Incidence of postoperative pain after single-visit and multiple-visit root canal therapy: a systematic review

Abstract

AIM- The objective of the systematic review is to evaluate the incidence of postoperative pain after single-visit and multiple-visit root canal therapy. METHODS- Published research indexed in PubMed or Scopus or Cochrane or DOAJ or Web of Science evaluating the frequency percentage of postoperative aching after one and several root canal therapy appointments through randomized controlled trials or prospectively were included. RESULT- Most surveys utilized VAS (Visual Analogue Scale) to estimate the degree of pain among the participants. The majority of the studies (n-8) showed no difference between postoperative pain during single-sitting endodontic treatment or multiple-sitting endodontic treatment. On the contrary, several studies (n-6) also revealed that post-obturation pain in a single-appointment root canal therapy is less compared to multi-visit root canal therapy. The current research results give insight into the incidence of postoperative endodontic pain among the study participants undergoing root canal treatment through single or multiple visit appointments. CONCLUSION- The lack of consistency between studies is due to the different ways in which pain intensity is measured and differences in treatment methods, patient selection and treatment outcomes.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12903-024-05412-1.

Introduction

Root canal treatment is a series of procedures to treat the affected dental pulp to cure the bacterial infection and prevent further microbial colonization of the cleaned tooth [1]. The advantages of performing root canal treatment are that it saves a natural tooth, avoids extraction, preserves normal chewing and biting forces, maintains the smile’s natural appearance, and prevents further infection and damage to adjacent teeth. The procedure involves three stages: (i) Extirpation, initial cleaning and removal of the bacterial infection from the infected tooth; (ii) Instrumentation: thorough cleaning and shaping of the cavity and pulp chamber together with the insertion of medication and removal of pulp debris; (iii) Obturation: filling the tooth canal with filling material. Root canal treatments have a high success rate, often exceeding 95%. With proper care, a treated tooth can last a lifetime. Regular dental checkups and good oral hygiene are key to maintaining the health of the treated tooth.

The treatment can be completed with one appointment or therapy of several appointments. Single-session root canal treatment is a non-surgical approach that allows patients to complete the process in one appointment. The root canal is cleaned, sculpted, and restored in a single treatment session. The canals are disinfected, modified and irrigated with an antibacterial liquid. Once the canals are free, clean and sterile, they are filled with a biocompatible substance and sealed [2]. In multi-visit root canal treatment, the canals are cleaned, shaped and sealed in several sessions. After the first visit, there will likely be a break of seven to ten days before the subsequent sessions occur. For the recall period between the access opening and biomechanical preparation session and the final restoration session, a short-term medication, such as calcium hydroxide, is used as part of multiple-visit therapy [3].

Endodontic treatment used to require numerous visits. One of the main reasons for this is that the treatment takes time. Non-surgical endodontic therapy with multiple visits is widely recognized as an effective and reliable technique. However, endodontics has long debated whether root canal treatment can be completed in one or several days [4]. Clinical outcome variability, inadequate microbiological control and pain are some unresolved issues [5].

Pain is a complicated, subjective experience that makes it difficult to assess accurately. The visual analogue scale is a popular research tool for quantifying pain sensations [6]. The technique has also helped with attention after sleep, anxiety, quality of life, nausea, dyspnea, and environmental settings [7]. Most of the studies included in this systematic review have used this technique to analyze the pain level of study participants [8]. Efficiency, problems, costs and likely patient/caregiver satisfaction should be considered when clinicians decide which treatments to recommend to their patients. The most substantial evidence currently available for teeth with infected pulp was found to show no difference in cure rates between the two therapies [9]. However, neither treatment modality’s side effects have been systematically studied.

There are several reasons for pain after obturation, either 24 h after completion of the treatment or a few days later. Some of the reasons mentioned are re-treatment, intracanal medication, physico-chemical damage to the radicular tissue, mechanico-chemical or microbial injury to the periapical tissue, infection of the bone, infected root canal, cement or air forced through the root apex, excessive filling and the number of sessions to complete the treatment [10]. One of the factors responsible for the development of pain after completion of the procedure is either a single session appointment or multiple session appointments [11].

