Effect of laser-assisted articaine local anesthesia in single visit root canal treatment for mandibular molar with symptomatic irreversible pulpitis - A randomized clinical trial

Abstract

Aim:

To evaluate the anesthetic efficacy of inferior alveolar nerve block (IANB) with 4% articaine versus laser-assisted articaine supplementation for profound pulpal anesthesia during single-visit root canal treatment (RCT) of the mandibular molars with symptomatic irreversible pulpitis.

Materials and Methods:

This prospective double-blinded randomized controlled trial enrolled 64 patients (aged 18–55 years) with clinically/radiographically confirmed symptomatic irreversible pulpitis in the mandibular molars. After standard IANB (1.8 mL 4% articaine 1:100,000 epinephrine), patients with persistent moderate–severe pain (Visual Analog Scale [VAS]: ≥4) were randomized into two groups (n = 32 each). The laser group received a 980-nm diode laser (1.5 W, continuous wave, noncontact, 60–180 s/canal, 10–30 J/cm²) at the apical third. The control group received supplementary intraligamentary (0.2–0.4 mL/canal) and buccal infiltration with articaine. Primary outcomes were pre operative and intraoperative pain (VAS:0-10). Secondary outcomes were supplemental anesthesia needs and treatment success. Wilcoxon signed-rank test (intragroup) and Mann–Whitney U-test (intergroup) tests (P < 0.05, SPSS v. 25) were used for statistical analysis.

Results:

The mean age was 33.97 ± 12.07 years in the diode laser group and 38.66 ± 12.22 years in the articaine group, with comparable gender distribution between groups. Preoperative pain scores were similar (median = 8; P = 0.320). Intraoperatively, the laser group demonstrated significantly lower pain scores (median = 0, IQR 0–1) compared with the articaine group (median = 3, IQR 2–4; P < 0.01). Both groups showed a significant reduction in pain from preoperative to intraoperative periods (P < 0.01). All cases completed single-visit without adverse effects.

Conclusion:

The 980-nm diode laser significantly enhances IANB over articaine infiltration, providing superior pain control for single-visit RCT in irreversible pulpitis.

INTRODUCTION

Lasers are increasingly used in endodontics for procedures such as canal disinfection, smear layer removal, and irrigation. However, their direct application to enhance intraoperative anesthesia remains underexplored. Early evidence indicates that low-level laser therapy (LLLT) may compliment local anesthetics by improving pain control in difficult cases. LLLT delivers red or near-infrared light to tissues, where mitochondrial absorption increases ATP production and modulates inflammatory and neural pathways, leading to reduced nociceptor sensitivity and improved tissue response.[1]

Achieving effective pulpal anesthesia in the mandibular molars with symptomatic irreversible pulpitis is particularly challenging. Although inferior alveolar nerve block (IANB) is the standard technique,[2] its failure rate rises from about 15% in healthy pulps to 44%–81% in inflamed pulps.[3] This reduced efficacy is attributed to anatomical variations and inflammatory changes, lower tissue pH, impaired anesthetic diffusion, increased vasodilation, sensitized nociceptors, nerve sprouting, and upregulated Tetrodotoxin (TTX)-resistant sodium channels, along with central sensitization and patient anxiety, all of which heighten pain perception.[4]

LLLT has gained interest as a supplemental method to enhance anesthetic success. Its inhibitory effects on A-delta and C fibers can reduce conduction velocity and nerve inflammation,[5] while increased ATP production, improved oxygen utilization, elevated endorphins and serotonin, and anti-inflammatory actions may further contribute to improved anesthesia.[6]

This study aims to assess the anesthetic effectiveness of IANB using articaine compared to diode laser irradiation in patients with symptomatic irreversible pulpitis in the mandibular molars undergoing single-visit root canal therapy.

MATERIALS AND METHODS

Approval for research protocol was received from the Institutional Review Board and Institutional Ethics Committee registered under the reference IGIDSIEC2024NRPI58PGJSCDE and verified through an assigned QR code, with the approval dated December 14, 2019. The Consolidated Standards of Reporting Trials guidelines were followed for the study [Figure 1].

Figure 1.

Consolidated Standards of Reporting Trials flowchart

This randomized clinical trial was prospectively registered (CTRI/2025/12/099956) prior to participant recruitment.

Study population

Patients aged 18–45 years with normal general health and symptoms of irreversible pulpitis in the mandibular molars with moderate-to-severe pain and lingering response to cold test were included in the study. Participants with systemic comorbidities, pregnant or lactating mothers, patients allergic to anesthesia, patients with the presence of any periapical radiolucency on radiographs, and patients with the pain indicative of irreversible pulpitis or no pain were excluded from the study.

This randomized controlled trial was conducted at the department of conservative dentistry and endodontics, from the respective college. Sixty-four patients with symptomatic irreversible pulpitis in the mandibular molars, confirmed by pain history and prolonged response to Endo-Frost cold testing (Roeko; Coltene Whaledent, Germany), were enrolled.

