Effect of various putty-wash impression techniques on marginal fit of cast crowns.
Marginal fit is an important clinical factor that affects restoration longevity. The accuracy of three polyvinyl siloxane putty-wash impression techniques was compared by marginal fit assessment using the nondestructive method. A stainless steel master cast containing three abutments with three metal crowns matching the three preparations was used to make 45 impressions: group A = single-step technique (putty and wash impression materials used simultaneously), group B = two-step technique with a 2-mm relief (putty as a preliminary impression to create a 2-mm wash space followed by the wash stage), and group C = two-step technique with a polyethylene spacer (plastic spacer used with the putty impression followed by the wash stage). Accuracy was assessed using a toolmaker microscope to measure and compare the marginal gaps between each crown and finish line on the duplicated stone casts. Each abutment was further measured at the mesial, buccal, and distal aspects. One-way analysis of variance was used for statistical analysis. P values and Scheffe post hoc contrasts were calculated. Significance was determined at .05. One-way analysis of variance showed significant differences among the three impression techniques in all three abutments and at all three locations (P < .001). Group B yielded dies with minimal gaps compared to groups A and C. The two-step impression technique with 2-mm relief was the most accurate regarding the crucial clinical factor of marginal fit.
Department of Oral Rehabilitation, The Maurice and Gabriela Goldschleger School of Dental Medicine, Tel Aviv University, Tel Aviv, Israel. nissandr@post.tau.ac.il
Joseph
J
Nissan
Ofir
O
Rosner
Mohammed Amin
MA
Bukhari
Oded
O
Ghelfan
Raphael
R
Pilo
D002133:Calcium Sulfate / Q000737:chemistry; D003442:Crowns; D000044:Dental Abutments; D003760:Dental Impression Materials / Q000737:chemistry*; D003761:Dental Impression Technique / Q000295:instrumentation; D018772:Dental Marginal Adaptation; D003764:Dental Materials / Q000737:chemistry; D017267:Dental Prosthesis Design; D006801:Humans; D006813:Humidity; D008422:Materials Testing; D008853:Microscopy; D010969:Plastics / Q000737:chemistry; D020959:Polyethylene / Q000737:chemistry; D011145:Polyvinyls / Q000737:chemistry; D012833:Siloxanes / Q000737:chemistry; D013193:Stainless Steel / Q000737:chemistry; D013499:Surface Properties; D013696:Temperature; D013997:Time Factors
D003760:Dental Impression Materials; D003764:Dental Materials; D010969:Plastics; D011145:Polyvinyls; D012833:Siloxanes; C034183:vinyl polysiloxane; D013193:Stainless Steel; D020959:Polyethylene; D002133:Calcium Sulfate