Effect of low-level laser therapy on postoperative pain following root canal filling with resin-based and bioceramic sealers: A double-blinded randomized clinical trial

Abstract

Context:

One of the most important aspects of endodontic treatment is pain management. Studies have reported conflicting results regarding postoperative pain following obturation with different sealers. Bioceramic sealers are promising alternative to other sealers. Low-level laser therapy (LLLT) is found to reduce postoperative pain.

Aim:

The study aimed to evaluate postoperative pain following root canal obturation with bioactive glass (BG)-based and resin-based sealer with or without adjunctive LLLT.

Materials and Methods:

Forty patients were included in the study according to the inclusion and exclusion criteria. Root canal treatment was performed using NiTi rotary instruments. Patients were randomly distributed into four groups of 10 in each: Group 1, resin-based sealers without LLLT; Group 2, resin-based sealers with LLLT; Group 3 bioceramic-based sealers without LLLT; and Group 4, bioceramic-based sealers with LLLT. Postoperative pain levels on the 1^st, 3^rd, 5^th, and 7^th day were recorded on the Visual Analog Scale. One-way ANOVA and least significant difference post hoc tests were performed to analyze the data (P < 0.05).

Results:

BG-based sealers in conjunction with LLLT showed the least postoperative pain compared to the resin-based sealers.

Conclusion:

Bioceramic-based sealers with LLLT may be used as an alternate strategy to control postoperative pain.

INTRODUCTION

One of the most important aspects of endodontic treatment is pain management. Postoperative pain after endodontic treatment is a frequent complication. Frequency of endodontic postoperative pain is between 3% and 58% of patients.[1] The presence of postoperative pain is associated with a number of endodontic treatment-related parameters, including the estimation of working length, number of visits, choice of instrumentation, and choice of root canal sealers. Particularly, postoperative pain associated with root canal sealers ranges between 5% and 20%.[2]

The anti-inflammatory and regenerative effects of low-level laser therapy (LLLT) have been well established in clinical dentistry. Due to the relatively large side effects of nonsteroidal anti-inflammatory drugs and limitations of use, safer treatment modalities such as low-level laser radiation have been taken into consideration by some researchers.[3] Laser applications with low-level parameters cause insignificant thermal changes and elicit biomodulatory effects. LLLT delays the initiation of pain and reduces the severity and duration of pain with limited side effects.[4] LLLT reduces postoperative endodontic pain.

One of the most important causes for postendodontic pain can be sealer extrusion and the type of sealer used. Resin-based sealers exhibit stronger bonding capacity and higher radiopacity, but have long-setting time with cytotoxic effects. It has been suggested that bioceramic materials improve the outcome of endodontic treatment by promoting the differentiation of odontoblasts and by releasing biologically active substances.[5]

Recently, several bioactive bioceramic-based sealers are introduced and used for root canal obturation. A recent study by Washio et al. stated that the “pain” level (0.5%) immediately after obturation with CS-bioactive glass (BG) was lower when compared with the other sealers, including eugenol-, noneugenol-, resin-, other bioceramic-based sealers.[2]

The BG-based sealer, Nishika Canal Sealer BG (CS-BG; Nippon Shika Yakuhin Co., Ltd., Yamaguchi, Japan), one of the bioceramic-based sealer, has been recently introduced. CS-BG demonstrates many desirable properties, such as physicochemical stability, biocompatibility, sealing ability, and removability. The in vitro and in vivo studies have reported that CS-BG has excellent biocompatibility for the periapical tissues.[2] However, there are no clinical studies of the characteristics of this newly introduced BG-based sealer (CS-BG) with adjunctive LLLT in patients with asymptomatic apical periodontitis. Data on the clinical behavior of bioceramic sealers and LLLT are scarce and of great interest. Hence, the aim of the study was to evaluate the postoperative pain following root canal obturation with bioactive bioceramic-based sealers with adjunctive LLLT. The null hypothesis stated that there is no difference in postoperative pain levels in teeth obturated with bioceramic sealers compared to those obturated with resin-based sealers with or without adjuvant LLLT in patients with asymptomatic apical periodontitis.

MATERIALS AND METHODS

The study was conducted after taking ethical approval from the Institutional Ethical Committee (IES) with reference no. KIDS/IES/2023/18 and adhered to PRIRATE guidelines 2020. The study comprised 40 patients aged between 18 and 45 years, diagnosed with asymptomatic apical periodontitis in premolars, who were referred to the Department of Conservative Dentistry and Endodontics at KLE Society’s Institute of Dental Sciences, Bengaluru, for endodontic therapy.

