Comparative assessment of marginal accuracy of grade II titanium and Ni-Cr alloy before and after ceramic firing: An in vitro study

ABSTRACT

Objective: The aims of the study are to assess the marginal accuracy of base metal and titanium alloy casting and to evaluate the effect of repeated ceramic firing on the marginal accuracy of base metal and titanium alloy castings. Materials and Methods: Twenty metal copings were fabricated with each casting material. Specimens were divided into 4 groups of 10 each representing base metal alloys castings without (Group A) and with metal shoulder margin (Group B), titanium castings without (Group C) and with metal shoulder margin (Group D). The measurement of fit of the metal copings was carried out before the ceramic firing at four different points and the same was followed after porcelain build-up. Results: Significant difference was found when Ni-Cr alloy samples were compared with Grade II titanium samples both before and after ceramic firings. The titanium castings with metal shoulder margin showed highest microgap among all the materials tested. Conclusions: Based on the results that were found and within the limitations of the study design, it can be concluded that there is marginal discrepancy in the copings made from Ni-Cr and Grade II titanium. This marginal discrepancy increased after ceramic firing cycles for both Ni-Cr and Grade II titanium. The comparative statistical analysis for copings with metal-collar showed maximum discrepancy for Group D. The comparative statistical analysis for copings without metal-collar showed maximum discrepancy for Group C.

Key words:

Ni-Cr (Nickel-Chromium) - titanium - titanium casting

• REFERENCES

• 1 Dalmau LB, Alberty HC. A study of nickel allergy. J Prosthet Dent 1984; 52: 116-20
• 2 Kelly JR, Rose TC. Nonprecious alloys for use in fixed prosthodontics: A literature review. J Prosthet Dent 1983; 49: 363-7
• 3 Parr GR, Gardner LK, Toth RW. Titanium: the mystery metal of implant dentistry. J Prosthet Dent 1985; 54: 410-5
• 4 D′Mello Wendy, Aras M, Chitra V. Titanium in prosthodontics: A review. J Indian Prosthet Soc 2004; 4: 14-7
• 5 Kurt M. Titanium and its alloys. Mat Engn 1974; 79: 61-5
• 6 Bronson MR, Lindquist TJ, Dawson D. Clinical acceptability of crown margins versus marginal gaps as determined by pre-doctoral students and prosthodontists. J Prosthodont 2005; 14: 226-32
• 7 Jahangiri L, Wahler C, Hittelman E, Matheson P. Assessment of sensitivity and specificity of clinical evaluation of cast restoration marginal accuracy compared to stereomicroscopy. J Prosthet Dent 2005; 93: 138-42,6
• 8 Gemalmaz D, Berksun S, Kasapoglu C, Alkumru HN. Distortion of metal-ceramic fixed partial dentures resulting from metal conditioning firing. Quintessence Int 1996; 27: 193-7
• 9 Bridger DV, Nicholls JI. Distortion of ceramometal fixed partial dentures during the firing cycle. J Prosthet Dent 1981; 45: 507-10
• 10 DeHoff PH, Annusavice KJ. Effect of metal design on marginal distortion of metal ceramic crowns. J Dent Res 1984; 63: 1327-32
• 11 Gardner FM, Tillman-McCombs KW, Gaston ML, Runyan DA. In vitro failure load of metal-collar margins compared with porcelain facial margins of metal-ceramic crowns. J Prosthet Dent 1997; 78: 1-4
• 12 Gemalmaz D, Berksun S. Thermal cycling distortion of porcelain fused to metal fixed partial dentures. J Prosthet Dent 1998; 80: 654-60
• 13 Lang BR, Gemalmaz D, Alkumru HN. Marginal fit changes during porcelain firing cycles. J Prosthet Dent 1995; 73: 49-53