Comparative evaluation of pain perception during conventional greater palatine injections versus the use of a novel barovibrotactile device - In vivo study

Abstract

Background

Pain control by means of local anesthesia is an intrinsic part of clinical practice in dentistry. It is an irony that the modality used for pain free procedure itself is a source of fear & anxiety to the patient. Several modifications have been made to the injecting devices, local anesthetic solutions and techniques to render their administration comfortably. The objective of this study was thus designed to evaluate and compare anxiety and pain perception during conventional greater palatine injections versus use of a novel barovibrotactile device named Accupal to give painless anesthesia. This device has an additional attachment which works on Vibra-pulse technology thus minimizing pain during injection technique.

Materials and methods

A prospective, split mouth, open label, randomized, crossover clinical study was conducted on 50 patients coming to our institute whereby on one side Accupal was used during administration of local anesthesia. And on other side, traditional local anesthetic injection technique was used with one week of time interval.

Results

A statistically significant difference was found as in the pain perception between the two techniques as per Visual Analogue Scale whereas no difference was seen in the anxiety levels as per the physiological parameters recorded by noninvasive blood pressure machine at various intervals.

Conclusion

The use of Accupal has thus proved to show better pain control as compared to traditional injection techniques of local anesthesia.

1. Introduction

Local anesthesia, a medium to pain control during extractions, itself causes fear, severe pain and a lot of distress¹ due to which people avoid and do not appear for dental appointments. Fear and anxiety are considered as one of the overlooked concerns affecting both, adult as well as children.² As a result the treatment procedures become complicated and time consuming while struggling for the patient's co-operation. Thus the skill of the practitioner lies in the ability to provide effective local anesthesia with minimum discomfort to the ailing patient. To provide good local anesthesia, the dentist must not only have knowledge about the neuroanatomy involved and drugs being used but also be updated with the recent painless techniques and devices. The newly introduced anesthetics and painless delivery systems are currently playing an essential role in the management of pain during local anesthesia.

Computer Controlled Local Anesthetic Delivery system (CCLAD), buffered local anesthesia administration, topical local anesthesia, Jet injectors, Safety dental syringes are some of the techniques and devices that help in combating pain prior to injection. These techniques and devices have their own extensions and limitations.¹ Lately, Vibratory devices and barovibratory devices are one of the most convincing devices which are effective in pain control. These devices work with the principle of vibration and pressure at the injection site.³ Effect of barovibrotactile device over conventional local anesthetic administration for pain control and reduction in anxiety requires evaluation. Hence, the objective of this study was thus designed to evaluate and compare anxiety and pain perception during conventional greater palatine injections versus use of a novel barovibrotactile device named Accupal to give painless anesthesia.

2. Materials and methods

A Prospective, Split mouth, open label, randomized, crossover clinical study conducted on 50 patients visited to department of oral and maxillofacial surgery, at our institute for extraction of bilateral maxillary posterior teeth were selected. Before start of the study, permission was obtained from Institutional Review board and Ethical committee clearance was taken from the ethical committee (DYPDCH/77/33/2018).