Randomization and blinding

The computerized randomization method was used to assign patients to the endodontic sealer used (AH Plus, CS-BG) (www.randomisation.com). Allocation concealment was done by opaque envelopes with sequential numbers. An unrelated research assistant opened the envelopes just prior to the use of sealers.

Trial design

The current study was carried out in an institute environment employing a double-blinded study. The patient and the observer were double blinded to prevent bias in the Visual Analog Scale (VAS). Samples were further divided into four groups (10 in each group). Single-visit root canal treatment was performed for all the participants. Exclusion criteria were medically compromised patients, pregnant women, patients who refused to participate, who had taken analgesic within the last 3 days, curved roots, swelling or sinus tract, and periodontally compromised teeth (probing depth >4 mm). Furthermore, patients exhibiting technical complications-such as severely curved roots, abnormal root length, separated instruments, over-instrumentation, overfilling, or incomplete filling, were excluded from the study. Informed consent form was obtained from each patient, local anesthesia was performed, and root canal treatment was done by a single endodontist. A straight-line access cavity was prepared, and the procedure was performed via rubber dam isolation. The working length was determined using an electronic apex locator (ROOT ZX MINI, J MORITA). Instrumentation was done using Protaper Gold (DENTSPLY) up to size F2 according to the manufacturer’s instructions. New set of instruments were used for each patient. A size 10 K-file was used to maintain apical patency, 2 mL of 1% sodium hypochlorite was used between in-and-out pecking motions, and a final rinse was performed using 5 mL of 1% NaOCl for 1 min and 5 mL of 5% EDTA for 1 min to remove the smear layer. After root canal preparation, the root canals were dried with paper points and obturated using matched single cones using either resin-based or bioceramic sealer. The patients were divided into four groups (n = 10) as follows:

• Group 1: Resin-based sealers without LLLT

• Group 2: Resin-based sealers with LLLT. After access filling, subsequent to root canal treatment, LLLT was performed using a 980 nm diode laser (IMDSL, India) [Figure 1c]. For laser irradiation, intraoral biostimulation tip was placed at a distance of approximately 10 mm from the tissue around the apex of the root and activated at 0.5 W and 10 Hz [Figure 1d]. The tissue around the apex of the root was treated for 30 s on both buccal and lingual surfaces. In Group 1 and 2, resin-based sealer was mixed in 1:1 ratio [Figure 1a] according to the manufacturer’s instructions and used for obturation

• Group 3: Bioceramic-based sealers without LLLT

• Group 4: Bioceramic based sealer with LLLT. Here after access filling, subsequent to root canal treatment LLLT was performed as previously explained in Group2. In Group 3 and 4, bioceramic based sealer with two phased paste system [Figure 1b] was mixed according to the manufacturer’s instructions and used for obturation.

Figure 1.

Root canal sealers and low-level laser therapy used: (a) Resin-based sealer (AH Plus, Dentsply), (b) bioceramic sealer (Nishika BG sealer, J Morita, Japan), (c) diode laser (IMDSL, INDIA), (d) low-level laser therapy with intraoral biostimulation

Postobturation, pulp chamber was filled with a flowable composite resin and a nanohybrid composite resin was inserted into the cavity using an incremental technique and cured for 20 s using an LED light-curing unit (BLUEPHASE) with an output of 1200 mW/cm² in all the participants from all the groups. The postoperative pain was evaluated using VAS on the 1^st, 3^rd, 5^th, and 7^th day. For that, each patient received a 10-cm-long line (VAS) divided from 0 to 10, presenting 10 intervals of 1 cm each. Patients were instructed to assign their intensity of postobturation pain experience with a value between 0 and 10 on the analog scale, in which 0 represented no pain and 10 represented the maximum level of pain. The Visual Analog Scale (VAS) was used to assess postoperative pain in teeth treated endodontically, categorized as follows: 0 – No pain (asymptomatic); 1–2 – Mild pain of short duration, not requiring analgesics; 3–4 – Moderate, tolerable pain, alleviated with analgesics; 5–6 – Strong, persistent pain disturbing sleep, necessitating narcotic analgesics; 7–8 – Severe, intermittent pain affecting daily activity and sleep, unrelieved by analgesics; 9–10 – Maximum, continuous pain with associated systemic symptoms (e.g., poor appetite, stress), resistant to analgesic intervention. All patients were contacted by phone at 1^st, 3^rd, 5^th, and 7^th day after endodontic treatment, and the score was recorded. The patient and the observer were double blinded to prevent bias in the VAS. Patients were instructed not to take any analgesic till the pain is severe. If the pain is intolerable, patients were instructed to take medication (ibuprofen 400 mg).

