A comparative clinical study to evaluate the efficacy of lignocaine 2% and articaine 4% for anesthesia of mandibular first molars with irreversible pulpitis

Abstract

Introduction:

Achieving anesthesia in mandibular molars with irreversible pulpitis (IP) is quite challenging. This study highlights the efficacy of two clinically effective local anesthetic agents – lidocaine 2% and articaine 4%.

Methodology:

Thirty healthy individuals belonging to the American Society of Anesthesiologists 1 with previously diagnosed acute IP of mandibular first molars requiring root canal treatment were randomly assigned to 2 groups of 15 each. Informed consent was obtained, and intradermal allergy test was performed. Group A: patients receiving lidocaine HCl 2% with 1:100,000 adrenaline (Septodont, France) and Group B: patients receiving articaine HCl 4% with 1:100,000 adrenaline (Septodont, France). After adhering to aseptic measures, a conventional inferior alveolar nerve block was administered by palpating the anatomical landmarks, and around 1.8 ml of the anesthetic solution was deposited. Onset of anesthesia, extent of pulpal anesthesia, pain on injection were assessed and statistically analyzed.

Results:

Onset of action was faster with articaine 4%. There was no significant difference between the EPT scores for both the groups, and pain was of mild intensity.

Conclusion:

Articaine is an efficient alternative for effective pain management in patients with IP.

INTRODUCTION

Local anesthetics (LAs) provide painless dental care reducing patient anxiety and fear.[1] Effective anaesthesia is fundamental to deliver pain-free endodontic treatment. Pulpal anaesthesia typically begins with the administration of conventional nerve blocks or infiltration techniques.[2] Successful pulpal anaesthesia of mandibular molars is achieved through administration of Inferior Alveolar Nerve Block [IANB].[3] Pain control would be difficult to achieve during root canal therapy of teeth with irreversible pulpitis(IP).[4] Achieving profound pulpal anesthesia in inflamed permanent mandibular molars is often difficult with an IANB alone. In many instances, supplemental anesthetic techniques are needed during root canal therapy.[5]

Lidocaine (lignocaine) is an amide anesthetic commonly used in dentistry. Lidocaine anesthetizes the pulp and soft tissue for approximately 1 h and 3–5 h, respectively. Articaine is the second most commonly used anesthetic.[3] Recent studies suggest that the IANB’s success rate with articaine is 96.96% in IP.[6]

The rate of IANB failures ranges from 44% to 81%. LA failure can result from several factors, including anatomical variations such as cross-innervation and accessory innervation, decreased local pH, anesthetic solution tachyphylaxis, and heightened nociceptor activity. In such situations, infiltration anesthesia can help overcome collateral nerve supply.[4]

A number of methodologies have been researched to improve the efficacy of IANB techniques, such as the use of different LA agents, various administration techniques, supplementary approaches, and premedication with analgesics.[7]

This study highlights the comparison between lidocaine HCl 2% and articaine HCl 4% for mandibular first molars anesthesia diagnosed with IP.

METHODOLOGY

Thirty patients with symptomatic pain reporting to Shri Krishna Multispeciality Dental Care were categorized into Group 1 and Group 2. The procedure was explained to the patients, and informed consent was obtained for the same. The participants underwent an intradermal allergy test and were blinded for the anesthetic agent utilized in the study. The pulp response was evaluated with an electric pulp tester (Digitest, Parkell, Inc., USA) before the administration of nerve block, and the values were documented for all the cases. The administration of the nerve block was carried out by a single operator.

Inclusion criteria

Patients satisfying the following criteria were included in the study:

• 18–65 years

• Systemically healthy (American Society of Anesthesiologists [ASA] I and ASA II)

• Reporting with spontaneous tooth pain (mandibular first molar) ranging between 7 and 9 on the Numerical Rating Scale.

Exclusion criteria

• Known case of allergy to LAs

• Significant medical history (ASA III or greater)

• Patients on central nervous system (CNS) depressants or any other analgesic medication within the last 48 h

• Pregnant and lactating women.

The patients were randomized into two groups of 15 each:

• Group 1 – Patients receiving lidocaine HCl 2% with 1:100,000 adrenaline (Septodont, France)

• Group 2 – Patients receiving articaine HCl 4% with 1:100,000 adrenaline (Septodont, France).

