The effect of investment type on the fit of cast titanium crowns

Abstract

In order to determine the best laboratory procedure for titanium crown casting, a set of thermal expansion measurements and casting experiments were carried out using a casting machine (argon arc, pressure difference type) and three different investments, two conventional SiO2 based investments and a new Al2O3/MgO based investment. The thermal expansion measurements involved a cycle of heating and cooling. The relatively low mould temperatures recommended (200 degrees C) or chosen (350 degrees C) for the conventional investments provided zero or negative mould expansion for the compensation of metal shrinkage. Crowns made from these investments exhibited heavy reaction with the mould, and the common cleaning method of sand blasting appeared to be essential. This cleaning process, however, was not adequate for the assessment of casting accuracy as the short sand blasting time (15 s) rapidly altered the fit of the crowns. The metal reacted little with the new investment and the best compensation (0.15 mm discrepancy) for the metal shrinkage, as assessed 'as cast', was achieved when the investment was heated to 950 degrees C and then cooled to the recommended mould temperature (600 degrees C).

Properties of experimental titanium cast investment mixing with water reducing agent solution

“…Therefore, some non-phosphate-bonded and non-silica investments for titanium have been successfully examined in dentistry [3][4][5][6][7][8][9][10][11][12][13]15,16,22) . Some of them have been commercialized, and some have remained at an experimental level.…”

“…As a result, the fired strength and thermal expansion of the mold seem to be insufficient. Generally, thermal expansion of the mold is caused by a refractory material, but may depend on additives 3,15,16) . We previously investigated mold materials for titanium casting 8,17,18) .…”

Influence of investment granulometry on the castability and surface roughness of castings obtained with Ni/Cr alloys

“…Various factors influence the castability of a metal, such as alloy composition 19 , investment type 11,18 , sprue design [20][21][22] , casting temperature 19 , type of casting machine 23 , surface tension of the alloy, and the direction of force during casting 18 . In this study, centrifugation may have influenced the castability test.…”

“…Various factors can influence the castability of an alloy, among them, its composition, surface tension and density, the direction of the force of cast, the types of machines used in the casting process, in addition to the sources of heating the alloy [7][8][9] . The investment used in the casting process of an alloy can also influence its castability, and has received a great deal of attention from researchers [10][11][12][13] . The granulometry of the investment, for example, can affect the setting time, surface roughness, in addition to a series of other properties of the casting [14][15][16] .…”

Effect of Zirconia‐Modified Magnesia Investment on the Casting of Pure Titanium

“…Titanium contamination with oxygen, hydrogen, and nitrogen during the casting procedure will result in alterations of its physical and mechanical properties. Several studies have focused on the casting of titanium [1][2][3][4]. Its reactivity with oxygen at elevated temperatures and low density make the casting process difficult.…”