JPH045957A - Curing and improving method for surface of dental material - Google Patents

Abstract

PURPOSE:To form a good-quality cured body having no polymn. inhibiting layers on the surface by spraying an inert gas to the surface of a packed or molded dental polymn. curing material and curing the material in this atmosphere. CONSTITUTION:Various kinds of commercially marketed chemical polymn. type or photopolymn. type materials are usable as the polymn. curing material contg. radical polymerizable methacrylate. The inert gas is exemplified by gaseous nitrogen, gaseous argon, gaseous xenon, etc., and the gaseous nitrogen is more preferably used in terms of the influence on living bodies and cost. While the inert gas, such as gaseous nitrogen, is blown to the packed part from a nozzle 4 for spraying connected to a high-pressure gas cylinder housing the inert gas, the curing is progressed with the chemical polymn. if the above- mentioned polymn. curing material 3 is packed directly into the cavity 2, groove, etc., of a tooth by an ordinary method. The material is cured by irradiating the same with light of a prescribed wavelength (450 to 520nm with camphar- quinone or its deriv.) in the case of the photosetting type.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention contains a radically polymerizable methacrylate used as a restorative material, a crown prosthesis material, a denture base material, etc. in dentistry. The present invention relates to a method for improving the hardness of dental materials, particularly the surfaces thereof.

(Prior Art) In recent years, the use of polymerizable hardenable materials called composite resins has been increasing as dental restorative materials, dental crown prosthesis materials, denture base materials, and the like.

This polymerizable curable material can be divided into chemical polymerization type and photopolymerization type depending on the polymerization method, but both basically consist of, for example, B15-GM A (reaction product of bisphenol A and glycidyl methacrylate), etc. A crosslinking agent that is a radically polymerizable methacrylate, an inorganic filler such as quartz or silica that has been chemically treated with a silane coupling agent, and a polymerization catalyst (in the case of a two-component chemical polymerization type, organic peroxide, etc. Polymerization initiator, polymerization catalyst such as tertiary amine on the other hand; photosensitizer and reducing agent in photopolymerization type)
It is called composite resin in the field of restorative materials. The polymerizable curable material is crosslinked by polymerization of a crosslinking agent, which is a radically polymerizable methacrylate, to form a network polymer, and an inorganic filler is dispersed between the networks to form a hard and strong cured product.

Conventionally, however, when using such a polymerizable material, the curing atmosphere is not particularly limited, and the curing atmosphere is simply filled into the cavities and grooves of an intraoral or indirect working model, or molded into a predetermined shape (17), and chemically applied. For polymerizable materials, a method of waiting for the passage of time was used, while for photopolymerizing materials, a method of curing by irradiating a certain amount of light was used; therefore, chemical polymerization materials,
Regardless of the photopolymerization type, a polymerization-inhibiting layer is formed on the surface of the cured product due to oxygen in the atmosphere, causing clinical discomfort, such as surface abrasion and marginal fracture when used as restorative materials or crown prosthetic materials. There was a problem in that it sometimes caused discoloration and the like. These discomforts have a large impact on product evaluation. For example, in the field of restorative materials, there are product approval standards for composite resins for molars set by the American Dental Association (ADA), and the surface abrasion of the resin can cause problems in the oral cavity. 50μms per year
Provisional approval will be granted as a product for molars if the diameter is 150 μm or less within 3 years, and permanent approval will be granted if the diameter is 250 μm or less within 5 years.

Conventionally, this problem has been solved by removing the polymerization-inhibiting layer on the surface after curing by polishing, but it is extremely difficult to polish the surface of the material after curing to form a fine anatomical shape. The task itself is difficult to perform, and the depth of this polymerization-inhibiting layer cannot be detected in a clinical setting, so it has been practically impossible to completely remove it.

(Problem to be Solved by the Invention) As described above, polymerizable hardenable materials called composite resins containing the above-mentioned radically polymerizable methacrylate crosslinking agent have been widely used as dental materials. However, there was a problem in that a polymerization inhibition layer was formed on the surface of the cured product. However, there is still no effective and easy solution to this problem, and its development is still required.