Postoperative endodontic pain due to root canal therapy has significant clinical implications for patient satisfaction and treatment outcomes. Managing this pain effectively is crucial for several reasons: (A)Recovery and Healing, (i)Inflammatory Response: Postoperative pain can indicate inflammation and infection, which can affect the healing process of the treated tooth. (ii)Procedure Success: Proper pain management is vital for the long-term success of endodontic treatments, ensuring that the tooth heals properly and remains functional; (B)Physiological Impact (i)Pain Perception: Dental pain can be intense and debilitating, affecting a patient’s ability to eat, speak, and perform daily activities, thereby impacting their overall quality of life.(ii)Systemic Effects: Severe pain can lead to systemic issues such as sleep disturbances, stress, and anxiety, which can further complicate the healing process. Thus, knowing the incidence of postoperative pain after root canal treatment is essential for better patient comfort. [12, 13]

It also impacts patient satisfaction: (A)Patient Experience(i)Comfort and Relief: Effective pain management post-endodontic treatment enhances the patient’s comfort, reducing anxiety and increasing overall satisfaction with the procedure. (ii)Expectations of Care: Patients who experience less pain are more likely to feel that their dentist and the healthcare team provided high-quality care, leading to a positive perception of the treatment [14]. (B)Trust and Confidence: (i)Patient-Provider Relationship: Managing pain effectively builds trust between patients and their dental providers, encouraging them to seek future care without fear or hesitation. (ii)Adherence to Recommendations: Satisfied patients are more likely to follow postoperative care instructions and attend follow-up appointments, ensuring better long-term outcomes. Adequate pain control supports the healing process, reducing the risk of complications such as persistent infection or reinfection [15]. Patients who experience less pain are more likely to resume normal oral functions more quickly, maintaining their overall oral health and thus enhancing the patient’s quality of life, allowing them to return to their daily activities without discomfort. Reducing postoperative pain can decrease the need for additional treatments or emergency visits, making the overall treatment more cost-effective [16]. The clinical significance of postoperative endodontic pain and its impact on patient satisfaction and treatment outcomes are profound. Thus, effective pain management is crucial for optimizing recovery, enhancing patient experiences, and achieving successful treatment outcomes. Dental professionals must prioritize comprehensive pain management strategies to address this critical aspect of endodontic care, ultimately improving patient well-being and the overall success of endodontic treatments [17]. Modern advancements in rotary instrumentation, irrigation techniques, and magnification have made single-sitting treatments more viable for many cases. However, specific clinical scenarios still necessitate a staged approach to achieve optimal outcomes [2]. A systematic review is necessary to establish a clear and evidence-based understanding of the advantages, limitations, and indications for single-sitting versus multiple-sitting root canal treatments. This will enhance patient care and guide practitioners in choosing the most appropriate treatment protocol based on individual cases and evidence. Thus, this systematic review provides critical evidence that informs clinical practice, enhances patient care, and guides future research. Systematic reviews play a pivotal role in advancing healthcare knowledge and improving treatment outcomes by systematically evaluating and integrating research findings. Therefore, this systematic review evaluates the incidence of postoperative pain after single and multiple root canal treatment.

Materials and methods

Study protocol and registration

The PRISMA 2020 (Preferred Reporting Items for Systematic Review and Meta-analysis) guidelines were strictly followed, and the review was registered in the PROSPERO database under the identification number CRD42023434249.

Search strategies

The research question was formulated: What is the incidence of postoperative pain in single and multiple visits to root canal treatment? What are the factors related to it?

A systematic and comprehensive search was performed for research publications based on specific keywords analyzing the incidence of post-obturation discomfort after root canal treatment with one or more appointments and published until June 2023. The total number of studies completed using each database is shown in Table 1. Using keywords from the Medical Subject Headings (MeSH), the full-text studies were searched electronically in 3 journal databases. The studies were analyzed in PubMed, Scopus and Web of Science.

Table 1.

