## 1 Introduction  
Chronic apical periodontitis is the most prevalent diagnosed oral disease; several studies have highlighted the high prevalence of the root canal treated teeth in the population [1]. Rehabilitation of endodontically treated teeth (ETT) with extensive coronal loss is a clinical challenge due to the higher risk of biomechanical failure [2]. The conventional approach is to re-build the coronal structural defect with an adhesive restore material along with the post and full veneer crown. The material and shape of the post influence the biomechanical behavior of the ETT teeth; besides its limited application of a post in the short, wide, and curved root canals. The endodontic post presents an additional risk of accidental root perforation and root fracture because of the incompatible modulus of elasticity with radicular dentin [3]. Advances in adhesive dentistry and emphasis to develop conservative options to rehabilitate ETT lead to the proposal of endocrowns by [PERSON] in 1985 [4]. Later, [PERSON] et al. [5], and [PERSON] et al. [6] reported the case reports and clinical evaluation of endocrowns. The endocrowns are monolithicallyrestored with core and crown restoration. Endocrowns utilizes the macro-retentive support from pulp chamber walls and micromechanical retention from adhesive cementation [7]. The tooth preparation for monolithic endocrowns restorations is specific; required to satisfy the biomechanical principles to succeed for longer clinical service [8]. Definite guidelines recommended by the researchers include 2 mm occlusal thickness, butt joint margin of 1-1.25 mm and 5-7\({}^{\circ}\) divergence of coronal pulp chamber walls [9; 10]. Fewer additional modifications like immediate dentin sealing, lesser occlusal height, and uniform ferrule are suggested to improve the esthetic and biomechanical performance [11; 12]. Endocrowns provide advantages of reduced stress due to fewer different materials; unlike conventional crowns with numerous interfaces resulting from luting cement, post, core, and crown. The removal of radicular dentin to accommodate the post is not required and prevents the risk of recontamination of the canal. The secondary benefits are lesser gingival inflammation due to the supra-gingival positioning of the preparation margin and a reduced predisposition to recurrent caries. Previous investigators have reported the exceptional performance of endocrowns, particularly on molar teeth [13]. [PERSON] [14] recorded no difference in survival rate between the molars restored with conventional full veneer crowns and endocrowns over 12 years of observation. Lithium disilicate (LD) reinforced glass-ceramics with an improved flexural strength of 400 MPa and fracture toughness of 2.0 MPa is preferred monoblack material for endocrowns fabrication [15]. An additional advantage is its superior bond strength with the tooth substrate [16]. Utilization of CAD-CAM (Computer-aided design-computer aided milling) technology to fabricate the endocrowns resulted in the utility of numerous materials like resin composite, lithium disilicate, polymer infiltrated ceramic, hybrid ceramic, monolithic zirconia. The combined Physico-Mechanical Properties of ceramic and polymers are utilized to simulate the natural tooth structure in the polymer infiltrated ceramic (PIC). The PIC reported with a flexural strength of 130 MPa, fracture toughness at 1.4 MPa and comparable elastic modulus with dentin; is a promising material to be employed for the fabrication of endocrowns [17]. The PIC materials reported to bear occlusal force up to 1000 N; its mechanical properties and edge sharpness allow the fabrication of a thinner crown up to 0.2 mm [18]. Meanwhile, High translucency zirconia (HTZ) was introduced to overcome two common drawbacks of conventional zirconia including Veneer cracking and white opaque color. HTZ can be used for fabrication of monolithic, fully anatomical restorations; it is promising addition with enhanced esthetics and higher flexural strength compared to LD ceramic.