JPS6257603B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a dental composite filling resin that is a low viscosity type composite filling resin with excellent filling properties and has improved storage stability. A variety of dental filling materials have been known for a long time, but among them, so-called composite filling resins made of polymerizable monomers and fillers are excellent in terms of aesthetics, operability, cost, etc., and are therefore suitable for restoring front teeth. Recently, it has also begun to be used for the restoration of deciduous molars. However, when filling with normal composite filling resin, it is necessary to carefully fill the cavity while pressing it against the wall of the cavity, and then after filling, it is necessary to press the entire filling with an appropriate material. Gaps are likely to form within the filling and between the filling and the cavity wall, leading to the filling falling off after repair and secondary caries. In particular, when filling deciduous molars, the shape of the molar cavity including the occlusal surface is complex, and the deciduous molars are located deep within the oral cavity, making the filling operation difficult and making it difficult to press the occlusal surface. Therefore, there is a problem that voids are easily formed during filling, and filling requires a lot of effort and a long time.Therefore, there has been a strong desire to improve composite filled resins. In order to solve such problems, the present inventors
The fluidity of uncured composite filling resin in the cavity was investigated. As a result, if a resin with a much lower viscosity than currently commercially available composite filling resins is filled into a cavity, it will flow under its own weight within a short period of time until it hardens (usually within 3 minutes), and the cavity can be filled uniformly. acknowledged. That is, it has been found that it is preferable to improve the composite filled resin in the direction of lowering its viscosity. In order to lower the viscosity of a composite filled resin consisting of a polymerizable monomer and a filler, a method is disclosed in JP-A No. 18380/1983 in which the amount of filler is reduced and the ratio of the polymerizable monomer is increased. There is a method using polymerizable monomers with low viscosity. However, the former method is undesirable because it lowers the thermal expansion coefficient, hardness, compressive strength, and other mechanical properties of the filled cured product, and the latter method has a problem in that the filler tends to settle. The present inventors conducted a more detailed study on the composition of composite filled resin in order to prevent filler sedimentation. As a result, in order to prevent such sedimentation, it is possible to use a dispersion stabilizer, but
The colloidal silica whose surface silanol groups have been made hydrophobized as described in No. 18380 cannot prevent precipitation. The present invention was achieved based on the recognition that when used in combination with a polymerizable monomer having a hydrophobicity index, a composite filled resin with excellent filling properties without filler sedimentation can be obtained. That is, the present invention provides (i) a weight average hydrophobicity index of 3;
~6 methacrylate polymerizable monomer 50~30
Volume % and (ii) area average particle diameter is in the range of 5 to 50 mμ, and there are 2 to 3 silanol groups on the particle surface.
50-70% by volume of a powdered filler comprising 0.5-20% by volume (based on the pasty composition) of hydrophilic colloidal silica present at a density of particles/100 Å
A paste-like composition consisting of a temperature of 25°C,
The viscosity measured at a shear rate of 1.35sec ^-1 is 2.0×10 ² ~
This is a dental composite filling resin with a density of 5.0×10 ³ poise. In the present invention, a methacrylate polymerizable monomer having a weight average hydrophobicity index of 3 to 6 is used as the polymerizable monomer. Here, the weight average hydrophobicity index is 16 for the ester group, 16 for the ether group, and 16 for the hydroxyl group in the methacrylate polymerizable monomer molecule.
When an index of 32 is given, it means the value obtained by dividing the molecular weight of the methacrylate by the sum of the indexes of the hydrophilic groups (ester group, ether group, or hydroxyl group) in the molecule, and if multiple polymerizable monomers are used. in case of,
It means the average value of the hydrophobic index calculated for each methacrylate according to the weight ratio of the composition. The methacrylate polymerizable monomer with a hydrophobicity index in the range of 3 to 6 is one having at least one of an ester group, an ether group, or a hydroxyl group, and is used in ordinary composite filled resins, as described in US Pat. Described in No. 3086112, Special Publication No. 46-24869, etc.
