The influence of mold temperature on the fit of cast crowns with commercially pure titanium

Abstract

Commercially pure titanium (CP Ti) has been widely applied to fabricate cast devices because of its favorable properties. However, the mold temperature recommended for the manufacture of casts has been considered relatively low, causing inadequate castability and poor marginal fit of cast crowns. This study evaluated and compared the influence of mold temperature (430 degrees C--as control, 550 degrees C, 670 degrees C) on the marginal discrepancies of cast CP Ti crowns. Eight bovine teeth were prepared on a mechanical grinding device and impressions were used to duplicate each tooth and produce eight master dies. Twenty-four crowns were fabricated using CP Ti in three different groups of mold temperature (n = 8): 430 degrees C (as control), 550 degrees C and 670 degrees C. The gap between the crown and the bovine tooth was measured at 50 X magnification with a traveling microscope. The marginal fit values of the cast CP Ti crowns were submitted to the Kruskal-Wallis test (p = 0.03). The 550 degrees C group (95.0 microm) showed significantly better marginal fit than the crowns of the 430 degrees C group (203.4 microm) and 670 degrees C group (213.8 microm). Better marginal fit for cast CP Ti crowns was observed with the mold temperature of 550 degrees C, differing from the 430 degrees C recommended by the manufacturer.

Effect of the use of die spacer on the marginal fit of copings cast in NiCr, NiCrBe and commercially pure titanium

“…The use of only one layer of die spacer produced an intermediate value (131.07 μm) with no significant difference in relation to the higher and lower values. These results are consistent with those of previous studies, and highlight the importance of using this technical resource to ensure a lower discrepancy of prosthetic castings fabricated with alternative alloys (3,17,19).…”

“…In spite of their lower cost, these alloys do not offer the proper biosafety for clinical use, as their formulation contains metals such as nickel and beryllium (1). The introduction of titanium cast by the lost wax technique has given the perspective of using a material with high biocompatibility and a cost not as high as that of traditional gold alloys (2), despite the needed sophisticated technology for accurate casting (3).…”

“…According to some authors (3,9), copings cast in commercially pure titanium (cpTi) have shown appropriate marginal fit. Other studies, however, have stated that, though considered satisfactory, titanium's marginal fit is inferior to that of gold alloys (9).…”

“…Despite the technological advancements in terms of the improvement of casting techniques, die fabrication (11), waxing pattern (5) and coping fabrication (3,8,9,12), a discrepancy remains between the restoration's margin and the cervical edge of the prepared tooth. This discrepancy will be filled with cements that have different degrees of degradation in the oral environment.…”

Avaliação da adaptação marginal de copings metálicos fundidos em ligas de níquel-cromo, níquel-cromo-berílio e em titânio comercialmente puro em função da aplicação de espaçadores

“…The obtained data (µm) were submitted to statistical analysis (ANOVA) and Tukey test (p<0.05). There was not statistically significant difference among the materials VB II (93,40) and VB (118,73), and there was statistically significant different to 35) . In terms of the die spacer, there was a statistically significant difference among the three conditions (G0=177,31; G1=121,51 e G2=81,66).…”