis through the application of the electric torpedo fish.[5] The use of electricity as a means of pain management and as a curative agent flourished well into the nineteenth century in Europe and the United States. Written case reports of pain control through the application of electric current in dentistry exist from the year 1770.[6] Dentistry has recently seen a rekindling of interest in this area.

Of course, some skepticism about the use, safety, and effectiveness of TENS remains. The currents generated are safe, reliable, and controlled. TENS has passed the scrutiny of the Food and Drug Administration successfully to become a Class II device restricted to use on the prescription of a licensed physician.[7] Mechanism of action of TENS: It is thought that pain may be alleviated by using peripheral stimulation, such as rubbing, vibration, heat or cold, or as in the case of TENS, electrical stimulation directly over the area of pain. This peripheral stimulation induces electrical activity, which inhibits the brain's perception of pain. The “gate control theory” is based on the principle that there is a gateway in the dorsal horn of the spinal cord, which somehow controls or regulates the flow of pain messages that are then sent to (ascending) and from (descending) higher levels of the brain for central processing, thus reducing the perception of pain. Other postulated mechanisms of the pain relief mediated by TENS include the promotion of endorphin release in the brain and local dilatation of blood vessels in injured tissue.[8]

The use of TENS as an analgesic in place of LAs during restorative and other dental procedures is supported by several clinical studies. Bishop reported restorative dental procedures were completed at a 93% rate of success in an active TENS group as compared with a 43% rate of success in an inactive TENS (sham) group.[9] In addition, TENS has been shown to reduce pain during orthodontic movement of teeth.[10]

The advantages of EDA are:

Elimination of pain and fear of dental injection, a noninvasive procedure

Elimination of inconvenience of postoperative anesthesia, unaffected speech

Elimination of adverse reactions of injectable LAs

Elimination of the possibility of infection at the injection site and residual analgesic effect for several hours.

In this study, we used a design of split mouth technique. In which the same subject served as his/her own control. This design was used to reduce response variability inherent in studies using separate treatment and control groups. One potential problem with this type of design is the possibility that there was continued analgesia after termination of the stimulation. However, we believe residual analgesia was not a problem in this study because high frequency stimulation administered at low intensity requires over 10 min of stimulation before a long duration analgesic effect is seen.[11] In this study, electrical stimulation was terminated 8 min after it was began.

Autonomic changes occur in response to painful stimuli; heart rate increases in response to the application of cold – pressor pain.[12] Increase in mean heart rate associated with TENS was significantly less compared to increase in heart rate with administration of conventional local anesthesia. In the current study, the increase in tooth pain threshold and the decrease in stress – associated tachycardia with respect to TENS suggest that electrical stimulation may be useful as an analgesic during dental procedures (such as placement of rubber dam for restorations).

However, it is inadequate, for oral surgical procedures[13] the results of VAS are inconsistent with the heart rate result. The inconsistent may reflect the lack of sensitivity to detect changes in comfort produced. Thus, future studies are required to evaluate the reliability, sensitivity, and validity of any VAS used with pediatric patients.

Conclusion

This study provides valuable information concerning the analgesic properties of peripheral electrical stimulation under highly controlled conditions. This study should help establish a useful baseline for future clinical studies of the efficacy of electrical stimulation during dental procedures.