Comparative Evaluation of Pain Perception and Postoperative Pain in Children with Precooled Injection Sites Using Popsicles for Local Anesthesia: A Randomized Controlled Trial

Abstract

Background

Pain management plays a pivotal role in pediatric dentistry, influencing a child's overall experience and future cooperation with dental care. Local anesthesia (LA) administration and postoperative discomfort following tooth extraction often contribute to anxiety and negative perceptions. Nonpharmacological methods, such as cryotherapy, have shown promise in reducing pain. Popsicles, commonly used as a cooling agent, may serve as a dual-function intervention—precooling the injection site and providing postoperative analgesia.

Aim

To evaluate and compare pain perception during LA administration and postoperative pain in children treated with and without popsicle-based precooling.

Materials and methods

This randomized controlled trial included 48 children aged 4–9 years requiring primary tooth extraction. Participants were randomly allocated into three groups: Group A (control, no precooling), group B (precooling with a standard popsicle), and group C (precooling with a popsicle of choice). Pain perception was assessed using the Wong–Baker FACES Pain Rating Scale (WB) and the Face, Legs, Activity, Cry, and Consolability (FLACC) scale during LA administration and 30 minutes postextraction. Data were analyzed using the Kruskal–Wallis and Wilcoxon signed-rank tests.

Results

Significant differences in pain scores were found among the groups during both LA administration and 30 minutes postextraction (p < 0.001). Both intervention groups reported significantly lower pain scores than the control group, with no significant difference between the two popsicle groups.

Conclusion

Precooling injection sites with popsicles effectively reduces pain perception and postoperative discomfort in children. This simple, cost-effective, and child-friendly approach offers a valuable addition to pediatric pain management strategies.

How to cite this article

Baldawa HS, Gurunathan D. Comparative Evaluation of Pain Perception and Postoperative Pain in Children with Precooled Injection Sites Using Popsicles for Local Anesthesia: A Randomized Controlled Trial. Int J Clin Pediatr Dent 2026;19(5):549–553.

Introduction

Effective pain management in pediatric dentistry is critical for ensuring a positive patient experience, minimizing anxiety, and fostering long-term acceptance of dental care.¹ Pain perception in children differs significantly from that in adults due to physiological, neurological, and psychological factors, necessitating tailored approaches to analgesia.^2,3 Local anesthesia (LA) is the standard method for pain control during invasive procedures; however, its administration is often a source of distress in young patients.^4,5 Similarly, postoperative discomfort following tooth extractions remains a challenge, with pharmacological interventions posing limitations, such as potential side effects and caregiver concerns over medication use.⁶ Consequently, there is growing interest in nonpharmacological pain management techniques, particularly cryotherapy, which has demonstrated efficacy in reducing pain through localized cooling, nerve desensitization, and anti-inflammatory effects.⁷

Despite extensive research on cryotherapy in dentistry, limited studies have explored its application in a dual role—both as a precooling agent to reduce injection-related pain and as a postoperative analgesic following dental extractions.⁸ Moreover, existing methods, such as ice packs, cooling gels, and cold compresses, may be less appealing or practical for young children, affecting compliance and efficacy. This study seeks to address this gap by evaluating the use of popsicles as a child-friendly cryotherapy intervention.⁹ Popsicles offer a dual advantage: Physiological pain relief through localized cooling and psychological comfort through a familiar and enjoyable medium. Unlike conventional cooling methods, they are cost-effective, widely available, and well-accepted by children, making them an ideal noninvasive analgesic modality in pediatric dentistry.¹⁰

A critical aspect of this study is the target population—children aged 4–9 years—a group particularly vulnerable to dental anxiety and pain-related distress.¹¹ Pain perception and coping mechanisms vary significantly across different pediatric age-groups, with younger children demonstrating heightened emotional responses and lower pain thresholds.¹² At the same time, older children may develop adaptive strategies that alter their pain experience. Selecting this age range allows for a focused investigation into the efficacy of an intervention specifically designed for a population that stands to benefit the most.¹³ Additionally, early childhood experiences with dental procedures play a pivotal role in shaping future attitudes toward oral healthcare, and reducing procedural pain in this age-group may have long-term benefits in preventing dental fear and avoidance behavior.¹⁴

Given these considerations, this study aims to evaluate the impact of popsicle-mediated cryotherapy on pain perception during LA administration and postextraction recovery in children. We hypothesize that precooling the injection site with a popsicle will significantly reduce pain perception during LA administration, and postoperative application will further minimize discomfort following tooth extraction. By integrating a noninvasive, readily available, and engaging intervention into routine pediatric dental care, this study seeks to establish a clinically viable and evidence-based approach to improving pain management in young patients.