Sources of information and search strategies

PubMed-MEDLINE	(“Incidence“[All Fields] OR “Prevelance“[All Fields] OR “Frequency“[All Fields] OR “Degree“[All Fields] OR “Amount“[All Fields] OR “Extent”) AND (“Postoperative“[MeSH Terms]) AND (“Pain” OR “Discomfort “[All Fields] OR “Aching“[All Fields]) AND (“Single“[All Fields] OR “one“[All Fields]) AND (“visit“[All Fields] OR “appointment“[All Fields]) (“Multiple“[All Fields] OR “multi“[All Fields] OR “numerous“[All Fields] OR “several“[All Fields] OR “multi-“[All Fields]) AND ((“visit“[All Fields] OR “appointment“[All Fields]) AND (“Root canal therapy“[All Fields] OR “Endodontic therapy“[All Fields] OR “Endodontic treatment“[All Fields]OR “Root canal treatment“[All Fields] OR “RCT“[All Fields]))	179
Scopus	(ALL(Incidence) OR ALL(Prevelance) OR ALL(Frequency))  OR (ALL(degree) OR (ALL(amount) OR (ALL(extent))) AND (((ALL(postoperative) AND ALL(pain) OR ALL(discomfort) OR ALL(aching)))) AND ((ALL(single) OR ALL(one))) AND ((ALL(visit) OR ALL(appointment)) AND (ALL(multiple) OR ALL(multi) OR ALL(numerous) OR ALL(several) OR ALL(multi) AND ((ALL(visit) OR ALL(appointment)) AND ALL(root canal therapy) OR ALL(endodontic therapy) OR ALL(endodontic treatrment) OR ALL(root canal treatment) OR ALL(RCT)))	341
Web of Science	((((ALL=(incidence)) AND ALL=(posoperative)) AND ALL=(pain)) OR ALL=(single)) AND ALL=(visit) AND ALL=(multiple)) OR ALL=(visit)) AND ALL=(root canal treatment)	92
Total		612

Two analysts conducted an electronic literature search on June 10, 2023. Suitable studies that met the inclusion criteria were searched using various databases. The keywords used were “incidence” (prevalence OR rate OR frequency OR degree OR quantity OR extent) and “postoperative” “pain” (discomfort OR pain) as well as “single visit” and “multiple visit” “root canal treatment” (endodontic therapy OR endodontic treatment). The Boolean operators used to combine the keywords were “OR” and “AND”. (Table 1) Rayyan, a systematic review tool, was utilized to eliminate duplicate studies. Additionally, two authors screened the titles and abstracts of the articles. The finalized articles were then thoroughly read by the same authors to assess the article’s eligibility according to the study’s inclusion criteria.

Eligibility criteria

The PICOS method was used for inclusion criteria as follows. P(Participant): Adults with teeth that have undergone single or multiple endodontic treatments (diagnosed according to all recognized diagnostic criteria), I(Intervention): Single seated non-root canal treatment, C(Comparison): Single and Multiple seated root canal treatment, O(Outcome): Incidence of postoperative pain and factors associated with postoperative pain, S(Study design): Randomized controlled trial (RCT) and cohort study designs.

Articles in full text and indexed in PubMed, Scopus, or Web of Science, results analyzing postoperative symptoms after single or multiple root canal treatments were considered in English.

Data extraction and synthesis

The articles that satisfied the eligibility criteria were selected, and the two authors manually extracted the data (A1 and A2). The titles and summaries of the literature search results were reviewed separately by the primary evaluating author (A1) and a designated co-screener. (A2) and (A3) supervised and verified the selection process. In case of conflicts, discussions were held, and, if necessary, either Author (A2) or Author (A3) was consulted before a decision was made. Subsequently, A1 and the selected co-screener evaluated each full-text article separately to decide whether it should be included and undergo further review. An exclusive Excel spreadsheet was created to collect the data obtained from the studies. The following information was collected individually by two authors(A4 and A5) using the data extraction sheet for each article included in the review based on the eligibility requirements. The data included were the Author’s name, year of publication, name of the Journal for basic data further for methodological data study design, sampling method, sample size data, the tool used to assess the pain and the resulting outcome.

Quality assessment

The Cochrane Risk of Bias Tool was used to evaluate the quality of the studies included in the current systematic review (n = 12). Four reviewers (A1, A2, A3, and A4) evaluated the included articles’ risk of bias to determine the studies’ quality. A fifth reviewer was consulted for any conflict. The RoB 2.0 tool [10] (Fig. 1) was utilized to analyze randomized clinical trials (n = 12). The five dimensions of the RoB 2.0 tool were used. Are: bias due to (1) randomization process; (2) deviating from intended interventions; (3) incomplete outcome data; (4) outcome measurement; and (5) selection of reported studies. Studies were grouped into three categories: “low” for low risk of bias (greenish colour), “high” for high risk of bias(reddish colour), and “some concern” for uncertain risk(yellowish colour).

