Pain control during root canal treatment is a fundamental aspect of endodontic practice and significantly impacts the patient’s comfort, cooperation, and overall treatment outcome. Achieving effective local anesthesia (LA) is crucial, particularly in cases involving acute pulpitis or irreversible pulp inflammation, where the inflamed tissue can impair anesthetic efficacy [1]. Despite advancements in anesthetic techniques and agents, achieving profound pulpal anesthesia remains challenging in certain clinical scenarios [2].

Local anesthetics used in dentistry are primarily amide-based agents, and their efficacy depends on multiple factors including concentration, pKa value, lipid solubility, and the presence of vasoconstrictors such as epinephrine [3]. Lidocaine, introduced in the 1940s, remains one of the most commonly used agents due to its favorable safety profile and consistent anesthetic effects [4]. However, newer alternatives such as articaine and bupivacaine have gained popularity, particularly in endodontic cases, due to their enhanced diffusion and longer duration of action [5].

Articaine, a thiophene ring-based amide anesthetic with an additional ester linkage, exhibits superior bone penetration and rapid onset, making it potentially more effective for infiltrations in dense maxillary and mandibular bone [6]. A study by Kanaa et al. demonstrated that articaine infiltration was more effective than lidocaine for mandibular first molar anesthesia in cases of irreversible pulpitis [7]. In contrast, bupivacaine, with its extended duration of action, is often preferred in procedures where post-operative pain management is a concern, though it may present a slower onset and increased cardiotoxic risk [8].

The complexity of achieving profound anesthesia in endodontics is further exacerbated by patient-related factors such as anxiety, anatomical variations, and systemic health conditions, as well as procedural variables including the presence of infection, technique of delivery, and selection of the anesthetic agent [9]. These variables highlight the necessity of evidence-based comparative studies to identify the most effective local anesthetic agents for various clinical presentations.

Recent literature emphasizes the importance of customizing anesthetic protocols for individual cases, particularly in patients presenting with symptomatic irreversible pulpitis where failure rates of conventional inferior alveolar nerve blocks (IANBs) using lidocaine can reach up to 30-40% [10]. Thus, the exploration of alternative anesthetic agents and adjunctive techniques such as buccal infiltrations, intraligamentary injections, or use of buffered anesthetics is of significant clinical relevance.

This study aims to comparatively evaluate the pain control efficacy of commonly used local anesthetic agents—lidocaine, articaine, and bupivacaine—during root canal treatment. By assessing both intraoperative and post-operative pain levels, the findings may guide clinicians in optimizing anesthetic choice for improved patient outcomes and reduced procedural discomfort.

Study Design and Setting

This was a prospective, randomized, single-blind clinical study conducted in the Department of Conservative Dentistry and Endodontics at a tertiary care dental institution over a period of 6 months.

Sample Size and Selection Criteria

A total of 90 patients requiring root canal treatment in mandibular first molars with symptomatic irreversible pulpitis were included in the study. The patients were randomly divided into three equal groups (n = 30) based on the local anesthetic agent administered:

• Group A: 2% Lidocaine with 1:80,000 epinephrine
• Group B: 4% Articaine with 1:100,000 epinephrine
• Group C: 0.5% Bupivacaine with 1:200,000 epinephrine

Inclusion criteria:

• Age between 18 and 50 years
• ASA I and II physical status
• Mandibular first molars diagnosed with symptomatic irreversible pulpitis
• No history of allergy to local anesthetics

Exclusion criteria:

• Pregnant or lactating women
• Systemic illness contraindicating LA administration
• History of analgesic intake within 24 hours
• Non-vital or previously treated teeth

Randomization and Blinding

Random allocation was performed using computer-generated random numbers. The patient was blinded to the anesthetic agent used. The procedure was performed by a single experienced endodontist to avoid operator variability.

Anesthetic Administration and Procedure

All patients received an inferior alveolar nerve block (IANB) with 1.8 ml of the allocated anesthetic agent. A standard aspiration technique was employed, and onset of anesthesia was confirmed by subjective symptoms (lip numbness) and objective tests (cold test with ethyl chloride).