Procedure

After adhering to all aseptic measures, the nerve blocks were administered using standard cartridges (1.8 ml) and an aspirating syringe equipped with a 27G, 1½” needle. Conventional IANB was achieved by depositing the anesthetic solution appropriately surrounding the nerve. The subjective symptoms and objective signs were recorded.

The following parameters were recorded:

• Onset of anesthesia: The time interval (in minutes) between the end of nerve block and the onset of subjective anesthesia was recorded using an electronic stopwatch

• Extent of pulpal anesthesia: The response to the electric pulp tester was assessed at three time points: prior to administration of the nerve block, after the onset of anesthesia, and at 30 min postanesthesia. Numerical readings were documented at each interval

• Pain assessment: Pain at the injection site was assessed using a Visual Analog Scale (VAS). Patients were instructed to indicate their perceived pain level on the scale, and the corresponding numerical score was recorded.

Statistical analysis

The compiled data were statistically assessed utilizing SPSS software version 21 (SPSS Inc., Chicago, IL, USA), and the Student’s t-test was applied.

RESULTS AND INTERPRETATION

The mean duration of onset of action between Group 1 and Group 2 was 3.54 ± 1.28 and 2.53 ± 0.40 min, respectively. There was a statistically significant difference (P = 0.007) between the duration of onset of action between the two groups. The onset of action was faster with articaine 4% compared with lidocaine 2% [Table 1].

Table 1.

Distribution of the duration of onset of action between the groups

Groups	Mean duration of onset of action (min)	t-test statistics	P*
Group 1	3.54±1.28	2.89	0.007
Group 2	2.53±0.40

*P<0.05 statistically significant

There was no marked difference between the Electric Pulp Testing (EPT) scores before and after nerve blocks in both study groups. Mild pain was experienced (VAS score 1) by 53% in Group 1, whereas in Group 2, 33% experienced mild pain. VAS score 2 was experienced by 20% of both the groups. There was no marked difference between mean VAS scores between the two groups [Table 2]. None of the subjects required additional anesthetic injections for lower molars.

Table 2.

Distribution of Visual Analog Scale score frequencies between Group 1 and Group 2

VAS scores	Group 1, frequency (%)	Group 2, frequency (%)	t; P
0	4 (26.67)	7 (46.67)	0.727; 0.472
1	8 (53.33)	5 (33.33)
2	3 (20.00)	3 (20.00)
Mean VAS scores	0.93±0.70	0.73±0.79	-

VAS: Visual Analog Scale

DISCUSSION

Effective pain management during endodontic treatment significantly reduces patient apprehension. Pain control, or its complete elimination, remains a fundamental and critical component of dental practice.[8]

The current study highlighted the differences between 2% lidocaine and 4% articaine, and noteworthy differences were observed in the duration of onset between the two groups. Articaine had a faster onset when compared to lidocaine which aligns with the observations of the other studies.[2,9,10]

The uniqueness of this study is that there were no differences in the volume of anesthetic solution injected into both the groups, and the intensity of pain felt during the injection phase and treatment phase was mild in both the groups. Depth of anesthesia and pain perception were found to be similar between the two groups. No additional block or supplemental injections were required during the procedure in our study.

Teeth with IP often require a greater concentration of anesthetic or direct pulpal anesthesia to achieve complete anesthesia even when the surrounding soft tissue and adjacent teeth have achieved anesthesia.[9] In acute inflammation and in patients with severe pain, conventional techniques often fail.[11]

Achieving anesthesia in IP is a critical yet distinct challenge compared with pulpal anesthesia in uninflamed teeth. Evidence indicates that while the IANB provides approximately 70% effectiveness in teeth with uninflamed pulp, its success rate drops sharply to about 30% in patients with IP.[11,12]

Lidocaine, the first commercially available amide LA agent, is preferred for most of the dental procedures due to high efficacy, low allergenicity, and low toxicity.[3,11] Lidocaine is considered the “gold standard” for dental anesthesia, and all other anesthetic agents must be compared with this anesthetic agent.[11,13,14]

To enhance the effectiveness of anesthesia and reduce the need for supplemental techniques, articaine was introduced as an alternative LA agent. Articaine is a remarkable amide LA agent in which the benzene ring is substituted by a thiophene ring. Articaine is dispensed as a preinstalled cartridge and equipped with a thin needle of 27G which can eliminate pain during injection.[14]

