IOSR Journal of Dental and Medical Sciences (IOSR-JDMS) e-ISSN: 2279-0853, p-ISSN: 2279-0861.Volume 20, Issue 6 Ser.2 (June. 2021), PP 57-68 www.iosrjournals.org DOI: 10.9790/0853-2006025768 www.iosrjournal.org 57 | Page An in vitro study to evaluate and compare the color stability and flexural strength of commercially available PMMA based computer-aided design/computer-aided manufacturing and heat cure polymethyl methacrylate provisional restorative materials. Dr. Girish Sadashiv Nazirkar 1 , Dr. Swati Vijay Patil 2 , Dr. Tejas Uttamrao Sagar 3 , Dr. Urvashi Vijay Pithadia 4 1 (MDS, Head of Department of Prosthodontics and Professor) 2 (MDS Department of Prosthodontics) 3 (PG Student, Department of Prosthodontics) 4 (PG Student, Department of Prosthodontics) Abstract AIM: The aim of this study was to evaluate and compare color stability and flexural strength of three different commercially available CAD/CAM and conventional provisional restorative materials in multiple implant supported prosthesis at a time interval of 4 weeks. MATERIAL AND METHODS: Total 18 samples were fabricated, each group containing 6 samples. Group A samples were made of DPI heat cure tooth molding powder. Group B were made of Telio CAD PMMA blocks. Group C were made of VITA CAD. Colour stability and Flexural strength were measured and values obtained were evaluated and compared. RESULTS: Group B (Telio CAD) showed the highest color stability values (3.94 FSI) followed by group C (VITA CAD temp) (4.03 FSI) and group A (DPI) (4.37 FSI). The mean flexural strength values in group B (Telio CAD) (125.2 MPa) and (117.97MPa) were higher compared to the specimens of group C (VITA CAD temp) (106.7 MPa) and (99.30 MPa) and group A (DPI) (103.0 MPa) and (97.88 MPa) on posterior and anterior region respectively of each group. CONCLUSION: Telio CAD group specimens exhibited highest colour stability and flexural strength values followed by VITA-CAD temp group and DPI heat cure tooth molding group in multiple implant prosthesis. Key Words: CAD/CAM, flexural strength, colour stability, provisional restoration, multiple implant prosthesis. --------------------------------------------------------------------------------------------------------------------------------------- Date of Submission: 20-05-2021 Date of Acceptance: 05-06-2021 --------------------------------------------------------------------------------------------------------------------------------------- I. Introduction Edentulism is widespread among elderly people, and it is mainly accredited to dental caries and periodontal diseases. However, there is an association between sociodemographic factors, gender, age, lifestyle, low family-income and tooth loss. 1 Now a days, the progress made by dentistry, especially in the field of dental implant, offers many treatment options for edentulous patients. Among these are full arch implant rehabilitation, implant supported removable denture (overdenture) and combination of both solutions. 2 Implant-supported prostheses are successful treatment modalities that can be used for single tooth replacement to full mouth rehabilitation. Depending on the number of the implants used in fully edentulous patients, the restoration can be removable or fixed. 3 Another concept for restoring a fully edentulous arch with a fixed prosthesis is called the All-on-4 protocol. An All-on-4 prosthesis is a screw retained hybrid prosthesis supported by four dental implants. 3 The All-on-4 immediate loading concept was developed in 2003 by a dentist Paulo Malo and colleagues. This concept uses two vertical anterior implants in conjunction with two distally tilted inclined implants with their apices positioned anterior to the sinus wall or mental foramen. It involves the use of straight and angled multiunit abutments, which support a provisional, fixed and immediately loaded, full arch prosthesis. 4 In restoration driven implant placement, implants are positioned in relation to anticipated requisites of the restorative phase rather than the availability of bone. 5,6 Provisional restorations are used as a diagnostic restoration to evaluate the position and contours of the planned definitive restoration prior to surgical implant placement and also during the healing phase. A provisional restoration immediately placed with ovate pontics extending into the extraction sockets can preserve the pre-extraction soft tissue morphology. 7 They can also guide the healing of the peri-implant tissue and allow clinician to determine any necessary aesthetic or phonetic