Journal of Pharmaceutical Negative Results ¦ Volume 13 ¦ Special Issue 6 ¦ 2022 1090 Comparative evaluation of retention of lithium disilicate crowns with four different cementation systems- An in-vitro Study Dr. Dhaniram Talukdar 1 , Dr. Bharti Dua 2 , Dr. Pankaj Datta 3 , Dr. Anupam Bhardwaj 4 1 Senior Lecturer, Department Of Prosthodontics, Divya Jyoti Dental College, Modinagar, 2 Senior Lecturer, Department Of Prosthodontics, Santosh Dental College, Ghaziabad. 3 Prof and Head, Department of Prosthodontics, Inderprastha Dental College, Sahibabad, 4 Senior Lecturer, Department of Oral & Maxillofacial Prosthesis, Santosh Dental College, Ghaziabad DOI: 10.47750/pnr.2022.13.S06.146 AIM OF THE STUDY: This in vitro study was performed to compare the retention of pressable lithium disilicate crowns cemented with four different cementation systems. METHODS: Eighty single rooted maxillary 1st premolars were collected after excluding teeth with caries and/or previous restorations. Preparation of the samples was standardized by using a diamond bur mounted onto a surveyor. An anatomic crown was waxed on each tooth and then hot pressed using lithium disilicate ceramic (IPS e.max PRESS, IvoclarVivadent). The samples were randomly divided into 4 groups (n = 20) according to different cementation systems. Each group sample was subjected to a seating force of 50N using universal testing machine. Each upper block was pulled along the path of insertion of the crown with a crosshead speed of 1mm/min. RESULTS: Self adhesive resin cement showed the maximum tensile strength among all adhesive luting cements (2.65 MPa). Self etch resin cement group showed mean tensile strength of (1.78 MPa) that was marginally less than total etch resin cement (1.86 MPa). Glass ionomer cement exhibited least tensile strength (1.41 MPa) compared to the other three luting cements. CONCLUSION: Within the limitations of this in vitro study, it was concluded that lithium disilicate full coverage crowns cemented with self adhesive resin cement showed higher bond strength followed by total etch resin cement, self etch resin cement and glass ionomer cement. Keywords: Lithium disilicate, Self adhesive resin cement, Self etch resin cement, Total etch resin cement, Glass ionomer cement, Self cure acrylic resin. INTRODUCTION Restorative dentistry has modified treatment planing in several aspects due to the myriad of options available for fabricating indirect restorations which have come up over the past few decades, especially pertaining to ceramics and resin cements.1 Ceramic is a solid mixture (metal and non-metal elements) with crystalline structure. Restorations with high crystalline content are very popular due to high esthetic value and increased mechanical properties compared to metal frameworks fused to ceramic (PFM) crowns.2 They are strong, inert, and stable at high temperature and have good optical properties to provide esthetic results.3 Despite the fact that for most of the fixed restorations, PFM (Porcelain fused to metal) option is used, the market interest is drifting towards greater use of all-ceramic. All-ceramic systems provide better esthetic advantage than PFM restorations; since the blackish hue of the metal is replaced by ceramic material with variable degree of value (opacity-translucency), which helps in achieving better esthetic results with certainty. Also, many a times the emergence profiles of PFM restorations are over contoured because a large amount of ceramic,