The Journal of Contemporary Dental Practice

Register      Login



Volume / Issue

Online First

Related articles

VOLUME 11 , ISSUE 4 ( July, 2010 ) > List of Articles


An Evaluation of the Fit of Metal-Ceramic Restorations Made with an Autoclaved Silicone-Based Impression Material

Ralf Kollefrath, Marcel Savary, Jörg Schwela

Citation Information : Kollefrath R, Savary M, Schwela J. An Evaluation of the Fit of Metal-Ceramic Restorations Made with an Autoclaved Silicone-Based Impression Material. J Contemp Dent Pract 2010; 11 (4):63-70.

DOI: 10.5005/jcdp-11-4-63

License: CC BY-NC 3.0

Published Online: 01-05-2007

Copyright Statement:  Copyright © 2010; The Author(s).



To demonstrate the clinical feasibility of autoclaving certain silicone impression materials in order to avoid potential cross-contamination during handling, transport, and subsequent processing.


Semicritical devices are recommended to be treated at least with high-level disinfectants or actually steam sterilized at 134°C. To date dental impressions have been disinfected rather than sterilized, so the question remains should they be sterilized before being sent to the dental laboratory?

Case Descriptions

Two identical impressions per case were made of metal-ceramic crown and fixed partial denture preparations on the same patient using addition type polyvinyl siloxane (PVS) impression materials (AFFINIS, R Coltene/ Whaledent AG, 9450 Altstatten, Switzerland) in different trays. The first impression (IMPx1) was cleaned and treated with an intermediate-level disinfectant (FD 322.Fast Disinfection Spray, Durr Dental, 74321 Bietigheim-Bissingen, Germany). The second impression (IMPx2) was cleaned, treated with an intermediate-level disinfectant as with IMPx1, subjected to a computer tomography (CT) scan with a dimensional resolution of ±10 μm, steam sterilized, and then subjected to a second CT scan. The dimensional changes of the second impression after steam sterilization were calculated by comparing the overlay of the two CT scans and expressed by color coding of the impression graphics. After the second scan, the impression was sent to a dental laboratory to fabricate a metal-ceramic crown or metal-ceramic fixed partial denture restoration to the one produced from the first impression (IMPx1) subjected only to disinfection. This process was repeated for four clinical cases.


Impressions made with AFFINIS® silicone impression materials in a rigid reinforced polycarbonate impression tray or in a metal dual-arch tray can be autoclaved. The overall dimensional stability of the impressions and the quality of single crowns and small fixed partial dentures made using IMPx2 was not compromised. The maximum dimensional differences at the preparations of the nonautoclaved and the autoclaved impressions were found to be within acceptable limits of about 50–100 ìm.

Clinical Significance

Steam sterilization of AFFINIS® impressions is possible without adversely affecting dimensional change. In addition, clinicians can clearly indicate to the dental practice and laboratory personnel that sterilization of the impressions has been performed, cross-contamination is unlikely, and the impressions present no apparent health hazard during transport and subsequent processing.


Dr. Kollefrath is head of Research and Development, Elastomers at Coltène/ Whaledent AG, Altstätten, Switzerland, the manufacturer of the impression material evaluated in this report.


Kollefrath R, Savary M, Schwela J. An Evaluation of the Fit of Metal-Ceramic Restorations Made with an Autoclaved Silicone- Based Impression Material. J Contemp Dent Pract [Internet]. 2010 July; 11(4):063-070. Available from: view/volume11-issue4-kollefrath

