The Influence of Laser-Assisted Irrigation on Root Canal Debris Removal

ABSTRACT

Background:

Root canal cleanliness is crucial to the success of endodontic treatment, as residual debris can harbor bacteria that may cause reinfection. Laser-assisted irrigation (LAI) has emerged as a potential method to enhance debris removal within the complex anatomy of the root canal system. This study evaluates the efficacy of LAI in removing debris from root canals compared to conventional irrigation techniques.

Materials and Methods:

Forty single-rooted mandibular premolars were selected and randomly divided into two groups of 20 teeth each. Group 1 was treated using conventional irrigation with sodium hypochlorite (5.25%), while Group 2 received LAI with the same irrigant. Both groups used EDTA as a final rinse. The debris remaining in the canals was evaluated under a scanning electron microscope (SEM) at three levels: coronal, middle, and apical thirds. Debris levels were quantified using a 4-point scale (0 = no debris; 1 = minimal debris; 2 = moderate debris; 3 = heavy debris).

Results:

Group 2 (LAI) showed a statistically significant reduction in debris compared to Group 1 (conventional irrigation) at all three canal levels (P < .05). Mean debris scores for Group 1 were 2.3 (coronal), 2.6 (middle), and 3.1 (apical), while Group 2 recorded scores of 1.2 (coronal), 1.4 (middle), and 2.0 (apical). LAI was particularly effective in the coronal and middle thirds, with a noticeable reduction in debris at the apical third as well, though less pronounced.

Conclusion:

Laser-assisted irrigation significantly enhances debris removal from root canals compared to conventional methods, especially in the coronal and middle thirds. Incorporating LAI may improve the overall success of endodontic treatment by reducing bacterial load and enhancing root canal cleanliness.

INTRODUCTION

Effective root canal cleaning and disinfection are fundamental to the success of endodontic treatment, as residual organic tissue and bacterial biofilms can lead to reinfection and treatment failure.[1] Standard irrigation techniques, typically involving sodium hypochlorite (NaOCl) and ethylenediaminetetraacetic acid (EDTA), have been widely used for debris removal due to their tissue-dissolving and antimicrobial properties.[2] However, these irrigants alone may not sufficiently penetrate the intricate anatomy of the root canal system, especially in the apical region where debris retention is common.[3]

To address this limitation, adjunctive technologies, such as laser-assisted irrigation (LAI), have gained attention for enhancing the efficacy of root canal debridement. LAI uses laser energy to create cavitation and acoustic streaming in the irrigant, increasing its penetration and ability to remove debris from otherwise inaccessible regions.[4,5] Studies have demonstrated that laser-activated irrigation techniques significantly reduce bacterial load and improve cleanliness compared to conventional irrigation.[6] Additionally, the thermal effects of certain laser wavelengths are minimized by optimizing energy settings, making LAI a safe option for clinical use.[7]

Recent research has shown promising results with LAI in various aspects of root canal therapy, such as improved cleanliness of the apical third and enhanced removal of smear layers.[8] Nonetheless, limited clinical studies are available that directly compare LAI with traditional irrigation techniques across the full length of the canal.

MATERIALS AND METHODS

Sample selection

Forty extracted human mandibular premolars with a single root and canal were selected for this study. Teeth with visible fractures, root resorption, or complex canal anatomy were excluded. The teeth were stored in a 0.9% saline solution at room temperature until the procedure.

Preparation of root canals

All teeth were decoronated to standardize the working length at 15 mm. Canal preparation was performed using ProTaper rotary files (Dentsply Sirona, Tulsa, OK, USA) up to size F3. During instrumentation, each canal was irrigated with 5 mL of 5.25% sodium hypochlorite (NaOCl) after each file to remove debris and provide antimicrobial action.

Grouping and irrigation protocol

The prepared samples were randomly assigned to two groups of 20 teeth each:

• Group 1 (Conventional Irrigation): Canals were irrigated with 5 mL of 5.25% NaOCl followed by 5 mL of 17% EDTA, each for one minute, using a 30-gauge side-vented irrigation needle placed 1 mm short of the working length.