2,2'-bis[p-(γ-methacryloxy-
β-Hydroxypropoxy)phenyl]propane Hereinafter, it will simply be abbreviated as Bis-GMA. , triethylene glycol dimethacrylate Hereinafter, it will be simply abbreviated as 3G. ), tetraethylene glycol dimethacrylate In addition to these, the following compounds are more representative. 2,2'-di(4-methacryloxy diethoxy phenyl)propane Diethylene glycol dimethacrylate glycerin dimethacrylate Furthermore, a highly hydrophilic methacrylate polymerizable monomer with a hydrophobicity index of 3 or less or a highly hydrophobic methacrylate polymerizable monomer with a hydrophobicity index of 6 or more cannot be used alone in the present invention; It can be used by adjusting the weight average hydrophobic index to a range of 3 to 6 by mixing it with a methacrylate polymerizable monomer. Examples of methacrylate polymerizable monomers that can be used in this manner include the following. Example of a methacrylate monomer with a hydrophobicity index of 3 or less 1.2-bis(3-methacryloxy-2-hydroxypropoxy)butane Hydroxyethyl methacrylate

[Formula] Dimethacrylate expressed by the following formula (A) However, R is hydrogen or methyl, and n is an integer of 1 to 4. Among these, 1.2-bis(3-methacryloxy-2-hydroxypropoxy)ethane in which R is hydrogen and n is 1 is preferred. ] Also, examples of methacrylate monomers with a hydrophobic index of 6 or more, bisphenol A dimethacrylate Neopentyl glycol dimethacrylate (hereinafter simply referred to as NPG), 1,4-butylene glycol dimethacrylate 1,6-hexane glycol dimethacrylate 2,2-di(4-methacryloxyethoxyphenyl)propane By using the above-mentioned polymerizable monomer, even if hydrophilic colloidal silica as described below is added, the composite filled resin has a shear rate of substantially 0 immediately after adjusting the paste by stirring.
However, since it has fluidity, it has excellent filling properties into the cavity, and when it is left still, it exhibits structural viscosity, so the filler does not settle during storage. However, when the hydrophobicity index of the polymerizable monomer is 3 or less, the hydrophilicity of the resulting composite filled resin becomes high, resulting in drawbacks such as increased water absorption. Further, when the hydrophobicity index of the polymerizable monomer is 6 or more, it is not preferable that hydrophilic colloidal silica is mixed in to an extent that prevents sedimentation of the filler because natural flow due to its own weight becomes difficult. In the present invention, a polymerizable monomer with a weight average hydrophobic index of 3 to 6 is used as described above, but in order to keep the viscosity of the composition within the range described below, it is necessary to It is necessary to select the quantity. For example, highly viscous monomers such as Bis-GMA, which are commonly used in dental composite filling resins, are appropriately diluted with low-viscosity methacrylate monomers such as 3G and NPG. It must be. When using Bis-GMA, it could not be used unless it was diluted by mixing at least 30% by volume (based on the polymerizable monomer) of a low-viscosity methacrylate monomer. Therefore, in the present invention, the polymerizable monomer may be used not only one type but also a mixture of two or more types, but even in this case, the polymerizable monomer has a hydrophobicity index of 3 to 3 on the weight average. Needless to say, it must be in the range of 6. In the present invention, the filler contains 0.5 to 20% by volume.
Contains hydrophilic colloidal silica (vs. pasty compositions). In the present invention, hydrophilic colloidal silica refers to fine particulate anhydrous silica with an area average particle diameter of 5 to 50μ, and a density of 2 to 3 silanol groups (Si-OH groups)/ ^100Å2 on the particle surface. Denotes the presence of silica. Examples of hydrophilic colloidal silica include Nippon Aerosil Co., Ltd.
