Journal of AdvancedMedical and Dental Sciences Research

Background: Impression making of indirect restorations remains technically intricate due to the presence of voids, bubbles and other defects. Objective: The objective was to compare the defects present in impressions between three different techniques using hand mixing elastomers. Materials and methods: This is a cross sectional study. Three master impressions were made from each 32 crown preparations with three different techniques totaling to 102 master impressions. PVS impression material, putty (Aquasil ) and light-body (Reprosil) viscosity combinations were used for every patient with the three techniques i) single stage double mix technique ii) two stage technique with using a spacer and iii) two stage technique without using a spacer. The impressions were rated by two evaluators using Heine binocular magnifying loupe (2.3×) and the results tabulated. The results were presented as percentages.  Kappa test was done to compare the agreement of various impression techniques with each other. Results: Among the three techniques used, the single stage double mix technique showed the least presence of any type of defects in the impressions with (21%) followed by two stage technique without using a spacer (35%) and then the two stage technique using a spacer (44%).  Kappa test was used to compare the agreement of the different methods. Between Technique 1 and 2 (kappa = 0.532, p<0.001), technique 1 and 3 (kappa= -0.097, p= 0.5) and techniques 2 and 3 (kappa=0.025, p= 0.881).  Majority of the defects were voids (59%) and bubbles (30%) followed by pulls (11%). The number of defects located at the margins were 75% and 25% were located at others areas. Conclusion: The single stage double mix technique and two stage technique without using a spacer had a more favorable outcome in comparison to the two stage technique using a spacer using hand mixing technique.
Key words: polyvinylsiloxaneimpressionmaterial, voids, bubbles, tears, pulls