• Group 2 (Laser-Assisted Irrigation—LAI): Canals were irrigated with 5 mL of 5.25% NaOCl, activated using an erbium, chromium-doped: yttrium, scandium, gallium, and garnet (Er, Cr) laser (Biolase, Irvine, CA, USA) with a 200-μm tip set at 0.5 W power. The laser tip was placed 1 mm short of the working length and activated in a 5-s cycle, repeated twice. A final rinse with 5 mL of 17% EDTA was performed, followed by laser activation as described.

Evaluation of debris removal

Following irrigation, the teeth were split longitudinally, and the canal surfaces were examined under a scanning electron microscope (SEM) (Zeiss, Germany) at 500× magnification. Each canal was assessed at three levels: coronal, middle, and apical thirds. The amount of residual debris was quantified using a 4-point scoring system:

• Score 0: No debris

• Score 1: Minimal debris

• Score 2: Moderate debris

• Score 3: Heavy debris.

Statistical analysis

Data were analyzed using SPSS software (version 25.0, IBM Corp., Armonk, NY, USA).

RESULTS

The effectiveness of debris removal was assessed by comparing the mean debris scores of the conventional irrigation group (Group 1) and the laser-assisted irrigation (LAI) group (Group 2) at three levels of the root canal: coronal, middle, and apical thirds.

The results are summarized in Table 1. Group 2 (LAI) demonstrated significantly lower debris scores across all levels compared to Group 1 (P < .05). The difference in debris removal was particularly notable in the coronal and middle thirds, where laser-assisted irrigation achieved a higher level of cleanliness. Although the apical third presented more challenges for both groups, LAI still showed an improvement over conventional irrigation.

Table 1.

Mean debris score

Canal Level	Group 1 (Conventional Irrigation) Mean Debris Score±SD	Group 2 (LAI) Mean Debris Score±SD	P
Coronal	2.3±0.5	1.1±0.3	<0.05
Middle	2.6±0.6	1.4±0.4	<0.05
Apical	3.1±0.7	2.0±0.5	<0.05

Detailed findings

• Coronal Third: Group 1 scored a mean of 2.3 ± 0.5, indicating moderate debris retention. In contrast, Group 2 had a significantly lower mean score of 1.1 ± 0.3, showing minimal debris.

• Middle Third: Group 1 recorded a mean score of 2.6 ± 0.6, whereas Group 2 showed a reduced mean score of 1.4 ± 0.4, with less debris retained.

• Apical Third: The apical third presented the highest levels of residual debris for both groups. Group 1 had a mean score of 3.1 ± 0.7, indicating heavy debris, while Group 2 demonstrated a moderate level with a mean score of 2.0 ± 0.5.

DISCUSSION

The results of this study indicate that laser-assisted irrigation (LAI) is significantly more effective than conventional irrigation in removing debris from the root canal, particularly in the coronal and middle thirds. These findings are consistent with previous studies that have highlighted the enhanced efficacy of laser-activated irrigation in root canal cleaning.[1,2]

Root canal debridement is challenging due to the complex anatomical variations within the canal system, particularly in the apical third, where accessory canals and dentinal tubules may harbor residual debris and bacteria.[3] Conventional irrigation methods using syringes and needles rely on the delivery of irrigants to dissolve tissue and bacteria; however, their effectiveness is limited by the irrigant’s inability to penetrate intricate canal spaces fully.[4] The laser in LAI creates cavitation and acoustic streaming effects within the irrigant, improving its reach and enhancing debris removal, as observed in this study.[5] This process appears to facilitate superior canal cleanliness, with significantly lower debris scores noted in the LAI group compared to the conventional irrigation group.

The coronal and middle thirds showed the greatest reduction in debris with LAI, which may be due to the more accessible nature of these regions for laser activation. Previous studies have demonstrated that laser energy, when coupled with an irrigant, allows for enhanced disinfection and debris removal, as the laser energy creates microbubbles that expand and collapse, effectively displacing debris.[6,7] George et al.[8] also observed improved outcomes with LAI, attributing these effects to the laser’s ability to activate the irrigant and reach areas where mechanical instrumentation alone may fall short.

CONCLUSION

This study supports the use of laser-assisted irrigation as a valuable adjunct to conventional irrigation in improving root canal cleanliness. While challenges remain in effectively cleaning the apical third, LAI demonstrates clear benefits in the coronal and middle thirds, potentially contributing to better endodontic outcomes.

Conflicts of interest

There are no conflicts of interest.

Funding Statement

Nil.