JPS6339534B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a new material used in dental supplies, dental treatment, etc., and more particularly to a new mica-based dental composition that has excellent resistance to contamination during use. The main purpose of dentistry is to replace or correct damaged or deformed teeth by fabricating and installing dental structures. Commonly used dental structures include tooth bases,
Dental appliances such as bridges and orthodontic brackets, accessories for such dental appliances, prosthetic appliances, e.g.
These include inlays, onlays, partial or complete dentures, and crowns or caps. These dental structures are inert in the mouth, can resist chewing forces, can provide a desired anatomical shape, and have an aesthetic appearance similar to that of natural teeth. It must be something that presents itself. However, there are few materials that simultaneously satisfy all of these requirements. Currently available dental structures are generally comprised of alloys, porcelain, amalgam, acrylic polymers, or combinations thereof. Alloys and amalgams look significantly different from regular teeth, so
This is undesirable when aesthetics are particularly important. Porcelain clay and acrylic polymers are often weak and cannot withstand chewing. There are composite structures, for example, those in which the lower structure is made of metal and the upper structure is made of porcelain clay to improve the appearance, but such composite structures require advanced technology and are often Bulk density is too high. Conventional dental structures thus represent a reasonable compromise between various requirements. As a recent promising research in the field of dental treatment, the use of mica-based glass-ceramics for manufacturing dental structures has been proposed by CHPameijer et al. a Castable
Ceramic Dental Restorative Material)
It is described in AADR Abstract 827, J.Dent.Res., 59 (March 1980 issue), p. 474. Glass-ceramic is a semi-crystalline material obtained by controlled crystallization of glass in situ with appropriate heat treatment; US Pat. No. 2,920,971 first disclosed such a material. Glass-ceramics consist primarily of crystals (over 50% by volume are crystals, often over 90% by volume are crystals) and therefore have a higher composition than the starting glass or precursor glass from which they are made. It exhibits properties very similar to those of the glass phase.
Thus, the properties of glass-ceramics can vary widely depending on the particular crystalline phase present therein. Among the more recently developed glass-ceramic materials are mica-containing glass-ceramics, first disclosed by U.S. Pat. No. 3,689,293. Mica-containing ceramics have relatively special properties that make them particularly desirable for making dental instruments and structures.
That is, the ceramic is not brittle, can withstand point impact, and does not propagate fracture. Thus, mica-based glass-ceramic bodies can be pushed through point hardness tests that would destroy conventional porcelain clay bodies.
This behavior occurs because the mica crystal, which is the main component, can flow plastically to some extent by transition sliding along the base plane or cleavage plane. The glass ceramic of U.S. Patent No. 3,689,293 is
It is described as a machinable glass ceramic because it can be cut and formed using conventional metal processing equipment and processing methods. The crystalline phase which is the main constituent of the ceramic is a fluorophlogopite solid solution (e.g. fluorophlogopite [KMg ₃ AlSi ₃ O ₁₀ F ₂ ] and/or boron fluorophlogopite [KMg ₃ BSi ₃ O ₁₀ F ₂ ] (consisting of crystals). Although these materials have excellent machinability,
CHPameijer et al. in the above-mentioned paper suggest that tetrasilicide mica glass ceramics should be used to obtain dental reinforcements. Glass ceramics of this type are described in U.S. Pat. No. 3,732,087 and contain tetrasilicic fluormica (e.g.
KMg _2.5 Si ₄ O ₁₀ F ₂ ). Further descriptions of the use of these materials for dentistry can be found in previously published European patent applications
Found in EP22655. Fluoromica tetrasilicide glass ceramics contain Al ^{+3 and}
In that both B ⁺³ are removed from the crystal structure,
Different from glass ceramics containing fluorophlogopite and boron fluorophlogopite.
Due to such substitution, the tetrasilicide glass ceramic material exhibits better chemical durability and mechanical strength. This specification refers to the above-mentioned U.S. patent no.