Materials and Methods

Study Design and Participants

This randomized controlled trial was conducted in the Pediatric Dental Department of a private dental college. Ethical approval was obtained from the institutional ethics committee (IHEC/SDC/PEDO-2204/24/121), and the trial was registered in the Clinical Trials Registry of India (CTRI/2025/02/081163). A total of 48 children were enrolled in the study calculated by G*Power (effect size = 0.5896, power = 80%, and alpha = 0.05).¹⁵

Inclusion and Exclusion Criteria

Children aged 4–9 years requiring primary tooth extraction were included in the study.¹⁶ Only healthy children with no systemic conditions affecting pain perception and cooperative children classified as Frankl scale 3 and 4 were considered eligible.¹⁴ Children with cognitive or neurological impairments affecting pain perception and those with oral ulcerations or soft tissue injuries before the procedure were excluded. Informed consent was obtained from the parents or legal guardians of all participants, and verbal assent was sought from the children prior to their inclusion in the study.

Randomization and Blinding

Participants were randomly assigned into three groups using a computer-generated randomization sequence to ensure unbiased group allocation:

1. Group A (control group): LA was administered without precooling the injection site, and a popsicle was not provided postoperatively.

2. Group B (popsicle group): An ice popsicle was given for 2 minutes before LA administration, followed by the same popsicle immediately after tooth extraction.

3. Group C (popsicle of choice group): Children were allowed to choose their popsicle flavor before precooling the injection site, followed by the same popsicle after extraction.

Blinding was ensured by keeping the pain assessor (dentist) unaware of group allocation. However, complete blinding was not possible, as children in groups B and C were aware of receiving a popsicle, which may have influenced their perceived pain levels due to psychological comfort or placebo effects. This potential bias in self-reported pain scores is acknowledged as a study limitation.

Standardization of Injection Technique

To minimize variability, a single experienced pediatric dentist performed all injections, following strict adherence to a standardized protocol. The mucosa at the injection site was dried using sterile gauze before the injection. In groups B and C, precooling was performed using a commercially available popsicle for 2 minutes before anesthesia administration. The ice popsicles used in this study were uniform in size, measuring 3 cm in width and 10 cm in length. They were maintained at an approximate temperature of 0°C to ensure consistent precooling effects intraorally.

Local anesthesia was administered using 2% lidocaine (XICAINE) with 1:1,00,000 epinephrine and a 26-gauge, 1.5-inch needle (HMD Unolok). The needle was inserted slowly, and aspiration was performed before administering the anesthetic to prevent intravascular injection. A standardized volume of 1.2 mL was deposited at a controlled rate of 60–90 seconds to minimize injection discomfort.

Physiological Monitoring

Heart rate (HR) assessment: To evaluate the physiological response to LA administration, HR measurements were recorded using a fingertip pulse oximeter at two time points:​

1. Baseline measurement: Prior to the administration of LA, each child's HR was recorded to establish a baseline.​

2. Postanesthesia measurement: Immediately following the administration of 2% lidocaine with 1:1,00,000 epinephrine, a second HR measurement was taken.

Procedure

Pain perception was assessed during LA administration using the Wong–Baker FACES Pain Rating Scale (WB) for child self-assessment and the Face, Legs, Activity, Cry, and Consolability (FLACC) scale, evaluated by the dentist (FLACCD) and parent (FLACCP).^17,18 After extraction, groups B and C received a popsicle for 2 minutes to aid in pain relief and minimize postoperative complications such as accidental lip or cheek biting. Pain scores were recorded 30 minutes postextraction using the same scales, referred to as WB1, FLACCD1, and FLACCP1.

