Effectiveness of topical ajwain oil in reducing pain during local anaesthesia administration in paediatric dental patients: A randomized controlled trial

Abstract

Background

Needle anxiety is one of the most common barriers to providing stress-free dental care in children. In paediatric dentistry, there is a consistent effort to identify painless techniques for administering local anaesthesia. Topical anaesthetics have long been considered a valuable aid in this regard. Recently, the efficacy of herbal topical anaesthetic agents has been compared with that of conventional sprays and gels. The present study is among the first to evaluate the effectiveness of Trachyspermum ammi (Ajwain) oil as a topical agent for pain control during local anaesthesia administration in paediatric dental patients.

Objective

The objective of this study was to evaluate and compare the analgesic efficacy of Ajwain (Trachyspermum ammi) oil with a conventional 15 % w/w lidocaine topical spray in reducing pain perception during the administration of local anaesthesia in paediatric dental patients.

Methods

A total of 52 children, aged 6–10 years and meeting the inclusion and exclusion criteria, were randomly divided into two equal groups (Group 1: Ajwain oil; Group 2: topical anaesthetic spray) using the chit method. Pain responses were assessed using the Visual Analogue Scale (VAS) and the Wong-Baker Facial Pain Rating Scale (WBFPRS).

Results

Independent t-tests revealed statistically significant differences between Group 1 and Group 2 for both VAS and WBFPRS scores, with p values of 0.001 for each scale, indicating a significant reduction in pain perception in the Ajwain oil group.

Conclusion

Ajwain oil shows potential as an effective alternative to conventional topical anaesthetic sprays for reducing injection pain in paediatric dental patients.

Graphical abstract

1. Introduction

Behaviour management remains one of the most significant challenges in paediatric dentistry, encompassing a range of strategies aimed at improving patient cooperation and delivering pain-free dental treatment. Among the various obstacles, needle anxiety is particularly common and often impedes the delivery of stress-free care to children. Consequently, there is a continual need in paediatric dentistry to develop painless techniques for the administration of local anaesthesia. Topical anaesthesia has long been recognised as a valuable tool in achieving this goal.¹

Local anaesthesia is widely regarded as an effective modality for pain management. However, the injection technique commonly used for its administration is paradoxically one of the primary contributors to fear and anxiety in paediatric patients. This fear can negatively affect a child's behaviour, thereby compromising the quality of treatment provided. To address this, various methods have been explored to minimise the discomfort associated with injections. These include altering the temperature and pH of the anaesthetic solution, employing behavioural management techniques, and applying topical anaesthesia to numb the mucosal surface prior to needle insertion. Notably, topical anaesthetics produce both pharmacological and psychological effects.^2,3

The incorporation of plant extracts into dental materials has shown considerable promise for various therapeutic applications. Despite this, the use of herbal agents as anesthetics remains relatively underexplored in dentistry.⁴ Several plants exhibit anaesthetic and analgesic properties, with clove, betel leaves, and clove-papaya-based anaesthetic gels being prominent examples. Ajwain oil, an essential oil derived from the fruit of trachyspermum ammi, is particularly rich in thymol (35.80 %) along with other minor constituents. This high thymol content is primarily responsible for its analgesic potential.^5,6

Biotechnology and nanotechnology are now being used to improve herbal medicines. With the help of nano-carriers such as emulsions, liposomes, and nanoparticles, the natural compounds from herbs can be made more stable, better absorbed, and released in a controlled way. This not only increases their effectiveness but also helps in delivering them to specific sites in the body, reducing side effects and making herbal treatments more dependable for different health conditions.⁷

Trachyspermum ammi is a well-known aromatic herb and a valuable commercial product widely used in the food and flavoring industries. Its fruits are edible and commonly used as a spice in India, the Middle East, and parts of the Americas. Pharmacological investigations of Trachyspermum ammi (Ajwain) have revealed a broad spectrum of therapeutic properties, including antibacterial,⁸ antiviral,⁹ antifungal,¹⁰ and anti-helminthic¹¹ activities; anti-inflammatory,¹² analgesic,¹³ and anti-nociceptive¹⁴ effects; antispasmodic,¹⁵ hepatoprotective,¹⁵ anti-ulcer,¹⁶ diuretic, and anti-lithiasis¹⁷ properties; as well as antihypertensive,¹⁵ anti-platelet,¹⁸ bronchodilatory,¹⁹ antitussive,²⁰ detoxifying,¹⁵ and antioxidant²¹ effects.

