title: Effect of investment type and mold temperature on casting accuracy and titanium-ceramic bond.
abstract: This study evaluated the casting accuracy of crown margins and metal-ceramic shear bond strength (SBS) of pure titanium injected into casting molds made using 2 investment types at 3 mold temperatures. Sixty crown (30-degree beveled finish line) and 60 cylinder (5mm diameter × 8mm high) patterns were divided into 6 groups (n=10), and cast using a phosphate-bonded investment (P) and a magnesium oxide-bonded investment (U), at 400°C (groups P400 and U400), 550°C (groups P550 and U550) and 700°C (groups P700 and U700) mold temperatures. Crown margins were recorded in impression material, the degree of marginal rounding was measured and margin length deficiencies (µm) were calculated. Titanium-ceramic specimens were prepared using Triceram ceramic (2mm high) and SBS was tested. Failure modes were assessed by optical microscopy. Data were subjected to two-way ANOVA and Tukey's HSD test (α=0.05). For casting accuracy, expressed by marginal deficiency (µm), investment U provided more accurate results (64 ± 11) than P (81 ± 23) (p<0.001). The increase in temperature resulted in different effects for the tested investments (p<0.001), as it provided better casting accuracy for U700 (55 ± 7) and worse for P700 (109 ± 18). Casting accuracy at 700°C (82 ± 31) was significantly different from 400°C (69 ± 9) and 550°C (68 ± 9) (p<0.05). For SBS, there was no significant differences among the groups for factors investment (p=0.062) and temperature (p=0.224), or for their interaction (p=0.149). Investment U provided better casting accuracy than investment P. The SBS was similar for all combinations of investments and temperatures.
authors: Department of Dentistry, Federal University of Sergipe, Aracaju, SE, Brazil.
authors: Mônica Barbosa
authors: MB
authors: Leal
authors: Valéria Oliveira
authors: VO
authors: Pagnano
authors: Osvaldo Luiz
authors: OL
authors: Bezzon
mesh_terms: D000704:Analysis of Variance; D003442:Crowns; D001840:Dental Bonding; D003734:Dental Casting Investment; D003735:Dental Casting Technique; D018772:Dental Marginal Adaptation; D003799:Dental Stress Analysis; D006801:Humans; D008277:Magnesium Oxide; D016876:Metal Ceramic Alloys; D010710:Phosphates; D033081:Shear Strength; D018709:Statistics, Nonparametric; D013696:Temperature; D014025:Titanium
chemical_list: D003734:Dental Casting Investment; D016876:Metal Ceramic Alloys; D010710:Phosphates; D008277:Magnesium Oxide; D014025:Titanium