Year : 2018

Volume : Volume 9

Issue : Issue 2

Abstract

Background:  Biologically acceptable fixed prosthodontics treatment demands that prepared teeth be protected and stabilized with provisional restoration that resembles the form and function of planned definitive treatment.  Aims and objective: The aim of study was to evaluate the effect of two different types of finish lines on marginal accuracy of provisional crowns made from bis-acryl composite resin provisional restorative materials using direct technique of fabrication. Material and method:  A total of 48 provisional restorations were made using bis-acryl composite resin provisional restorative materials, 24 specimens for each type of finish lines (shoulder and chamfer) using direct technique. Two artificial maxillary right first molar ivorine tooth were prepared for complete crown restoration, one with a 1 mm chamfer finish line and other with 1 mm shoulder finish lines and a taper of approximately 5 degrees and then casted  in non precious Ni-Cr alloy and 1 vertical reference line was marked at the midpoint of metal die finish line, each on mesial, distal, buccal and palatal sides. The provisional restorations were fabricated using bis-acryl composite resin on this metal die with a vinyl polysiloxane impression as matrix. The marginal discrepancies were measured using stereomicroscope at 30X magnification using Image J software.  Results:  No statistically significant difference was found between the adaptation of the temporary of the chamfer and shoulder type finish lines, although the marginal gap of the chamfer type finish lines increased from day 1 to day 7, this increase was not statistically significant. No statistically significant difference was found between the specimens of the shoulder type finish lines evaluated immediately after seating and those evaluated, after 1 or 7 days storage in a water bath. However, a significantly higher degree of marginal discrepancy was observed in the specimen stored 7 days as compared to those stored 1 day. Conclusion:  The type of finish lines may have a period influence on the marginal adaptation of temporary crowns.

Keywords: Temporary crowns, Marginal accuracy, Finish line, Stereomicroscopy.