FI59021B - STOED CONSTRUCTION FOER TAENDER - Google Patents

Description

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Patents and Registration Cases and Orders. «Krtft * n pubikend 27-02.81 (32) (33) (31) utuoikeut — Buglrd prlorltut 05-07-73 USA (US) 376767 , 501 George Street, New Brunswick, New Jersey, USA (72) Pei Sung, Lawrenceville, New Jersey, Irving Klaus, Highland Park, New Jersey, James Lee-You, Cranbury, New Jersey, USA (US) ( 7 * 0 0y Kolster Ah (5 ^) Dental support structure - Stödkonstruktion för tinder

The invention relates to a tooth support structure consisting of a metal core made of a base metal alloy and shaped to a desired shape, and a porcelain shell attached to the metal core, the support structure being characterized in that the metal core is made of an alloy consisting mainly of about 65-75 nickel. 15-23.5 by weight of # chromium, about 3.5-6 by weight of # silicon, about 3 ~ 5 by weight of # molybdenum, about 0.2-2 by weight of # boron and / or up to 1 by weight of # manganese, with an alloy melting point in the range of 1,232-1,288 ° C.

The percentages given are by weight based on the total amount of nickel, chromium, silicon, molybdenum, manganese and boron present in the alloy. The alloys have excellent dental physical properties with a melting point in the range of 1,232-1,288 ° C, good corrosion resistance compared to the corresponding cast gold or other commercial non-precious metal-tooth alloys, and good resistance to oxidation. When cast, they also have a tensile strength of at least 6,300 kg / cm, an elongation of about 0.5-5.0 # and a Rockwell B hardness in the range of about 9 ^ -110.

59021

Gold has been used for many years as a basic metal in dentistry for the manufacture of teeth, bridges, crowns, etc. Due to its high price, several attempts have been made to make non-precious metal alloys that could be used instead of gold. Such compositions are described, for example, in U.S. Patent Nos. 1,736,053, 2,089,500, 2,156,757, 2,131 * 1 + 23, 2,162,252, 2,631,095, 3,121,629, 3,1 + 6U 817, and 3 5 ^ 315. However, gold has many advantageous properties when used as a dental alloy, and many of the non-precious metal alloys hitherto made have proved unsatisfactory in many respects, especially compared to the gold metal commonly used.

One of the problems encountered in attempting to make non-noble alloys for use in dentistry instead of gold is that many of these alloys are difficult to cast because the melting point range is too high. In order for those working in dental laboratories to generally accept the alloy, its melting point should not be higher than 1,316 ° C and should preferably be in the range of about 1220 U to 1,288 ° C. A practical reason for this is that many dental laboratories use oxygen gas type lamps that do not heat much higher than 1 371 ° C, so that when using higher melting alloys, special heating equipment such as oxygen-acetylene lamps must be procured for metalworking.

Another problem with many hitherto well-known non-legged metal-li dental alloys is the corrosion problem. Alloys are generally not as resistant as gold to corrosion by oral acids. For example, it has been proposed to add beryllium to lower the melting temperature of dental alloys. However, the result has often further further reduced the corrosion resistance of the resulting non-precious metal alloy. An additional problem experienced in attempts to manufacture non-noble metal-tooth alloys is that the alloys cause discoloration to the porcelains when the porcelain is fused to the metal base during the manufacture of porcelain crowns, bridges, etc. For example, when cobalt or copper is included in a significant amount in an alloy, this tends to cause the porcelain to lose color when fused to a non-noble metal alloy. A further serious disadvantage of the commonly available dental metal alloys made for dental use is that these non-precious metal alloys cannot be easily soldered to each other or to gold using conventional dental soldering equipment that is readily available and used by dental laboratory personnel. In addition, hitherto designed non-precious metal-tooth alloy materials designed to be used as structural materials instead of gold have often been found to be considerably harder than gold, with the result that more time and effort is required to accurately grind metals into the mold after casting.

3,59021 The support structures of this invention use base metal alloys that are free from the disadvantages set forth above.

These base metal-tooth alloys, although not as resistant to corrosion as gold, have excellent anti-corrosion properties that are close to gold and are significantly more resistant to corrosion than the base metal-tooth alloys generally available. In many applications, these base metal-tooth alloys are significantly better than gold, in that they are considerably lighter than gold, but still have a higher tensile strength than gold. The dental alloys used in the support structures of the invention are also slightly harder than gold, but not too hard to cause any significant difficulty in grinding.

These dental alloys also have the property that they can be re-cast without a clear effect on their mechanical properties, soldering properties and corrosion resistance properties.

It has now been found that the above problems can be avoided by using an alloy consisting mainly of about 65 ~ 75 wt.% Nickel, about 15-23.5 wt.% Chromium, about 3.5 "6 wt. silicon, about 3 ~ 5 by weight of molybdenum, about 0.2-2 by weight of # boron and / or up to 1 by weight of # manganese, the alloy having a melting point in the range of 1,232-120 ° C.