• 1.Calculation of sample size: The sample size was calculated using online OpenEpi software version 3.01 using the data from the study conducted and published by Chaudhary et al.,⁴ with VAS (Visual analogue scale) for conventional and Vibraject with Mean of 51.5 ± 17.55 and 36.55 ± 17.85 keeping alpha 0.05 and power of this study as 80%. Minimum sample size calculated was 50 sites with 25 in each group. The total sample size for each individual group was maintained 50 sites per group (100 sites in total) considering the acceptability of the patients to participate in the study. Any patient who drops out in between the study or is lost to follow up will be excluded from the study.
• 2.Study size and enrolment: The subjects were informed about their voluntary participation in the study. Detailed case history & valid written informed consent will be obtained from the patient.
• 3.Inclusion and Exclusion criteria: The inclusion criteria were subjects who were aged between 18 to 50 years (Mean: 41 years) patients indicated for bilateral posterior teeth extraction with similar grade of mobility and requiring same palatal local anaesthesia technique and who were willing to participate in study. Subjects with any pre-operative pain, radiographic evidence of any periapical infections, periapical granuloma or cyst, with history of drug allergy, patients on antidepressant or anti-psychotic drugs and with systemic medical conditions like Diabetes or any bleeding disorders were excluded.
• 4.Patient selection, randomization, and allocation: Fifty patients (22 Males and 28 Females) requiring bilateral dental extractions (Hundred sites) were selected from January 1, 2019, to July 31, 2020. The investigator designated all the right sided extraction sites into A and left sided extraction sites into B. Accordingly Sequentially Numbered Opaque Sealed Envelope (SNOSE) method was used to decide the side on which the Accupal (Hot Springs, AR, USA) ® will be used (Fig. 1). Site A was written on 50 pieces of paper, and site B was on another 50 pieces of paper. These papers were placed in opaque, sealed envelopes. Each participant was allowed to pick an envelope. The investigator then opened the sealed envelope, and the participant was treated accordingly. Both the sites were treated with minimum interval of one week. This one week of wash out period between treatments of two sites prevents the alteration in the subjective response scores of pain assessment. This was an open-label study because the patient could not be blinded due to the nature of the device under investigation.
• 5.Procedure: A detailed operative procedure was explained to the patient by the investigator and the procedure was commenced. 30 minutes prior to the injection, blood pressure and pulse rate was recorded. On site A pre-conditioning of the palatal mucosa was done for 30 seconds using Accupal. The device continues to give vibrations and simultaneously the needle is bent at 90° angulation and pass through the central hole of the applicator tip for administration of local anaesthesia (Lox 2% adrenaline 1: 200000, Neon Laboratories Ltd, India). Then the Accupal will continue vibration for next 30 seconds. (Fig. 2). Thus total of 1 and ½ minutes of vibratory stimulations are given. 0.5ml Local anaesthetic solution was injected. During the anesthetic technique, non-invasive blood pressure (NIBP) monitor was connected to the patient and blood pressure and pulse rate were recorded. Pain perception was recorded by Visual Analogue Scale (VAS)¹² (Fig. 3) post injection. On site B 0.5 ml local anaesthetic injection (Lox 2% adrenaline 1: 200000, Neon Laboratories Ltd, India) will be administered without Accupal (Fig. 4) and again pain perception was recorded by VAS post injection. A single clinician performed the procedure to prevent bias. The data collected will be tabulated and subjected for statistical analysis.
• 6.Statistical analysis: Data compiled in Microsoft Excel Sheet and was analyzed using IBM SPSS version 21. Data was compared by applying specific statistical tests to find out statistical significance. Comparison of anxiety and pain perception during posterior palatal injections with and without barovibrotactile device (Accupal) was analyzed with unpaired ttest. P-value ≤ 0.01 was considered statistically significant.

Fig. 1.

Accupal (Barovibrotactile device, HOT SPRINGS, AR, USA) ®.

Fig. 2.

Greater palatine injection technique using Accupal.

Fig. 3.

Visual analogue scale (VAS).

Fig. 4.

Conventional greater palatine injection technique.

3. Results

This experimental split mouth study was conducted from January 2019 to July 2020. In our study, a total of 50 patients in the age group of 18–50 (Mean: 41 years) years participated. The gender distribution was 28 females (56%) and 22 males (44%).

The pain perception by the patient was compared between two sides, immediately after injection administration, using the analysis of VAS score. In this, 0 indicated no pain while 10 score was for unbearable pain. On Site A, with highest VAS score of 4 and minimum of 0 whereas, Site B had highest VAS score of 9 and minimum of 3. Site A and Site B had a median score of 1.96 and 6.08 respectively, with P-value of <0.01 (Table 1).

Table 1.

Comparison of VAS score between two groups using unpaired t test.

VAS SCORE	GROUP 1	GROUP 2
N	50	50
M ±SD	1.96 ± 1.098	6.08 ± 1.579
Mean difference	−4.120
t -value	10.709
P - value	0.01 (* Highly significant)

N - Number of patients, M - Mean Score, SD - Standard. Deviation, Student ttest.

Significant – difference between two groups.

$t-\mathrm{value}-\frac{{\left(\mathrm{Mean}1-\mathrm{Mean}2\right)}^{\mathrm{Meandifference}}}{\left(\mathrm{SE}1-\mathrm{SE}2\right)}$

Anxiety was assessed by checking the levels of the physiological parameters using NIBP monitor. The variations in the pre injection and the post injection levels of the blood pressure and pulse rate were not significantly different between the two techniques at different time intervals (Table 2).

Table 2.

Comparison of pre-operative and intra-operative BP, Pulse rate between two groups using unpaired t test.

