Comparative evaluation of anesthetic efficacy of articaine vs lignocaine during root canal therapy in hypomineralized second primary molars

Abstract

BACKGROUND

Achieving reliable pulpal anesthesia during root canal treatment of hypomineralized second primary molars (HSPM) is clinically challenging, as structural alterations in enamel and dentin can impair the performance of conventional local anesthetic agents. Although 2% lignocaine remains the standard anesthetic in pediatric dentistry, its efficacy may be diminished in hypomineralized teeth. In contrast, 4% articaine, characterized by higher lipid solubility and superior hard-tissue penetration, has been proposed as a more effective option for attaining profound pulpal anesthesia in such cases.

AIM

To evaluate the anesthetic efficacy of 4% articaine vs 2% lignocaine, when administered as an inferior alveolar nerve block for root canal therapy of HSPM.

METHODS

The study comprised 20 pediatric participants, each undergoing two treatment sessions. At the initial appointment, children were randomized to receive either 4% articaine or 2% lignocaine, with the alternate anesthetic administered in the second session as part of the split-mouth design. Injection discomfort and anesthetic effectiveness were systematically evaluated using the Wong-Baker Faces Pain Rating Scale (WBFPRS) and the Face, Legs, Activity, Cry, and Consolability (FLACC) scale. Data were entered into a Microsoft Excel spreadsheet and subsequently analyzed using the IBM SPSS version 26.0 software.

RESULTS

The participants had a mean age of 7.15 ± 0.67 years. Pain scores during injection showed no statistically significant difference between articaine and lignocaine when assessed using either the WBFPRS or the FLACC scale. In contrast, during access cavity preparation, articaine produced significantly lower pain ratings on both the WBFPRS and the FLACC scale. Furthermore, during instrumentation, articaine continued to yield reduced pain responses, with a statistically significant difference observed on the FLACC scale, although the WBFPRS did not reach statistical significance.

CONCLUSION

Articaine 4% exhibited superior anesthetic performance compared with lignocaine 2%, particularly during access cavity preparation and canal instrumentation in HSPM. Although both agents showed comparable pain levels during injection, articaine achieved more profound and consistent pulpal anesthesia throughout operative phases of treatment. These findings suggest that articaine may represent a more reliable anesthetic agent for endodontic management of HSPM.

Key Words: Local anesthesia; Articaine; Lignocaine; Hypomineralized second primary molars; Efficacy

Core Tip: Achieving effective pulpal anesthesia in hypomineralized second primary molars is often challenging with conventional local anesthetics. This split-mouth clinical study demonstrates that 4% articaine provides superior intraoperative anesthetic efficacy compared with 2% lignocaine during root canal treatment of hypomineralized second primary molars, particularly during access cavity preparation and canal instrumentation. While both agents showed comparable discomfort during injection, articaine achieved more profound and consistent pulpal anesthesia. The findings underscore the clinical importance of selecting anesthetic agents with enhanced tissue penetration for hypomineralized teeth and provide evidence-based guidance for improving pain control and treatment outcomes in pediatric endodontic practice.

INTRODUCTION

Developmental defects of enamel represent one of the most common conditions affecting children globally[1]. They frequently present in multiple forms, one of which is molar incisor hypomineralization, a condition that predominantly affects one or more first permanent molars, with or without involvement of the incisors[2]. Hypomineralization is a qualitative enamel defect resulting from disturbances during the initial stages of calcification and/or enamel maturation, leading to enamel of normal thickness but increased porosity and fragility due to reduced protein content and disorganisation of the enamel prisms[3]. These enamel defects are clinically evident as well-demarcated areas of altered translucency (opacities), with coloration ranging from cream to yellow or brown[4].

Lesions resembling those seen in molar incisor hypomineralization have also been identified in second primary molars and primary canines[5]. Hypomineralized second primary molars (HSPM) is the currently accepted term for the condition previously referred to as deciduous molar hypomineralization. It is a qualitative developmental enamel defect arising from disturbances during enamel formation and typically presents as a well-demarcated opacity with altered translucency affecting second primary molars. The opacity may vary in severity, ranging from opaque white to yellow or brown enamel lesions[6]. HSPM demonstrates a wide spectrum of clinical presentations, posing a significant challenge in dental practice, and is characterised by well-demarcated opacities, post-eruptive enamel breakdown, atypical carious lesions or restorations, and, in severe cases, extractions[7].

