The Effect of Transcutaneous Electric Nerve Stimulation (TENS) on Anxiety and Fear in Children Aged 9-14 Years

Abstract

Introduction

Dental fear or dental phobia is caused by previous unpleasant dental experiences and pain. It can result in delaying or avoiding dental visits. Most often it leads to individuals avoiding visiting the dentist until physical pain completely impairs the quality of life.

Objectives

Transcutaneous electrical nerve stimulation (TENS) is a method of pain relief involving the use of a mild electrical current. The main aim of this study was to examine whether the TENS device affects the reduction of anxiety and fear during dental procedures.

Material and Methods

The study was conducted on a sample of 125 respondents, aged 9-14 years. Statistical significance of differences between pre- and post-treatment results on all applied measuring instruments was verified by the t-test for dependent samples. The calculation was performed for all respondents and individually for the three observed groups. The Children`s Fear Survey Schedule – Dental Subscale test was used to assess anxiety and fear.

Results

The results on the CFSS-DS scale in all subjects did not differ statistically significantly before and after treatment (p > 0.05). The results on the CFSS-DS scale in subjects who received TENS were statistically significantly different before and after treatment (p < 0.01). The results on the CFSS-DS scale in subjects who received local anesthesia were statistically significantly different before and after treatment (p < 0.05).

Conclusion

The TENS device had an anxiolytic effect after the first visit.

Introduction

Anxiety is a state of fear and dread all the way to panic, with psychomotor tension and inner restlessness. Dental anxiety is a narrower term and is caused by a specific stressful situation in the dental office setting. Fear most often arises due to traumatic childhood experiences or the adoption of phobic behavior by parents (1). Anxiety can be caused by the expectation of a dangerous situation in the perception of which cognitive processes are involved. According to a study of Bajrić and Jurić there is no difference in the prevalence of dental anxiety/fear regarding age (2). One of the parameters that have great influence on these cognitive processes is fear of dental pain along with knowledge, feelings, and attitudes of the patient. There are two main types of dental fear: subjective and objective. Subjective dental fear is based on personal opinions and feelings rather than on facts. Objective dental fear is a reaction to a known danger because it occurs in people who have already had certain negative dental experiences; therefore, they expect it to necessarily recur. The most intense form of fear of the dentist is dental phobia (3). Anxious patients tend to seek treatment only in the case of current pain caused by complications, thus emphasizing the anxiety condition in the office. The psychological characteristics of a person and potentially negative experience are stronger than the objective state related to the procedure itself. A circle of anxiety and pain is created, with a constant tendency to increase. Pain during dental procedures is associated, among other things, with the emotional state. Other factors that affect the experience of pain are age, gender, oral health, the frequency of visits to the dentist, socioeconomic status, and the way the patient is treated. Despite advances in dental procedures and pain control methods, most patients describe a visit to the dentist as a painful and uncomfortable experience (4, 5). After determining the cause of pain and anxiety, it is the dentist’s task to find optimal pain control. This is achieved by a special psychological approach and anesthesia. Pain control depends on the recognition of psychological needs, knowledge, and skills necessary for the proper performance of the dental procedure and postoperative care of the patient. Transcutaneous electrical nerve stimulation (TENS) is a method of pain relief involving the use of a mild electrical current. Previous research has shown that the use of TENS reduces anxiety in the pediatric population; hence TENS is used effectively to suppress pain during various procedures, such as fissure sealing, minor extractions, and endodontic procedures (6). Since TENS is a non-invasive method, the assumption is that just one TENS device treatment will be enough to reduce the anxiety in the child. Clinical examination in children is a potentially stressful event as the child encounters a new situation that can be daunting. He encounters new smells, the sound of a drill, the water produced by it, the white coat of the dentist and many other factors that significantly affect the mental state of the child (7-9). Children may also experience fear of choking on water, fear of injections or needles, and fear of pain during dental procedures. At the first clinical examination, only the dental status is usually taken, and a minimally invasive procedure is performed for the child to relax and realize that no terrible or painful sensation will occur. For many years, behavioral methods have been developed that would relax the child during the dental procedure (10). Some of them are a "tell-show-do" method that explains to the child and shows what will happen during the procedure (11). This method gives the young child and preadolescent (age 3-12) a sense of control over the procedure and thus avoids the fear of unknown sounds and other factors that can scare the child (12). There are numerous ways of distracting the child such as listening to music during the procedure, watching cartoons, using tablets or large screens in the office, and using 2D or 3D glasses (13-15).