There is Aerosil 380 (trade name) manufactured by Manufacturer Co., Ltd., which has a particle size of 8 mμ and has the property of completely dispersing in water. By using such colloidal silica, precipitation of other inorganic fillers can be prevented. Such an effect was not observed in hydrophobic colloidal silica in which H of the silanol group was substituted with a hydrophobic group such as a hydrocarbon. When hydrophobic colloidal silica is mixed with water, more than 90% by weight does not disperse in the water and floats on the water surface.
It has completely different properties from the hydrophilic colloidal silica. Hydrophilic colloidal silica is not effective in preventing sedimentation of other fillers unless it is used in an amount of 0.5% by volume or more based on the paste composition.
On the other hand, when 20% by volume is strained, the fluidity of the paste decreases, which is not preferable. The filler used in the present invention has a particle size of 100μ, which is normally used in dental composite filling resin.
Examples of inorganic filler powders with high hardness and low thermal expansion coefficients include the following silica powder, quartz powder, glass powder, ceramic powder, and metal oxide powder. Additionally, hydrophobic colloidal silica (e.g.
Aerosil R972 (manufactured by Nippon Aerosil Co., Ltd.) can also be used in combination with the hydrophilic colloidal silica. These fillers are used after being surface-treated with a silane treatment agent or an organic polymer in order to improve the bondability with the polymerizable monomer. In the present invention, it is necessary that the ratio of the polymerizable monomer to the filler is 50-30% by volume: 50-70% by volume. More preferably 47-35% by volume: 53-35%
It is 65% by volume. If the proportion of filler exceeds 70% by volume, a paste with good fluidity cannot be obtained, and if it is less than 50% by volume, the scientific and engineering properties of the cured product deteriorate, which is not preferable. The paste composition of the present invention has a viscosity of 2.0×10 ² when measured at a temperature of 25°C and a shear rate of 1.35 sec ^-1 .
~5.0×10 ³ poise (more preferably 4.0×10 ²
~2.0×10 ³ poise). The above-mentioned viscosity measurement is carried out using a Weissenberg rheogoniometer (manufactured by Sangamo Control). In addition, the paste-like composition of the present invention is further mixed with a polymerization curing agent as described later before use. In this case, the viscosity of the paste increases when curing begins, so it is necessary to determine the viscosity value in a system in which no curing agent system exists (a system in which neither a catalyst nor an activator is present). be.
Alternatively, as a convenient method, either the catalyst or the activator may be inactivated, the two pastes may be mixed, and the viscosity may be measured. In the present invention, if the viscosity is less than 2.0 x 10 ² poise, it is not preferable if the cavity opening surface is inclined from horizontal because the filled composition will flow out before it hardens, and if the viscosity is 5.0 x 10 ³ poise or more, the filling will be difficult. This method requires a pressure-contacting operation, and also has the disadvantage that it tends to form voids because it does not wet the tooth structure well. In obtaining the dental composite filling resin, the viscosity is adjusted to the above range, and the ratio of the polymerizable monomer to the filler is adjusted to the above range from the viewpoint of the fluidity of the composition and the scientific and engineering properties of the cured product. By setting the amount within this range, it is possible to obtain a composite filling resin that has excellent filling properties and is suitable for filling baby molars and the like. The viscosity of the composition of the invention is
Composite filling resin, which has been commercially available for a long time,
This is extremely low compared to the viscosity of 1.0×10 ⁴ to 1.0×10 ⁵ poise. When placed under such low viscosity, the filler tends to settle, and in order to prevent such settling, a polymerizable monomer having a weight average hydrophobicity index of 3 to 6 and hydrophilic colloidal silica are used. It was recognized that the use of A feature of the present invention is that such a polymerizable monomer and hydrophilic colloidal silica are used in combination in a low-viscosity composite filled resin. In the present invention, ultraviolet sensitizers, catalysts, activators, polymerization inhibitors, ultraviolet absorbers, colorants, etc. are appropriately added in addition to the above-mentioned components. When the composite filled resin is cured by ultraviolet light after being filled into a cavity, it is preferable to add an ultraviolet sensitizer such as benzoyl methyl ether or benzoyl phenyl ether. In addition, when the composite filled resin is cured with a curing agent, a curing agent consisting of a room temperature curing catalyst-activator combination such as amine-peroxide or p-toluenesulfinic acid-peroxide is added. .