Anesthetic procedure

IANB was administered using 4% articaine diluted with 1:100,000 epinephrine (Septodont, Saint-Maur-des-Fossés, France) delivered through a conventional aspirating syringe fitted with a 1.5-inch, 27-gauge needle. Adequate lip numbness within 15 min indicated a successful block; failure resulted in exclusion. Pulpal anesthesia was confirmed using an electric pulp tester (Waldent, New Delhi, India) and Visual Analog Scale (VAS). Access opening was initiated after rubber dam isolation, and any discomfort during entry or during insertion of a #10 K-file was recorded. Successful anesthesia was defined as a VAS score of 0–3.

Patients who continued to experience moderate-to-severe pain (VAS: 4–6) were randomly allocated into two groups of 32 each using a lottery method with opaque-sealed envelope concealment.

Group allocation

• Group 1 (diode laser group): A 980-nm semiconductor diode laser (INDILASER, Delhi, India) was applied to the pulp canals (1.5 W, continuous, noncontact mode) for 60–180 s per canal, following international laser safety guidelines [Figure 2a and b]

• Group 2 (supplementary articaine group): Patients received 0.2 mL intraligamentary and 0.9 mL buccal infiltration with articaine and epinephrine. Pulse rate and intraoperative pain were monitored throughout [Figure 2c and 2d].

Figure 2.

(a) Diode laser apparatus; (b) 980-nm laser anesthetic administration; (c) syringe loaded with cartridge and needle; (d) local anesthesia administration

Pain assessment

Preoperative and intraoperative pain levels were recorded using a 10-point VAS score.

Endodontic procedure

Root canal treatment (RCT) was performed by a single operator. Working length was determined using an apex locator (Root ZX Mini, J Morita, Japan). Glide path was created to size 20 or 25 K-file, followed by rotary instrumentation. Cleaning and shaping were completed 0.5 mm short of the working length, with mesial canals enlarged to F2 (25/.08) and distal canals to F3 (30/.09) using ProTaper Gold files (Dentsply Maillefer, Ballaigues, Vaud, Switzerland) driven by an Endomate TC2 motor (NSK Inc., Japan). EDTA (10%) (Endoprep RC, Chennai, Tamil Nadu, India) was used for lubrication and smear layer removal, and 3% sodium hypochlorite served as the primary irrigant. Irrigation was delivered with a 25-gauge side-vented needle, followed by final saline irrigation. The canals were obturated with a bioceramic sealer (Bioroot RCS, Septodont, France) and gutta-percha. A composite resin was used for the access restoration, and 1 mm occlusal reduction was performed to relieve occlusal contacts.

Statistical analysis

The collected data were entered into Microsoft Excel (Microsoft Corporation, Redmond, Washington, USA) and were analyzed using IBM SPSS Statistics version 26.0 (IBM Corporation, Armonk, New York, USA). Data distribution was tested for normality using the Kolmogorov–Smirnov test and Shapiro–Wilk test. Wilcoxon signed-rank test was used to compare the values before and after treatments. Mann–Whitney U-test was used to compare the values between the two groups. P <0.05 was considered statistically significant, which was calculated using post hoc power test.

RESULTS

The age distribution of participants in both the groups demonstrated a wide range. In the diode laser group, the mean age was 33.97 ± 12.07 years. In contrast, the infiltration group had a slightly higher mean age of 38.66 ± 12.22 years. Gender distribution was comparable across the two groups, with the laser group comprising 14 males and 18 females and the articaine group including 16 males and 16 females, indicating a balanced representation.

Table 1 presents the comparison of pain scores between the laser group and articaine group during the pre- and intraoperative periods. The median preoperative pain scores were comparable between the groups (8), with no significance statistically (P = 0.320). However, in the intraoperative period, the laser group recorded a median pain score of 0 (IQR: 0-1), which was significantly lower than the articaine group (median: 3, IQR: 2–4; P < 0.01). This showed that the laser provided superior intraoperative pain relief compared to infiltration anesthesia.

Table 1.

Comparison of pre- and intraoperative pain scores between the laser and articaine groups

Assessment period	Laser group, median (IQR)	Articaine group, median (IQR)	Z-statistics	P
Preoperative pain	8.0 (7.0–8.0)	8.0 (7.0–9.0)	−0.994	0.320
Intra- operative pain	0 (0-1)	3.0 (2.0–4.0)	−7.151	<0.01*

*P<0.05 statistically significant. IQR: Interquartile range

Table 2 shows the intragroup comparison of pain scores in the laser and articaine groups. Both the groups demonstrated a statistically significant reduction in pain from preoperative to intraoperative period (P < 0.01). In the laser group, the median pain score decreased from 8 (IQR: 7–8) preoperatively to 0 (IQR: 0-1) intraoperatively, while in the articaine group, the median pain score reduced from 8 (IQR: 7–9) to 3 (IQR: 2–4). This indicated that although both interventions significantly decreased intraoperative pain, the laser group achieved greater pain relief.

Table 2.