All percentages are by weight, based on the total content of nickel, chromium, silicone, molybdenum, boron and manganese in the alloy. The melting point of these alloys is in the range of 1,232-1,288 ° C; they have good corrosion resistance, 2 good oxidation resistance, tensile strength, min. 6,300 kg / cm, percentage elongation about 0.5_5.0 and Rockwell B hardness about 9 ^ -110.

These dental alloys are very well suited for use as structural metals in dental work. Their melting point is in the range in which dental laboratories are usually accustomed to working and for which they are usually equipped. They adhere easily to the porcelain without staining or tensioning and have a coefficient of expansion such that the joint remains. They can be machined with dental soldering equipment, which is usually used by dental laboratory staff when working with gold. They can also be remelted and cast without compromising their excellent physical properties. In terms of their physical properties, they have good strength, hardness and resistance to corrosion and oxidation, while being lighter, stronger and harder than gold. They can be used instead of gold in most dental applications. They are designed for use where gold is now used and can be soldered, ground and 11,59021 machined in the same way as gold, requiring no changes to equipment or technology. Admittedly, the term good is relative, but as used herein, it means good when used in dental technology for which the material is intended. Thus, there is good corrosion resistance to corrosion by hydrochloric acid, which is superior to currently commercially available base metal-tooth alloys, and corrosion resistance to aqueous brine, which is comparable to conventionally used dental gold alloys. A good resistance to oxidation is such that the surface of the metal is not oxidized during work so that it cannot be easily attached to porcelain. Good strength and hardness means tensile strength and hardness that are better than currently used gold alloys, with a hardness of preferably less than about 120 Rockwell B, so that castings can be easily finished by grinding. The gold alloys currently used have a tensile strength of about 1+ 550 kg / cm and a Rockwell B hardness of about 86.

Preferred boron-containing compositions are those consisting mainly of $ 69-72 nickel, 18-20 # chromium, $ 0.05-5.5 silicon, U, O-U, 5%. Preferred compositions containing molybdenum and $ 1-1.5 boron and manganese mainly consist of 65 ~ 75 # nickel, $ 15-23.5 chromium, 3.5-6% silicon, 3 ~ 5% molybdenum and 1.0 # manganese.

The inclusion of boron and / or manganese in the alloy compositions used together with molybdenum improves to some extent the bond strength between the alloy and the porcelain when the porcelain is fused to the alloy such as in the manufacture of prostheses, crowns, bridges, etc.

Molybdenum used in alloys improves corrosion resistance and, together with boron and / or manganese, also improves other physical properties of the alloy.

When the chromium content is allowed to become too high relative to nickel, the thermal expansion of the alloy has been found to be too small to achieve good incorporation into porcelain. When the chromium content becomes too low, the alloy has generally been found to have significantly lower oxidation and corrosion resistance than is desirable.

The dental alloy compositions in question may contain small amounts of other materials such as titanium, zinc, magnesium and aluminum. However, any titanium should not be present in amounts higher than about 1% in amounts of tin and aluminum greater than about 2%, in amounts of zinc greater than about 0.5%, and in amounts greater than about 0.5% of magnesium. However, none of these are considered essential materials in alloy compositions and may or may not be included. Thus, the alloy compositions consist essentially of nickel, chromium, silicon, molybdenum, boron and / or manganese in the proportions indicated above.

The dental alloys used in the support structures according to the invention replace the heavier and more expensive gold, which has been a conventional structural metal in dental technology. Alloys are ideal for use when the alloy needs to be attached to porcelain, such as in the manufacture of dentures, crowns, bridges, etc. The alloy can also be used in the manufacture of both plastic and porcelain coatings. Their physical properties also make alloys very useful in the manufacture of metal crowns when the metal completely covers the fabricated tooth as well as in the manufacture of pin teeth and shells. In such use, the dental alloy rings now described have been found to be, not only as good as the gold hitherto used, but in many respects much better than such gold.

The practical aspect of the invention is further illustrated by the following examples, which are given by way of illustration only; the invention is not limited to the examples.

Example 1

To the annealed aluminum crucible add 1 U g of boron powder, 1 +, 1 g of granular silicon in the form of small lumps,> 1.2 g of molybdenum and 19.0 g of chromium in the form of a plate. 71.3 g of nickel bullets are then added. The crucible is then heated with resistance heat in an argon atmosphere to prevent oxidation. The contents are brought to a temperature of about 1600 ° C. The melt is then allowed to cool to about 500 ° C, after which the solid alloy is removed.

Test bars are cast from this alloy and have the following values: 2 2 6 2 tensile strength 9 2k0 kg / cm, yield strength 7 700 kg / cm, modulus of elasticity 1, 75 x 10 kg / em, elongation at 1.1 + 5% and Rockwell B hardness 106 R. The alloy has a thermal expansion coefficient of “6” of 79 x 10 cm / cm C, a melting temperature in the range of 1,232-1,260 ° C and a casting temperature of 1,316 ° C.