PDF Share
  1. Guidelines for infection control in dental health care settings—2003. J Am Dent Assoc. 2004; 135(1):33-47.
  2. Disinfection and communication practices: a survey of U.S. dental laboratories. J Am Dent Assoc. 2000; 131(6):786-92.
  3. Bundesgesundheitsbl— Gesundheitsforschung Gesundheitsschutz. 2006; 49(4):375-94.
  4. Chemical disinfection of medical and surgical materials. In: Lawrence CA, Block SS, editors. Disinfection, sterilization and preservation. Philadelphia: Lea & Febiger; 1968. p. 517-31.
  5. Creutzfeldt-Jakob disease: recommendations for disinfection and sterilization. Clin Infect Dis. 2001; 32(9):1348-56.
  6. Testing of several methods of sterilization in dental practice. East Mediterr Health J. 1995; 1(1):80-6.
  7. Disinfection of impression materials: an evaluation of products and procedures. J Dent Res. 2002;81(Spec Iss A):3627.
  8. Antimicrobial biocides in the healthcare environment: efficacy, usage, policies, and perceived problems. Ther Clin Risk Manag. 2005; 1(4):307-20.
  9. Clinical Einzelevaluation of the efficacy of removing microorganisms to disinfect patient-derived dental impressions. Int J Prosthodont. 2008; 21(6):531-8.
  10. Sterilizing dental equipment. Nat Med. 1995; 1(12):1224-5.
  11. Disinfection and sterilization in health care facilities: what clinicians need to know. Clin Infect Dis. 2004; 39(5):702-9.
  12. S. Department of Labor, Occupational Safety and Health Administration. Best practices for the safe use of glutaraldehyde in health care [Internet]. 2006 [cited 2009 Feb 24]. Available from:
  13. Disinfection and sterilization of patient-care items. Infect Control Hosp Epidemiol. 1996; 17(6):377-84.
  14. Multidrug efflux pump overexpression in Staphylococcus aureus after single and multiple in vitro exposures to biocides and dyes. Microbiology. 2008; 154(Pt 10):3144-53.
  15. Reproducibility of sterilized rubber impressions. Braz Dent J. 2004; 15(3):209213.
  16. Dimensional stability of a polyvinylsiloxane impression material following ethylene oxide and steam autoclave sterilization. J Prosthet Dent. 1991; 65(4):519-25.
  17. Cross-contamination in the dental laboratory through the polishing procedure of complete dentures. Braz Dent J. 2004; 15(2):138-43.
  18. Infection control in the prosthodontic laboratory. J Indian Prosthodont Soc. 2007; 7(2):62-5.
  19. An analysis of the persistent presence of opportunistic pathogens on patient-derived dental impressions and gypsum casts. Int J Prosthodont. 2008; 21(1):62-8.
  20. Cross infection control of impressions: a questionnaire survey of practice among private dentists in Hong Kong. Hong Kong Dent J. 2006; 3:89-93.
  21. Contamination level of alginate impressions arriving at a dental laboratory. Clin Oral Investig. 2002; 6(3):161-5.
  22. In vitro study of transmission of bacteria from contaminated metal models to stone models via impressions. Clin Oral Investig. 2002; 6(3):166-70.
  23. Disinfection of impression materials and casts. Br Dent J. 2007; 202(1):36-7.
  24. A survey of the methods of disinfection of dental impressions used in dental hospitals in the United Kingdom. Br Dent J. 1996; 180(10):369-75.
  25. Disinfection of impressions. Methods and effects on accuracy. N Y State Dent J. 1997; 63(6):34-6.
  26. Dimensional stability and accuracy of elastomeric impression materials following steam autoclave sterilization. J Tokyo Dent Coll Soc. 1999; 99(3):193-205.
  27. Dimensional stability of addition cured silicone impressions following autoclave sterilisation. J Dent Res. 1999;78(5):1072.
  28. The effects of sterilization on addition silicone impressions in custom and stock metal trays. J Prosthet Dent. 1994; 71(6):625-30.
  29. Polyvinyl siloxane impression materials: an update on clinical use. Aust Dent J. 1998; 43(6):428-34.
  30. Accuracy and stability of impression materials subjected to chemical disinfection—a literature review. J Oral Rehabil. 2008; 35(4):291-9.
  31. Bestimmung der Randspaltbreite hochgoldhaltiger Restaurationen unter Berücksichtigung der Präparationsform der Abformmethodik und des Abformmaterials [dissertation]. Giessen: Justus-Liebig-Universität; 2003. p. 14-7.
  32. The significance of marginal gap and overextension measurement in the evaluation of the fit of complete crowns. J Contemp Dent Pract. 2005; 6(4):26-37.
  33. Histologischmorphometrische Studie zur Bestimmung des zervikalen Randschlusses von Einzelevaluation und Pfeilerkronen. [Histologic-morphometric studies to determine the cervical marginal fit of singe and pontic crowns.] Z Stomatol. 1987; 84(2):53-73.
  34. Marginal adaptation of fixed prosthodontics: a new in vitro 360-degree external examination procedure. Int J Prosthodont. 2004; 17(2):218-23.
  35. Prüfungsergebnisse zahnärztlicher Gussverfahren. Dtsch Zahnärztl Z. 1958;13:461–9.
  36. Marginal fit of gold inlay castings. J Prosthet Dent. 1966; 16(2): 297-305.
  37. The estimation of cement film thickness by an in vivo technique. Br Dent J. 1971; 131(3):107-11.
  38. Dimensional changes of dental impression materials by thermal changes. J Biomed Mater Res. 2001; 58(3):217-20.
PDF Share
PDF Share

© Jaypee Brothers Medical Publishers (P) LTD.