TITLE : Comparative evaluation of two different endodontic instrumentation kinematics and cryotherapy on post endodontic pain and periapical healing in teeth with asymptomatic apical periodontitis - A double blind, prospective randomized clinical trial Background : Root canal treatment is done to save teeth that are infected or damaged. Although this procedure relieves pain in the long term, many patients experience discomfort or pain after treatment, known as post-endodontic pain (PEP). The way dentists clean the root canals and the methods used to reduce inflammation may influence how much pain patients feel and how well the bone around the tooth heals. This study will compare two modern ways of cleaning root canals using special nickel-titanium files. The first method uses a rotary system, where the files continuously rotate inside the canal. The second method uses a reciprocating system, where the files move back and forth. Both systems are commonly used in dentistry, but it is still not clear which one leads to less pain and better healing. The study will also test the benefit of cryotherapy, which means rinsing the canal with very cold saline at the end of the cleaning. Cold therapy reduces blood flow and nerve activity, helping to control pain and swelling without the side effects of medicines.

Methodology: Sixty patients with asymptomatic apical will be included. They will be randomly assigned into four groups: Group1:Rotary system with cryotherapy, Group 2:Rotary system without cryotherapy, Group 3: Reciprocating system with cryotherapy, Group 4 : Reciprocating system without cryotherapy.Patients will record their pain on a simple scale at different times after treatment. Healing of the infection will be checked with X-rays after six months.

OBJECTIVES:

Primary Objective:

To compare the post endodontic pain following instrumentation with a rotary vs reciprocating kinematic instrumentation system at different irrigant temperature using NRS-11 scale.

Secondary Objective:

To assess the periapical healing following endodontic treatment with or without adjunctive use of cryotherapy assessed with periapical healing index .

The results of this study will help dentists understand whether cryotherapy and the choice of instrumentation system can reduce patient discomfort and improve treatment success. This may lead to better patient care and less need for pain medications after root canal treatment.

II. INTRODUCTION:

Post-endodontic pain (PEP) is a common occurrence following endodontic procedures, affecting a significant number of patients. The intensity and duration of pain can vary widely, ranging from mild discomfort to severe, debilitating pain. Factors contributing to post-endodontic pain (PEP) include the complexity of the procedure, preoperative pulpal and periapical status, and individual patient characteristics. Proper management of post-endodontic pain (PEP) is crucial for patient comfort and overall treatment success. Clinicians typically employ a combination of pharmacological and non-pharmacological approaches to address this issue. These may include the use of analgesics, such as nonsteroidal anti-inflammatory drugs (NSAIDs) or opioids, as well as patient education on self-care measures. Additionally, recent advancements in endodontic techniques and materials have shown promise in reducing PEP, emphasizing the importance of continuous research and improvement in this field.

The common factors influencing the occurrence of PEP include insufficient instrumentation, irrigant extrusion, intracanal interappointment dressing extrusion, hyperocclusion, missed canals, presence of preoperative pain, presence of periapical pathosis, apical debris extrusion, and apical patency during root canal preparation. A small, inadvertent extrusion of debris and irrigants into periapical tissues is a frequent complication during the cleaning and shaping procedures, both with manual stainless steel and nickel-titanium rotary instrumentation techniques. However, some recent in vitro findings have shown that reciprocating instrumentation techniques seem to significantly increase the amount of debris extruded beyond the apex and, consequently, the risk of PEP and inflammation. Based on these premises, the goal of the present study is to evaluate and compare the incidence and intensity of PEPusing two different nickel-titanium instrumentation techniques: a rotary crown down technique and a reciprocating single-file technique.

Cryotherapy aims to reduce tissue temperature by applying cold and extracting heat with therapeutic purposes to manage PEP, swelling and oedema. Initial reaction to cold is a decrease in blood flow due to vasoconstriction that restricts the pro-inflammatory substances. Lowering tissue temperature causes cold-induced neuropraxia and decreases the neural activity of nociceptor fibers through deactivation. Cooling the target tissue also slows down the cell metabolism and prevents the increase of oxidative stress due to injury. The resultant analgesic effect is achieved by a combination of reduced chemical mediators of pain and slowed neural pain signals.

Cryotherapy was introduced to endodontics with the in vitro study of Vera et al. , which showed a decrease in temperature of the external root surface is achieved and maintained for 4 min after cryotherapy. Delivery of cold saline by a negative pressure irrigation method for 5 min as final irrigant is termed intracanal cryotherapy and has been associated with reduced PEP and analgesic intake, particularly in teeth with necrotic pulps and symptomatic apical periodontitis .Intracanal cryotherapy emerged as a simple, economical and non-toxic pain control technique that aims to eliminate the side effects of acetaminophen and NSAIDs by reducing their intake after root canal treatment. This technique can be easily integrated into the endodontic treatment routine and represents an alternative for PEP control, especially in patients with drug allergies, geriatric patients or pregnant women who avoid the use of painkillers.