Hypomineralized enamel acts as a poor thermal insulator, resulting in inadequate pulpal protection from external temperature changes. Consequently, affected teeth often exhibit hypersensitivity to hot and cold stimuli. Persistent thermal stress induces pulpal inflammation and pH alterations in the periapical tissues, leading to heightened excitability of pulpal nerve fibers, which respond to lower-than-normal levels of stimulation. Clinically, this manifests as a hypersensitive tooth that is often difficult to achieve adequate anesthesia, even with increased doses of local anesthetic[8]. Inadequate anesthesia in such teeth can result in increased pain perception, treatment difficulty, behavioural management issues, and compromised treatment outcomes in pediatric patients[9].

Several local anesthetic agents are available for use in children, with the most commonly employed being 4% articaine and 2% lignocaine. Although numerous studies have compared 2% lignocaine with 4% articaine in pediatric patients, the findings have been inconsistent[10]. To date, there is no randomized clinical study comparing lignocaine with articaine when an inferior alveolar nerve block (IANB) is used for local anesthesia of HSPMs. Hence, the study aimed to evaluate the anesthetic efficacy of 4% articaine vs 2% lignocaine, when administered as an IANB for root canal therapy of HSPM.

MATERIALS AND METHODS

Study design

This split-mouth, double-blinded, randomized controlled trial was conducted in the Department of Pedodontics and Preventive Dentistry at Goa Dental College and Hospital, Bambolim, Goa, India over a period of five months (from August 2025 to December 2025). Ethical approval was obtained from the Institutional Ethics Committee of Goa Dental College and Hospital (No. GDCH/IRB/V-2025/RPN29-29), and the study was prospectively registered with the Clinical Trials Registry of India (CTRI/2025/08/092581; dated August 7, 2025). Each child was administered 2% lignocaine with 1:80000 epinephrine and 4% articaine with 1:100000 epinephrine in a split-mouth design.

Participants

The study included medically and mentally healthy children aged six to nine years with bilateral mandibular HSPMs, diagnosed according to the criteria proposed by Ghanim et al[11], presenting with signs of irreversible pulpitis and requiring root canal therapy. Children demonstrating positive or definitely positive behavior, as classified by the Frankl Behavior Rating Scale were included[12]. The participating children were not receiving any analgesic or sedative medication at the time of enrolment, and written informed consent was obtained from their parents or legal guardians prior to participation. Children with a known hypersensitivity to the local anesthetic agents used in the study and those presenting with non-vital pulp in the involved teeth were excluded.

Sample size

The study was designed as a split-mouth crossover trial. The sample size was calculated using G*Power software (version 3.1.9.4), with an alpha error probability of 5% (α = 0.05) and a statistical power of 95% (β = 0.05). Based on the expected differences in pain scores between the two anesthetic agents[10], a minimum of 20 children (40 paired sites) was required, and all were included in the study. A total of 32 children were assessed for eligibly.

Randomization and blinding

Randomization of anesthetic type for each injection was performed using a computer-generated random numbers table. Twenty injections were assigned to either 4% articaine or 2% lignocaine, with the injection site (right or left) also randomly allocated. To ensure allocation concealment, each assignment was placed in a sequentially numbered, opaque, sealed envelope, which was opened by an independent assistant immediately prior to administration. This method ensured that the clinician performing the procedure remained blinded to the anesthetic allocation, minimizing selection bias. Both the child and the outcome assessors were also blinded to the anesthetic solution used.

Outcomes

Injection pain and the effectiveness of anesthesia were assessed using both subjective and objective measures. Subjective pain was evaluated with the Wong-Baker Faces Pain Rating Scale (WBFPRS)[13]. Objective assessment was performed using the Face, Legs, Activity, Cry, and Consolability (FLACC) scale[14]. The effectiveness of anesthesia was specifically assessed during access cavity preparation and canal instrumentation.

Intervention

All procedures were performed by the same investigator. Before starting the session, the investigator explained the WBFPRS to the child. The child randomly received either an IANB of 4% articaine or 2% lignocaine at each session. The assistant, upon identifying the anesthetic solution, drew it into a 27G syringe, taking care to do so out of the investigators and child’s view. Subsequently, the assistant selected a sealed envelope from the allocation box to determine whether the injection would be administered on the right or left molar. Local anesthesia was administered via an IANB following confirmation of negative aspiration. The child was asked to indicate the face that represents his/her feeling during the injection on the WBFPRS. The FLACC score during administration of anesthesia was recorded by an assistant not involved in the intervention. The pain experienced by the child was further assessed during opening the pulp chamber with endodontic burs and when the endodontic files were introduced into the root canals. If the patient experienced pain, the dental treatment was halted, and the pain level during the procedure was recorded using the WBFPRS and the FLACC scale. An anesthetic failure was considered if pain persisted and intrapulpal anesthesia was required. In such cases, the highest scores on the WBFPRS and the FLACC scale were recorded. The second session was carried out one week later, with the contralateral tooth receiving anesthesia and treatment using the alternate anesthetic solution, following the same protocol as the first session.

