The main goal of root canal treatment is the removal of existing microorganisms and the prevention of introducing new ones to the root canal system. This will require the application of strict aseptic measures. Microorganisms may also find their way into the root canal system through dental materials and instruments that are used during the treatment.

Some studies have suggested the necessity of decontamination of these materials and instruments prior to using. Also, the practice of changing gloves and disinfecting the tooth and rubber dam may help to reduce the possibility of introducing bacteria into the root canal space.

This study is aimed to evaluate the success rate of initial root canal treatment using an enhanced sterility protocol.

Patients will be randomized to either group 1 or 2.Randomization by blocks will be performed by a statistician at Kings College Dental Institute. Group 1 will receive a conventional root canal therapy. While in group 2,clinician will follow sterile protocol. This will be carried out at KCL Dental Institute at Guy's Hospital as a part of the routine dental treatment at the endodontic postgraduate unit. Potential participants will be given a written information sheet and sufficient time to consider participation. Fully informed written consent will be obtained if they are interested in participation.

After providing consent, all participants will receive dental periapical (PA) radiograph and Cone Beam Computed Tomography (CBCT) scans which are part of standard care in root canal treatment. Then, a clinical assessment will be carried out for the tooth needing treatment which is routinely done before treatment.

Participants will then be randomly assigned to one of treatment groups. Treatment will be carried out by MclinDent postgraduate students (PG) supervised by their assigned clinical supervisor. It is a standard of care for PG students to undertake this type of treatment. During the treatment, clinical samples will be taken from tooth decay and from the root canal. These samples will undergo microbiological analysis by the research team.

After one year, all patients will be contacted for follow up appointment. Paired clinical and radiographic examination (PA and CBCT) will be carried out, matching the baseline measures. Healing will be evaluated radiographically and clinically. The tooth of interest will be examined for any pain or discomfort, the restoration will be evaluated, and the scans will be checked for radiographic healing. This follow up procedure is a standard of care.

Inclusion Criteria:

1. Patients seeking root canal treatment over 18 years old.
2. Healthy patients.
3. Diagnosed with Irreversible pulpitis or pulpal necrosis on any molar tooth and accepting root canal treatment.

Exclusion Criteria:

1. Patients with clinical and radiographic diagnosis of previously treated root canal.
2. Anterior or premolar teeth.
3. Evidence of external or internal root resorption.
4. Pregnant women.
5. Patients younger than 18.
6. Patients unable to give consent.
7. Patients with compromised medical condition that affect the outcome of root canal therapy.
8. Non-restorable teeth.

Consented patients will be allocated an a pseudo anonymized number. This number will be used for the sample collection and all study analysis.

The Principal Investigator will maintain a document database of all patient's allocation numbers. Personal data, clinical notes and treatment records will be recorded in SALUD software as part of routine dental treatment at Guy's hospital. Only the chief investigator and supervisors will have access to the participants' allocation numbers and thus treatment records in SALUD during the study.