Statistical analysis

The SPSS statistics program (IBM Corp., version 24.0, Armonk, NY, USA) was used to analyze the data. The descriptive statistics such as mean and standard deviation of postoperative pain was calculated. One-way analysis of variance was performed with least significant differences post hoc for intergroup comparison of postoperative pain at different time points. Significant results were defined as P < 0.05 with 95% confidence interval (P < 0.05).

RESULTS

Graph 1 depicts that LLLT with bioceramic sealers (Group 4) showed the least postoperative pain on the 1^st and 3^rd day with a statistically significant difference, followed by Group 3, Group 2, and Group 1 (P < 0.05). Although on the 7^th day, postoperative pain was less in all the groups compared to the 1^st day of posttreatment. Bioceramic sealers without LLLT and AH Plus sealers with LLLT showed similar results with no statistically significant difference between them (P > 0.05). Using resin-based sealers without LLLT showed more postoperative pain compared to other three groups with a statistically significant difference. However, resin-based sealers with LLLT showed the least postoperative pain compared to resin-based sealer without LLLT with a statistically significant difference (P < 0.05).

Graph 1.

Mean values of postoperative pain scores of different groups at 1, 3, 5, and 7 time points

DISCUSSION

Postendodontic pain is due to stimulation and release of local inflammatory mediators like reactive oxygen species (ROS).[6] Endodontic therapy involves a number of intricate procedures that include chemical as well as mechanical debridement and obturation, making it difficult to ascribe pain occurrence to a single factor. During this study process, precautions were taken to minimize the elements that could possibly cause postendodontic pain. It is a well-known fact that pre-endodontic pain is more likely to cause postendodontic pain. As a result, only patients who were symptom free were invited to participate in this study.

LLLT is the use of coherent beams of laser light to diagnose or treat medical conditions. The laser technology for LLLT treatment is used with proper setting of parameters and may be used for the treatment of wound healing, soft tissue injury, and relief of pain.[7]

According to the results of the present study, LLLT resulted in lower pain levels than those observed in the control reported on days 1 and 3 (P < 0.05). Thus, the null hypothesis was rejected. The lower pain levels on the 1^st and 3^rd day may be due to the anti-inflammatory action of LLLT. Mechanisms for pain reduction following laser radiation has been related to lowering levels of prostaglandin E2, interleukin 1-beta, tumor necrosis factor-alpha, the cellular influx of neutrophil granulocytes, oxidative stress, edema, and bleeding.[8] LLLT also decreases the activity of C fibers and exerts regenerative effects. It can neutralize the effects of high concentrations of inflammatory cytokines on gingival fibroblast functions, which are related to the late wound-healing process.[3,9] Arslan et al. in their study reported that LLLT reduced postoperative pain after root canal retreatment.[4] This finding is in accordance with the present study, with the same parameters used.

Bioceramic-based materials have recently been introduced into endodontics as both repair cement and root canal sealer. Bioceramic-based materials exhibit an alkaline pH, possess antibacterial activity and radiopacity, and are biocompatible, non-toxic, nonshrinking, and chemically stable in the biological environment. A further advantage of bioceramic materials is that they promote the formation of hydroxyapatite, ultimately facilitating a bond between dentin and the filling material during the setting process.[10] In this study, Nishika Canal Sealer BG (CS-BG), a bioceramic material derived from bioactive glass and originally designed for both dental pulp and bone regeneration, was utilized. CS-BG is a two-phased paste; Paste A consists of fatty acids, bismuth subcarbonate, and silica dioxide, whereas Paste B consists of magnesium oxide, calcium silicate glass (a type of BG), and silica dioxide.[11]

In this study, bioactive bioceramic-based sealers (NISHIKA CS-BG) were compared with resin-based sealers. The results stated that bioactive bioceramic-based sealers showed lower postoperative pain levels on the 1^st day and 3^rd day. This may be due to the higher biocompatibility and more calcium release with bioactive bioceramic sealers compared to resin-based sealers. CS-BG (bioactive bioceramic sealers) predominantly releases 10–18 times more silicate ions than the other bioactive root canal sealers, suggesting the possible enhancement of biological properties due to the release of therapeutic ions. Root canal sealers containing bioceramics (CS-BG) release Ca²⁺ and OH− during as well as after it sets.[12] Furthermore, when they come into contact with interstitial tissue fluids which contain phosphate, they release bone-like apatite to the surrounding area.[13] Ca²⁺ increases the production of osteopontin and bone morphogenic protein-2 in the mesenchymal stem cells of bone marrow and periodontal ligament stem cells, respectively, to enhance osteogenic development.[14] Similarly, OH− stimulates osteoblast and cementoblast proliferation and mineralization. In addition, the bone-like apatite crystals stimulate cementum formation by acting as a substrate for cementoblast attachment. Therefore, in addition to mechanically sealing the root canal system, root canal sealers containing bioceramics also physiologically promote tissue repair. With an ample setting time of 3–4 h, excellent radio-opacity, and minimal to no inflammation in case of an overfill, bioceramic sealers are highly preferred.[15] A previous study evaluating postendodontic pain with the use of CS-BG sealer reported significantly fewer pain episodes, which aligns with the findings of the present study.[2,14]

