Pain and Anxiety Levels During Dental Restorations in Primary Molars: INJEX Needleless System vs Traditional Syringe

Introduction

Local anesthesia (LA) remains an indispensable tool in dentistry due to its effectiveness in providing pain relief during intensive dental procedures [1]. LA efficiently blocks the synthesis and transmission of nerve impulses responsible for the sense of pain by preventing the inflow of Na ions within neuronic structures or fibers [2]. This ensures that patients do not experience any pain and also promotes a sense of trust and understanding between the dentist and patient, alleviating fear and anxiety and promoting a positive outlook on oral health care [3]. Most local anesthesia procedures in pediatric dentistry involve traditional methods of infiltration or nerve block techniques with a dental syringe, disposable cartridges, and needles. Several alternative techniques, including computer-controlled local anesthetic delivery, periodontal injection techniques, needleless systems, and intraseptal or intrapulpal injection, are available. Such techniques may improve injection comfort by better control of the administration rate, pressure, and location of anesthetic solutions and result in more successful and controlled anesthesia [3].

One of the challenging facets of dental treatment has been the lingering problem of dispensing a pain-free administration of LA to children. Managing pain effectively and keeping the fear linked with administering injections under control could help children undergo dental treatment with a more positive outlook [4] and even deflect the child’s unease. The primary reason for fear and anxiety in children subjected to LA is the use of a regular needle syringe for administering the anesthesia. The fear and anxiety can even lead to patients seeking postponement or discontinuation of their treatment [5]. There are research results showing that anxiety, fear, and pain perception levels are interconnected to each other – in fact, anxiety and fear can reduce a patient’s ability to withstand pain owing to an increase in stress levels [6]. Such fear and anxiety can be by enhancing the child’s comfort levels by modifying certain aspects of the treatment [6].

There has been commendable progress and continuous improvements with respect to the needles and anesthetic agents’ quality and design, but surprisingly we have not seen many variations brought to the methodology of anesthesia administration [7]. Delivering LA by making use of the age-old method of a needle often brings about discomfort during both phases – piercing and injecting. Some of the most common reasons for such discomfort include handling the syringe inappropriately, injecting great amounts of solution rapidly, and exerting too much pressure on the needle [5]. Administering topical LA before the injection [8], adjusting the injection speed manually [9], using a computerized injection system [10], and use of needleless jet injection devices are some commonly cited methods in the literature to relieve discomfort in patients during LA [11].

A highly recommended alternative to conventional injection technique is use of jet injection devices, which work on the principle of using high-velocity fluids to enter tissues. These needle-free injectors function using compressed gas or a spring that is used to push small quantities of medicine via a thin opening. Using such a methodology instills the primary advantage of nullifying any fear or pain generally linked with injections and needles [4,12]. Since the 1970s, various dental jet injectors have displayed commendable outcomes in anesthetizing target tissue, which automatically enhances the comfort level of patients [13]. Some recent advances in administration of LA in dentistry include newer jet systems, which have shown promising results [14–16].

Therefore, this study aimed to compare pain perception levels and the behavior (anxiety levels) of pediatric patients during the restoration process using the INJEX needleless local anesthetic system versus the conventional anesthesia technique.

Material and Methods

STUDY DESIGN, ETHICAL CLEARANCE, AND INFORMED CONSENT:

This split-mouth, single-blind, randomized controlled study (REC-44/07/503) was approved by the Institutional Human Ethics Council of Jazan University’s College of Dentistry. This study was registered in the clinical trials registry with ref no NCT06576609 with study duration from 16-02-2024 to 30-06-2024.

The study flow chart is illustrated in Figure 1. The parent or guardian was thoroughly briefed regarding the protocol of the study. Participation in the study was purely voluntary, and enrollment happened only after obtaining signed informed consent. Consent was obtained from the parent or guardian, or from the child whenever necessary. All ethical standards detailed in the Declaration of Helsinki (1964) and their subsequent amendments were met while conducting this study.

SAMPLE SIZE ESTIMATION:

A difference in the FLACC scores of 1.2 and a combined SD of 1.89 from an earlier study were used to determine the sample size [17]. An estimated 21 participants made up the sample. To accommodate sampling loss, the expected sample size was increased by 20%, resulting in 25 teeth per group.