The present invention has been made in response to the above-mentioned conventional circumstances, and it is possible to cure a dental polymerizable hardenable material containing a radically polymerizable methacrylate without forming a polymerization-inhibiting layer on the surface during the curing process. It is an object of the present invention to provide a method for easily preventing the occurrence of clinical discomfort caused by a polymerization-inhibiting layer.

[Structure of the Invention] (Means for Solving the Problems) The first aspect of the present invention is to fill cavities and grooves in the oral cavity or in an indirect working model with a dental polymerizable curable material containing a radically polymerizable methacrylate. Alternatively, when molding into a predetermined shape and curing it, an inert gas is sprayed onto the surface of the filled or molded dental polymerizable hardenable material using a device equipped with an inert gas spraying function to create an inert gas atmosphere. It is characterized by being cured at the bottom.

The second aspect of the present invention is that when filling the dental polymerizable curable material into the cavities and grooves of an indirect working model or molding it into a predetermined shape and hardening it, the material is placed in a container filled with an inert gas. The method is characterized in that an indirect working model filled or molded with the dental polymerizable hardenable material is held and hardened under an inert gas atmosphere.

As the polymerizable curable material containing radically polymerizable methacrylate in the present invention, various commercially available chemical polymerization type or photopolymerization type materials can be used.

That is, B1 as a radically polymerizable methacrylate
5-G M A (reaction product of bisphenol A and glycidyl methacrylate), urethane dimethacrylate (UDMA), ethylene glycol dimethacrylate (IG), triethylene glycol dimethacrylate)
(3G), neopentyl glycol dimethacrylate (
NPG), tetramethylolmethane triacrylate (
Contains a cross-linking agent that is a polyfunctional methacrylate monomer such as TMMA), which is chemically treated with a silane coupling agent, etc. as an inorganic filler such as finely powdered quartz, silica, alumina, or glass, and a two-part polymerization catalyst. In the chemical polymerization type, one contains an organic peroxide polymerization initiator such as benzoyl peroxide or lauryl peroxide, and the other contains dimethyl para-toluidine or 2-hydroxyethyl-p-).
Chemically polymerized materials containing polymerization promoters such as tertiary amines such as luidine, and further containing polymerization inhibitors, antioxidants, pigments, X-ray imaging agents, etc. as necessary, or these materials. Among the components, a visible light-curable polymerizable material containing a visible light sensitizer such as camphorquinone or a derivative thereof and a reducing agent such as dimethylaminoethyl methacrylate or dimethyl para-toluidine is used as a polymerization catalyst.

Further, examples of the inert gas include nitrogen gas, argon gas, xenon gas, etc., and the type thereof is not particularly limited, but the use of nitrogen gas is particularly preferable from the viewpoint of influence on living organisms and cost.

In the present invention, the above-mentioned polymeric curable material is directly filled into the cavity or groove in the oral cavity to be repaired by a conventional method, or the cavity of an indirect working model is prepared by taking an impression in advance and using plaster. The material is filled or molded by a method depending on the purpose, such as filling in a container, and is cured, for example, as follows.

In other words, when filling directly into the cavity or groove of a tooth, inert gas is sprayed onto the filling area from a spray nozzle connected to a high-pressure gas cylinder containing an inert gas such as nitrogen gas, and the chemical polymerization type cures. In the photo-curing type, light of a specified wavelength (for camphorquinone and its derivatives, 4
50 to 520 nn+) for curing.

In addition, when filling the cavity of an indirect model made by impression, in addition to the above method, place it in an airtight container or plastic bag (for photocurable type, made of a light-transparent material), etc.
The air inside is replaced with an inert gas such as nitrogen gas, and the chemical polymerization type allows hardening to progress, similar to when the tooth is directly filled.
In addition, in the photo-curing type, it is cured by irradiating light of a predetermined wavelength. The cured product obtained here is adhered to the cavity of the oral cavity using an adhesive such as cement.

In chemical polymerization type materials, curing starts at the same time as mixing of the components before filling starts, so it is desirable to carry out the process from mixing to filling to spraying or replacing with inert gas as quickly as possible. On the other hand, with photocurable materials, there is no such fear, and curing can be started reliably in an inert gas atmosphere.