Statistical analysis

Statistical analysis was performed using the IBM SPSS version 26.0 software. Continuous variables, such as age and weight, were summarized as mean ± SD, while categorical variables, including gender and behavior scores, were expressed as n (%). Pain scores measured using the WBFPRS and FLACC scale were treated as ordinal data and compared between anesthetic groups using the Wilcoxon signed-rank test. A P value of less than 0.05 was considered statistically significant.

RESULTS

The flow of participants through the study is presented in the CONSORT diagram (Figure 1).

Figure 1 The CONSORT flow diagram.

Baseline characteristics

A total of 20 children (12 males, 8 females) with a mean age of 7.15 ± 0.67 years and mean weight of 25.4 ± 1.47 kg participated in the study. According to the Frankl Behavior Rating Scale, during the first visit, 6 children (44%) exhibited positive behavior and 14 (56%) demonstrated definitely positive behavior. At the second visit, positive behavior was observed in 9 children (45%), while 11 children (55%) showed definitely positive behavior (Table 1).

Table 1 Baseline characteristics of the participants, n (%)/mean ± SD.

Baseline characteristics
Age	7.15 ± 0.67
Gender	Males: 12 (60)
	Females: 8 (40)
Weight	25.4 ± 1.47
Frankl behaviour rating-visit 1	Positive: 6 (44)
	Definitely positive: 14 (56)
Frankl behaviour rating-visit 2	Positive: 9 (45)
	Definitely positive: 11 (55)

Pain experienced during administration of anesthetic agents

Pain experienced during anesthetic injection did not differ significantly between 4% articaine and 2% lignocaine. According to the WBFPRS, the median pain response in both groups corresponded to “hurts little bit”, with no statistically significant difference observed (P = 0.16; Table 2). Similarly, assessment using the FLACC scale demonstrated comparable pain responses between the two anesthetic agents, with both groups demonstrating "mild pain" (P = 0.856; Table 3). These findings indicate that both anesthetics provided similar pain levels during injection.

Table 2 Pain experienced during injection with 4% articaine and 2% lignocaine according to the Wong-Baker Faces Pain Rating Scale, n (%).

Item	No hurt (0)	Little bit (2)	Little more (4)	Even more (6)	Whole lot (8)	Hurt worst (10)	Median (interquartile range)	P value
Articaine	3 (15.0)	8 (40.0)	5 (25.0)	3 (15.0)	1 (5.0)	0 (0.0)	2 (2, 4)	0.16
Lignocaine	7 (35.0)	7 (35.0)	4 (20.0)	1 (5.0)	1 (5.0)	0 (0.0)	2 (0, 4)

Table 3 Pain experienced during injection with 4% articaine and 2% lignocaine according to the Face, Legs, Activity, Cry, and Consolability scale, n (%).

Item	Relaxed (1)	Mild (2)	Moderate (3)	Severe (4)	Median (interquartile range)	P value
Articaine	8 (40.0)	8 (40.0)	3 (15.0)	1 (5.0)	2 (1, 2)	0.856
Lignocaine	7 (35.0)	8 (40.0)	5 (25.0)	0 (0.0)	2 (1, 2)

Pain experienced during access cavity preparation

During access opening, children receiving 4% articaine experienced significantly less pain compared with those receiving 2% lignocaine. On the WBFPRS, the median pain response for articaine corresponded to “no hurt”, whereas lignocaine demonstrated a median response corresponding to “hurts little bit”, with the difference reaching statistical significance (P = 0.043; Table 4). Assessment using the FLACC scale further supported this finding, with articaine showing a median response consistent with “relaxed", compared with "mild pain" for lignocaine (P = 0.010; Table 5). A total of four children in the lignocaine group experienced severe pain and required supplementary anesthesia. These results indicate superior anesthetic efficacy of articaine during access cavity preparation.

Table 4 Pain experienced during access cavity preparation with 4% articaine and 2% lignocaine according to the Wong-Baker Faces Pain Rating Scale, n (%).