INCLUSION CRITERIA:

Children visiting the outpatient department of the pediatric dentistry department and who were between the ages of 7 and 10 years were recruited. We enrolled hildren who had general physical and mental well-being, who exhibited “positive” or “definitely positive behavior” as assessed according to Frankl Behavior Rating scale (FBRS) during preliminary examination and intra-oral radiographs, and had at least 2 deep carious lesions in deciduous molars that required indirect pulp capping. Written informed consent was obtained from the parents/guardians of all the selected participants and all of them displayed an eagerness to participate in the study.

EXCLUSION CRITERIA:

Exclusion criteria for the study included any child aged below age 7 years, children showing “negative” or “definitely negative” behavior as per FBRS during the initial examination, any child who was compromised mentally or medically, and children who displayed symptoms of dentoalveolar abscess and irreversible pulpitis.

RANDOMIZATION AND ALLOCATION CONCEALMENT:

Teeth designated for restoration were assigned to 1 of 2 groups using a simple randomization method with a 1: 1 allocation ratio. The allocation was performed using a predetermined list, with the first list for the right side and the second for the left side. Allocation concealment was maintained through sealed envelopes until the time of intervention to prevent selection bias. On the intervention day, patients were identified by number on either the right or left side lists.

GROUP I:

All teeth in this group underwent restoration using the traditional syringe system using a conventional syringe with local infiltration of 2% Scandicaine Special.

GROUP II:

Teeth in this group received treatment with INJEX (INJEX Pharma AG, Germany).

The INJEX system comprises several components: the injector containing 0.3 mL of Scandicaine 2% Special, a reset box to reset the device for the injection process, and an adaptor facilitating the drug transfer into the ampule. The injector must be reset for recharging before every use [6]. Once reset, the prepared injector is placed securely on the mucosa, and 0.3 mL of 2% Scandicaine is supplied by briefly pressing the trigger.

INTERVENTION PROCEDURE:

A single operator carried out the full anesthetic process for each trial participant to reduce any potential bias because of the operator. All pertinent treatment equipment and techniques were presented through the “Tell-Show-Do” method. A detailed description of the injection was given, utilizing age-appropriate vocabulary and suitable euphemisms.

Sterile dry gauze was used to cleanse the treatment area at the injection site before administering LA. Following this, a very small quantity of topical anesthetic was applied and left on for at least 1 minute. Following the application of topical anesthesia, LA was administered based on the participant’s assigned group. After a waiting period of 3 minutes for the anesthesia to take effect, indirect pulp capping was performed.

OUTCOMES:

The evaluators were blinded to the type of anesthesia administered. The results were assessed by 2 researchers: one evaluated primary outcomes such as Face, Legs, Activity, Cry, Consolability Scale (FLACC Scale) [18] and the Wong-Baker scale (WBS) [19], while the other focused on secondary outcomes such as pulse rate, the FBRS [20], and the time it took to give the anesthesia.

:

The FLACC scale is an objective pain assessment tool that evaluates pain severity based on 5 behavioral domains. Each domain was scored between 0 and 2, with the number 0 indicating the absence of any pain or discomfort and 2 indicating maximum pain or distress. Summing the individual domain scores produced a score range between 0 and 10, which was used to calculate the total FLACC score. A higher total score indicates more severe pain, as the severity of pain is directly proportional to the overall score.

:

Six facial expressions are used in the subjective pain evaluation tool (WBS) [19]. Each expression is given a numerical value between 0 and 10 to represent the degree of pain. Mild pain is represented by a score of 0–4, severe pain by a score of 4–6, and terrible pain by a score of 8–10. The WBS was rated 4 times by the children in both groups to rate their level of pain: prior to injection, right after injection, during therapy, and following treatment.

:

Wright’s modification of the FBRS [20] was used to assess the child’s behavior during dental procedures, during intra-oral examination, radiography, and topical anesthetic application (grouped as “before” values), as well as during local anesthetic administration and restoration (categorized as “after” values).

TIME:

The time required to administer the LA solution was recorded using a stop watch.

PULSE OXIMETER:

A pulse oximeter was used for measuring anxiety. Physiological parameters were measured at 3 intervals: 15 minutes before LA administration, during the injection, and 1 minute after the injection. Variations in measurements were noted, and mean values were calculated. Individual pulse rate readings were recorded, and averages were calculated for the “during” and “after” intervals. In accordance with the anesthesia protocol, a third evaluator measured these outcomes without prior knowledge of the protocol.

FOLLOW-UP:

Postoperative pain and discomfort were recorded when the child returned after 1 week.