III. AIM:

To compare the post-endodontic pain (PEP) and periapical healing following chemo-mechanical preparation with two different instrumentation kinematics along with cryotherapy in teeth with pulpal necrosis and asymptomatic apical periodontitis

IV. OBJECTIVES:

IVa. Primary Objective:

To compare the post endodontic pain following instrumentation with a rotary vs reciprocating kinematic instrumentation system at different irrigant temperature using NRS-11 scale.

IVb. Secondary Objective:

To assess the periapical healing following endodontic treatment with or without adjunctive use of cryotherapy assessed with periapical healing index

V. NULL HYPOTHESIS The null hypothesis (H0) is that there is no difference between rotary and reciprocating file systems with or without intracanal cryotherapy in postendodontic pain and periapical healing in teeth with asymptomatic apical periodontitis(AAP).

VI. LACUNAE IN LITERATURE The literature lacks any studies regarding the effect of different instrumentation kinematics (rotary and reciprocating motions) and cryotherapy on periapical healing. Moreover, the results of previous studies about the effect of different instrumentation kinematics (rotary and reciprocating motions) on PEP was contradictory .

VII. MATERIALS AND METHODS Study design This will be a prospective, block-randomized, double-blinded, and parallel-group clinical trial. The study will obtain ethical clearance from the Institutional Ethics Committee, and the protocol will be registered in the Clinical Trial Registry of India, ensuring adherence to ethical standards and transparency in research procedures. All the procedures will be followed conforming to the Helsinki Declaration of the World Medical Association. A patient information sheet and consent form will be distributed to all participants.

Study setting AIIMS Nagpur is a premier medical institution in India, known for its advanced medical care, research, and education. It is located in MIHAN, Nagpur, Maharashtra. It is easily accessible via major transport links, making it convenient for participants to attend follow-up visits. The Dentistry OPD at AIIMS Nagpur serves a large number of patients daily, providing ample recruitment opportunities for study participants. It is equipped with modern dental chairs, advanced diagnostic tools (such as digital radiography), and treatment facilities. A robust electronic medical records (EMR) system ensures accurate data collection and management, facilitating longitudinal follow-up of patients. The cost of treatments available in AIIMS is affordable and minimal when compared to other hospitals and private clinics.

Clinical setting Treatment rooms are equipped with dental chairs and necessary instruments for performing endodontic treatment using rotary and reciprocating file systems. Sterilization Facilities ensure aseptic conditions for all procedures. The digital radiographic facilities available in the department for pre- and post-treatment evaluation are of great help for evaluating treatment outcomes.

Baseline Assessment Each participant will undergo a clinical examination and radiographic assessment to confirm the presence of tooth necrosis with AAP.

Sample size Considering the mean value of post instrumentation, in rotary group as 1.29 (SD of 1.06) and reciprocating group 0.57(SD of 0.68) ,80% power and α value of 0.05 the estimated sample size is 26 per group (a total of 52). Considering 15 % dropout rate, required sample size per group is 30.

Inclusion criteria

1. Systemically healthy (ASA (American Society of Anesthesiologists)-I,II )(22) participants between 18 - 60 years of age with diagnosis of pulp necrosis and AAP in single rooted lower anteriors and premolars Tooth will be diagnosed as AAP if it shows no clinical symptoms (no pain on percussion or palpation).
2. Radiographic evidence of periapical pathology with PAI score between 2 - 5. Exclusion criteria

The patients with the following clinical and radiographic features will be excluded from the study:

Clinical features:

1. Teeth with previous history of root canal treatment.
2. Teeth requiring severe prosthetic rehabilitation.
3. Pregnant or nursing mothers.
4. Periodontally compromised teeth.
5. Analgesic consumption for at least 12hrs before the visit.

Radiographic features:

1. Immature/ Open apex
2. Non-patent apical foramen
3. Root resorption
4. External resorption
5. Calcified pulp canals.

Treatment protocol:

Method of Random Sequence Generation Enrolled and consenting patients will be randomly assigned to one of the four study groups based on the instrumentation kinematics and treatment with/without cryotherapy. The random allocation sequence will be generated using computer-generated random numbers (http://www.random.org/). This method ensures an unbiased allocation of participants to these groups.

Allocation concealment The allocation sequence will be concealed using sealed opaque envelopes. These envelopes will be prepared by an independent third party not involved in the recruitment, treatment, or assessment of participants. Each envelope will contain a unique code corresponding to the randomization sequence. The methods for all four treatments will be labelled with code identifiers and only the independent party who prepared the materials will know which code corresponds to which treatment.

Blinding The participants will be blinded to the instrumentation system as well as the themperature of an irrigant. Additionally, the outcome assessors who evaluate the clinical and radiographic outcomes, will also be blinded to the treatment allocation. Any instances of accidental unblinding will be documented including the circumstances and any potential impact on the study's results.

Enrolment of participants:

The post-graduate student will be responsible for enrolling the participants. After obtaining the consent and verifying the eligibility, the student will assign a sequential number to the participant and retrieve the corresponding envelope. The envelope will then be opened to reveal the allocation.

Handling of Attrition Attrition will be handled by intention-to-treat analysis. All the participants who are randomized will be included in the analysis, and the reasons for dropout or loss to follow-up will be documented and reported.