This randomized controlled trial aimed to evaluate and compare the analgesic efficacy of Ajwain oil (Trachyspermum ammi) with a conventional 15 % w/w lidocaine topical spray in reducing pain during inferior alveolar nerve block (IANB) in children aged 6–10 years, and to assess its potential as a natural alternative for paediatric dental pain management. In this study, the null hypothesis was that there would be no statistically significant difference in pain perception during inferior alveolar nerve block (IANB) in children aged 6–10 years when Ajwain oil (Trachyspermum ammi) topical application was used in comparison with 15 % w/w lidocaine topical spray. The null hypothesis assumes that Ajwain oil possesses neither superior nor inferior analgesic efficacy compared to the conventional lidocaine spray.

2. Materials and methods

2.1. Study design and setting

This in vivo, double-blinded, randomized clinical trial was conducted in the Department of Paediatric and Preventive Dentistry at Teerthanker Mahaveer Dental College & Research Centre, Moradabad, Uttar Pradesh, India. The study protocol received approval from the Institutional Ethical Committee and Review Board (TMDCRC/IEC/SS/24–25/PEDO01), and the trial was registered with the Clinical Trials Registry of India (CTRI/2024/11/077086). A total of 52 children, aged between 6 and 10 years, who reported to the department, were enrolled based on predefined eligibility criteria.

2.2. Inclusion criteria

• •Children aged 6–10 years
• •Requiring local anaesthesia via Inferior Alveolar Nerve Block (IANB) for dental procedures
• •Cooperative behaviour (Frankl's Behaviour Rating Scale III or IV)

2.3. Exclusion criteria

• •Children unwilling to participate
• •Presence of systemic diseases (including bleeding disorders and immunocompromised conditions)
• •Highly uncooperative children (Frankl's I or II)
• •History of abscess, redness, or fistula at the injection site
• •Known phobia of needles (Aichmophobia)
• •Any history of allergy to the solutions used
• •Patients with behavioral disorders

2.4. Sample size

A power analysis was performed using G*Power software version 3.0.1 (Franz Faul, Universität Kiel, Germany). A total sample size of 52 (26 participants per group) was calculated to achieve 80 % power at a 5 % significance level, assuming an effect size of 0.8.

Initial screening was done for 109 children, out of which 52 (22 males and 30 females) met the inclusion criteria and were enrolled in the study between September 2024 and April 2025. Participants were randomly allocated into two groups:

• •Group 1 (Study Group): Ajwain oil
• •Group 2 (Control Group): Topical anaesthetic spray

2.5. Randomization

Randomization was performed using a chit method by an independent senior paediatric dentist (AB) to avoid bias. Each participant was asked to pick one of two folded paper chits from a bowl—one indicating the Ajwain oil group and the other indicating the control group (Fig. 1).

Fig. 1.

Consolidated standards of reporting trials flow diagram.

2.6. Procedure

The Ajwain oil solution was formulated at the College of Pharmacy, Teerthanker Mahaveer University, Moradabad. The essential oil from ajwain seeds (Trachyspermum ammi) was extracted using the steam distillation method with a Clevenger apparatus. Essential oils are volatile aromatic compounds derived from herbs. In steam distillation, steam carries these volatile compounds from the raw seeds. Since the process operates below 100 °C (212 °F), it enables vaporization at temperatures lower than their normal boiling points, thereby preventing thermal decomposition. This technique utilizes the vapor pressure of volatile constituents (primarily thymol) to separate them from non-volatile compounds without exceeding the boiling temperature of water.

For the procedure, 250 g of dried ajwain seeds were coarsely crushed and transferred into a round-bottom flask containing 2 L of distilled water. The flask was connected to a Clevenger apparatus fitted with a condenser, ensuring proper circulation of cooling water. The mixture was heated using a water bath to generate steam, and distillation was continued for 3–4 h until no additional oil separated in the apparatus. Within the Clevenger apparatus, the oil formed a distinct layer above the water, which was collected carefully using a pipette.