After 10 minutes, access cavity preparation was initiated. If patients experienced moderate-to-severe pain (≥4 on the Heft-Parker Visual Analog Scale), supplemental intra-ligamentary or intrapulpal anesthesia was administered, and the case was excluded from analysis.

Pain Assessment

Pain was recorded using the Heft-Parker Visual Analog Scale (HP-VAS) at three time points:

1. During access cavity preparation (intraoperative pain)
2. Immediately after the procedure (post-operative pain at 0 hour)
3. At 6 and 12 hours post-operatively

Patients were instructed to mark their pain level on the HP-VAS scale (0 = no pain; 170 = maximum pain). Post-operative data was collected via telephonic follow-up.

Statistical Analysis

Data were analyzed using SPSS version 25.0 (IBM Corp., Armonk, NY). Mean and standard deviation were calculated for continuous variables. Intergroup comparisons of pain scores were performed using one-way ANOVA followed by post hoc Tukey’s test. A p-value < 0.05 was considered statistically significant.

Table 1: Baseline Characteristics of the Study Groups

Interpretation: No statistically significant difference in baseline demographic variables between the groups, ensuring comparability.

The baseline demographic parameters, including mean age, gender distribution, and BMI, were comparable across all three groups (Lidocaine, Articaine, and Bupivacaine). The mean age ranged from 31.9 to 33.1 years, and there was a near-equal gender distribution in all groups. The BMI values showed no significant intergroup difference (p = 0.65), ensuring homogeneity of the sample population. The absence of statistically significant differences in these parameters (p > 0.05 for all) confirmed that the groups were well-matched at baseline, minimizing any potential confounding influence on pain perception.

Table 2: Intraoperative Pain Scores (HP-VAS) During Access Preparation

Interpretation: Articaine showed significantly lower intraoperative pain scores compared to Lidocaine and Bupivacaine (p < 0.001).

Intraoperative pain was assessed using the Heft-Parker Visual Analog Scale (HP-VAS). Patients in the Articaine group reported significantly lower pain scores (32.6 ± 14.9) during access cavity preparation compared to the Lidocaine group (55.2 ± 18.5) and the Bupivacaine group (48.9 ± 16.4). The difference was statistically significant (p < 0.001). These findings suggest that Articaine provided more effective and rapid anesthesia during the active endodontic procedure, likely due to its superior bone diffusion properties and faster onset of action.

Table 3: Postoperative Pain Scores at 6 Hours

Interpretation: Bupivacaine demonstrated the lowest pain scores at 6 hours post-treatment, with a statistically significant difference among the groups (p = 0.002).

Postoperative pain levels evaluated 6 hours after the procedure showed a notable reduction in the Bupivacaine group (24.1 ± 12.8), followed by the Articaine group (28.7 ± 13.2), and the highest pain scores were observed in the Lidocaine group (40.3 ± 15.7). The intergroup differences were statistically significant (p = 0.002). These results reflect the longer duration of action of Bupivacaine, which appears to provide sustained analgesia in the early postoperative period compared to the other agents.

Table 4: Postoperative Pain Scores at 12 Hours

Interpretation: Bupivacaine continued to provide the most effective pain relief even at 12 hours, followed by Articaine, both significantly better than Lidocaine (p = 0.001).

At the 12-hour follow-up, the Bupivacaine group again showed the lowest pain scores (12.3 ± 8.9), followed by Articaine (19.6 ± 10.5) and Lidocaine (28.5 ± 14.0). The pain reduction across the groups was statistically significant (p = 0.001). These findings reinforce the prolonged anesthetic effect of Bupivacaine, which appears to deliver extended postoperative pain control. While Articaine also demonstrated better performance than Lidocaine, its duration of analgesia was inferior to that of Bupivacaine over this extended period.

Effective pain control is a cornerstone of successful endodontic therapy, particularly in cases of symptomatic irreversible pulpitis where achieving profound anesthesia can be challenging. This study aimed to evaluate and compare the anesthetic efficacy of three commonly used local anesthetics—Lidocaine, Articaine, and Bupivacaine—during and after root canal treatment in mandibular first molars.

