Comparision of Marginal Accuracy of Interim Restorations Fabricated From Autopolymerising Acrylic Resin: An In Vitro Study
*Corresponding Author: Dr. Sankar M, PG Student, Department of Prosthodontics, Sri Hasanamba Dental College and Hospital, Vidyanagar, Hassan
Background & Objectives
Fabrication of interim restorations is an important step towards achieving a successful prosthetic treatment. One of the most important morphologic and physiologic requirements for an interim restoration is good marginal adaptation. Poor marginal fit allows passage of fluids and bacteria in to the gap and may predispose the tooth to caries and pulpitis. The prime objective of this study was to compare the marginal accuracy of interim restorations made from two polymethyl methacrylate (PMMA) interm restorative materials.
An in-vitro method was used to simulate a clinical procedure in which the interim crown was made using a direct technique. An artificial maxillary first molar typhodont tooth was prepared for full cast crown restoration with 1mm chamfer and a taper of 5 degrees, and then the prepared artificial tooth was cast into a standard metal die. The metal die was lubricated and a wax pattern was made on it using Type 2 inlay wax. The impression of the die with the wax pattern was made with a putty type poly vinyl siloxane and this impression served as a matrix for making interim restorations.
Two PMMA provisional crown materials were distributed as follows:-
Group A: -Unifast Trad
Group B: -DPI Self cure tooth moulding material
15 interim restorations were made from each of the material used and a total of 30 interim restorations from all the four materials were fabricated. The marginal discrepancy of the interim restoration was determined by measuring the space between the margin of the interim restoration and the finish line of the metal die. The marginal discrepancies were visualized at 45X magnification using a steriomicroscope and interpreted using ProgRes image capture software.
The mean marginal gap obtained for PMMA materials was 269μm for DPI, 205μm for Unifast Trad.
Interpretation & Conclusions
Comparison of marginal accuracy between the two PMMA groups demonstrated that, Unifast Trad (GC dental) had a better marginal accuracy than DPI.
Polymethyl methacrylate (PMMA), Marginal integrity, Interim restoration.