Within-group comparison of pre- and intraoperative pain scores in the laser and articaine groups (n=32)

Group	Preoperative, median (IQR)	Intraoperative pain, median (IQR)	Z-statistics	P
Diode laser	8.0 (7.0–8.0)	0 (0-1)	−4.970	<0.01*
Infiltration	8.0 (7.0–9.0)	3.0 (2.0–4.0)	−4.964	<0.01*

*P<0.05 statistically significant. IQR: Interquartile range

DISCUSSION

Achieving sufficient anesthesia in the mandibular molars with irreversible pulpitis remains challenging due to the combined influence of anatomical complexity, altered physiology, and inflammatory changes.[7] These factors frequently contribute to inadequate anesthetic depth, patient discomfort, and procedural difficulties.[8] Various approaches have been explored to improve local anesthetic efficacy using different anesthetic agents, different volumes of anesthetic solution, different methods to activate anesthetic solutions, modified injection techniques, preoperative medications, and alternative mandibular block methods.[9,10,11,12,13,14,15]

The present study addresses these limitations by comparing conventional articaine-based IANB with adjunctive 980-nm diode laser irradiation in single-visit RCT and optimizes patient comfort. Articaine offers enhanced tissue penetration, rapid onset, and superior efficacy in inflamed tissues,[16] whereas diode lasers provide targeted tissue interaction, improved disinfection, and photobiomodulation capable of modulating nerve conduction and reducing inflammation.[17] Pain assessment using VAS and electric pulp test (EPT) ensured sensitive and reliable measurement, supported by standardized endodontic protocols to enhance procedural consistency. Nevertheless, variations in canal anatomy or pulp status may influence the anesthetic response to laser application and affect reproducibility in routine practice.

In the present study, the diode laser group demonstrated a median intraoperative pain score of 0 (IQR: 0-1), significantly lower than the infiltration group’s median of 3 (IQR: 2–4). Both the groups exhibited identical baseline median pain scores of 8, with no significance statistically, confirming that the intraoperative differences were attributable to the intervention rather than preexisting variability.

Within-group comparisons revealed a significant pain reduction in both interventions, though the extent of reduction differed markedly. The diode laser group improved from a median pain score of 8–0, while the infiltration group declined from 8 to 3. These findings align with Subashri et al.,[18] who reported an 81.3% decrease in intraoperative pain following laser activation. In contrast, complete elimination of intraoperative pain in the present study reflects a more pronounced effect, likely due to differences in laser parameters, application technique, or patient characteristics. Subashri et al.[18] also noted that 8% of patients required supplemental anesthesia, whereas no additional intervention was needed in the current study, indicating potentially greater anesthetic efficacy of the parameters employed.

Other studies further support the superiority of laser-assisted anesthesia. Asthana et al.[19] demonstrated significantly lower intraoperative pain in laser-treated teeth compared to lignocaine alone, while Abduljalil et al.[20] reported that none of the laser group required supplemental anesthesia during dentin cutting compared to 40% in the placebo group. Although supplemental anesthesia was not explicitly measured in the present study, these findings underscore an important clinical advantage worthy of future investigation. Topçuoğlu and Akpınar[21] additionally found that LLLT improved IANB success rates from 34% to 57%, though not eliminating failures entirely, highlighting the persistent challenge in the mandibular molars with complex innervation.

A major challenge across the literature is the heterogeneity of laser parameters, including wavelength, power density, exposure duration, and irradiation sites. The present study used diode laser irradiation, whereas other studies employed diode, Nd: YAG, or LLLT devices with variable dosing. Ramalho et al.[22] demonstrated that neither 4 J/cm² nor 40 J/cm² outperformed placebo and noted increased supplemental anesthesia requirements in the 4 J/cm² group, emphasizing that suboptimal energy densities may compromise outcomes. This highlights the need for precise optimization of laser parameters rather than assuming uniform benefit across protocols. Mann et al.[23] also reported significant improvements in their laser group compared to the placebo, though with a more modest effect size, likely reflecting variations in patient characteristics, pulp status, or laser application methods.

This study has limitations, including a modest sample size, single-center design, and limited reporting of laser parameters, all of which restrict generalizability and limit understanding of pain progression. The brief description of blinding also raises the possibility of expectancy effects, though the anesthetic benefits observed appear clinically meaningful. Future research should establish standardized laser parameters, investigate underlying mechanisms using robust pain measures, assess long-term outcomes and cost-effectiveness, and identify patient groups most likely to benefit. Notably, differences between vital and necrotic pulps suggest that laser anesthesia may operate through distinct mechanisms, underscoring the need for pulp-status based stratification in future studies.

CONCLUSION

The study concludes that laser-assisted articaine markedly improves intraoperative pain control compared to conventional articaine-based anesthesia in patients with symptomatic irreversible pulpitis in the mandibular molars. Patients receiving diode laser therapy experienced lower pain scores during and after the procedure, along with reduced need for supplemental anesthesia, demonstrating superior overall efficacy and comfort. These findings suggest that incorporating diode laser irradiation into the anesthetic protocol can enhance anesthetic outcomes, support smoother single-visit treatment, and improve pain management strategies in endodontic practice.

Conflicts of interest

There are no conflicts of interest.

Funding Statement

The study was financially supported by Indira Gandhi Institute of Dental Sciences, Sri Balaji Vidyapeeth (Deemed to be University), Puducherry, India.