To purify the oil, a small quantity of anhydrous sodium sulfate was added to remove residual moisture, followed by filtration through filter paper. The essential oil was then transferred into amber-colored vials and stored in a cool, dry place. The final product was a light-yellow oil with a characteristic pungent, spicy, thyme-like aroma. Since ajwain essential oil is hydrophobic and does not mix with water, it was diluted with 95 % ethanol to obtain a homogeneous mixture suitable for topical application. For this purpose, 1–2 drops of concentrated essential oil were freshly mixed with 5 mL of ethanol, stored in a dark-colored vial, and protected from direct sunlight until use.

• •Group 1 (Study Group): The prepared Ajwain oil solution was applied topically to the injection site using a flocked tip applicator (Dentsply Sirona).
• •Group 2 (Control Group): A conventional topical anaesthetic spray, lidocaine 15 % w/w (Nummit; ICPA), was applied to the injection site.

After 5 min, local anaesthesia (Lignox 2 % A, Indoco Remedies Ltd.) was administered using the Inferior Alveolar Nerve Block technique. Non-pharmacological behaviour management strategies were used before the injection. In order to avoid intravascular injection and associated complications, aspiration was performed prior to slow deposition of the anaesthetic.

Pain perception during the injection was assessed using two validated pain rating tools:

• •Visual Analogue Scale (VAS)
• •Wong-Baker Facial Pain Rating Scale (WBFPRS)

All procedures were performed by the same operator (AT), and the pain scores were recorded and validated independently by another senior paediatric dentist (AB).

3. Statistical analysis

Data were entered into Microsoft Excel 2007 and analysed using SPSS version 23.0. Descriptive statistics included mean, standard deviation, frequency, and percentage. The level of significance was set at p < 0.05.

Intergroup comparisons were performed using independent t-tests. The Shapiro-Wilk test was used to evaluate the normality of the data, and Levene's test was applied to assess homogeneity of variances.

4. Results

4.1. Demographic distribution

The gender distribution across both groups was identical, with females comprising 57.7 % (n = 15) and males 42.3 % (n = 11) in both Group 1 (Ajwain oil application) and Group 2 (topical anaesthetic spray). The mean age of participants in Group 1 was 7.76 years, while that of Group 2 was slightly higher at 8.07 years (Table 1). These findings indicate that both groups were comparable in terms of gender and age distribution, ensuring baseline homogeneity for the study (Graph 1).

Table 1.

Gender distribution of the study subjects.

Groups	Female (n)	Male (n)	Mean Age (In Years)
Group 1(Ajwain oil)	15	11	7.76
	57.7 %	42.3 %
Group 2 (Topical anaesthetic spray)	15	11	8.07
	57.7 %	42.3 %

Graph-1.

Gender distribution of study subjects.

4.2. Intergroup comparison of Visual Analogue Scale (VAS) scores

An independent t-test was performed to compare the mean VAS scores between Group 1 and Group 2.

• •Group 1 (Ajwain oil): Mean = 2.384, SD = 0.852, SE = 0.167
• •Group 2 (Topical anaesthetic spray): Mean = 5.307, SD = 1.667, SE = 0.327

The p-value obtained for the comparison was 0.001, which is below the significance threshold of 0.05, indicating a statistically significant difference between the two groups (Table 2). This suggests that the pain perception, as measured by VAS, was significantly lower in the Ajwain oil group (Graph 2).

Table 2.

Intergroup comparison of mean Visual Analogue Scale scores between the groups.

Groups	Mean	Std Dev	Std Error	P value	Significance
Group 1(Ajwain oil)	2.384	0.852	0.167	0.001*	Significant
Group 2 (Topical anaesthetic spray)	5.307	1.667	0.327

*p < 0.05.

Graph 2.

Intergroup comparison of mean visual analogue scale scores between the groups.

4.3. Intergroup comparison of Wong-Baker Facial Pain Scale (WBFPS) scores

The intergroup comparison of WBFPS scores also revealed a significant difference:

• •Group 1: Mean = 2.538, SD = 0.904, SE = 0.177
• •Group 2: Mean = 5.692, SD = 1.463, SE = 0.287

The p-value for this comparison was 0.001, confirming that the difference is statistically significant (Table 3). These results support the finding that pain perception was notably lower in the Ajwain oil group compared to the conventional topical anaesthetic spray group (Graph 3).

Table 3.

Intergroup comparison of mean Wong-Baker Facial Pain Scores between the groups.