Fig. 1.

Flow chart summarizing the article selection process

Results

Study selection results

A total of 612 documents were identified, of which 179 studies were from PubMed, 341 from Scopus and 92 from Web of Science (Table 1). The search was conducted using Medical Subject Heading (MeSH) terminology. After reviewing the titles and abstracts of the publications, 304 studies were discarded. Of the remaining 24 complete articles that did not meet the inclusion criteria, 11 studies were excluded. A total of 13 articles were included in the final results (Fig. 2).

Fig. 2.

Quality assessment of the studies

Data summary of included study

Thirteen articles that met the inclusion criteria were included in the review (Table 2). The included articles appeared in reputable journals indexed in PubMed, Scopus, Cochrane, DOAJ, and Web of Science. The publication year of the studies ranged from 2010 to 2022, with most articles published in 2021 by Patel R et al., Gupta N.K et al. and Awinashe M.V et al.

Table 2.

Result summary of the included study

Study Reference	Authors	Year	Journal	study design	sample size (N)	result	conclusion	measurement of pain	Statistical Result
[11]	Dhyani V.K et al..	2022	Medical Journal Armed Forces India	RCT	60	While the variation was minor in seven days and thirty days after treatment, there was a greater incidence of postoperative pain (mild variety) and tender on percussion in single appointment treatment 24 h after the obturation. Following a single appointment treatment, pain reliever usage increased noticeably over the next 24 h. After chemo-mechanical preparation in a multi visit regime significant discomfort and soreness were seen.	Single-visit treatment is a reliable, useful, and efficient technique. The outcomes of the therapy are comparable to the multiple visit regimen. Thus, it ought to be taken into account for broad acceptance and usage.	evaluated preoperative and postoperative pain at 24 h, seven days and 30 days of the treatment	SS
[12]	Anagha CS et al.	2022	Journal of Conservative Dentistry	RCT	90	Patients participating in single-visit and multi-visit Root Canal Treatment reported that their pain level peaked on the first day of therapy and then gradually decreased. There was no discernible difference in pain levels between patients who visited just once and those who visited twice during the corresponding time periods.	There was no discernible variation in how painful single- and multiple-visit endodontics felt.	VAS	NS
[13]	Patel R et al.	2021	International Journal of Current Research and Review	RCT	198	Subjects who underwent treatment at a single visit and those who underwent treatment in two visits experienced the same level of discomfort following the procedure.	Post-obturation discomfort with non-surgical endodontic therapy was typical after the first day, but after the second day, there was decreased discomfort or no discomfort at all. After first, second, and seventh days for the teeth with post-obturation discomfort, the single-visit cohort experienced less intense discomfort, while the multiple-visit cohort experienced more severe pain.	Heft- Parker visual analogue scale (VAS) method
[14]	Gupta N.K et al.	2021	Journal of Conservative Dentistry	RCT	70	After Twelve and forty-eight hours, the pain score in multiple visits (MV) was significantly greater than in one day appointments (P = 0.039 and 0.043, respectively).	Short-term postoperative pain was greater in Multi visit appointment than Single visit Root Canal Treatment of mandibular 1st molar teeth.	Heft parker visual analog scale.	SS
[15]	Awinashe M.V et al.	2021	International Journal of Dentistry and Oral Science	RCT	100	Participants treated in one appointment compared to those treated in two appointments experienced the same level of postoperative discomfort. Within 24 to 48 h of the surgery, most of the participants in both batches disclosed no discomfort or very little discomfort.	Post-obturation tenderness was normal after the 1st and 2nd days of endodontic therapy, but after 7 days, the pain decreased or vanished entirely. After 1st, 2nd, and 7th days, the teeth in the single-visit group were less sore than those in the multiple-visit group.	VAS	SS
[16]	Singh A et al.	2020	Journal of Indian Society of Pedodontics and Preventive Dentistry	RCT	65	Incontrast to the single-visit category, the multiple-visit cohort’s mean pain index was greater.	In comparison to the multiple-visit participant, the single-visit participant’s mean pain index was less.	VAS	SS
[17]	Alomaym M.A.A et al.	2019	Journal of International Society of Preventive and Community Dentistry	RCT	400	The degrees of pain before and after surgery for both groups’ vital and nonvital teeth were similar at various points in time.	Multi visits cohort had a lower prevalence of discomfort than a single appointment	Visual analog scale	SS
[18]	Riaz A et al.	2018	Journal of the Pakistan Medical Association	RCT	60	In Group-I, the postoperative mean pain score was 2.231.736, while in Group-II, it was 2.381.94 (p = 0.8).	Therapies done in the single appointment or several appointments revealed no dissimilarity in pain frequentness.	VAS	NS
[19]	Sevekar S.A et al.	2017	Journal of Clinical and Diagnostic Research	RCT	80	In both the categories, 4 cases revealed postoperative discomfort (10%) at one day recall, p = 0.74. No patients revealed discomfort after 7 days and 30 days follow up. Postoperative discomfort was noted in 5 dead teeth (13.5%) and 3 vital teeth (6.9%).	There are no variations in postoperative pain rate in between treatment procedures requiring a single visit and those requiring multiple visits. Pulp vitality and the likelihood of postoperative discomfort have no discernible relationship.	The appearance of postoperative discomfort was assessed one, two, three, and seven days and a month post therapy	NS (p = 0.53)
[20]	Patil A.A et al.	2016	Journal of Clinical and Diagnostic Research	RCT	65	In Group A, 32 individuals were examined, while 33 patients were examined in Group B. Pain levels in Group B were significantly greater than the other group after 6, 12, and 24 h of obturation.	There is no discernible distinction between the incidence of aching following one- or two-visit endodontic therapy.	-	NS
[21]	Wong A.W et al.	2015	BMC Oral Health	RCT	220	The incidence of postoperative complications did not differ significantly between single-visit and multiple-visit therapies.	There was no discernible variation in outcome degree of postoperative discomfort between single-visit and multiple-visit therapy. Single-visit treatments required less chairside duration as compared to the treatments requiring several visits.	VAS	NS
[22]	Shaikh A.G et al.	2013	Medical Forum Monthly	prospective study	66	Post-obturation discomfort was similar in intensity in both patient groups.	No difference in rate of pain evaluated among the participants of both the group	-	NS
[23]	ElMubarak A.H.H et al.	2010	Journal of Endodontics	RCT	234	After 12 and 24 h, there was a 9.0% overall incidence of postoperative discomfort. 15.9% of patients who had a history of preoperative pain experienced postoperative pain, compared to 7.1% of those who had no such experience.	After a traditional Root Canal Treatment, postoperative discomfort was rare.	VAS	NS