Item	No hurt (0)	Little bit (2)	Little more (4)	Even more (6)	Whole lot (8)	Hurt worst (10)	Median (interquartile range)	P value
Articaine	10 (50.0)	9 (45.0)	1 (5.0)	0 (0.0)	0 (0.0)	0 (0.0)	1 (0, 2)	0.043a
Lignocaine	5 (25.0)	9 (45.0)	2 (10.0)	3 (15.0)	1 (5.0)	0 (0.0)	2 (0, 4)

^aP < 0.05.

Table 5 Pain experienced during access cavity preparation with 4% articaine and 2% lignocaine according to the Face, Legs, Activity, Cry, and Consolability scale, n (%).

Item	Relaxed (1)	Mild (2)	Moderate (3)	Severe (4)	Median (interquartile range)	P value
Articaine	14 (70.0)	5 (25.0)	1 (5.0)	0 (0.0)	1 (1, 2)	0.010a
Lignocaine	5 (25.0)	9 (45.0)	2 (10.0)	4 (20.0)	2 (1, 3)

^aP < 0.05.

Pain experienced during canal instrumentation

Since four children in the lignocaine group required supplementary anesthesia during access cavity preparation, they were given the worst WBFPRS and FLACC scale scores during canal instrumentation. According to the WBFPRS, the majority of children in the articaine group reported “no hurt” or “hurts little bit”, whereas lignocaine showed greater variability, with some children reporting “hurt worst” (P = 0.132; Table 6). FLACC scale assessments mirrored this trend: (1) 85% of children in the articaine group were "relaxed", 15% exhibited "mild pain"; and (2) Whereas in the lignocaine group, 60% were "relaxed", 20% experienced "severe pain" (P = 0.032; Table 7). These findings indicate that articaine provided slightly lower and more consistent pain scores compared with lignocaine during root canal instrumentation.

Table 6 Pain experienced during canal instrumentation with 4% articaine and 2% lignocaine according to the Wong-Baker Faces Pain Rating Scale, n (%).

Item	No hurt (0)	Little bit (2)	Little more (4)	Even more (6)	Whole lot (8)	Hurt worst (10)	Median (interquartile range)	P value
Articaine	15 (75.0)	5 (25.0)	0 (0.0)	0 (0.0)	0 (0.0)	0 (0.0)	0 (0, 0)	0.132
Lignocaine	10 (50.0)	5 (25.0)	1 (5.0)	0 (0.0)	0 (0.0)	4 (20.0)	0 (0, 10)

Table 7 Pain experienced during canal instrumentation with 4% articaine and 2% lignocaine according to the Face, Legs, Activity, Cry, and Consolability scale, n (%).

Item	Relaxed (1)	Mild (2)	Moderate (3)	Severe (4)	Median (interquartile range)	P value
Articaine	17 (85.0)	3 (15.0)	0 (0.0)	0 (0.0)	1 (1, 1)	0.032a
Lignocaine	12 (60.0)	3 (15.0)	1 (5.0)	4 (20.0)	1 (1, 2)

^aP < 0.05.

DISCUSSION

Effective local anesthesia helps build patient-dentist trust, reduces fear and anxiety, and encourages a positive attitude toward dental care. Conversely, inadequate pain management during dental procedures can lead to considerable physical discomfort as well as adverse psychological effects[15]. Hypomineralized teeth present a significant clinical challenge during the administration of local anesthesia. At present, there is insufficient evidence to determine the most effective local anesthetic agent for achieving adequate anesthesia in HSPM. Hence, the present split-mouth, double-blinded randomized controlled trial compared the anesthetic efficacy of 4% articaine and 2% lignocaine administered as IANB for root canal therapy in mandibular HSPM.

The diagnostic criteria proposed by Ghanim et al[11] were employed to identify HSPM due to their standardised, validated, and widely accepted framework that ensures diagnostic consistency and reproducibility, which is essential in clinical research where subjective interpretation of enamel defects may introduce examiner bias. By providing clear definitions and visual reference standards, these criteria facilitate reliable differentiation of HSPM from other developmental enamel defects such as fluorosis, enamel hypoplasia, and early carious lesions.

