THE DIMENSIONAL STABILITY OF ELASTOMERIC DENTAL IMPRESSION MATERIALS
High accuracy dental impression is usually a first step during fabrication of indirect restorations that have to be seated in or on prepared teeth. The dimensional stability of the impression material could have an influence on the accuracy of the final restoration. Elastomeric materials (addition- cured silicones and condensation- cured silicones) are most frequently used as the impression material in fixed prosthodontics. The composition and the type of the chemical reaction determine the urgency to cast or digitize the impression. The aim of this study was to asses the dimensional stability of addition and condensation - cured silicones in time.
Stainless steel model of two cylinders with the spherical top was fabricated. First, individual tray of acrylic resin was made according to the standard procedure. Addition and condensation cured silicon impressions were taken using monophase technique in acrylic tray. Impressions were cast in type IV dental stone after different periods of time, and dental stone replica models were made. Master model and dental stone replica models were scanned using Carl Zeiss Coordinate measuring machine Contura G2 with associated volumetric probing tolerance of 1µm. Processing was done using Calypso software.
Addition and condensation cured silicon impressions were cast after different periods of time. Master model and dental stone replica models were scanned and the differences between the models were measured. The dimensional differences between the master model and the replica models occurred due to the dimensional instability of the impression material. The differences were significantly greater when condensation cured silicon impression material was used comparing to the addition cured silicon impression material.
Both condensation and addition silicon showed satisfactory dimensional stability if cast according to the manufacturer’s instructions. If so, the linear dimensional changes did not exceed 1%.
 E. E. Daou, The elastomers for complete denture impression: A review of the literature. The Saudi dental journal 22 (2010) 153-160.
 J. F. McCabe, A. W.G. Walls, Applied dental materials, Blackwell Publishing (2008) 167-172.
 A. M. Lacy, T. Bellman, H. Fukui, M. Jendersen, Time dependent accuracy of elastomer impression materials. Part I: condensation silicones. J.Prosthet. Dent 45/2 (1981) 209-214.
 A. M. Lacy, H. Fukui, T. Bellman, M. Jendersen, Time dependent accuracy of elastomer impression materials. Part II: polyether, polysulfides, and polyvinylsiloxane. J. Prosth. Dent 45/3 (1981) 329-333.
 ISO 10360-2:2001, Geometrical Product Specifications (GPS) – Acceptance and reverification tests for coordinate measuring machines (CMM) – Part 2: CMMs used for measuring size, ISO, 2001.
 M. Goldfogel, W.L. Harvey, D. Winter, Dimensional change of acrylic resin tray materials, Journal of Prosthetic Dentistry 54 (1985) 284-286.
 R. H. Hshamati, W. W. Nagy, C. G. Wirth, V. B. Dhuru, Delayed linear expansion of improved dental stone. The journal of prosthetic dentistry 88 (2002) 26-31.
 N. Martina, M.V. Martinb, N. M. Jedynakiewiczc, The dimensional stability of dental impression materials following immersion in disinfecting solutions, Dental materials 23 (2007) 760–768.
 J. M. Rodriguez, D. W. Bartlett, The dimensional stability of impression materials and its effect on in vitro tooth wear studies, Dental materials 27 (2011) 253–258.
 I. Budak, Dj. Vukelić, D. Bracun, J. Hodolić, M. Sokolović, Pre-Processing of Point-Data from Contact and Optical 3D Digitization Sensors, SENSORS 2012;12(1):1100-1126.
 M. L. Piter, Successful impression taking, First time. Everytime. Heraeus Kulzer 1st ed (2005) Armonk, NY.
 Ch.P.K Wadhwani, G.H. Johnson, X. Lepe, A.J. Raigrodski, Accuracy of newly formulated fast-setting elastomeric impression materials, Journal of Prosthetic Dentistry 93 (2009) 530-539.
 R. Pant, A. S. Juszczyk, R. K.F. Clark, D. R. Radford, Long-term dimensional stability and reproduction of surface detail of four polyvinyl siloxane duplicating materials, Journal of dentistry 36 (2008) 456–461.
 R. Butta, Ch. J. Tredwin, M. Nesbit, D. R. Moles. Type IV gypsum compatibility with five addition-reaction silicone impression materials, The Journal of Prosthetic Dentistry 93 (2008) 540-544.
 A. C. L. Faria, R. C. S. Rodrigues, . P. Macedo, M. G. C. de Mattos, R. F. Ribeiro, Accuracy of stone casts obtained by different impression materials, Brazilian oral research 22/4 (2008) 293-298.
 American National Standards institute/ American Dental Association. ANNSI/ADA specification no.19, dental elastomeric impression materials. Chicago: ADA. Journal of the American Dental Association 94 (2007) 733-741.
 J. R. Pereira, K. Y. Murata, A. L. de Valle, J. S. Ghizoni, F. K. Shiratori, Linear dimensional changes in plaster die models using different elastomeric materials, Brazilian oral research. 24/3 (2010) 336-341.
 M. Ona, H.Takahashi, M. Sato, Y. Igarashi, N. Wakabayashi, Effect of reactive adhesives on the tensile bond strength of polyvinyl siloxane impression materials to methyl methacrylate tray material, Dental Materials Journal 29 (2010) 336–340.
 Y. Marafie, S. Looney, S. Nelson, D. Chan, W. Browning, F. Rueggeberg, Retention strength of impression materials to a tray material using different adhesive methods: An in vitro study, J Prosthet Dent 100 (2008) 432-440.