Abstract
one of the main factors that affect the success of the cast crown is the accuracy of the internal and marginal fit, a well-fitting crown reduces the chance for recurrent caries and periodontal disease, whereas the space between a poorly-fitting crown and tooth preparation enables accumulation of bacterial plaque, the use of paint- on die spacing technique to produce the cement gap and subsequently to improve the seating of the cast crowns has become quite popular in the recent years. The purpose of the study is to compare the marginal gap and the internal fit produced by two paint-on die spacing materials (Manicure and paint on die spacer ). Twenty four identical stone dies were made, 12 were coated with paint- on die spacer material, and 12 were coated with nail varnish material, the dies coated with die spacer were divided into three groups (DA,DB,DC), and the dies coated with nail varnish were also divided into three groups (VA,VB,VC), groups DA and VA were coated with one layer, DB and VB were coated with two layers, DC and VC were coated with three layers, for both groups wax patterns were made and casted using the lost waxing technique and all steps were standardized, impression replicas of the casted crowns were made and sectioned by means of the impression replica technique, measurements were taken using Scanning Electron Microscope, from 4 points (marginal gap, mid-axial, axio-occlusal and mid-occlusal). There was no statistical significant difference in accuracy between crowns fabricated on die spacer coated dies and crowns fabricated on nail varnish coated dies. with the crowns fabricated on die spacer coated dies being slightly more accurate.