Scientific Online Resource System

Journal of the Union of Scientists - Varna. Medicine and Ecology Series

Laboratory evaluation of the three-dimensional accuracy of three-unit zirconia fixed partial dentures

Kiril Gogushev, Zornica Vulcheva



From a clinical point of view, two of the main criteria for achieving long-term success in any prosthetic treatment with fixed partial dentures are good marginal adaptation and internal fit.


The aim of the present study is to measure and evaluate the three-dimensional cement layer of three-unit zirconium dioxide fixed partial dentures made by conventional and digital impression techniques.



To achieve the aim, 36 patients were examined. Two three-unit zirconium dioxide fixed partial dentures were fabricated on each patient using two different impression techniques. During the laboratory experiment, 144 silicone samples of the fabricated fixed partial dentures were made and 144 removable dies were scanned, of which 72 were plaster and 72 were 3D printed models. A total of 720 points were measured and evaluated on 144 sections.


The results of the analysis show that there is a significant difference between the distance in pt. Am to pt. Sd according to the impression technique used, with the values being higher in the fixed partial dentures made by conventional impression technique. No significant difference was found in the measured distances in the two jaws in the case of fixed partial dentures made by conventional impression, as in pt. Ad, pt. Vm, pt. Vd, pt. Om, and pt. Od larger distances are observed in the upper jaw.


The unsatisfactory accuracy of the fixed partial dentures may be the cause of plaque accumulation in the marginal area, leading to the appearance of a local inflammatory process, hypersensitivity, a thicker cement layer, micro-leakage and the appearance of secondary caries.


No statistically significant difference was found in the clinical parameter “marginal adaptation“ in the fixed partial dentures of the two studied groups.


digital impression, conventional impression, fixed partial denture, internal fit, laboratory scanner

Full Text


Abdel-Azim T., K. Rogers, E. Elathamna, A. Zandiejad, M. Metz, D. Morton. Comparison of the marginal fit of lithium disilicate crowns fabricated with CAD/CAM technology by using conventional impressions and two intraoral digital scanners. J Prosthet Dent. 2015 Oct; 114(4):554-9.

Ahrberg D, Lauer HC, Ahrberg M, Weigl P. Evaluation of fit and eficiency of CAD/CAM fabricated all-ceramic restorations based on direct and indirect digitalization: a double-blinded, randomized clinical trial. Clin Oral Investig 2016;20:291-300.

Almeida e Silva JS, Erdelt K, Edelhoff D, Araújo É, Stimmelmayr M, Vieira LC, et al. Marginal and internal fit of four-unit zirconia fixed dental prostheses based on digital and conventional impression techniques. Clin Oral Investig 2014;18:515-23.

Anadioti E, Aquilino SA, Gratton DG, Holloway JA, Denry I, Thomas GW, et al. 3D and 2D marginal fit of pressed and CAD/CAM lithium disilicate crowns made from digital and conventional impressions. J Prosthodont 2014;23:610-7.

Anadioti E, Aquilino SA, Gratton DG, Holloway JA, Denry IL, Thomas GW, et al. Internal fit of pressed and computer-aided design/computer-aided manufacturing ceramic crowns made from digital and conventional impres- sions. J Prosthet Dent 2015;113:304-9.

Benic GI, Sailer I, Zeltner M, Gütermann JN, Özcan M, Mühlemann S. Randomized controlled clinical trial of digital and conventional workflows for the fabrication of zirconia-ceramic fixed partial dentures. Part III: marginal and internal fit. J Prosthet Dent 2019;121:426-31.

Christensen G.J. The Challenge to Conventional Impressions, JADA, 2008, 139(3), p.347-349.

Clancy J.M., F.R. Scandrett, R.L. Ettinger. Long-term dimensional stability of three current elastomers. J Oral Rehabil, 1983, 10(4), p.325-333.

Davidowitz G, Kotick P.G. The Use of CAD/CAM in Dentistry. Dental Clinics of North America, 2011, 55(3), p.559-570.

Endo T., W.J. Finger. Dimensional accuracy of a new polyether impression material. Quintessence Int, 2006, 37(1), p.47-51.

Felton DA, Kanoy BE, Bayne SC, Wirthman GP. Effect of in vivo crown margin discrepancies on periodontal health. J Prosthet Dent 1991;65:357-64.

Haddadi Y, Bahrami G, Isidor F. Accuracy of crowns based on digital intraoral scanning compared to conventional impressionda split-mouth randomised clinical study. Clin Oral Investig 2019;23:4043-50.

Hondrum S.O. Changes in properties of nonaqueous elastomeric impression materials after storage of components. J Prosthet Dent, 2001, 85(1), p.73-81.

Kokubo Y, Ohkubo C, Tsumita M, Miyashita A et al. Clinical marginal and internal gaps of Procera All-Ceram crowns. J Oral Rehab, 2005, 32:526–530.

Koulivand S, Ghodsi S, Siadat H, Alikhasi M. A clinical comparison of digital and conventional impression techniques regarding finish line locations and impression time. J Esthet Restor Dent 2020;32:236-43.

May K.B., M.M. Russell, M.E. Razzog, B.R. Lang. Precision of fit: the Procera AllCeram crown. J Prosthet Dent, 1998, 80, p.394-404c.

Miyazaki T, Hotta Y, Kunii J, Kuriyama S, Tamaki Y (2009) A review of dental CAD/CAM: current status and future perspectives from 20 years of experience. Dent Mater J 28: 44-56.

Nawafleh NA, Mack F, Evans J, Mackay J, Hatamleh MM. Accuracy and reliability of methods to measure marginal adaptation of crowns and FDPs: a literature review. J Prosthet Dent 2013,22:419-28.

Papadiochos I., Papadiochou S, Emmanouil I. The Historical Evolution of Dental Impression Material. J Hist Dent. 2017 Summer/Fall; 65(2):79-89.

Rekow D. Computer-aided design and manufacturing in dentistry: a review of the state of the art. J Prosthet Dent, 1987, 58(4), p.512–6.

Schlenz M.A., Wöstmann B., Vogler J., Schmidt A., Rehmann P., Wöstmann W. New Intraoral Scanner-Based Chairside Measurement Method to Investigate the Internal Fit of Crowns:A Clinical Trial. Int J of Environ. Res. Public Health, 2020, 17,2182.

Shen C. Impression materials. In: Anusavice KJ, editor. Phillip’s science of dental materials 11 th edition. Philadelphia: Saunders; 2003. p. 210–30.

The Glossary of Prosthodontic Terms. 9Ed. Journal Prosthet Dent. 2017,117:10-92.

Tsirogiannis P, Reissmann DR, Heydecke G. Evaluation of the marginal fit of single-unit, complete-coverage ceramic restorations fabricated after digital and conventional impressions: a systematic review and meta-analysis.J Prosthet Dent 2016,116:328-35.

Tuntiprawon M, Wilson PR. The effect of cement thickness on the fracture strength of all-ceramic crowns. Aust Dent J 1995; 40: 17–21.

White SN, Ingles S, Kipnis V. Influence of marginal opening on microleakage of cemented artificial crowns. J Prosthet Dent 1994;71:257-64.

Zarauz C, Valverde A, Martinez-Rus F, et al: Clinical evaluation comparing the fit of all-ceramic crowns obtained from silicone and digital intraoral impressions. Clin Oral Investig 2016,20:799-806.



Font Size