Statement of problem
The accuracy of impressions has been described in 1 or 2 dimensions, whereas it is most desirable to evaluate the accuracy of impressions spatially, in 3 dimensions.
The purpose of this study was to demonstrate the accuracy and reproducibility of a 3-dimensional (3-D) approach to assessing impression preciseness and to quantitatively comparing the occlusal correctness of gypsum dies made with different impression materials.
Material and methods
By using an aluminum replica of a maxillary molar, single-step dual viscosity impressions were made with 1 polyether/vinyl polysiloxane hybrid material (Identium), 1 vinyl polysiloxane (Panasil), and 1 polyether (Impregum) (n=5). Corresponding dies were made of Type IV gypsum and were optically digitized and aligned to the virtual reference of the aluminum tooth. Accuracy was analyzed by computing mean quadratic deviations between the virtual reference and the gypsum dies, while deviations of the dies among one another determined the reproducibility of the method. The virtual reference was adapted to create 15 occlusal contact points. The percentage of contact points deviating within a ±10µm tolerance limit (PDP10 = Percentage of Deviating Points within ±10µm Tolerance) was set as the index for assessing occlusal accuracy. Visual results for the difference from the reference tooth were displayed with colors, whereas mean deviation values as well as mean PDP10 differences were analyzed with a 1-way ANOVA and Scheffé post hoc comparisons (α=.05).
Objective characterization of accuracy showed smooth axial surfaces to be undersized, whereas occlusal surfaces were accurate or enlarged when compared to the original tooth. The accuracy of the gypsum replicas ranged between 3 and 6 µm, while reproducibility results varied from 2 to 4 µm. Mean (SD) PDP10-values were: Panasil 91% (±11), Identium 77% (±4) and Impregum 29% (±3). One-way ANOVA detected significant differences among the subjected impression materials (P<.001).
The accuracy and reproducibility of impressions were determined by 3-D analysis. Results were presented as color images and the newly developed PDP10-index was successfully used to quantify spatial dimensions for complex occlusal anatomy. Impression materials with high PDP10-values were shown to reproduce occlusal dimensions the most accurately.
To read this article in full you will need to make a payment
Purchase one-time access:Academic & Personal: 24 hour online accessCorporate R&D Professionals: 24 hour online access
One-time access price info
- For academic or personal research use, select 'Academic and Personal'
- For corporate R&D use, select 'Corporate R&D Professionals'
Subscribe:Subscribe to Journal of Prosthetic Dentistry
Already a print subscriber? Claim online access
Already an online subscriber? Sign in
Register: Create an account
Institutional Access: Sign in to ScienceDirect
- Dimensional accuracy of 2-stage putty-wash impressions: influence of impression trays and viscosity.Int J Prosthodont. 2007; 20: 573-575
- Three-dimensional analysis of dual-arch impression trays.Quintessence Int. 2003; 34: 189-198
- The effect of tray selection, viscosity of impression material, and sequence of pour on the accuracy of dies made from dual-arch impressions.J Prosthet Dent. 2003; 90: 143-149
- Accuracy of a reformulated fast-set vinyl polysiloxane impression material using dual-arch trays.J Prosthet Dent. 2009; 101: 332-341
- Accuracy and stability of impression materials subjected to chemical disinfection - a literature review.J Oral Rehabil. 2008; 35: 291-299
- Mechanical properties of 3 hydrophilic addition silicone and polyether elastomeric impression materials.J Prosthet Dent. 2004; 92: 151-154
- Detail reproduction, contact angles, and die hardness of elastomeric impression and gypsum die material combinations.Int J Prosthodont. 2000; 13: 214-220
- Accuracy of impressions obtained with dual-arch trays.Int J Prosthodont. 2009; 22: 158-160
- Clinical trial investigating success rates for polyether and vinyl polysiloxane impressions made with full-arch and dual-arch plastic trays.J Prosthet Dent. 2010; 103: 13-22
- Temperature effects on the rheological properties of current polyether and polysiloxane impression materials during setting.J Prosthet Dent. 2003; 90: 150-161
- Influence of prolonged setting time on permanent deformation of elastomeric impression materials.J Prosthet Dent. 2010; 103: 288-294
- Effect of different retraction and impression techniques on the marginal fit of crowns.J Dent. 2008; 36: 508-512
- Analysis of three-dimensional distortion of two impression materials in the transfer of dental implants.J Prosthet Dent. 2010; 103: 202-209
- Accuracy of implant impressions without impression copings: a three-dimensional analysis.J Prosthet Dent. 2011; 105: 367-373
- The effect of surface moisture on detail reproduction of elastomeric impressions.J Prosthet Dent. 2003; 90: 354-364
- Clinical parameters influencing the accuracy of 1- and 2-stage impressions: a randomized controlled trial.Int J Prosthodont. 2008; 21: 322-327
- Surface detail reproduction of elastomeric impression materials related to rheological properties.Dent Mater. 2008; 24: 951-956
- Hydrophilicity of unset and set elastomeric impression materials.Int J Prosthodont. 2010; 23: 552-554
- Dimensional accuracy and surface detail reproduction of two hydrophilic vinyl polysiloxane impression materials tested under dry, moist, and wet conditions.J Prosthet Dent. 2003; 90: 365-372
- Shark fin test and impression quality: a correlation analysis.J Dent. 2007; 35: 409-415
- Polyvinyl siloxane impression materials: an update on clinical use.Aust Dent J. 1998; 43: 428-434
- Full arch scans: conventional versus digital impressions–an in-vitro study.Int J Comput Dent. 2011; 14: 11-21
- Accuracy of intraoral data acquisition in comparison to the conventional impression.Int J Comput Dent. 2005; 8: 283-294
- Digitization of simulated clinical dental impressions: virtual three-dimensional analysis of exactness.Dent Mater. 2009; 25: 929-936
- ANSI/ADA Specification 19/ISO 4823:2000. Dental elastomeric impression materials. ADA, Chicago2004
- Effect of mixing technique on surface characteristics of impression materials.J Prosthet Dent. 1998; 79: 495-502
- Three-dimensional fit of CAD/CAM-made zirconia copings.Dent Mater. 2011; 27: 1273-1278
- Accuracy of newly formulated fast-setting elastomeric impression materials.J Prosthet Dent. 2005; 93: 530-539
- Impression material thickness in stock and custom trays.J Prosthet Dent. 1985; 54: 170-172
- Dimensional stability of elastomeric impression materials in custom-made and stock trays.J Prosthet Dent. 1984; 52: 514-517
- Effect of surface treatments on the wettability of vinyl polysiloxane impression materials.J Prosthet Dent. 2000; 84: 98-102
- A comparison of three wetting agents used to facilitate the pouring of dies.J Prosthet Dent. 1995; 74: 341-344
- The effect of a surface wetting agent on void formation in impressions.J Prosthet Dent. 1997; 77: 54-56
- An in vitro study of a surface wetting agent for addition reaction silicone impressions.J Prosthet Dent. 1994; 71: 390-393
- Comparison of two measurement techniques for clinical wear.J Dent. 1999; 27: 479-485
- Dental occlusion: a critical reflection on past, present and future concepts.J Oral Rehabil. 2008; 35: 446-453
- Report of a special test. NIST test No. 681/280055-10 October 8, 2010.accessed November 11, 2011.)
Supported in part by Kettenbach GmbH. Presented in part at the General Session of the International Association for Dental Research, Barcelona, Spain, July 2010.
© 2012 The Editorial Council of the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.