Influence on dimensional accuracy of volume of wash material introduced into pre-spaced putty/wash impressions.
This study compared the accuracy of stone models obtained from two-stage, pre-spaced putty/wash impressions under conditions in which known volumes of wash material were introduced during the second stage of the impression: Group I, a quantity of wash material corresponding to the space provided; Group II, double the quantity of wash material as the space provided; Group III, double the quantity of wash material, but with V-shaped vents in the putty for escape of excess material. Percentage deviations of the vertical dimensions of stone dies with respect to the master model were significantly different between Groups I and II (the latter being shorter) (p < 0.05). For horizontal dimensions, differences were less consistent, although the deviations for Groups I and II and Groups II and III, with respect to the master model, were significantly different from each other for two of the three dimensions measured (Group II inter-abutment distances were generally larger) (p < 0001 and p < 0.05, respectively). It is concluded that putty recoil, resulting from compression by excess wash material, plays a significant role in the undersizing of working dies, although the level of clinical relevance is less clear.
Omar
Ridwaan
R
Department of Prosthetic Dental Sciences, College of Dentistry, King Saud University, PO Box 60169, Riyadh 11545, Saudi Arabia. romar.ksa@zajil.net
Abdullah
Mohamed Aleem
MA
Sherfudhin
Haneef
H
D003760:Dental Impression Materials; D003761:Dental Impression Technique; D003830:Denture, Partial, Fixed; D003765:Models, Dental; D015203:Reproducibility of Results; D012826:Silicone Elastomers; D018709:Statistics, Nonparametric; D014716:Vertical Dimension
D003760:Dental Impression Materials; D012826:Silicone Elastomers