Outcome Measures

The primary outcome was pain perception during LA injection and 30 minutes postextraction, assessed using:

• WB scale (child self-assessment).

• FLACC scale (assessed by the dentist and parent).

Results

Preliminary analysis using the normality test indicated that the pain score data did not follow a normal distribution (p < 0.05). Consequently, nonparametric statistical methods were employed. The Kruskal–Wallis test was used for intergroup comparisons of pain scores, and the Wilcoxon signed-rank test was applied for intragroup comparisons. For physiological data (HR), which met the assumptions for parametric testing, repeated-measures analysis of variance (ANOVA) was performed to assess temporal and groupwise interactions.

The Kruskal–Wallis test revealed statistically significant differences among the three groups in pain perception during LA administration and at 30 minutes postextraction. During injection, FLACC-D (p < 0.001), FLACC-P (p < 0.001), and WB scores (p < 0.001) were significantly different across groups. Similar significance was observed at 30 minutes postextraction for FLACC-D1 (p < 0.001), FLACC-P1 (p < 0.001), and WB1 scores (p < 0.001), highlighting superior pain control in the precooled groups which is depicted in Table 1.

Table 1:

Pain scores during LA and 30 minutes postextraction, comparing all groups

Variable	Control	Popsicle	Popsicle choice
FLACC-D (during LA)	5.75 ± 1.44	2.13 ± 1.36	2.00 ± 1.63
FLACC-P (during LA)	6.00 ± 1.03	2.25 ± 1.44	2.25 ± 1.61
WB (during LA)	6.50 ± 1.37	2.38 ± 1.50	2.25 ± 1.61
FLACC-D1 (30 min post)	3.00 ± 1.03	0.38 ± 0.80	0.50 ± 0.89
FLACC-P1 (30 min post)	3.00 ± 1.03	0.38 ± 0.80	0.50 ± 0.89
WB1 (30 min post)	3.25 ± 1.24	0.38 ± 0.80	0.50 ± 0.89

The Wilcoxon signed-rank test showed a statistically significant reduction in pain scores within each group between the two time points. Pain scores decreased consistently postoperatively across all scales: FLACC-D1 vs FLACC-D (p < 0.001), FLACC-P1 vs FLACC-P (p < 0.001), and WB1 vs WB (p < 0.001), confirming the temporal effectiveness of cryotherapy with popsicles in reducing both perceived and observed pain (Table 2).

Table 2:

Kruskal–Wallis test results comparing pain scores among the three groups during LA and 30 minutes postextraction

Pain scale	Chi-square	df	p-value
FLACC-D	27.887	2	<0.001
FLACC-P	30.645	2	<0.001
WB	30.118	2	<0.001
FLACC-D1	45.12	2	<0.001
FLACC-P1	45.12	2	<0.001
WB1	30.971	2	<0.001

Repeated-measures ANOVA demonstrated a highly significant main effect of time on HR (F(p < 0.001), indicating that anesthesia administration led to measurable physiological changes. A significant time × intervention group interaction was also observed (p < 0.001), suggesting differential modulation of stress response by the intervention method in Table 3. These findings reinforce the physiological basis of pain mitigation achieved through precooling (Figs 123).

Table 3:

Comparison between pain scores during LA administration and 30 minutes postextraction within groups using the Wilcoxon signed-rank test

Pain scale	N	Z-score	p-value
FLACC-D1–FLACC-D	48	−5.719	<0.001
FLACC-P1–FLACC-P	48	−5.684	<0.001
WB1–WB	48	−5.722	<0.001

Fig. 1:

Comparison of pain scores during LA and 30 minutes postextraction between WB and WB1

Fig. 2:

Comparison of pain scores during LA and 30 minutes postextraction between FLACCP and FLACCP1

Fig. 3:

Comparison of pain scores during LA and 30 minutes postextraction between FLACCD and FLACCD1

Discussion

This study demonstrated that precooling the injection site with popsicles significantly reduced pain perception during LA administration and at 30 minutes postextraction in children aged 4–9 years. Both intervention groups—those receiving a standard popsicle and those choosing a popsicle flavor—showed markedly lower pain scores compared to the control group, as measured by the WB scale and the FLACC assessments by both parents and clinicians. Additionally, a significant decrease in HR elevation postanesthesia in the intervention groups further corroborated the analgesic effect of cryotherapy, with the control group showing a mean increase of 52.5 bpm compared to 26.13 bpm and 24.38 bpm in the popsicle and popsicle-of-choice groups, respectively (Tables 4 to 6).