Material and methods

A TENS device is a battery-operated, small device that has leads connected to sticky pads called electrodes. The pads are attached directly to the person’s skin. When the machine is switched on, small electrical impulses are delivered to the affected area of the body, which is felt as a tingling sensation. TENS is not a cure for pain and often provides only short-term relief, while the TENS device is being used. The electrical impulses can reduce the pain signals going to the spinal cord and brain, which may help relieve pain and relax muscles. They may also stimulate the production of endorphins, which are the body's natural painkillers (16). The subjects were included in the study based on the established dental diagnosis of anxiety and selection of patients in need of restorative procedure on a permanent molar. Subsequently, they were randomly grouped into three groups at the first visit to the dentist: 1) Group A, including 41 children, with no anesthesia; 2) Group B, including 42 children on whose skin of the face the TENS device was applied; 3) Group C, including 42 children who underwent classical local anesthesia. The research was conducted by one therapist who was calibrated. In the waiting room, the patient`s parents received information forms, which they ultimately signed, on which it was written that all information collected during the study will be obtained with the informed consent of the patient, and they are strictly confidential. The identity of the research participant is known to the dentist conducting the research and to the institution for which the responsible doctor conducts the research. The children received instructions on how to complete the "STRESS TEST" immediately before the examination, informative interview, and dental procedure (class I filling on a permanent molar in the upper or lower jaw). Children were randomly divided one to each group. All the cavities had similar dimensions and depth. Children in all groups suffered low to mild pain (the local anesthesia group reported mild pain from the needle) which was the potential stressor and the cause of anxiety. The stress test validated in the Republic of Croatia was used: CFSS-DS (Children's Fear Survey Schedule – Dental Subscale) (17). This test consists of 15 particles in which the level of fear is measured on a scale from 1 to 5 (1 = not afraid at all to 5 = very afraid). The range of points is from 15-75, and the intensity of the patient's fear is proportional to the number of points. The overall score of the scale (either as a sum or as the average value of points on individual issues) indicates a degree of anxiety – a higher score indicates a higher degree of anxiety. The Cronbach`s alpha was 0.86. The respondents were regular patients of the Department of Pediatric and Preventive Dentistry at the School of Dental Medicine in Zagreb. The study was approved by the Ethics Committee of the School of Dental Medicine University of Zagreb. For the results obtained by the research, basic indicators of descriptive statistics (arithmetic mean, standard deviation, Pearson's asymmetry coefficient) were calculated. Statistical significance of differences between pre- and post-treatment results on all applied measuring instruments was verified by t-test for dependent samples. To further determine the interrelationship of the observed variables, a complex (two-factor) analysis of variance was performed.

Results

With a sample size of N = 125 and a risk level of 5%, Power analysis of the test determined a test power of 0.78, which satisfies the generally accepted conditions. The study included 85 girls (68%) and 40 boys (32%) treated over a two-year period (Figure 1). The arithmetic mean of age of the patients was 11.53 years (range 9-14 years), with a standard deviation of 1.78 years and a Pearson asymmetry coefficient (α) of 0.03 (results were evenly distributed around the arithmetic mean) (Table 1: Figure 2). Statistical significance of differences between pre- and post-treatment results on all applied measuring instruments was verified by t-test for dependent samples. The calculation was performed for all respondents and individually for the three observed groups (Table 2: Figure 3). Results on the CFSS-DS scale in all subjects did not differ statistically significantly before and after treatment (p > 0.05). Results on the CFSS-DS scale in subjects who received TENS were statistically significantly different before and after treatment (p < 0.01). Results on the CFSS-DS scale in subjects who received local anesthesia were statistically significantly different before and after treatment (p < 0.05). Lower results were achieved by subjects before treatment. Results on the CFSS-DS scale in subjects who did not receive any anesthesia were statistically significantly different before and after treatment (p < 0.01). Lower results were achieved by subjects before treatment. In order to further investigate the influence of two factors (measurement time “before treatment” and “after treatment”) and method of anesthesia (“TENS”, “local anesthesia” and “without any anesthesia”)) on the results in the scales used in the study we are a complex (two-factor) analysis of variance. The results indicate the following:

Figure 1.

Structure of all respondents by gender

Table 1. Statistical indicators of the age of the respondents.

AGE
N	MIN	MAX		M	SD	α
125	9	14		11,53	1,78	0,03
LEGEND:
MIN			minimum
MAX			maximum
M			Arithmetic mean (average)
SD			standard deviation
α			Pearson's asymmetry coefficient

Figure 2.

Distribution of all respondents by age

Table 2. Results of t-test for dependent samples of CFSS-DS (before and after treatment).

t-test CFSS-DS
		BEFORE TREATMANT		AFTER TREATMANT
GROUP	N	M	SD	M	SD	p-value
ALL RESPONDENTS	125	2,28	0,80	2,34	1,09	0,5127
TENS	42	2,64	0,79	1,82	0,56	0,0000**
LOCAL ANESTHESIA	42	2,18	0,78	2,54	1,22	0,0159*
WITHOUT ANESTHESIA	41	2,02	0,72	2,67	1,17	0,0000**
** level of statistical significance p < 0,01
* level of statistical significance p < 0,05

Figure 3.

Arithmetic means, standard deviations, and p-values ​​of the t-test of the CFSS-DS scale before and after treatment

1. There is no statistically significant influence (p > 0.05) of the method of anesthesia on the results in the CFSS-DS scale (neglecting time factor (before - after treatment)).

2. There is no statistically significant effect (p > 0.05) of measurement time (before / after) on the results in the CFSS-DS scale (neglecting the method of anesthesia).

3. There is a statistically significant interaction (p < 0.01) between the measurement time and the method of anesthesia in influencing the results in the CFSS-DS scale.

Discussion

It is thought that when a patient shows only mild anxiety, it can be alleviated by developing a relationship based on trust and by giving detailed information about the procedure to be performed, so that the patient has a sense of control over what happens in the office (5, 6, 18). In patients who feel higher anxiety, it is possible to alleviate it with some of the pharmacological (Nitrous oxide (19), oral sedation and drugs (20, 21)) and non-pharmacological (distraction (7, 8), listening to music (22, 23), breathing exercises (24, 25), hypnosis (26, 27)) methods. In a randomized controlled trial, Kritsidima, Newton and Asimakopoulou found that dental patients exposed to the scent of lavender, while waiting in the waiting room, show less anxiety compared to control group (28). This research is consistent with the results of previous research where the scent of lavender or orange was used in waiting rooms (29-31). In more recent times, virtual reality has also been used by wearing 3D glasses (14, 15). Giving the patient a way to communicate with the dentist during the procedure (to which the dentist responds) increases the patient’s sense of control and trust. Specific signals can be determined ahead of time, e.g. raising a hand means stopping. When performing the procedure, it is also advisable to take short breaks for the child to calm down and rest from keeping his mouth open. Positive reinforcement in terms of small tangible rewards or verbal recognition could provide a useful collaboration or appropriate behavior (9, 11). This method, and particularly positive feedback, is considered a universally accepted behavioral management technique in providing dental care to children and is based on psychological principles that have been shown to be effective over a longer time period (32). An exercise believed to be beneficial to almost every timid patient is relaxation through breathing exercises. The physiological changes that accompany breathing (relaxed or diaphragmatic) effectively create the opposite effect to the struggle or flight reaction that characterizes anxious individuals (24, 25). There are several ways to achieve relaxation through breathing. Milgrom et al. describe a procedure in which patients learn to inhale slowly and deeply and hold each breath for approximately 5 seconds, before exhaling slowly (33). Slow, continuous breathing for 2 to 4 minutes is considered effective in reducing the patient's heart rate and makes the anxious patient noticeably calmer. In his research, Ackley advised that patients should be asked to breathe so slowly that if a feather was to be under their nose, it wouldn`t move (34). These breathing techniques can be taught at a dental clinic, or the patient can apply them at home before the initial examination. Physiological monitoring of respiration through a heart rate monitor or other biofeedback device can be beneficial to both the patient and the dentist and has been shown to be effective in reducing dental anxiety and negative emotions about dental injections (35). In working with children, it is important to find out, through conversation and with a lot of patience, which type of distraction makes them happy and which technique will most successfully distract attention from the procedure to be performed. Performing a dental procedure should certainly be a positive experience so that children continue to come to further procedures with pleasure and without fear. In 2014, a study about waiting rooms showed in a relatively high percentage that equipping waiting rooms with toys or allowing a child to hold a toy during the procedure is a way to distract difficult or anxious children (36). Other studies have shown the benefits of using distractions, where access to a distractor, such as a personal music player, depends on collaborative behavior (37). The use of the TENS device as a distractor is an innovative method used to relieve anxiety in frightened children.

A study of usage of TENS in dentistry is limited to minimally invasive clinical procedures where a low level of pain is expected. It is not recommended for surgical procedures, extensive and deep restorations, or extractions. Limitations of this study were different emotional development stages in children due to different ages of study participants. Respondents’ level of pain perception was also variable.

Conclusions

In this study, the TENS device proved to be a successful distraction method. The results showed that the group on which the TENS device was applied felt less anxiety after the procedure, unlike the groups with and without local anesthesia where patients felt more anxiety after the procedure. The TENS device used during the entire procedure served to distract the subjects from the procedure itself, as well as the feelings of some of the sensations which occurred during it. Since each child had a different pain tolerance threshold, the same amount of electricity could not be given equally to all subjects, and for this reason the control of the current given to each subject individually was optional. The children were focused on the tingling caused by mild administration of electricity and on dosing it to make their treatment more comfortable and less painful. The TENS device also served as a kind of "toy" for the child to have fun during the procedure.