The catalyst is usually benzoyl peroxide (hereinafter referred to as
It is called BPO. ) is used, and as an activator,
Amine compounds such as N·N-dipropanoltoluidine and N·N-diethanoltoluidine are used. In the present invention, if necessary, ultraviolet absorbers (e.g., 2-hydroxy-4-methoxybenzophenone, etc.), polymerization inhibitors (e.g.,
2,6-di-t-butyl-p-cresol, etc.),
etc. are added. Since curing begins when both a catalyst and an activator are added to the composite filled resin, it is usually
As disclosed in No. 24869, the composite filled resin is divided into two parts, a catalyst or an activator is added to each part, and the two are mixed and kneaded before use. That is, in a composite filled resin consisting of a polymerizable monomer, a filler, a catalyst, and an activator,
The components are packaged in at least two parts so that the catalyst and activator are mixed only before use, and are mixed together before use. 2
Separate packaging formats include a paste/catalyst type consisting of a paste consisting of a polymerizable monomer, a filler, and an activator, and a catalyst (the catalyst may be mixed with a suitable filler); There is a two-paste type in which a paste consisting of a filler and a filler is divided into two and a catalyst or an activator is added to each, but essentially any type may be used in the present invention. The resin divided into two parts is mixed and kneaded at the time of use to obtain a composite filled resin having a viscosity within the above-mentioned range. Low viscosity composite filled resin is generally undesirable when packaged in a regular container as it will flow and stick to the lid.Also, when packaged in a syringe etc., the filler will settle as mentioned above, so it is necessary to stir the composite filled resin before use. However, it was difficult to achieve uniformity. However, although the composite filled resin of the present invention has a low viscosity, the above structure prevents the filler from settling, so it can be filled into a syringe, making it easy to use clinically. It became something. Note that one syringe is filled with one of the two divided packaging forms. The composite filling resin of the present invention obtained as described above has a viscosity and fluidity within the above-mentioned range, making the filling operation easy and having good adhesion to the cavity. It was recognized that it has an excellent effect of suppressing the formation of caries and preventing the occurrence of secondary caries. Furthermore, even though the composite filled resin of the present invention exhibits fluidity during use, no filler sedimentation was observed when it was allowed to stand for a long period of time. Furthermore, despite the low viscosity, the cured product had excellent scientific and engineering properties due to the high filler content. Hereinafter, the present invention will be explained in further detail with reference to Examples. Example 1 Pastes A and B with a filler content of 58% by volume were prepared with the following composition. Paste A Bis-GMA (hydrophobicity index 4) 11.5 parts by weight 3G (hydrophobicity index 4.5) 11.5〃 Quartz powder (particle size 60μ or less, surface treated with silane binder) 75〃 Hydrophilic colloidal silica (Aerosil 380 2〃 N・N-diethanol-p-toluidine 0.2〃 Paste B Bis-GMA 11.5 parts by weight 3G 11.5〃 Quartz powder (same as above) 75〃 Hydrophilic colloidal silica (same as above) 2〃 BPO 0.4 parts by weight 2.6-di -t-Butyl-p-cresol (hereinafter referred to as BHT) Trace amount The viscosity of pastes A and B was measured using a Weisenberg goniometer at 25°C and a shear rate of 1.35 sec ^-1 , and the viscosity of both was 6.3 × 10 ² poise. It showed good fluidity.It should be noted that Bis-GMA and 3G