Nos. 3,689,293 and 3,732,087 are cited and used as reference for the explanation of the known mica-based glass ceramic materials mentioned above. The present invention now relates to improvements in mica tetrasilicide glass ceramics used in the manufacture of dental structures and other applications, and the ceramics according to the present invention have significantly improved resistance to contamination. Pollution resistance is
Although most important in applications such as dental prosthetics, it is also desirable in other applications where frequent contact with contaminating media is expected (eg tableware). In accordance with the present invention, thermal crystallization for tetrasilicated fluoromica glass ceramics with significantly improved contamination resistance is achieved by controlling the addition of small amounts of Al ₂ O ₃ and ZrO ₂ to a specific tetrasilicated fluoromica composition. A synthetic glass is obtained. That is, the present invention provides thermocrystalline glass and in-situ processing of the glass.
site) Contains stain-resistant tetrasilicated fluoromica products (e.g. dental structures) made by crystallization. The preferred composition of the glass and glass-ceramic products of the present invention is approximately 45-70% by weight as the composition of the batch of glass.
_SiO2 , 8-20% MgO, 8-15% _MgF2 , 5
~35% R ₂ O + RO, where R ₂ O is
in the range of 5-25% and 0-20% _K2O ,
consisting of one or more oxides selected from the group consisting of 0-23% Rb ₂ O and 0-25% CS ₂ O, and RO is in the range 0-20%, and SrO , an oxide selected from the group consisting of BaO and CdO, further comprising 0.5 to 7% ZrO ₂ ,
It contains 0.05-2% _Al2O3 , and the total _{amount of ZrO2} + _Al2O3 is 1-9%. Optional ingredients that are also advantageous for use in dental applications include 0-7% _TiO2 and 0-10% conventional glass colorants. Of course, in addition to the above-mentioned components, other components that are well known to be compatible with tetrasilicated fluoromica compositions may also be added, such as metals from Groups of the Periodic Table. and oxides of transition metals. Glasses in the above composition range may be crystallized in situ into glass-ceramic products by nucleation and crystallization heat treatments conventionally used to produce glass-ceramics. Can be done. A preferred heat treatment involves heating the glass for a period of time ranging from 0.25 to 10 hours for approximately
Subjected to a nucleation temperature of 650-850°C, and about 1-850°C
It consists of subjecting to a crystallization temperature ranging from 800 to 1200° C. for a time ranging from 100 hours. The present invention will be described in further detail below with reference to the accompanying drawings. This figure shows the high stain resistance of the glass-ceramic material obtained according to the invention. A method for objectively evaluating the color of candidate materials for teeth and dental structures has recently been developed by DG.
“Evaluation of the Color of a Cast Ceramic Reinforcement Material” by Grossman et al.
Cast Ceramic Restorative Material)”AADR
Abstract 1094, J.Dent.Res., 59 (March 1980 issue), page 542. This method is
It consists of analyzing the light reflected by a sample of the material to be evaluated using a photometer such as a Chromascan shaded scanner (available from Sterndent, Stanford, Conn., USA). By operating this scanner, the intensity in the red, green and blue spectral regions of the light reflected by the material to be evaluated is measured, and the obtained values are used to calculate the hue of the reflected light (the proportion of the three primary colors). ), saturation (color saturation) and lightness (overall brightness on the white-black scale)
Calculate. The stain resistance of a certain candidate material can be determined objectively by performing the above color evaluation before and after subjecting the material to a stain treatment. Using the method described in the above-mentioned paper by Grossman et al., the hue is approximately 0.2 to 0.8, the saturation is approximately 20 to 180, and the lightness is approximately 350 to 800, within the coloration range that normally occurs in human teeth. It was found that the When developing prosthetic materials, it is desirable to have the reflected light properties within this range, and this is usually achieved by adding a coloring agent to the material. . the important thing is,
The aim is for the material not to show significant changes in color during use, so that the development of the basic materials for manufacturing the structures can be directed towards obtaining good pollution resistance. Coffee is a contaminating medium that attracts particular attention when developing dental prosthetic materials. As far as the field of dental applications and/or cooking is concerned, coffee belongs to one of the most severe polluting media. One of the currently relied upon contamination tests to evaluate and compare the contamination resistance of candidate materials is the coffee contamination test, which consists of exposing a sample of a particular material to coffee at 80°C with an exposure interval of every 7 days. be. This test results in measurable changes in hue, brightness, and saturation in many ceramic materials. The best pollution resistance according to the invention is Al ₂ O ₃ and
obtained by a composition containing both _ZrO2 .