Groups	Mean	Std Dev	Std Error	P value	Significance
Group 1(Ajwain oil)	2.538	0.904	0.177	0.001*	Significant
Group 2 (Topical anaesthetic spray)	5.692	1.463	0.287

*p < 0.05.

Graph 3.

Inter-group comparison of mean wong-baker facial pain scores between the groups.

5. Discussion

One of the most universally encountered challenges in dentistry, irrespective of whether a procedure is invasive or non-invasive, is the effective management of patient fear and anxiety prior to treatment. This is particularly evident in children, who often resist dental procedures due to fear and anxiety, which are typically associated with the anticipation of pain.

Topical anesthetics provide superficial anaesthesia up to 2–3 mm within the oral mucosa, with their efficacy influenced by concentration, formulation, and route of application. Historically, cocaine was employed because of its anaesthetic and vasoconstrictive properties; however, concerns of toxicity and abuse have led to its discontinuation in clinical practice.²²

Among currently available agents, lidocaine and benzocaine are the most frequently used. Benzocaine, an ester derivative of p-aminobenzoic acid (PABA), has a rapid onset but carries a higher risk of allergic reactions, though systemic absorption is minimal due to poor solubility. Tetracaine, another ester-based agent, is more potent but its higher mucosal absorption limits its routine dental use.²³

Amide derivatives such as lidocaine and prilocaine are considered safer alternatives. Lidocaine, available in multiple concentrations and formulations, has a fast onset (1–2 min) and predictable efficacy, making it the most widely preferred topical anaesthetic.²² In the present study, a 15 % w/w lidocaine aerosol spray (Nummit; ICPA) was selected for the control group, as it provides reliable surface anaesthesia prior to inferior alveolar nerve block administration. Prilocaine, though less frequently used alone, enhances efficacy when combined with lidocaine in eutectic mixtures (e.g., EMLA), which have shown effectiveness in reducing procedural pain during rubber dam clamp placement, palatine nerve block, and gingival probing.²³

The main limitations of conventional topical anesthetics in paediatric dentistry include the risk of systemic toxicity from accidental ingestion or aspiration and the lack of standardized dose calculation, unlike injectable local anesthetics. These concerns are particularly relevant in children, where safety margins are narrower. In recent years, interest has grown in exploring natural alternatives with anaesthetic properties.³

Herbs and medicinal plants have been used since ancient times to relieve pain from surgery, injuries, or diseases. Many of these natural remedies have contributed to the evolution of modern anaesthesia.²⁴ Essential oils, which are concentrated plant extracts containing volatile phytochemicals, are known for their complex structure and diverse pharmacological effects. While widely used in perfumes and flavors, essential oils from plants like lavender, clove, betel leaves, and Ajwain have demonstrated analgesic and anaesthetic properties.^25,26 Although analgesia and anaesthesia are distinct concepts, in dental practice, topical analgesics and anaesthetics are often used interchangeably due to their common goal of inducing surface analgesia.²²

The key constituent of Ajwain oil, derived from Trachyspermum ammi (T. ammi), is thymol, which constitutes approximately 35–60 % of the oil.^27,28 Thymol is a phenolic compound with well-documented analgesic, antispasmodic, antifungal, and germicidal properties.²⁹ Terpenoid phenols, such as thymol, exhibit antibacterial and antinociceptive effects, and are widely utilized in dentistry as analgesic or sedative agents for conditions such as toothache, dental hyperalgesia, and pulpitis. Additionally, compounds like eugenol and thymol, along with structurally related molecules, have demonstrated general anaesthetic activity.²⁵

James and Glen conducted structural-activity relationship studies, synthesizing a range of alkylphenols, including thymol analogues, to assess their anaesthetic efficacy. Their work suggested that diisopropyl phenol derivatives show potential for use as intravenous anaesthetics.³⁰ An in vivo study by Gilani et al. (2013) tested the antimicrobial activity of Ajwain oil against various bacterial and fungal species. In the same study, a topical paste containing Ajwain oil exhibited wound healing properties in rabbits.¹⁵ To date, no adverse effects of Ajwain oil have been reported. However, caution is advised during pregnancy, as animal studies have suggested teratogenic effects in rat foetuses.³¹ A recent study by Dahake et al. (2023) on albino rats revealed that zinc oxide mixed with a combination of Ajwain and eugenol (in a 1:1 ratio) can be effectively used as an obturating material in primary teeth.⁴

In the present study, participants in both groups were comparable in age and gender, with a mean age of 7.76 years in the Ajwain oil group and 8.07 years in the lidocaine spray group, and females comprising 57.7 % of each group. Pain assessment using both the Visual Analogue Scale (VAS) and Wong-Baker Facial Pain Scale (WBFPS) revealed significantly lower scores in the Ajwain oil group, suggesting superior efficacy in reducing injection-related discomfort in children aged 6–10 years.

