Coating processes – Medical or dental purpose product; parts; subcombinations;... – Dental product
Reexamination Certificate
1999-07-15
2001-04-17
Beck, Shrive (Department: 1762)
Coating processes
Medical or dental purpose product; parts; subcombinations;...
Dental product
C427S430100, C106S035000, C252S188200, C118S400000, C118S428000, C118S425000, C118S429000, C118S423000, C422S028000, C424S466000, C424S049000, C424S052000
Reexamination Certificate
active
06217933
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a method for applying a polymeric, surface coating to dentures and similar articles that are placed within the mouth, such as orthodontic brackets and the like. In particular, the invention relates to the application of a polymeric, silicone coating to dentures by passing the denture through an air-solution interface at which the polymer is concentrated. The coating resists the growth of plaque on the denture.
BACKGROUND
Tablets and powders for cleansing dentures and the like are well known in the art. A common method for using such a product is to place a tablet and a denture in a beaker and then to fill the beaker with water, thereby dissolving the tablet and creating a cleansing bath in which the denture is immersed for a period of from a few minutes to several hours. The aim of a denture cleanser product is to clean the denture as fully and as quickly as possible and especially to remove the accumulation of plaque, mucilaginous and bacterial deposits which collect while the denture is being worn. To wear a denture which has not been completely cleaned of plaque and bacterial deposits is not only unhygienic but can also within a short space of time result in a detrimental effect on the mucous membrane. Consequently, agents which can reduce the adhesion of bacteria to the cleaned denture and thus retard plaque build-up have also been described in the art. Many silicones are suitable for this purpose as described, for example, in WO 96/19563 and WO 96/19191. WO 96/16630 also describes the use of fluorocarbon containing polymers for coating hard tissue and surfaces of the oral environment, including dentures and the like.
To be fully effective, such coatings must be applied uniformly over the whole denture surface. It has now surprisingly been found that the effectiveness of application of such coatings can be enhanced by careful control of the passage of the denture through the air interface of an aqueous bath comprising a polymeric coating agent. In particular, it has been found that coating is enhanced if the denture is withdrawn through the air interface or if the bath is drained from below such that the interface passes over the denture, rather than, for example, decanting the bath contents by tipping. Whilst not wishing to be bound by theory, it is believed that an important factor may be the avoidance of an increase in the surface area of the interface, which could lead to the surface pressure at the interface dropping, whilst the denture passes through it.
Accordingly, it is an object of this invention to provide a method for enhancing the deposition of a polymeric coating on a denture.
It is a further object of this invention to provide a method, for using a denture bath comprising a liquid denture treating composition, to control the interaction of the denture with the air interface of the composition.
SUMMARY OF THE INVENTION
The invention provides a method for treating a denture, comprising:
a) soaking the denture in an aqueous composition comprising a polymeric coating agent having a surface tension in 0.1% aqueous solution of less than 37 mNm
−1
and a weight average molecular weight of 1,000 or greater, said composition having an interface with the surrounding air; and
b) passing the denture through the interface by draining the composition from a position beneath the denture or by lifting the denture through the interface.
The invention further relates to a method for coating a denture with a silicone or fluorocarbon polymer having a weight average molecular weight of 1,000 or greater, the method comprising the step of passing the denture through an interface between an aqueous composition comprising the polymer and the surrounding air, said interface having a rest surface area, whilst maintaining the surface area of the interface at about or below the rest surface area.
The invention yet further relates to use of a denture bath comprising:
a) an outer container for containing an aqueous composition;
b) means for supporting a denture in said container which allows said denture to be immersed in the aqueous composition; and
c) an aqueous composition comprising a silicone polymer having a weight average molecular weight of 1,000 or greater;
wherein the denture bath comprises a means for passing the denture through an interface of the aqueous composition with the surrounding air, said means being selected from means for draining the composition from a position beneath the denture and means for lifting the denture through the interface.
The methods enhance the coating of the denture with the polymer, thereby delivering improved plaque prevention.
All percentages and ratios herein are by weight, unless otherwise indicated.
DETAILED DESCRIPTION OF THE INVENTION
The methods herein are for treating a denture, especially by coating it. By “denture” is meant any device that is manufactured for placement within the mouth over a period of several days or more but that may be temporarily removed from it by the wearer for the purpose of cleaning or hygienic treatment. This includes artificial teeth and also orthodontic brackets, bridges and the like. The methods of treatment and coating herein take place outside of the mouth.
The methods of treatment comprise soaking the denture in an aqueous composition comprising an anti-plaque coating agent which is a polymer having a weight average molecular weight of about 1,000 or greater. The weight average molecular weight is preferably in the range from about 1,000 to 100,000, more preferably from about 2,000 to about 50,000 and especially from about 5,000 to about 20,000. To reduce the adherence of bacteria and other soils, the coating should have a low surface energy. Particularly preferred therefore are polymers or polymer mixtures having a surface tension in aqueous solution of less than about 37 mNm
−1
, preferably less than about 32 mNm
−1
, and more preferably less than about 30 mNm
−1
. Surface tensions herein are measured at 25° C. in a 0.1% w/w solution of the polymer or polymer mixture in water using the Wilhelmy Plate method.
Preferred classes of polymers include polymers comprising silicone or fluorocarbon moieties. Homopolymers or copolymers can be used. The polymers are preferably liquid at 25° C. Preferred herein from the point of view of low toxicity, oral acceptability and/or cost and commercial availability are silicone polymers, especially those based on a siloxane backbone. Suitable classes of silicone polymers include, but are not limited to, dimethicones, dimethiconols, dimethicone copolyols and aminoalkylsilicones. Mixtures of suitable polymers can be used.
Preferred silicone polymers are dimethicone copolyol or aminoalkylsilicone antiplaque agents such as those described in WO 96/19563 and WO 96/19554.
Suitable aminoalkylsilicones are selected from noncyclic, hydrophobic aminoalkylsilicones having a formula comprising two basic units:
1) (R
1
)
m
(R)
n
SiO
(4-m-n)/2
wherein m+n is 1,2 or 3; n is 1,2 or 3; m is 0,1,2; and
2) (R
1
)
a
(R
2
)
b
SiO
(4-a-b)/2
wherein a+b is 1,2, or 3, and a and b are integers, wherein R
1
and R
2
are independently selected from H ,alkyl and alkenyl of about 1 to about 10 carbons optionally substituted with fluoro or cyano groups, hydroxy, alkoxy, and acetoxy, for example, wherein R
1
and R
2
are independently selected from methyl, ethyl, phenyl, vinyl, trifluoropropyl and cyanopropyl, and R is
wherein R
3
is a divalent alkylene of about 1-20, preferably about 3-5 carbon atoms optionally substituted or interrupted by O atoms, R
4
, R
5
and R
6
which may be the same or different are selected from H, alkyl of about 1-20, preferably about 1-10, more preferably about 1-4 carbons optionally substituted or interrupted by N and/or O atoms, and X
−
is a monovalent anion such as halide, hydroxide, and tosylate, said aminoalkylsilicone including from about 0.1-2%, preferably from about 0.5-2% of unit (1) on a repeating unit basis. Preferred aminoalkylsilicones comprise amodimethicones. Amod
Edwards Mark Ieuan
Hughes Iain Allan
Beck Shrive
Clark Karen F.
Dinsmore & Shohl
Kolb Jennifer
The Procter & Gamble & Company
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