STATISTICAL ANALYSIS:

A standard statistical package (SPSS 20 for Windows, SPSS, Inc., Chicago, USA) was used to conduct the statistical analysis. The Shapiro-Wilk test was used to determine whether the data were normal. The chi-square test was used to examine the group distribution by age, gender, and accompanying person. Intergroup comparison of pulse rate and time taken for LA administration was performed using the unpaired t test, whereas patient behavior and subjective and objective assesment of pain were analyzed using the Mann-Whitney test. The paired t test was used for intragroup comparison of pulse rate, while the Wilcoxon signed-rank test was utilized for intragroup comparisons of patient behavior and subjective and objective assesment of pain.

Results

TIME TAKEN FOR LA ADMINISTRATION:

Comparing the time taken for administering LA during restoration among the 2 groups showed a very large and significant difference (P value <0.001), in which a shorter time (18.84 seconds) was required for the INJEX group. Additionally, a statistically significant difference (P value <0.05) was observed in pulse rates during anesthesia between the 2 groups. Specifically, the traditional system group had a higher pulse rate (99.48±9.95) compared to the INJEX group, as shown in Table 1.

PATIENT BEHAVIOR DURING PROCEDURE:

FBRS scores before, during, and after anesthetic administration for restoration did not differ significantly, and most children had a median score of 4. However, when analyzing FLACC scores during the delivery of LA, a highly significant difference (P value <0.001) was evident between the 2 groups.

PAIN PERCEPTION DURING PROCEDURE:

The median FLACC score for the traditional system group was 4 (1, 5), while for the INJEX group, it was 0(0, 2). Similarly, a notably significant difference (P value <0.001) was found for WBS scores before the procedure and immediately after the injection between the groups, with higher scores [0(0, 2), 4(2, 6)] observed for the traditional system group. Statistically significant differences were also noted for WBS scores during and at the end of treatment, as indicated in Table 2.

INTRAGROUP COMPARISON OF PULSE RATE, FBRS, AND WBS BEFORE, DURING, AND AFTER LA ADMINISTRATION:

Pulse rates showed statistically significant differences when comparisons were made between “before versus during,” “before versus after,” and “during versus after” in the traditional system group. Regarding FBRS scores, statistically significant differences (“before versus during” and “during versus after”) were observed only in the traditional system group. For WBS scores, out of the 6 pairwise comparisons, statistically significant differences were obtained for all except the “during the treatment versus at the end of the treatment” comparison in the traditional system group. In the INJEX group, statistically significant differences were observed for the following comparisons: “before versus immediately after injection,” “immediately after injection versus during the treatment,” and “immediately after injection versus at the end of treatment” (Tables 3, 4). No statistically significant difference was observed for the comparison of various parameters during LA administration concerning arches (Tables 5, 6).

Discussion

LIMITATIONS:

Although the focus of this research was not on evaluating the pain levels experienced by children of both groups after the operation, still these participants were followed up, examined completely, and provided with all needed interventions correctly and on time. Children with negative behavior were not a part of our study, which focused predominantly on the use of single-needle gauges. In addition, we did not compare INJEX and conventional needle anesthesia with respect to the dental arch; therefore, all these limitations must be considered when applying these findings to a broader population in the future. Incorporating needle-free injections and evaluating their efficacy and utility for other treatment procedures in dentistry needs further research. No studies have reported postoperative complications using INJEX. Patients receiving INJEX injections reported no complications after 1 week and had no postoperative numbness in the lips after administration, whereas with traditional needle technique the patients had postoperative numbness for a few hours. The amount of anesthesia was drastically less with INJEX than with the traditional needle method. One of the limitations of our study is that we did not evaluate the potential difference in the duration of anesthesia provided by INJEX versus the traditional method. We recommend further research to evaluate the long-term effect of anesthesia, which will be useful for longer procedures.

Conclusions

Administering INJEX can greatly alleviate the level of pain that children feel during restoration of primary teeth and assist them in maintaining an optimistic outlook. The children showed more positive behavior compared to the traditional technique. Additionally, INJEX was shown to be superior in the amount of anesthetic and time needed for delivery.

The INJEX technique manifested benefits in the form of reduction in pain intensity levels felt by children, and their attitude remained positive throughout the restorative procedure, thus making the experience more positive for both the child and the dental practitioner. The INJEX system could be a versatile alternative to the conventional technique. INJEX can be used to reduce preoperative fear, postoperative pain, and the amount of anesthesia delivered.