These findings contrast with several previous studies evaluating herbal topical anesthetics. Alqareer et al.³² reported no significant difference between clove oil and benzocaine during maxillary canine infiltration in adults aged 17–25 years, while Anantharaj et al.⁶ observed similar pain levels among clove gel, papaya-based gel, ice, and benzocaine in children aged 9–10 years. Mohite et al.³³ found comparable pain perception between herbal gels (anacyclus pyrethrum and spilanthes acmella) and lignocaine during inferior alveolar nerve block in children aged 8–14 years. In contrast, Havale et al.⁵ reported lignocaine to be more effective than clove and betel leaf extract gels in children aged 6–10 years, although no significant difference was seen when compared with ice application.

Overall, while previous studies generally found herbal agents to be similar or slightly less effective than conventional topical anesthetics, the present study demonstrates that Ajwain oil may provide superior analgesic effect in paediatric injections. This suggests a potential role for Ajwain oil as a safe, effective, and natural alternative to conventional agents, warranting further research to validate its efficacy and optimize application protocols.

Herbal preparations have long been used for self-management of oral and dental conditions due to their efficacy, accessibility, and safety.³⁴ Apart from thymol, several other herbal compounds, including clove, cinchona, and jasmine, possess anaesthetic properties and have been employed in dental applications, although their full potential remains underexplored.^25,26 Given this context, the present study is the first of its kind to explore the use of Ajwain oil as a topical anaesthetic agent prior to inferior alveolar nerve block (IANB) administration in dentistry, thus opening avenues for the potential incorporation of natural alternatives in pain management protocols.

The present study has several notable strengths, including its novelty as the first clinical evaluation of Ajwain oil as a topical anaesthetic for inferior alveolar nerve block in paediatric patients. Traditionally, herbal formulations in dentistry have been primarily limited to roles such as irrigants, pulp capping agents, or antimicrobial applications, with few studies exploring their potential as topical analgesics or anesthetics. This study expands the scope of intraoral herbal use by demonstrating the efficacy of Ajwain oil in reducing injection-related pain.

However, the study also has certain limitations. The sample size was relatively small, and the trial was conducted at a single center, which may limit the generalizability of the findings. The characteristic pungent, spicy, thyme-like aroma and taste of Ajwain oil may influence behavior management in some children, representing a practical consideration for clinical use. Despite these limitations, the findings highlight Ajwain oil as a promising, safe, and natural alternative to conventional topical anesthetics, warranting further investigation in larger, multicenter trials and exploring strategies to optimize its sensory acceptability in paediatric patients.

6. Conclusion

This pioneering study is the first to evaluate the effectiveness of topical Ajwain oil (Trachyspermum ammi) in managing pain during the administration of local anaesthesia in paediatric dental patients. Based on the findings, the following conclusions can be drawn:

• 1.Ajwain oil demonstrates significant potential as a natural alternative to conventional topical anaesthetic sprays prior to inferior alveolar nerve block (IANB) procedures in children.
• 2.No sex-specific differences were observed in the analgesic effect of Ajwain oil, indicating equal efficacy in both male and female paediatric patients.

Patient's/Guardian's consent

Informed consent was obtained from the parents or legal guardians of all participants prior to their inclusion in the study.

Ethical clearance

The study protocol received approval from the Institutional Ethical Committee and Review Board (TMDCRC/IEC/SS/24–25/PEDO01), and the trial was registered with the Clinical Trials Registry of India (CTRI/2024/11/077086).

Funding

Nil.

Declaration of competing interest

the authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Akash Bhatnagar reports was provided by Teerthanker Mahaveer University Teerthanker Mahaveer Dental College and Research Centre. Akash Bhatnagar reports a relationship with Teerthanker Mahaveer University Teerthanker Mahaveer Dental College and Research Centre that includes:. Akash Bhatnagar has patent pending to Nil. Nil If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.