Most of the articles (n = 2) were published in J Cons Dent [12, 14], and the rest were published in Med J Armed Forces Ind [11], Int J Cur Res Rev [13], Int J Denti Oral Sci [15], J Indian Soci Pedo Prev Denti [16], J Int Soc Prev Community Dent [17], J Pak Med Assoc [18]., J Clin Diagn Res [19], J Clin Diagn Res [20]., BMC Oral Health [21], Journal of Endodontics [22], Medical Forum Monthly [23].

Outcome measures

Most studies used the Visual Analogue Scale to assess the severity of pain in participants after one or more postoperative endodontic treatments. The VAS (Visual Analogue Scale) is a psychometric measurement tool that can document the severity of disease-related symptoms. It is a 10 cm line with two endpoints representing zero (no pain) and ten (worst pain). Patients are asked to rate their current level of pain by placing a mark on the line. Nine of fourteen studies included in the systematic review used the Visual Analogue Scale to assess the degree of pain after postoperative endodontic surgery. Two other studies assessed pre- and postoperative pain 24 h, one week and one month after treatment. The majority of studies (n = 8) showed no difference in postoperative pain between single-session endodontic treatment and multi-session endodontic treatment. On the contrary, several studies (n = 5) also showed that postoperative pain was lower with single-stage root canal treatment than with multiple-stage root canal treatment.

The included studies were prospective; the remaining studies (n = 12) were RCT studies that directly differentiated between a one-day and a multi-day appointment procedure. In the prospective study, no direct distinction was made between one-day and multi-day appointments; instead, one of many components was queried.