Sample N = 50 (100 sites)	M ± SD		Mean difference	t - value	P – value
	Group 1 (50 sites)	Group 2 (50 sites)
Systolic pre	111.60 ± 13.077	117.80 ± 10.805	−6.20	1.827	0.07
Diastolic	70.00 ± 9.215	72.40 ± 8.746	−2.40	0.945	0.35
Systolic intra	112.36 ± 12.877	118.20 ± 10.444	−5.84	1.761	0.09
Diastolic	70.60 ± 8.761	74.00 ± 8.206	−3.40	1.416	0.16
Pulse pre	77.68 ± 14.026	82.60 ± 15.703	−4.92	1.168	0.25
Pulse intra	78.80 ± 11.569	79.56 ± 10.352	−0.76	0.245	0.81

N - Number of patients, M − - Mean Score, SD - Standard. Deviation, Student ttest.

Insignificant -no difference.

4. Discussion

Dental anxiety and dental phobia are one of the major challenges faced by the dental surgeon mostly due to fear of the needle or previous bad experience. Many strategies have been tried to reduce such pain and anxiety like music therapy, counter distraction, psychosomatic techniques, low level laser therapy, precooling of the soft tissues, and usage of various topical analgesics.⁵ Such anxiety and fear make the job of the dentist a challenging task. It is hence important to control fear, anxiety, distress and pain to have a comfortable procedure with minimum patient discomfort.

Many advanced devices have shown their drawbacks in the management of pain during local anaesthesia viz. The CCLAD provides continuous administration of small amount of anesthetic solution at a slower speed which helps in reducing the pain. However, it is difficult to use this on posterior teeth as it does not have a syringe needle.³ Jet injectors proved to have faster absorption of the anesthetic solution and cause less tissue damage. However, further controlled studies are needed for evaluation of its efficacy.⁶ Literature study reveals that vibratory devices viz. DentalVibe and VibraJect provides comfort to the patient while administration of local anesthesia injections since 1982 and are known to deliver vibrations and/or pressure to minimize the pain during injection.⁷ These devices work on the principle of ‘Gate Control theory’.⁸The DentalVibe, is a battery operated vibratory device that delivers pulsed micro-oscillations to the site where the injections is to be administered. It showed significantly lowered self-reported pain during local anesthesia injection.⁹ However a study by Raslan et al., proved that DentalVibe did not prove effective enough in reducing pain and it is difficult to use while dealing with the pediatric patients.¹⁰ VibraJect is a small motor vibrating dental injection with a clip bracket which is attached to most kind of dental injections.¹¹ Roeber et al. reported that the VibraJect failed to provide adequate pain relief and comfort to the patients since it provided small vibrations which were inadequate to activate larger nerve fibers.¹²Various studies using different devices have shown variable results.^13,14 (Table 3).

Table 3.

Various studies using different devices.

Sr. No	Author	Year	Device	Result
1	Yoshikawa F	2003	VibraJect	No significant difference
2	Saijo M	2005	VibraJect	Effective
3	Roeber B	2011	VibraJect	Non- Effective
4	Chandrasekaran J	2014	VibraJect	Effective
5	Shilpapriya M	2015	DentalVibe	Effective
6	Chaudhary K	2015	VibraJect	Effective
7	Elbay Ü	2016	DentalVibe	Non- Effective
8	Raslan N	2018	DentalVibe	Non- Effective
9	Ghorbanzadeh S	2019	DentalVibe	Effective

The greater palatine nerve block or palatal infiltrations are one of the most painful injections commonly employed for anaesthetizing hard palatal tissue distal to the canines and medial to midline on the same side.¹⁵ While options ranging from gels, ointments to anesthetic sprays are available for topical use, the operator's limited ability to simultaneously reduce the rate of injection while maneuvering the needle has been cited as a cause for patient discomfort during palatal injections¹⁶ yet it still remains the most painful injection. Its bad taste may cause discomfort to many patients.¹⁷ Because of these problems, a predictable means of pain control for injections is desirable. Use of vibration was stated to be an effective alternative. The vibration might also be more effective if it was continued during the injection or if a more effective vibration transfer device than the foam swab were employed.

English medical literature search failed to reveal any study regarding the effectiveness of Accupal device for pain control during local anesthetic techniques. Hence this study was done for comparing anxiety and pain perception during posterior palatal injections with and without this barovibrotactile device. It was a split-mouth study because second extraction in the same mouth would be easier and it allowed for intra-individual comparison and reduced the bias. VAS was used to compare the pain levels between the two groups. Since pain perception by every patient is different, it should be considered as an inter-individual bias. Blood pressure and pulse rate with and without Accupal were measured using digital NIBP monitor to assess and compare the pre injection and post injection fear and anxiety.