The hydrophobicity index of the polymerizable monomer consisting of is 4.25. Further, hydrophilic colloidal silica is mixed at 1.8% by volume with respect to the paste composition. A sample obtained by mixing and curing equal amounts of pastes A and B had a compressive strength of 2460 kg/cm ² after one day. Further, each of pastes A and B was filled into a polypropylene container to a thickness of 4 mm and stored. Even after one year, the filler and the polymerizable monomer did not undergo phase separation and remained uniformly mixed. Next, the composite filling resin obtained by mixing and kneading the pastes A and B described above was filled into a class 2 cavity of a molar tooth. The cavity was acid-treated with a 40% orthophosphoric acid aqueous solution in accordance with a conventional method, and then a liner containing phenyl phosphate monomer as a main component was applied and dried. After curing, the model tooth was cut in the tooth axis direction and visually observed, and no cavities were observed, confirming that the composite filling resin of the present invention has excellent filling properties. Example 2 3G in Example 1 was changed to NPG (hydrophobicity index 7.5), and paste C corresponding to paste A and paste D corresponding to B were prepared in the same composition ratio. The viscosities of C and D were measured under the same conditions as in Example 1, and
It was 7.1×10 ² poise. Note that the hydrophobicity index of the monomer consisting of Bis-GMA and NPG is 5.75. C and D were filled and packaged in syringes with the same diameter and extruded into equal lengths to take out equal amounts.The cured product obtained by mixing them had a compressive strength of 2490 Kg/cm ² after one day. Although it was stored under the same conditions as in Example 1, no phase separation between the filler and the polymerizable monomer was observed even after one year. Comparative Example 1 Pastes E and F were prepared with the following compositions. Paste E Bis-GMA 11.5 parts by weight 3G 11.5 Quartz powder (same as Example 1) 72 Hydrophobic colloidal silica (Aerosil R-972 5 N.N-diethanol-p-toluidine 0.2 Paste F Bis-GMA 11.5 3G 11.5 Quartz powder (Same as Example 1) 72 Hydrophobic colloidal silica (Aerosil R-972)
5 BPO 0.4 BHT Trace amount When pastes E and F were stored under the conditions of Example 1, the filler settled after 3 months due to its hydrophobicity, even though the amount of colloidal silica was 2.5 times larger. . In this comparative example, the hydrophobicity index of the polymerizable monomer was 4.25, the ratio of the polymerizable monomer in the paste composition was 41% by volume, the ratio of the filler was 59% by volume, and the hydrophobic colloidal in the filler The ratio of silica to the paste composition was 4.4% by volume. Comparative Examples 2 to 5 Pastes were prepared with the compositions shown in Table 1.

[Table] Comparative Examples 2 to 5 both showed sufficient softness during the paste kneading operation normally performed by dentists, but once the kneading operation was stopped, the fluidity due to its own weight was poor, and the paste surface became soft. The unevenness that occurred during kneading did not disappear within 5 minutes. For dental composite filling resins containing polymerizable monomers, it is essential for treatment efficiency to begin curing within 5 minutes from the start of polymerization, and therefore the above four examples have insufficient fluidity. Furthermore, when Comparative Examples 3 and 5 were stored as in Example 1, phase separation between the filler and the polymerizable monomer was observed after 2 months. Comparative Example 6 Pastes G and H having a filler content of 48% by volume, which is out of the range of the present invention, were prepared using the following formulation ratio. Paste G Bis-GMA 24.0 parts by weight 3G 8.0〃 Quartz powder (same as Example 1) 66.0〃 Hydrophilic colloidal silica 1.0〃 N.N-diethanol-p-toluidine 0.32〃 Paste H Bis-GMA 24.0 parts by weight 3G 8.0〃 Quartz powder (same as Example 1) 66.0〃 Hydrophilic colloidal silica (same as Example 1)
1.0〃 BPO 0.64〃 The hydrophobicity index of the polymerizable monomer of this product was 4.13, and the proportion of hydrophilic colloidal silica was 0.8% by volume. The viscosity of Pastes G and H was 1.1×10 ³ poise as measured by the method of Example 1, and the viscosity was within the desired range of the present invention. However, when the compressive strength of the cured product obtained by mixing equal amounts of pastes G and H was measured after one day, it was 2160 kg/