The baseline demographic characteristics including age, gender, and BMI were statistically comparable among the groups, indicating that differences in pain perception could be attributed primarily to the pharmacological performance of the anesthetic agents rather than patient variability. Previous studies have emphasized the importance of controlling baseline parameters to ensure the internal validity of randomized trials involving pain assessment [6].

In terms of intraoperative pain control, Articaine significantly outperformed both Lidocaine and Bupivacaine. This finding is consistent with earlier studies by Kanaa et al. and Srinivasan et al., who reported that Articaine, due to its unique thiophene ring and superior lipid solubility, provides better diffusion through soft and hard tissues, particularly in dense mandibular bone [7,8]. Its lower pKa value enables a higher proportion of non-ionized form at physiological pH, resulting in a faster onset and more effective nerve blockade [9].

Lidocaine, despite being the most widely used anesthetic in dentistry, showed the highest intraoperative pain scores among the three groups. This aligns with the findings of Aggarwal et al., who reported limited efficacy of 2% Lidocaine in patients with irreversible pulpitis, especially when administered through conventional inferior alveolar nerve block (IANB) technique [10]. The presence of inflamed, hyperemic pulpal tissue alters local pH, further reducing the efficacy of Lidocaine [11].

Postoperative pain evaluation revealed that Bupivacaine provided superior pain relief at both 6 and 12 hours post-treatment. This can be attributed to its long duration of action—up to 12 hours in some cases—due to its high protein-binding capacity and slower systemic absorption [12]. Malamed and colleagues noted that Bupivacaine is ideal for procedures where extended postoperative analgesia is desired, despite its slower onset of action [13]. Our findings concur with this, as Bupivacaine demonstrated moderate intraoperative control but excellent postoperative results.

Articaine provided intermediate postoperative analgesia—superior to Lidocaine but inferior to Bupivacaine. This supports the conclusion by Evans et al. that Articaine offers a balanced anesthetic profile: faster onset and good intraoperative efficacy, with moderate duration of postoperative analgesia [14]. On the contrary, Lidocaine not only underperformed intraoperatively but also resulted in higher pain scores postoperatively, reaffirming the need for more effective agents in endodontic pain management protocols [15].

Another key aspect is the mechanism of action and anatomical limitations of the IANB technique. Failure of mandibular anesthesia is often attributed to accessory innervation, variations in nerve pathways, and incomplete anesthetic diffusion. Although not addressed in this study, future investigations could benefit from incorporating supplemental techniques such as buccal infiltration, intraosseous, or intraligamentary injections, especially when using agents like Articaine that perform well through infiltration routes [6,7].

It is also important to consider patient safety. While Articaine and Bupivacaine offer superior analgesic profiles, their toxicity profiles differ. Articaine has been associated with a higher incidence of paresthesia in some reports when used for nerve blocks, while Bupivacaine's cardiotoxic potential, though rare, warrants caution, particularly in elderly or medically compromised patients [13].

Limitations of the present study include its single-blind design, reliance on subjective pain scales, and a relatively small sample size. Future research should explore multi-center, double-blinded trials and assess the efficacy of buffered anesthetics or combinations with analgesics for enhanced outcomes. Moreover, incorporating anxiety scales and patient satisfaction ratings could offer a more holistic view of anesthesia effectiveness.

In summary, the results of this study suggest that the choice of local anesthetic significantly influences both intraoperative and postoperative pain outcomes in endodontic therapy. Articaine appears to be the agent of choice for intraoperative pain control due to its rapid onset and effective nerve penetration, whereas Bupivacaine is superior for extended postoperative analgesia.

This comparative clinical study demonstrated that Articaine provided the most effective intraoperative pain control during root canal treatment, while Bupivacaine offered superior postoperative analgesia at both 6 and 12 hours. Lidocaine, though widely used, showed limited effectiveness, especially in inflamed pulpal conditions. The findings support a more case-specific approach to anesthetic selection in endodontics, favoring Articaine for procedures requiring rapid onset and Bupivacaine where long-lasting pain relief is desired. Larger, multi-centered studies are needed to validate these findings and guide comprehensive anesthetic protocols in dental practice.

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