Accupal is a battery operated device which works on the principle of pressure and vibration, it is cordless and easily applied in routine local anesthetic procedures. Vibration and touch receptors stimulates the inhibitory interneurons in the spinal cord and result in elimination of pain transmitted by A-delta and C fibers. Vibrating needle with Accupal can therefore result in reduction of pain during injection.³ 360° proximal to the needle penetration, it provides pressure and vibrates the injection site. This shuts the pain gate mechanism which blocks the pain sensation.¹⁸ It has disposable plastic applicator tip connected to a hole headed slot which is attached to motor. When the device starts the bulb at the head is illuminated. The tip has elevated points which applies pressure on the palatal mucosa. Needle is then placed through a hole in the head to express anesthetic solution without pain to the patient.¹

Additionally, the comfort tip provides gentle pressure at the injection site, through Vibra-Pulse Technology and prevents a swelling of the bolus of the anesthetic solution as it is injected. This causes dissipation of the solution faster, and causes a profound anesthetic effect.

The “Gate Control Theory” given by Melzack and Wall in 1965 stated that stimulation of the larger diameter non-nociceptive mechanoreceptors fibers (vibration and pressure) can close a neural gate to nociceptive signals and consequently reduces the perception of pain.¹⁹ As per the theory the vibrations would stimulate the mechanoreceptors on the nerve endings of the large diameter fibers which carry the pressure sensation, thus inhibiting the smaller diameter fibers carrying the pain sensation. This kind of interference stimulation by vibration relieves pain and gives comfort to the patients.^20,21

When vibration is applied as a counter stimuli to an anesthetic injection, it will reach the brain prior to the pain sensation. The brain can perceive only single sensation at a given time. Hence, the sensation that reached the brain first is the one that will be felt. Therefore as counter stimulation vibration decreases pain perception.⁵

In our study, the VAS readings showed that patients had less pain with Accupal as compared with traditional injection technique. This may be influenced by the sound and appearance of the device. But, the effect is also based on Gate control theory. The mode of action of this device has been slightly modified. In addition to pre conditioning effect given before the administration of local anesthesia. Accupal has also been left in place for further 30 secs during administration. Better results are thus achieved due to pre conditioning and post conditioning methods. This modification was done under the hypothesis that when the solution is injected, it leads to pain due to firmly adherent mucosa. Accupal helps to counteract this with the help pressure and vibratory stimulus.

Our study clearly states that the barovibrotactile devices have a role in reducing pain during local anesthetic injection in adults. The P-value was <0.01 i.e. highly significant, leading to the conclusion that barovibrotactile device have a high potential of use in routine dental practice.

Its advantage lies in being user friendly, handy due to its small size and easy to use as compared to DentalVibe. Peripheral tissue vibrations, needle vibrations and topical pre-coating allows tissue penetration very comfortable. Its disposable tip helps in preventing cross infections. It can also be used safely in pediatric patients because it provides a very novel distraction. The ribbed side of the tip is designed to vibrate the topical unattached tissues like buccal vestibule and mandibular fossae for an inferior alveolar nerve block. Hence, Accupal is versatile and could be used in both maxillary and mandibular nerve blocks. Furthermore, controlled studies are required for proving its efficacy in buccal infiltrations and IAN Blocks.

In our study, we noticed there was a significant difference between two groups. We observed that use of Accupal resulted in significant reduction in pain perception. However, physiologic parameters did not show any significant change before and during the procedure. The search for better Vibrotactile device will still be on.

One of the limitations of this study was that is was assessed in a single nerve block techniques hence further studies are required to prove its role in management of fear and anxiety in other areas as infiltration (Buccal) and other nerve block techniques.

We thus conclude that use of Accupal provides significantly less pain perception while giving local anesthetic injections in comparison to the conventional injection technique in adults receiving posterior palatal injections. However assessment of anxiety revealed no significant difference.

Use of Accupal is easier due to its small size and user-friendly design. Unlike other Vibrotactile devices like VibraJect and DentalVibe, Accupal is a barovibrotactile device (Vibration + Pressure) due to its serrated tips with elevated points which gives pressure on underlying mucosa.

Funding's

None.

Declaration of competing interest

None.

Appendix A. Supplementary data

The following is the Supplementary data to this article: