Evaluation of the Impact of Different Final Irrigation Activation Modes on Healing of Periapical Lesions Related to Permanent Mandibular First Molars Using CBCT.

Periapical lesions are areas of infection and inflammation at the tip of a tooth's root. They develop when bacteria from inside the tooth's root canal system spread to the surrounding bone. Endodontic treatment (root canal treatment) aims to remove these bacteria so the infection can heal.

A key part of endodontic treatment is irrigation, which means rinsing the inside of the tooth with cleaning liquids to wash out bacteria, infected tissue, and debris. The two main cleaning liquids used in this study are sodium hypochlorite (NaOCl), which dissolves infected tissue and kills bacteria, and EDTA, which removes the smear layer (a thin film of debris left on the canal walls after cleaning).

The standard way to deliver these liquids is with a needle and syringe. However, the inside of a tooth has complex shapes, narrow areas, and side branches that a needle may not reach. To improve cleaning, dentists can use special devices that activate the liquid, helping it flow into these hard-to-reach areas. Different activation methods work in different ways:

Positive pressure activation uses sound waves to push the liquid deeper into the canals Negative pressure activation uses gentle suction to pull the liquid through the canals toward the root tip, which also helps stop the liquid from being pushed out beyond the root Combined activation uses both suction and sound waves at the same time

It is not yet clear which activation method leads to the best healing of periapical lesions over time. This study will compare four irrigation methods in adults to find out.

Study Design

This is a randomized controlled clinical trial. A total of 52 adults aged 20 to 40 years will take part. Participants will be randomly placed into one of four equal groups (13 people per group):

Group A (control group): Conventional needle irrigation. The cleaning liquid is delivered with a regular side-vented needle placed 2 mm short of the root tip.

Group B: Ultra X activation. A device that uses sound waves to activate the liquid.

Group C: Endo Vac activation. A device that uses suction to pull the liquid through the canals.

Group D: I Vac activation. A device that combines suction and sound waves.

Who Can Take Part

People may join the study if they:

Are between 20 and 40 years old Are in good general health Have a lower first molar that can be restored, with signs of symptomatic apical periodontitis and a small to moderate periapical lesion seen on a CBCT scan Agree to take part and sign a consent form

People cannot join the study if they:

Have a serious medical condition Are pregnant or breastfeeding Have an allergy to any medication used in the study Have a tooth that is loose, cannot be restored, has unusual anatomy, or has already had a root canal

What Participants Will Do

All endodontic treatment will be done in one visit by the same dentist. The steps are:

A full medical and dental history will be taken Before treatment, X-rays and a 3D dental scan (CBCT) will be taken to measure the size of the infection. This scan is the baseline for comparing how much healing happens later The tooth area will be numbed with local anesthesia Any decay will be removed and the tooth will be opened to reach the canals A rubber dam will be placed around the tooth to keep it clean and dry The length of each canal will be measured using an electronic device and confirmed with an X-ray The canals will be shaped and cleaned using rotary files, with 2.5% sodium hypochlorite used between each file The final rinse will be done using the method assigned to the participant's group, with 17% EDTA followed by 2.5% sodium hypochlorite. Saline will be used between liquids to prevent them from mixing The canals will be dried and filled using gutta-percha and a resin-based sealer The tooth will be restored with a resin composite filling

Follow-Up Participants will return for follow-up visits at 3, 6, 9, and 12 months. At each visit, the dentist will check the tooth and take a regular X-ray. At the 12-month visit, a new CBCT scan will be taken to measure how much the infection has healed.

How Healing Is Measured

The main outcome is healing of the periapical lesion at 12 months, measured using the Cone Beam Computed Tomography Periapical Index (CBCT-PAI). At 12 months, each tooth will be placed into one of three groups:

Healed: No symptoms and a CBCT-PAI score of 1 or 2, or no sign of infection on the scan Healing: No symptoms and a smaller lesion on the scan Diseased: Symptoms are present, or the lesion is the same size or larger

Teeth that are healed or healing will be counted as successful treatment. Teeth that are diseased will be counted as unsuccessful.

Risks and Confidentiality Any side effects will be recorded. All participant information will be kept private and stored securely. Data will be password-protected and kept for one year after the study ends.

Inclusion criteria

• - Medically free patients with no systemic disease: (American Society of Anesthesiologists / (ASA Class I or II).
• The age range is between 20 to 40 years.
• Patients have restorable Mandibular permanent molars that were diagnosed with necrotic pulp with symptomatic apical periodontitis (with small to moderate periapical lesion/≤ 5mm) .
• Positive patient's acceptance for participating in the study.
• Patients able to sign informed consent.
• Both male and female patients are eligible.
• Good oral hygiene.
• Mandibular first molars with two roots (mesial and distal), each presenting a Weine Type III canal configuration.

Exclusion criteria

• - Medically compromised patients.
• Pregnant or lactating females.
• Psychologically disturbed patients.
• Patients with a history of allergy to any medication used in the study were excluded.
• Mandibular first molar with:

• Wide or open apex.
• Vital pulp tissues.
• Periodontally affected with grade 2 or 3 mobility.
• Not restorable teeth.
• Abnormal anatomy and calcified canals.
• Previous root canal treatment.