195 © 2017 Annals of Medical and Health Sciences Research Original Article How to Cite this Article: Kohli S, Bhatia S, Sexana K, Kalsi R, Rajeshwari K, Arora M. Discolouration of Polymethyl Methacrylate versus bis‑acrylic based Provisional Crown and Bridge Dental Resins: Effect of Storage Me‑ dia and Duration. Ann Med Health Sci Res. 2017; 7: 195‑199 This is an open access article distributed under the terms of the Creative Commons Attribution‑NonCommercial‑ShareAlike 3.0 License, which allows others to remix, tweak, and build upon the work non‑commercially, as long as the author is credited and the new creations are licensed under the identical terms. Abstract Background: Provisional restorations are frequently needed for several days to weeks, demanding them to be well made and stable with distinctive functions and purposes. In aesthetically critical region, the provisional restoration must not only deliver an initial shade match, furthermore must preserve its aesthetic appearance over the service period. Noticeable colour change may compromise the suitability of provisional restorations. Aim: This study aimed to determine the discolouration of poly (methyl methacrylate) (PMMA) and bis‑acrylic based provisional crown and bridge auto‑polymerizing resins when exposed to cofee, tea, orange and cranberry juice. Materials and Methods: Four auto‑polymerizing provisional crown and bridge resins, two methyl methacrylate and two bis‑acrylic were used. Specimens were randomly divided into fve groups (N=120, n=30) to be stored in artifcial saliva, artifcial saliva+tea, artifcial saliva+cofee, artifcial saliva+orange juice and artifcial saliva+cranberry juice. Colour measurements were taken before immersion, after 1 week and 1 month of immersion with the Spectrophotometer. Data were analysed using analysis of variance (ANOVA), independent samples t‑test, Schefe’s post‑hoc test, and paired t‑test. A signifcance level of a = 0.05 was used for all statistical analyses. Results: After the immersion period of 1 week and 1 month period, the post hoc analysis indicated that highest ∆E values were observed for Protemp II‑artifcial saliva + cofee as compared to other materials. Conclusion: The degrees of discolouration increased with immersion time. Methyl methacrylate resins were more resistant to discolouration than bis‑acrylic resins. After immersion for 1 month, artifcial saliva + cofee solution resulted in unacceptable discolouration for all the tested materials. Keywords: Crown and bridge resins, Discolouration, Duration, Provisional, Storage media Corresponding author: Shivani Kohli, Department of Prosthodontics, MAHSA University, Kuala Lumpur, Malaysia, Tel: 60-010-5472186; E-mail: shivani@mahsa.edu.my Discolouraton of Polymethyl Methacrylate versus Bis‑Acrylic based Provisional Crown and Bridge Dental Resins: Efect of Storage Media and Duraton Shivani Kohli 1 , Shekhar Bhatia 2 , Kirti Sexana 3 , Rupali Kalsi 4 , K. Rajeshwari 5 and Mansi Arora 6 1 Department of Prosthodontics, MAHSA University, Kuala Lumpur, Malaysia, 2 Division of Restorative Dentistry, School of Dentistry, International Medical University, Kuala Lumpur, Malaysia, 3 Department of Orthodontics, MAHSA University, Kuala Lumpur, Malaysia, 4 Department of Periodontics, Shree Bankey Bihari Dental College, Ghaziabad, U.P, India, 5 Department of Prosthodontics, Kle institute of dental sciences, Bangalore, 6 Department of Prosthodontics, Private Practioner, New Delhi, India Introduction Aesthetic provisional restorations are frequently needed for several days to weeks, demanding them to be well made and stable with distinctive functions and purposes. They act as a vital diagnostic and assessment tool for evaluating function, colour, shape, contour, occlusion, periodontal response, implant healing and largely aesthetics [1,2]. Although provisional restorations are usually intended for short-term use and then discarded, irrespective of that they should always be made to provide pleasing aesthetics, adequate support and good protection for teeth while maintaining periodontal health [3]. In aesthetically critical region, the provisional restoration must not only deliver an initial shade match, furthermore must preserve its aesthetic appearance over the service period. Noticeable colour change may compromise the suitability of provisional restorations. Staining of provisional materials may perhaps result in patient discontent and surplus expense for replacement. This is predominantly challenging when provisional restorations are exposed to pigments during lengthy treatment [4]. Henceforth, colour stability is a signifcant criterion in the selection of a particular provisional material for usage in aesthetically critical area. Amongst the materials used for constructing provisional fxed partial dentures polymethyl methacrylate has been extensive in practice. Poly(ethyl methacrylate), poly (vinylethyl methacrylate), bis-acrylic composite resin, and visible light- cured (VLC) urethane dimethacrylate and microflled have originated in current years. Epimine resin which was used in the past is no longer been used [4-6]. Provisional restorations can be prepared chair side directly in the mouth or indirectly outside on the patient’s cast [7]. The indirect technique is preferred over the direct technique for its accuracy [8,9]. Requisite of a crown and bridge interim material is to retain lasting colour stability in order to avoid replacement of restorations. Irrespective of their chemicophysical composition and the use of stabilizers [9,10]. dental resins incline to imbibe