To demonstrate the effect of the addition of small amounts of alumina and zirconia on the stain resistance of glass-ceramic prosthetic materials, the behavior of six glass-ceramic materials in the coffee stain test described above was compared. The compositions of these materials are set forth in the following table, which is the batch composition expressed on a weight basis. Basic component SiO ₂ ,
The total amount of K ₂ O, MgO and MgF ₂ is 100 parts, so the values of these components shown in the table correspond to the weight percentages of the underlying glass. The remaining ingredients are 100% the base glass composition.
When expressed as %, it can be considered as an additive component added in excess of 100%. As can be seen from the table, samples 4 to 6 are samples 1 to 6, respectively.
3, except that the former contains a small amount of Al ₂ O ₃ .

[Table] The materials shown in the table are all tetrasilicated fluoromica glass ceramic compositions, and the basic crystal forming components are SiO ₂ , K ₂ O, MgF ₂ and
containing MgO and, in some cases,
Contains TiO ₂ and a colorant (adjusts the color of reflected light). Glass ceramics were made from each composition by forming a glass assembly from molten glass of each composition and then converting the glass assembly into a high crystallinity glass ceramic through heat treatment. Maximum crystallization temperature is 1075
~1090°C, and the crystallization time was 6 hours. Glass ceramic pieces were cut into plates approximately 0.25 inch thick and polished prior to testing. In the contamination test, each sample was first checked for color, then soaked in coffee for 7 days at 80°C, after which the samples were removed, rinsed with deionized water, checked for color again, and finally, commercially available After brushing the teeth for 1 minute, a third color test was performed. The data obtained from these tests are shown in the table below. This table shows, for each of the six samples, the color before staining (initial color), the color after staining and washing (color after staining/washing), and the color after staining and brushing (color after toothbrushing). The hue (H), brightness (V) and saturation (C) of the color after staining/polishing are recorded.

[Table] Examination of the data shown in the table, as well as similar data obtained for glass-ceramic products having the composition shown in the table, but with a different heat treatment and/or a different surface finish, shows that they contain only ZrO ₂ Although the contamination resistance of compositions 1 to 3 is tolerable to some extent, those with alumina added as shown in compositions 4 to 6 have a high resistance to contamination, regardless of the thermal history of the glass ceramic or its surface finish. First, it is recognized that the contamination resistance is further improved. As the data in table shows,
Such additions are most effective in reducing variations in brightness and/or saturation, but are also often found to stabilize color. The color stabilizing effect of the addition of alumina is shown in the accompanying drawings. This figure shows the data for samples 1 and 4 in the table, as well as the color data from the coffee contamination test for samples of the same composition as those samples but crystallized for 12 hours instead of 6 hours at the highest temperature. This shows that. In the graph of the same figure, the horizontal axis represents the stage at which the contamination test was conducted, and the vertical axis plots hue, brightness, and saturation. The stages tested were: before contamination (I), after contamination and cleaning (S/R), and after contamination and polishing (S/B).