Table 4:

Postanesthesia HR across groups and post hoc comparisons (Tukey's HSD)

Group	n	Mean post-HR (bpm) ± SD	Compared to	Mean difference (bpm)	p-value
Control	16	138.50 ± 6.47	Popsicle	24	<0.001
			Popsicle of choice	27.38	<0.001
Popsicle	16	114.50 ± 6.51	Popsicle of choice	3.38	0.285
Popsicle of choice	16	111.13 ± 5.66	–	–	–

Table 6:

Pre- and postanesthesia HR and net change by group

Group	Pre-HR (mean ± SD)	Post-HR (mean ± SD)	Mean HR change (bpm)
Control	86.00 ± 4.68	138.50 ± 6.47	52.5
Popsicle	88.38 ± 5.94	114.50 ± 6.51	26.13
Popsicle of choice	86.75 ± 7.41	111.13 ± 5.66	24.38

Table 5:

Repeated-measures ANOVA: Effects of time and method on HR

Source	df	F	p-value
Time (pre vs post)	1, 45	783.55	<0.001
Time × method interaction	2, 45	55.01	<0.001

These results align with existing literature on the physiological mechanisms of cryotherapy, which include reduced nerve conduction velocity, vasoconstriction, and diminished local inflammatory response.^19,20 Moreover, the act of consuming a popsicle introduces a sensory distraction that may further modulate pain perception through cognitive-emotional pathways. Unlike other cryotherapy methods, such as ice packs or cooling gels, popsicles provide a practical, cost-effective, and child-friendly modality that is well accepted by pediatric patients.^21–23 Importantly, no statistically significant difference was observed between the two intervention groups, suggesting that flavor choice—though potentially beneficial for cooperation—did not significantly influence analgesic outcomes.

Despite the positive findings, several confounding factors must be considered. Pain perception in children is influenced by variables such as prior dental experiences, baseline anxiety, and parental behavior—none of which were formally measured in this study.²⁴ For instance, children with previous negative encounters may exhibit heightened fear responses, which can amplify perceived pain. Similarly, the psychological environment created by parental presence—whether calming or stress-inducing—may affect both subjective reporting and physiological markers, such as HR. Although randomization aimed to evenly distribute, such variables across groups, their influence remains a limitation.

This study provides robust evidence supporting the use of popsicle-mediated cryotherapy as an effective, practical adjunct for managing procedural and early postoperative pain in children. The combination of physiological and psychological analgesic mechanisms, alongside high acceptability, emphasizes its value in clinical practice. However, future trials with larger samples, longer follow-up, and controlled confounding variables are warranted to confirm these findings and guide broader implementation.

Limitations and Future Directions

This study's limitations include potential psychological effects of flavor choice, individual variability in pain perception, and a short follow-up period. Complete blinding was not feasible, which may have introduced bias, and the relatively small sample size limits the generalizability of findings. Subjective pain assessments, though supported by physiological measures, also pose inherent limitations. Future research should explore long-term effects, optimal cooling durations, and should compare popsicle-mediated cryotherapy with other methods such as ice packs or chilled air. Studies assessing pain at multiple time points (e.g., 1 hour, 3 hours, and 6 hours postextraction) would help determine the duration of analgesic effect. Additionally, multicentric studies involving diverse populations and clinical settings are recommended to enhance external validity and establish standardized protocols for broader implementation.

Conclusion

Precooling the injection site with popsicles significantly reduced pain during LA and postextraction recovery in children. This simple, cost-effective, and child-friendly method offers a practical nonpharmacological approach to enhance comfort in pediatric dental care. Further research is needed to explore long-term benefits and compare its efficacy with other analgesic techniques.

Orcid

Harsh S Baldawa https://orcid.org/0009-0009-2295-6875

Deepa Gurunathan https://orcid.org/0000-0002-6014-946X