## 1 Introduction  
The infection of the dental root canal system is called an endodontic infection [1]. Most endodontic infections are caused by bacteriawhich can cause an apical periodontitis [2]. This is viewed as a dynamic encounter between microbial factors and host defenses at the interface between infected radicular pulp and periodontal ligament that results in local inflammation, resorption of hard tissues, destruction of other periapical tissues, and eventual formation of various histopathological categories of apical periodontitis [3].The microorganisms reach the pulp by dental tubules especially when there is an open cavity after a coronal fracture and the pulp is in contact with the septic oral environment. Anotherpathway for the microorganism is the periodontal membrane when they use the lateral channel or the apical foramen [1]. Studies have shown that apical periodontitis could be associated with endodontic treatments. Despite technological advances made during the last couple of decades, studies continue to find high frequencies of substandard root fillings. Some reports show improvement in the quality of root fillings as assessed radiographically, but without a concomitant improvement in the apical health in connection with the root-filled teeth [4].Various studies have elucidated the importance of quality of root canal filling and coronal seal in the success for non-surgical endodontic therapy [5]. The imagistic diagnostic techniques are essential from the diagnostic viewpoint in various domains of the dental medicine. As the aim of the endodontic treatment is to maintain healthy periapical status, the radiographic exam allows the assessment of the changes of the periapical area related to the bone density and the progression of the periapical inflammation [6]. The absence of the periapical radio transparence confirms the effectiveness of the cleaning, disinfection and sealing provided by the root filling and coronal filling [7]. Ideal features of an imaging system are geometric accuracy, minimal superimposition, ease of availability and usage, reliable, reproducible, relatively inexpensive, and most importantly minimum radiation exposure to the patient [8]. Superimposition and image distortion can be some potential disadvantages of conventional radiographic examination which increased the interest for cone beam computed tomography (CBCT), despite the limited use of only 17% investigations in the endodontics field. However, CBCT should not be used routinely in the diagnosis of periapical lesions and endodontic applications due to the ALARA (As Low As Reasonably Achievable) [6,8]. Radiographic evaluation of the apical periodontitis can be made using the PAI scoring system given by [PERSON] in 1986. This is a five-point scale radiographic interpretation aimed to assess the absence, presence or changing of a diseased state. The reference is made up of a set of five radiographs with corresponding line drawings and their associated score on a photographic print [9]. Table 1 represents the description of PAI scores. Endodontic materials are used in endodontic treatment, which is the procedure to save the tooth when the pulp and/or peri radicular tissues are injured. These materials can be generally classified into two groups: materials used to maintain the vitality of the pulp (pulp capping materials) and materials used to disinfect (irrigants and intracanal medicaments) and fill the pulp in root canal therapy [10]. The use of an interappointment medicament has been shown to significantly improve disinfection after chemo mechanical procedures [11]. Calcium hydroxide is a commonly used intracanal medicament. It possesses several advantages such as tissue dissolving ability and antibacterial properties [12]. Chlorhevidine (CHX) is an antiseptic with a broad antimicrobial spectrum and high substantivity. It is commonly used as an interappointment root canal medication [13]. Camphor mono-chlorophenol (CMCP) has high antimicrobial activity.