cm ² was considerably lower than that of Example 1, and the strength of the filling was insufficient. Example 3 A paste was prepared by mixing a mixture of a polymerizable monomer with a hydrophobicity index of 3 or less and a monomer with a hydrophobicity index of 6 or more with a filler in the following composition. Paste 1,2-bis(3-methacryloxy-2-hydroxypropoxy)ethane (hydrophobicity index 2.7) (Note)
14 parts by weight 1,6-hexanediol dimethacrylate (hydrophobic index 7.9) 10〃 Quartz powder (same as Example 1) 74〃 Hydrophilic colloidal silica (Aerosil 380) 2〃 (Note) In the above formula (A), It is a monomer in which R=H and n=1. The weight average hydrophobicity index of the above polymerizable monomer mixture is 4.9, the ratio of polymerizable monomer in the paste composition is 42% by volume, the ratio of filler is 56% by volume, and the ratio of hydrophilic colloidal silica. is 2% by volume
It is. This paste was able to flow under its own weight, and when stored under the conditions of Example 1, no sedimentation of the filler was observed even after one year. Example 4 A paste/catalyst (paste-like) type composite resin was prepared with the following composition. Paste J Bis-GMA 14 parts by weight 3G 3 parts by weight NPG 5〃 1,2-bis(3-methacryloxy-2-hydroxypropoxy)ethane 3〃 Quartz powder (same as Example 1) 73〃 Hydrophilic colloidal silica (Aerosil 380) 2〃 N・N-diethanol-p-toluidine 0.2〃 Paste K (catalyst) Dibutyl phthalate 25 parts by weight Quartz powder (same as Example 1) 66〃 Hydrophilic colloidal silica (Aerosil 380) 5〃 BPO 4〃 Weight ratio of paste J and paste K (catalyst): 30:
1 and mixed. The mixture cured within 5 minutes at room temperature, and the compressive strength of the cured product was 2560 Kg/cm ² . The proportion of filler in the mixed paste was 54% by volume, the proportion of colloidal silica in the filler was 2% by volume, and the proportion of monomer was 42% by volume. The weight average hydrophobicity index of the monomer composition is 4.6. Even if Paste J was stored in a polypropylene syringe with an inner diameter of 13 mm for one year, no sedimentation of the filler was observed. It also showed good fluidity when kneaded with a catalyst during use.

Claims (1)

[Scope of Claims] 1. 50 to 30% by volume of a methacrylate polymerizable monomer having a weight average hydrophobicity index of 3 to 6, an area average particle diameter in the range of 5 to 50 mμ, and a silanol group on the particle surface. A paste-like composition consisting of 50-70% by volume of a powdered filler containing 0.5-20% by volume (relative to the paste-like composition) of hydrophilic colloidal silica in which silica is present at a density of 2-3 pieces/100 Å. A dental composite filling resin having a viscosity of 2.0×10 ² to 5.0×10 ³ poise when measured at a temperature of 25° C. and a shear rate of 1.35 sec ⁻¹ . 2. The dental composite filled resin according to claim 1, further comprising a curing agent consisting of a catalyst and an activator. 3 A methacrylate polymerizable monomer with a weight average hydrophobic index of 3 to 6, an area average particle size of 5 to 50 m
It is composed of a powdered filler comprising hydrophilic colloidal silica having a density of 2 to 3 silanol groups/100 Å on the particle surface, and a curing agent comprising a catalyst and an activator. It is a dental composite filled resin that is packaged in at least two parts so that the catalyst and activator are not packaged in the same package. is added at least 0.5% by volume (based on the composition consisting of the polymerizable monomer and filler), and when the separately packaged components are mixed at the time of use, the methacrylate polymerizable monomer is 50 to 30% by volume. and
A paste-like composition comprising 50 to 70 volume % of a filler comprising 0.5 to 20 volume % of hydrophilic colloidal silica, at a temperature of 25°C and a shear rate.
Viscosity measured at 1.35sec ^-1 is 2.0×10 ² ~ 5.0
A dental composite filling resin which is divided and packaged so as to obtain a composition of ×10 ³ poise.