It is. The data shown shows that the compositions of Examples 1 and 4 of the table were crystallized in situ for 6 hours (designated 6-HR HT) and 12 hours (designated 12-HR HT). This is the value for the converted item. According to the present invention, the best stain resistance is obtained for compositions containing both Al ₂ O ₃ and ZrO ₂ , although the stain resistance is significantly improved using only ZrO ₂ . For example, by weight, approximately 60.5% SiO ₂ , 13.5%
of K ₂ O, 14.5% MgO and 11.5% MgF ₂ as the first composition, and a composition containing these components in the same proportions and further comprising 2.5% by weight of ZrO ₂ as the second composition. When these compositions were subjected to the same heat treatment and then subjected to a coffee stain test, the first composition showed light staining;
The second composition did not show any contamination. This fact reflects the acid resistance of the second composition (95°C
The weight loss of the sample after 24 hours of immersion in a 5% HCl solution was measured, albeit slightly lower than that of the first composition. Based on the above data and the like, preferred composition ranges for thermocrystalline glass and stain-resistant mica tetrasilicide glass ceramic products have been established. They are particularly suitable for obtaining dental structures and are based on mica-based compositions containing ZrO ₂ and Al ₂ O ₃ to increase stain resistance. That is, the composition of the glass and the product, calculated as a batch component, is SiO ₂
About 45-70%, MgO8-20%, _MgF2 8-15%,
_{K2O5 5} ~20%, _{Al2O3 0.05} ~2%, ZrO2 _0.5 ~7
%, total amount of ZrO ₂ + Al ₂ O ₃ 1-9%, TiO ₂ 0-7
% and the total amount of conventionally used glass colorants from 0 to 10%. Coloring agents include manganese oxide, iron oxide, nickel oxide, or any conventionally known compound or element used to color glass. The presence of zirconia in these compositions not only increases resistance to acids, but also controls the translucency of the glass-ceramic product and prevents recrystallization of the glass-ceramic at high crystallization temperatures. It is especially important to ensure that The mechanism by which coffee and other contaminating agents permanently stain tetrasilicated mica glass ceramics is not fully understood, but is dependent on factors other than composition, such as the thermal history of the glass ceramic and the nature and degree of crystallization of the glass ceramic. is also believed to have some influence on the final contamination resistance of the material. However, holding such other factors constant,
Tetrasilicated fluoromica compositions used in dental structures and other applications can be significantly improved by adding small amounts of zirconia and alumina to certain given compositions to increase their durability.

[Brief explanation of the drawing]

The figure is a graph showing the stain resistance of a glass-ceramic material according to the invention.

Claims (1)

[Claims] In weight percent when calculated as 1 batch,
_SiO2 45-70%, MgO8-20%, _MgF2 8-15%,
_R2O +RO5~35%, _{Al2O3 0.05} ~2%, ZrO2 _0.5 ~
7%, _Al2O3 + _ZrO2 1-9%, _TiO2 0-7%, and a total amount of glass colorant 0-10%, provided that _R2O is _in the range of 5-25% and K ₂ O0~20
%, Rb ₂ O from 0 to 23% and Cs ₂ O from 0 to 25%, and having an RO in the range from 0 to 20% and selected from the group consisting of SrO, BaO and CdO. Thermocrystalline glass which can be crystallized by heat to form a tetrasilicated fluoromica glass ceramic material having excellent contamination resistance. 2 When calculated as a batch, it is a weight percentage,
_SiO2 45-70%, MgO8-20%, _MgF2 8-15%,
_R2O +RO5~35%, _{Al2O3 0.05} ~2%, ZrO2 _0.5 ~
7%, total amount of Al ₂ O ₃ + ZrO ₂ 1-9%, TiO ₂ 0-7
%, and a glass colorant from 0 to 10%, provided that _R2O is in the range of 5 to 25% and K2O is in the range of ₀ to 20%.
%, Rb ₂ O 0-23% and Cs ₂ O 0-25%, with RO in the range 0-20% and selected from the group consisting of SrO, BaO and CdO. A tetrasilicified fluoromica glass ceramic product with excellent stain resistance. 3. The glass-ceramic product according to claim 2, which forms a dental structure.