Discussion

Root canal treatment is a dental procedure in which diseased pulp tissue is removed from the inside of a tooth. An infected or abscessed tooth can be treated to relieve pain. It can also save a tooth that would typically have to be extracted [24]. It is one of the most sophisticated treatment procedures in dentistry. This procedure is performed with extreme precision by experienced, certified clinicians. With increasing awareness and knowledge of the benefits of good oral health, people are becoming increasingly attracted to this painless and less invasive procedure that allows them to save their teeth [25]. The three steps of this treatment procedure are Extirpation, instrumentation and obturation. After the three treatment steps, the entire therapy can be performed in a single session, or several visits are required to complete the therapy [26]. The main focus of this systematic review was to evaluate the occurrence of postoperative discomfort after single and multiple root canal treatments.

This review included 14 studies that exclusively assessed postoperative pain after a single or multiple appointments. Compared to older systematic reviews, we included more recently conducted studies where clinical trials were conducted among the participants to compare the pain between single or multiple appointments. Thus, evidenced-based factual data were obtained from the studies to provide the effectiveness of single vs. multiple root canal treatment. The ultimate goal of root canal treatment is painless, long-term tooth retention. Thus, to clarify the debate regarding the success rate of treatment between single or multiple appointments, this systematic review will help in future examinations. The studies included in the systematic review assessed postoperative pain after single-visit and multiple-visit root canal therapy, which resulted in heterogeneous data, thus preventing the possibility of doing a meta-analysis.

The review conducted by Dhyani V.K. et al. found that milder postoperative pain was more familiar with single-visit treatment and concluded that it is a reliable, valuable, and efficient technique [11]. Few studies found no discernible differences in how painful single-visit and multiple-visit endodontics were perceived [12, 18–23].

The study by Patel R et al. investigated the discomfort after root canal treatment with one visit compared to treatment with several visits. They found that the single-visit cohort experienced less severe discomfort, while the multi-visit cohort experienced more severe pain [13]. Similar results were demonstrated in the study by Gupta N.K et al., Awinashe M.V et al., Singh A. et al. and Alomaym M.A.A et al. [14–17].

The current systematic review has shown that single-visit endodontic treatments are as reliable as multi-visit ones [27]. Ultimately, it depends on the choice of the surgeon and the patient. The efficiency of both techniques has already been proven in several studies and has been practised for a long time [9, 28].

Strength and limitations

Research has many strengths. It provides a comprehensive overview of the occurrence of postoperative pain after single and multiple root canal treatments. The study design included in this review was a randomized controlled trial and cohort study design where the majority of the study design was RCT, which gives an evidence-based result regarding the topic of discussion. The scales used to measure pain in participants were well described in all included studies, and the study design of the included study for the review is an absolute plus point of this investigation. Many databases were analyzed before including all published research on the topic.

A significant shortcoming of this study was that pain measurement is subjective and patients’ statements are the primary data source. Since everyone perceives their feelings differently, patients receiving comparable treatments will rate their discomfort differently on a pain index. The definitions of individual pain scales varied, particularly in the included studies. This means that although the same 4-point pain ratings were used in many studies, the interpretation of each scale and the degree of pain may have been different. In addition, the dichotomizing point varied from study to study. These different dichotomizing points made direct comparisons between studies or statistical combinations impossible. In addition, different researchers and clinicians often interpret pain scale measurements differently depending on the criteria used. The usefulness of additional studies must be questioned when considering the fourteen studies’ shortcomings. It is unlikely that the presence of mild, transient pain will influence the choice of therapy.

Conclusions

The results of this study provide insight into the occurrence of endodontic complaints after obturation in the study participants who underwent root canal treatment in one or more appointments. However, insufficient convincing information exists to conclude that root canal treatment with one or more appointments has a remarkably different incidence of postoperative discomfort. The lack of consistency between studies is due to the very different ways in which pain intensity is measured and differences in treatment methods, patient selection and treatment outcomes.

Electronic supplementary material

Below is the link to the electronic supplementary material.

Author contributions

Conceptualization, GK., SJ and MIK; Data curation GK and SJ; Formal analysis, NM., GK and MF; Investigation, GK., SJ and MIK; Methodology, GK and MIK; Project administration, GK; Resources, NM and MF; Supervision, MIK; Validation, NM and MF; Writing – original draft, GK., SJ and MIK; Writing – review & editing, GK., NM., MF and MIK. All authors have read and agreed to the published version of the manuscript.

Funding

None.

Data availability

Any data related to the study can be readily provided upon reasonable request to the corresponding author.

Declarations

Ethics approval and consent to participate

Not applicable.

Consent for publication

Not applicable.

Competing interests

The authors declare no competing interests.