Funding This study is a Post graduate thesis, no funding will be provided, and all expenses will be borne by the post graduate student.

Informed consent All participants were given s patient information sheet in a local, informal language. Once all participants decided to take part in the trial, written informed consent was obtained.

Groups

All participants (n=60) were randomly categorized into four goups as follows:

Group 1 (n=15): Biomechanical preparation of root canals with rotary file system along with the adjunctive use of cryotherapy Group 2(n=15): Biomechanical preparation of root canals with rotary system without the use of cryotherapy Group 3(n=15): Biomechanical preparation of root canals with reciprocating file system along with the adjunctive use of cryotherapy.

Group 4(n=15): Biomechanical preparation of root canals with reciprocating file system without the use of cryotherapy.

Outcome measures:

Primary Outcome: NRS-11 scale, Patients will self-evaluate themselves using the scale provided based on the NRS 11 (Numerical Rating Scale) for PEP at 24hrs, 48hrs, 72 hrs. and 7 days at their residences. All participants will be instructed to consume analgesics (TAB.IBUPROFEN 400 mg ) in case of severe pain and note down in a chart provided.

Secondary Outcome: Periapical Index(PAI) Periapical healing will be assessed using the Periapical Index (PAI). The teeth will be classified as

1. Healed (scores 1 or 2);
2. Healing (reduced score compared to baseline, but higher than 2); or
3. Not healed (teeth that presented the same or worst pai score than that observed at baseline).

Clinical and radiographic evaluation will be done after an interval of 6 months postoperatively using Intraoral periapical radiographs and evaluated according to the above-mentioned index and criteria.

Assessment of Preoperative Pain Patients will be asked to record the preoperative pain on the Numerical Rating Scale-11 in accordance to the below mentioned standard criteria.

0 No Pain 1-3 Mild Pain 4-6 Moderate Pain 7-10 Severe Pain 10- Worst possible Pain

Assessment of Preoperative Periapical Pathology

It will be assessed using the Periapical Index (PAI) which follows as:

PAI 1 - Normal periapical bone structure PAI 2 - Small changes in bone structure with no demineralisation PAI 3- changes in bone structure with some diffuse mineral loss PAI 4- Apical periodontitis with well-defined radiolucent area PAI 5- Severe apical periodontitis with exacerbating features Administration of Local Anaesthesia The participants will be instructed to rinse their oral cavity with 0.2% chlorhexidine gluconate solution. The tooth will be anaesthetized using an inferior alveolar nerve block by local anaesthesia of 1.8 mL of 2% Lignocaine HCl with 1:100 000 epinephrine. Epinephrine is added to lidocaine to minimize the hemorrhage, systemic absorption of lidocaine and increase the duration of anesthesia. All subjective signs and symptoms (eg - lip numbness) of successful administration of IANB were checked after 15 minutes.

Clinical Steps After rubber dam isolation, the operative field and the tooth will be disinfected using 5% sodium hypochlorite prior to caries excavation. Access opening followed by biomechanical preparation will be performed using either rotary (TruNatomy 36/.03) or reciprocating (R-Motion 40/.04) instrumentation system as decided through randomisation following the manufacturer's instructions. Final use of cold saline for cryotherapy after root canal preparation will be performed as decided by randomisation of treatment allocation. The canals will be dried, filled with intracanal medicament (Calcium Hydroxide) and access cavities will be sealed with restorative cement.

The patient will be recalled after a week for completion of obturation using a single cone technique and resin-based root canal sealer. The access cavities will be restored with composite resin core and PFM crown.

Assessment of Postoperative Pain:

Patients will be asked to record the severity of post endodontic pain at 12h, 24h, 48h, 72h and 7 days on NRS-11 scale.

Assessment of periapical healing Periapical healing will be assessed using the Periapical Index (PAI). The teeth will be classified as healed (scores 1 or 2); healing (reduced score compared to baseline, but higher than 2); or not healed (teeth that presented the same or worst PAI score than that observed at baseline).

Clinical and radiographic evaluation will be done after an interval of 6 months postoperatively using Intraoral periapical radiographs and evaluated according to the above-mentioned index and criteria.

Inclusion Criteria:

1. Systemically healthy (ASA (American Society of Anesthesiologists)-I,II )(22) participants between 18 - 60 years of age with diagnosis of pulp necrosis and AAP in single rooted lower anteriors and premolars Tooth will be diagnosed as AAP if it shows no clinical symptoms (no pain on percussion or palpation).
2. Radiographic evidence of periapical pathology with PAI score between 2 - 5.

Exclusion Criteria:

The patients with the following clinical and radiographic features will be excluded from the study:

Clinical features:

1. Teeth with previous history of root canal treatment.
2. Teeth requiring severe prosthetic rehabilitation.
3. Pregnant or nursing mothers.
4. Periodontally compromised teeth.
5. Analgesic consumption for at least 12hrs before the visit.

Radiographic features:

1. Immature/ Open apex
2. Non-patent apical foramen
3. Root resorption
4. External resorption
5. Calcified pulp canals.