Portions of the alloy prepared as described above are tested for casting properties using standardized Lost Wax Technique casting procedures. The alloy is found to drain well. Using standard methods, parts of alloys are used to make metal crowns and bridges, and to make porcelain-bonded crowns and bridges where porcelain is attached to metal. The disappearance of the porcelain color is not observed and a good bond is obtained.

6 59021

The alloy can also be used for plastic-bonded crowns and bridges, using conventional methods used in their manufacture.

When machining the alloy, it is preferable to use an oxygen gas flame for melting rather than an oxygen-acetylene flame, although the latter can be used with caution.

Example 2 Using the technique described in Example 1, a dental alloy having a composition by weight of nickel of 67.8% chromium 22.0% molybdenum h, 2% silicon 5.0% manganese 1.0% 2 2 This tensile has a tensile strength of 8 275 kg / cm, yield strength 5,750 kg / cm, elastic modulus 1.7 x 10 kg / cm, elongation 3.5% and Rockwell B hardness 98 R_.

D

The alloy is also found to flow well using the Lost Wax technique and is found to behave well in the fabrication of metal crowns and bridges, porcelain-bonded crowns and bridges, in the manufacture of stud teeth and shells, and in the manufacture of plastic-bonded crowns and bridges. No staining of the porcelain is observed when making porcelain-metal joints. Excellent bond strengths are also obtained.

Example 3 Using the method of Example 1, alloys are prepared, the compositions of which are shown in Table 1 below. These alloys are used for the applications shown in the "Applications" column. In each use, the alloy is found to behave well using approved, normal dental laboratory methods.

The alloys in Table 1 have the physical properties shown in Table 2.

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The following Tables III and IV show values comparing the corrosion resistance and oxidation resistance of the alloys of Examples I and II to the corrosion resistance and oxidation resistance of a few commercially available materials. In order to obtain uniform comparison results, all samples used in the oxidation and corrosion tests are prepared in the same way. The samples are heated to their casting temperatures and then cast in air using standard Lost Wax technique. After cooling to room temperature, the castings are ground with Buehler Ab Handimet sandpaper to a grit of 600 grit, then polished with Buehler Selvyt fabrics (cotton cloth) using 0.3 μm alumina polishing powder.

To test for oxidation resistance, Table IV, the polished samples are then washed with water followed by washing with acetone. These are then heated in air to 53 ° C and then placed in a desiccator. After cooling, the samples are weighed and the weight recorded. The samples are then placed in a small oven, 7.56 x 7.56 x 3.78 cm, and heated to 982 ° C before being placed there. After heating for 5 minutes, the samples are removed and placed back in the desiccator and cooled. The samples are then weighed and the weight recorded when the difference in weight indicates the degree of oxidation.

To test for corrosion resistance, Table III, polished samples are washed with water followed by washing with acetone. The samples are then heated in air to 538 ° C and then placed in a desiccator to cool. The samples are then weighed and the weight recorded. The samples are then placed in aqueous solutions of known concentration and remain immersed in such a solution at ambient temperature for 20 days. The samples are then dried, weighed and the weight loss calculated.

Table I, Corrosion Resistance, gives values for human tooth enamel, dental amalgam, and copper-zinc tooth alloy. Values for these three metals are published by Kazuo Nagai in the Journal of Nihon University School of Dentistry, Tokyo, Japan, Vol 11. No. U, Issue 1969- In describing his method of preparing the sample, Mr. Nagai suggested that the samples were cast and then polished according to the manufacturer's instructions. .

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Claims (5)

12 59021 1. A tooth support structure consisting of a metal core made of a base metal alloy and shaped to a desired shape and a porcelain shell attached to the metal core, characterized in that the metal core is made of an alloy consisting mainly of about 65-75 nickel, about 15-23.5 weight - of # chromium, about 3.5 ~ 6 weight - of # silicon, about 3 ~ 5 weight - of - # molyhydene, about 0.2-2 weight - of # boron and / or up to 1 by weight of manganese, the alloy having a melting point in the range of 1,232-1,288 ° C. A dental support structure according to claim 1, characterized in that in the alloy the ratio of chromium to nickel is about 0.21 + -0.30 and the tensile strength of the alloy is at least 6,300 kg / cm. Dental support structure according to claim 1, characterized in that the alloy consists mainly of about 69 ~ 72 wt.% Nickel, about 18-20 wt.% Chromium, about U-5.5 wt.% Silicon, about UU, 5 by weight of # molybdenum and about 1-1.5 by weight of # boron. U-tooth support structure according to claim 3, characterized in that in the alloy the ratio of chromium to nickel is about 0.25 to 0.26 and the tensile strength of the alloy 2 is at least 6,300 kg / cm 3. A dental support structure according to claim 1, characterized in that the alloy consists mainly of about 65-75 wt.% Nickel, about 15-23.5 wt.% Chromium, 3.5-6 wt.% Silicon. , about 3-5 by weight of molybdenum and 1 by weight of # manganese, the alloy having a melting point in the range of 1,232-1288 ° C.