Bond strength of porceiain on cast vs. wrought titanium
Tore Derand^ and Hakon 'Department of Oral Technology, Lund Centre for Oral Health Sciences, Malmo, Sweden, ^Scandinavian institute of Dental Materiais, Oslo, Norway
Derand T, Hero H: Bond strength of porcelain on cast vs. wrought titanium. Scand J Dent Res 1992; 100: 184-8.
The bond strength of porcelain fused to cast and wrought titanium surfaces was calculated from fracture loads in a 4-point bending test. Two different porcelain were applied (O'Hara and Duceratin). The surface of Ti-cast specimens was treated in two different ways to produce variations in the impurity level before porcelain veneering. Microhardness measurements as well as scanning electron microscopy with EDX analysis were conducted. The results showed no significant difference in bond strength between the two porcelains. Nor was any difference in bond capacity found between thoroughly blasted castings and wrought titanium. Significantly lower bond strengths were observed for lightly blasted specimens and for specimens treated with Gold bonding agent. Impurities in the surface region of the castings were found to be due to contact with the investment during solidification. This indicates that a thin surface layer (50-100 |im) of the casting should be removed before firing of the porcelain.
Alloys for porcelain veneering have been successfully used for several years. At first high gold alloys were mostly applied, but in recent years a number of alternative noble and base metal alloys have been available. During the past decade efforts have been made to develop techniques and processes for crown and bridgework of pure titanium and even titanium alloys. Casting of titanium can be carried out but it demands special machines and protection gas to avoid oxidation of the metal. Other techniques are to use electro eroding or machining of the metal framework (1). Titanium also demands low fusing porcelains as temperatures above 800°C will give an increasingly thick oxidation layer with a rather weak bond to the underlying titanium. Table 1
«=10 * P
Tore Derand^ and Hakon 'Department of Oral Technology, Lund Centre for Oral Health Sciences, Malmo, Sweden, ^Scandinavian institute of Dental Materiais, Oslo, Norway
Derand T, Hero H: Bond strength of porcelain on cast vs. wrought titanium. Scand J Dent Res 1992; 100: 184-8.
The bond strength of porcelain fused to cast and wrought titanium surfaces was calculated from fracture loads in a 4-point bending test. Two different porcelain were applied (O'Hara and Duceratin). The surface of Ti-cast specimens was treated in two different ways to produce variations in the impurity level before porcelain veneering. Microhardness measurements as well as scanning electron microscopy with EDX analysis were conducted. The results showed no significant difference in bond strength between the two porcelains. Nor was any difference in bond capacity found between thoroughly blasted castings and wrought titanium. Significantly lower bond strengths were observed for lightly blasted specimens and for specimens treated with Gold bonding agent. Impurities in the surface region of the castings were found to be due to contact with the investment during solidification. This indicates that a thin surface layer (50-100 |im) of the casting should be removed before firing of the porcelain.
Alloys for porcelain veneering have been successfully used for several years. At first high gold alloys were mostly applied, but in recent years a number of alternative noble and base metal alloys have been available. During the past decade efforts have been made to develop techniques and processes for crown and bridgework of pure titanium and even titanium alloys. Casting of titanium can be carried out but it demands special machines and protection gas to avoid oxidation of the metal. Other techniques are to use electro eroding or machining of the metal framework (1). Titanium also demands low fusing porcelains as temperatures above 800°C will give an increasingly thick oxidation layer with a rather weak bond to the underlying titanium. Table 1
«=10 * P