(Function) In the method of the present invention, contact between the radically polymerizable methacrylate and oxygen in the air that inhibits the polymerization of the methacrylate is blocked, and the formation of a polymerization-inhibiting layer on the surface of the cured product is prevented.

(Examples) Next, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited thereto.

Example 1 A photopolymerizable commercially available silax (
3M Co., Ltd. (trade name), into the cavity to be repaired (approximately 4.0 am deep) of tooth 1, as shown in Figure 1.
2, this polymerizable curable material 3 is sprayed with nitrogen gas from a nozzle 4 connected to a high-pressure nitrogen gas cylinder (not shown), and a light beam irradiator 5 is used to spray nitrogen gas at a wavelength of 470n+1.
It was cured by irradiating it with light for 20 to 30 seconds.

Next, in order to examine the degree of polymerization of the cured product thus formed, changes in Knoop hardness with respect to depth from the surface were measured. For comparison, the same material and the same method were used except that nitrogen gas was not blown into the tooth cavity (about 4 mm deep).
．． Regarding the cured product obtained by filling the material to a depth of 0 mm) and curing, the change in Knoop hardness with respect to the depth from the surface of the cured product was similarly measured.

The results are as shown in the graph of Figure 2. In the cured product of the comparative example, a polymerization inhibition layer with a low degree of polymerization was confirmed from the surface to a depth of about 0.5+n+n, whereas in the example, such a polymerization inhibition layer was observed. was not observed, indicating the highest degree of polymerization on the surface.

Example 2 Into the cavity of the tooth model created by making an impression of the tooth to be restored,
The same visible light curable material Silax as in Example 1 was filled and placed in a polyester bag, and then the air in the bag was replaced with nitrogen gas.

Next, the polymeric curable material filled from above the plastic bag is filled with
The same light irradiator as in Example 1 was used to emit light with a wavelength of 470 nm for 20 minutes.
Irradiated for ~30 seconds to cure.

Regarding the thus obtained cured product, the change in Knoop hardness with respect to the depth from the surface of the cured product was also measured, and as in Example 1, no polymerization inhibition layer was observed on the surface.

[Effects of the Invention] As is clear from the above examples, according to the method of the present invention, contact between radically polymerizable methacrylate and oxygen in the air, which inhibits the polymerization of this methacrylate, is blocked, and polymerization occurs on the surface. A high-quality cured product without an inhibiting layer is formed.

Therefore, it is possible to easily and reliably prevent the occurrence of clinical discomfort such as surface abrasion, edge fracture, discoloration, etc. caused by the polymerization inhibition layer, without removing the polymerization inhibition layer by polishing as in the conventional method. I can do it.

[Brief explanation of the drawing]

FIG. 1 is a diagram for explaining the method of the present invention, and FIG. 2 is a graph showing changes in Knoop hardness with respect to depth from the surface of a cured product, which was conducted to investigate the curing of the present invention. 2..... Cavity to be repaired in the tooth 3..
...Polymerization curable material 4...Nitrogen gas nozzle 5...
...Light irradiator applicant Menshi Dental Industry Co., Ltd.

Claims (2)

[Claims] (1) When filling or molding into a predetermined shape and hardening a dental polymerizable curable material containing radically polymerizable methacrylate into the cavity or groove of an intraoral or indirect working model, the above-mentioned material that is filled or molded A method for improving the hardening of the surface of a dental polymerizable material, which comprises spraying an inert gas on the surface of the dental polymerizable material using a device equipped with an inert gas spraying function, and curing the material in an inert gas atmosphere. . (2) When the dental polymerizable hardenable material according to claim 1 is filled into the cavities and grooves of an indirect working model or molded into a predetermined shape and hardened, the dental polymerizable material according to claim 1 is placed in a container filled with an inert gas. A method for improving the hardening of the surface of dental materials, which comprises holding an indirect work model filled with or molded with a dental polymerizable hardening material, and hardening it in an inert gas atmosphere.