In the present study, pain assessment was performed using both the WBFPRS and the FLACC scale to obtain a comprehensive and age-appropriate evaluation of pain in pediatric patients. The WBFPRS is a validated self-report pain scale that is simple, child-friendly, and widely used in clinical and dental settings for children. It enables children to express pain intensity visually, thereby improving the accuracy in subjective pain reporting and enhancing cooperation during dental procedures[13]. However, self-reported pain scores may be influenced by cognitive development, anxiety, or communication limitations, especially in younger children or those experiencing dental fear. To overcome this limitation, the FLACC scale was additionally employed as an objective behavioural pain assessment tool. The FLACC scale evaluates observable behaviours across five domains, allowing reliable pain assessment in children who may be unable or unwilling to verbalise pain accurately during invasive procedures[16]. The combined use of WBFPRS and FLACC scales strengthens the methodological rigour of the study by enabling cross-validation of pain responses, reducing reporting bias, and providing a more holistic assessment of pain perception during local anesthetic administration and operative procedures. This dual-scale approach is especially relevant in children with hypomineralized teeth, where heightened sensitivity and anxiety may influence pain reporting.

Injection pain is influenced by multiple factors, including solution pH, rate of injection, tissue distension, and psychological factors, rather than solely the anesthetic agent used[17]. Articaine 4% has a lower solution pH (2.43) than lignocaine 2% (3.19), a factor that may contribute to increased burning discomfort during injection[18]. In the present study, pain perception during local anesthetic administration did not differ significantly between the two anesthetic solutions, as assessed by both the WBFPRS and the FLACC scale. This finding is consistent with the results reported by Jorgenson et al[19]. However, the present result differed from that reported by Haidar and Raslan[10], who observed higher pain scores with 4% articaine compared with 2% lignocaine on both subjective and behavioural pain scales.

In contrast, significant differences were observed during access cavity preparation, where children receiving articaine experienced lower pain scores compared with those receiving lignocaine. This observation holds clinical significance because access cavity preparation can elicit increased pain in hypomineralized teeth as a result of enhanced dentinal sensitivity and underlying pulpal inflammation. Hypomineralized enamel and dentin exhibit increased porosity, reduced mineral density, and altered tubular structure, facilitating rapid stimulus transmission to the pulp and lowering the pain threshold[20,21]. These pathological changes may partly explain the reduced efficacy of lignocaine in achieving adequate pulpal anesthesia in HSPM.

The superior performance of articaine observed in this study may be attributed to its unique pharmacological properties. Articaine possesses a thiophene ring, which increases lipid solubility and enhances diffusion through both soft and hard tissues[22]. Additionally, its higher concentration (4%) and dual metabolism – via plasma esterases and hepatic enzymes – may contribute to faster onset and greater depth of anesthesia compared with lignocaine[23]. These properties are particularly advantageous in inflamed pulpal tissues, where acidic pH can impair the dissociation and efficacy of local anesthetic agents[24].

During canal instrumentation, articaine produced more consistent and lower pain responses than lignocaine, as indicated by FLACC scores. In contrast, several children in the lignocaine group required supplementary anesthesia during access cavity preparation and were therefore categorized as anesthetic failures. However, as no previous clinical studies have specifically evaluated anesthetic efficacy in HSPM, direct comparisons with existing literature could not be made.

The behavioural implications of inadequate anesthesia are particularly important in paediatric patients. Children experiencing pain during treatment are more likely to exhibit anxiety, negative behaviour, and reduced cooperation, which can compromise treatment outcomes and long-term dental attitudes[25]. The improved anesthetic reliability of articaine observed in this study may therefore have beneficial effects beyond pain control, contributing to better behaviour management and treatment acceptance in children with HSPM.

Despite its strengths, including a split-mouth design, blinding, and the use of both subjective and objective pain assessment tools, this study has certain limitations. The relatively small sample size and restriction to mandibular HSPMs limit the generalizability of the findings. Additionally, the study evaluated only IANB administration; future studies should explore alternative techniques such as buccal infiltration, intraosseous anesthesia, or combined approaches. Long-term outcomes and post-operative pain were also not assessed and warrant further investigation.

CONCLUSION

Within the limitations of this study, 4% articaine demonstrated superior anesthetic performance compared with 2% lignocaine, particularly during access cavity preparation and canal instrumentation in HSPM. While both anesthetic agents produced comparable pain responses during injection, articaine provided more profound and sustained pulpal anesthesia during the operative phases of treatment. This was reflected by lower pain scores, greater patient comfort, and reduced need for supplementary anesthesia when articaine was used. The more consistent anesthetic efficacy observed with articaine suggests that it may be a more reliable and effective local anesthetic agent for the endodontic management of HSPM in pediatric patients.

ACKNOWLEDGEMENTS

I gratefully acknowledge the Department of Pedodontics and Preventive Dentistry, Goa Dental College and Hospital, for their support throughout the study. I also sincerely thank the parents of the patients for their cooperation and trust.