Dentistry – Prosthodontics – Denture liner or cushion
Reexamination Certificate
1999-09-17
2003-04-15
Lewis, Ralph A. (Department: 3732)
Dentistry
Prosthodontics
Denture liner or cushion
C523S120000, C524S731000
Reexamination Certificate
active
06547563
ABSTRACT:
DETAILED DESCRIPTION OF THE INVENTION
The present invention relates to a lining material for a denture base used in the dental treatment, particularly a dental tissue conditioner for a patient wearing a denture whose oral mucosa is deformed or inflamed, and to a kit therefor.
When a denture is used for a long time, it becomes gradually ill-fit with alveolar ridge because of, for example, the resorption of the alveolar ridge, whereby the denture becomes difficult to hold and loses stability. If the ill-fitting denture is continued to be used as it is, a non-uniform pressure is applied to the mucosa under the denture base, so that ulcer and/or inflammation may emerge on the mucosa or pain is caused by an occlusion pressure. Therefore, when the above ill-fitting occurs, it is necessary to prepare a new denture or to recover the fitness of the ill-fit denture for the mucosa by adjusting its base.
However, since the oral mucosa of the patient is unstable because of the ulcer and inflammation as described above, the preparation of a new denture or the adjustment of the denture base must not be done until the oral mucosa recovers to a normal condition, in order to secure the good fitness of the denture for the mucosa under the denture base.
The material used under such circumstances is a dental tissue conditioner. The dental tissue conditioner is continued to be used for lining the mucosa under the denture in use until the form and color of the mucosa recover to a normal condition.
Further, currently, the soft materials associated with the denture base are roughly classified by a denture adhesive, a dental tissue conditioner and a soft lining material. They are different from one another in the purpose, method and period of use, required properties and the like.
For example, the denture adhesive is used temporarily for such a short time as one day to a few days after applied by a patient himself. Therefore, the denture adhesive is required to show the adhesive strength to the extent of “sticking” rather than perfectly “bonding” to the denture base. On the other hand, the dental tissue conditioner and the soft lining material are the same in that they are applied by a dentist. However, they are quite different from each other in required physical properties because of the difference in the purposes of their use. Specifically, as described above, the dental tissue conditioner is used for treating the oral mucosa prior to the repair of the denture. Therefore, in view of the purpose, it must be flexible and plastically deformable, and the period of its use must be relatively short, for example, one week to a few weeks, until the oral mucosa recovers to a normal condition. On the contrary, since the soft lining material is used for repairing the denture, it must not be deformed for a long time after the repair of the denture.
Thus, all the above three types of materials are the same in that they are associated with the denture base, however, they are clearly divided into different groups as dental materials according to the purposes of their use and required properties.
Currently, as the dental tissue conditioner, there is widely used a mixed material that consists of a powder component comprising a polyethylmethacrylate or a copolymer thereof and a liquid component comprising a phthalate ester plasticizer containing about 4 to 20 wt % of ethanol. As for the tissue conditioner, a soft elastic product is obtained when the powder component and the liquid component are mixed together. Therefore, when the mucosa under the ill-fitting denture is lined with the material, it recovers the fitness of the denture and relieves the pain caused by the occlusion pressure. Further, when the pain is relieved, the ulcer or inflammation of the oral mucosa gradually disappears and, at the same time, the form of the oral mucosa recovers to its normal condition with time. At this point, the tissue conditioner shows an excellent characteristic that it deforms along with the change in the deformation of the oral mucosa.
However, the conventional dental tissue conditioner as described above has the following problems (1) to (3).
(1) The elution of the plasticizer and ethanol during the use of the conditioner deteriorates the conditioner with time, raises a concern for a possible influence upon a living body and causes an unpleasant taste and irritation. (2) The conditioner becomes dirty or gives off an odor by absorbing oils contained in foods, saliva and the like, during its use. (3) It is necessary to remove a spent dental tissue conditioner from the denture base for the application of the lining material after the treatment of the ailments; at this point, however, it is extremely difficult to remove (specifically, by grinding) the dental tissue conditioner which is firmly stuck on the denture base because the conditioner is made of basically the same material as that of the denture base.
It is an object of the present invention to provide a dental tissue conditioner which has overcome the above problems (1) to (3).
Other objects and advantages of the present invention will be apparent from the following description.
That is, the present inventors have made intensive studies to overcome the above problems and succeeded in obtaining a dental tissue conditioner which has no such problems as the above (1) to (3) by using a silicone rubber which has not been used heretofore for a dental tissue conditioner, particularly a room-temperature addition-polymerization-type silicone rubber, as a material. Thus, the present invention has been completed.
According to the present invention, the above objects and advantages of the present invention are achieved by a method which comprises using a silicone rubber as a material for a dental tissue conditioner.
The “silicone rubber” as used herein means a crosslinked organopolysiloxane. Further, a visco-elastic body obtained by uniformly dispersing fillers and various additives in the silicone rubber is called a “silicone rubber composition”.
A silicone rubber is a material having excellent characteristics as a dental material, such as repellency, non-cohesiveness and non-toxicity to a living body. A dental tissue conditioner which is substantially formed of a silicone rubber has not been known heretofore.
The dental tissue conditioner according to the present invention substantially comprises a silicone rubber whose main components are colorless, tasteless, odorless, non-volatile and non-toxic. Therefore, basically, it does not have the above problems (1) and (2). Further, since the silicone rubber is different from the resin used in the denture base, it is possible to design an adhesive which has a controlled adhesive force to the resin. Thus, the above problem (3) can also be solved.
The dental tissue conditioner of the present invention has an advantage that it can be directly formed in a mouth if the silicone rubber is a room-temperature addition-polymerization-type silicone rubber.
Further, the dental tissue conditioner of the present invention shows an excellent performance as a dental tissue conditioner that it can be moderately plastically deformed with moderate elasticity retained as the damaged mucosa under the denture base heals, when a silicone rubber composition to be used has (i) an elastic strain of preferably 15% or more, more preferably 20% or more, and a permanent strain of preferably 0.5% or more, (ii) a loss tangent of preferably 0.5 or more, or (iii) a Shore A hardness of preferably 15 or less.
Such physical properties can be attained by controlling the crosslinking density of a silicone rubber, the amount of a silicone resin filler, a silica filler or other filler as a reinforcing material, and the like.
Any filler which is generally added to a silicone rubber can be used as the above filler without any restriction. Illustrative examples of the fillers include a silica filler such as pulverized quartz, fused silica powder, colloidal silica powder and fumed silica powder; a silicone resin filler such as polymethylsilsesquioxane powder, polyphenylsilsesquio
Hosoi Yasuhiro
Imakura Takaaki
Iwamoto Osamu
Lewis Ralph A.
Tokuyama Corporation
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