The aim of the present study is to assess with PA x-rays and CBCT scans the volumetric changes in periapical radiolucencies in endodontically treated teeth 1 year after endodontic treatment and evaluate how well the lateral canals are filled after irrigation with the new generation of negative irrigation pressure unit with and without the ultrasonic irrigation.

This is a single center, prospective clinical study conducted in patients who present for routine endodontic therapy. The study has been reviewed and approved by the Institutional Review Board (Ethics Committee) Aspire IRB located at Santee, CA. The clinical investigator will treat patients who present with radiographic evidence of periapical pathology and will randomize the subjects to either negative pressure irrigation system treatment (EndoVac Pure) with ultrasonic irrigation or negative pressure irrigation system treatment (Endovac Pure) without ultrasonic irrigation. All other aspects of the treatment (access, instrumentation and obturation will be according to clinicians conventional clinical judgment. Subjects will have a pre-treatment PA x-ray and CBCT scan before treatment, a PA x-ray at six months and a CBCT scan at one year post-treatment.

Inclusion Criteria:

• Demonstrates understanding of the study and willingness to participate as evidenced by voluntary written informed consent and has received a signed and dated copy of the informed consent form.
• Aged at least 18 years.
• Understands and is willing, able and likely to comply with all study procedures and restrictions.
• Good general and mental health in the opinion of the investigator or medically qualified designee;
• No clinically significant and relevant abnormalities of medical history or oral examination;
• Absence of any condition that would impact on the subject's safety or wellbeing or affect the individual's ability to understand and follow study procedures and requirements.
• Single or multi rooted-canal teeth diagnosed with pulp necrosis and symptomatic/ asymptomatic apical periodontitis as tested with routine diagnostics.
• Radiographic evidence of periapical lesion.

Exclusion Criteria:

• Women who are known to be pregnant or who are intending to become pregnant over the duration of the study.
• Women who are breast-feeding.
• Pre-existing oral irritations. b) Recent (within 30 days) gingival/oral surgery. c) Any clinically significant or relevant oral abnormality.
• Known or suspected intolerance or hypersensitivity to the study materials (or closely related compounds) or any of their stated ingredients.
• Any subject requiring re-treatment.