Articaine has certain benefits: enhanced liposolubility and high tissue penetrability to nerve and bone.[2,3,4,14] The penetration property of articaine is enhanced by an internal hydrogen bond which is formed when Articaine enters the nerve membrane.[15]

Symptomatic IP is that the acute pain transmission is carried over by A-delta fibers and later taken over by small C-fibers. Articaine demonstrates greater efficacy than 2% lidocaine in reducing action potentials generated by A-fibers and in achieving complete suppression of C-fiber-mediated action potentials.[2]

The potency of articaine is >1.5 times than lidocaine owing to the existence of thiophene ring. Articaine with 1:100,000 epinephrine provides approximately 75 min of pulpal anesthesia.[3,11,14] Articaine’s anesthetic success was 2.17 times of lidocaine.[1] Articaine has a serum half-life of 20–30 min due to rapid hydrolysis within the plasma. Articaine possesses substantial plasma protein binding property in comparison with other commonly used LAs such as prilocaine and mepivacaine. Clinically, this forms the basis of shorter duration of action and greater diffusion through hard and soft tissues than other LAs.[3,16]

Articaine is considered safe due to its short action. It can be administered safely at higher concentrations. Articaine is considered a low-risk LA, even with repeated injections, due to its rapid metabolism into an inactive metabolite, which significantly reduces the risk of systemic toxicity and overdose. A contemporary investigation study revealed a low number of adverse reactions when compared to lignocaine in 211 pediatric patients.[17] Stirrup and Crean in their mini-systematic review inferred that there was no evidence of nerve damage associated with articaine compared to lidocaine in IANB.[18]

Studies conducted previously on the success rate of anesthesia suggested that failed local anesthesia was eight times more likely among IP patients than normal patients.[2,19] Various hypotheses have been proposed for the failure of pulpal anesthesia. The most important among them is the pH variation that limits the diffusion of LA solution into the nerve.[3,11,20,21]

In addition, inflammatory mediators can activate or sensitize peripheral neurons by binding to specific receptors. This peripheral sensitization and activation have been shown to increase neural resistance to LA agents.[2,21]

Inflamed pulpal tissues exhibit a reduced pH, which limits the penetration of the basic anesthetic solution into the nerve membrane. This impairs or delays the onset of pulpal anesthesia, resulting in what is commonly termed a “hot pulp/tooth.”[22] This condition necessitates supplementary infiltration.

Bartlett and Mansoor have opined in their critical appraisal that supplementary injections have emerged as an alternative to IANB, but it cannot replace IANB.[7,23] Along with this, the hypotheses of central sensitization have to be considered in cases where there is a heightened CNS response to even gentle stimuli.[20]

Xiao et al. concluded that articaine was more effective than lidocaine for maxillary anesthesia for IP; however, similar effectiveness was noted for mandibular anesthesia.[24] Katyal reported that articaine is a superior anesthetic for routine dental procedures and is more effective than lidocaine in achieving anesthesia in the maxillary and mandibular first molar regions.[25] Miglani et al. demonstrated that articaine is comparable to other anesthetic agents, with reported success rates ranging from 64% to 87%.[2]

The observations of the current study imply that articaine had a swift onset of action when compared to lidocaine, which could be attributed to high potency of articaine (1.5 times higher). The literature review suggested that the onset of anesthesia is comparable to the pace of epineural diffusion, which in turn is dependent on dissociation constant. The dissociation constant of articaine is less than that of lidocaine.[3,11,16]

The present study is remarkable in that articaine is an appropriate alternative for effective pain management in subjects diagnosed with IP. Articaine acts faster in comparison to lidocaine. Pain experienced by both the groups in the due course was rated as mild pain when interpreted on VAS. Further, high-quality and specific clinical research with sufficient number of participants are mandatory to draw conclusions on the anesthetic agents, pain assessment, and effective pain management.

CONCLUSION

Articaine is well suited for the definitive management of acute IP due to its rapid onset and ability to achieve profound anesthesia. Its safety profile is statistically comparable to that of lidocaine. Collectively, the evidence supports articaine as a potent LA with a broad clinical applicability.

Conflicts of interest

There are no conflicts of interest.

Funding Statement

Nil.