AH Plus is a resin-based sealer used in our study. A previous study stated that it creates harmful byproducts like bisphenol A diglycidyl ether.[16] The cytotoxicity of this resin-based sealer revealed that their interaction with the periapical tissues might cause postendodontic discomfort. A brief postendodontic pain may be linked to the initiation of ROS formation caused by leaching of unpolymerized sealer components during the first 24 h of setting.[17] AH Plus, because of its delayed setting time, causes biocompatibility issues and triggers the potential release of cytotoxic components before it sets, contributing to higher episodes of pain, than in the CS-BG group (short setting time) during the first 24 h. This might be one of the reasons for resin-based sealers to show more postoperative pain compared to CS-BG. The results of this study are in accordance with previous studies.[18,19] Although previous studies have compared different endodontic sealers, the novelty of the present study lies in its use of low-level laser therapy (LLLT) to evaluate postoperative pain. Pandey et al. conducted a randomized controlled clinical trial using three different sealers and observed that patients experienced minimal postoperative discomfort with bioceramic (CeraSeal) sealers. Notably, even in cases with apical extrusion, patients reported no postobturation pain, and this absence of discomfort persisted during follow-up visits.[6]

Our study showed the least postoperative pain in Group 4. The probable reason for this could be because of additive effects of both LLLT and using bioactive sealer for the root canal obturation would have reduced the inflammatory process, increased lymphatic drainage and induced calcium release. Previous studies showed lower postoperative pain levels for single-visit treatments than double-visit treatments; however, some other studies contradict this outcome.[20,21] Due to the homogeneity of samples, we only included single-visit treatments in the present study. The lower incidence of postoperative pain in single-visit root canal treatment might be attributed to immediate obturation, thereby avoiding passage of medications, repeated instrumentation, and irrigation.[22]

In our study, we used a wavelength of 980 nm for irradiation at the apex region of the premolar tooth. Wavelengths in the near-infrared spectrum can penetrate biological tissue deep to 5 mm; it is more profound than the blue-visible or red-visible spectrum. Therefore, it is eligible to affect periapical tissues. In most of the previous similar studies, wavelengths within 808–980 nm were used for pain relief.[23]

Gender, preoperative endodontic pain, and type of the involved tooth are considered risk factors for a higher prevalence of post endodontic pain (PEP). Confirming some previous studies, the levels of PEP did not correlate with age in the present study. Watkins et al. stated that PEP significantly decreased with increasing age.[24] Nevertheless, Ali et al. reported that PEP levels were higher in the old age group.[22] These vast controversies in reports may be related to the multifactorial nature of PEP, making it hard to evaluate and manage.

In our study, female patients experienced more postoperative pain compared to male patients, the results of which are in accordance with the previous studies.[19,22,25] However, a recent study stated that there was no association between gender and postendodontic pain in their investigation.[18]

In our study, mandibular premolars exhibited significantly higher postoperative pain compared to maxillary premolars. This may be attributed to the denser trabecular architecture of the mandible, which potentially limits blood flow and leads to localized infection and inflammation, thereby delaying healing.[22] Laser irradiation was applied to both the buccal and lingual surfaces at the apical region of the tooth. When irradiation is limited to the buccal surface alone, the lingual periapical tissues may receive reduced energy exposure compared to the buccal side, and vice versa.[26]

Our findings demonstrated that patients in the group treated with low-level laser therapy (LLLT) and bioactive bioceramic-based sealer required significantly fewer analgesics than those in the control group, consistent with observations reported in previous studies. Collectively, it can indicate that using LLLT may reduce the need for analgesic medications. It is beneficial, especially when analgesics are contraindicated for any reason. However, it is worth noting that only a limited number of studies and researchers have reported significantly less postoperative pain with LLLT. Notably, one study confirmed that LLLT can be a viable alternative for managing postoperative pain.[9]

CONCLUSION

Within the limitations, the study concluded that LLLT reduced postoperative pain compared to the control groups. Using bioactive bioceramic-based sealers showed the least postoperative pain compared to other groups at the 1^st and 3^rd day posttreatment. An adjunctive treatment using LLLT after obturation with bioceramic-based sealers could reduce postoperative pain at the 1^st and 3^rd day time points.

Conflicts of interest

There are no conflicts of interest.

Funding Statement

Nil.