Dentistry – Method or material for testing – treating – restoring – or... – By filling – bonding or cementing
Reexamination Certificate
1999-05-18
2001-11-13
Wilson, John J. (Department: 3732)
Dentistry
Method or material for testing, treating, restoring, or...
By filling, bonding or cementing
C106S035000, C523S116000
Reexamination Certificate
active
06315566
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to dental compositions. More specifically, the present invention relates to compositions that have unique handling properties for use in the dental arts in the treatment of teeth.
BACKGROUND OF THE INVENTION
Dental materials comprising resin and, in certain circumstances, filler, are used as restorative materials to repair tooth structure, or as sealants or adhesives. These materials are applied in an uncured state, and then cured in the mouth, often by exposure to a curing light that initiates a polymerization reaction. The consistency of the materials when first applied in an uncured state may be problematic in that they may flow more than desired. This is particularly the case for adhesives or sealants, which may tend to flow in an uncontrolled manner. More highly filled materials, in the category of dental restoratives, tend to exhibit a slower flow characteristic called “slump.” Slump may be a problem because the shape imparted to the dental material may change in the time between shaping by the practitioner and polymerization of the material by exposure to light.
Certain restoratives, particularly those for materials that are to be used as posterior composites, are designed to be of particularly high viscosity. Ideally, a resin based material would be formulated such that it mimics the placement characteristics of amalgam filling materials, which are condensed in the mouth by packing. During this packing process, the amalgam condenses such that it will displace a matrix band, a thin metal strip that acts as a form for the restoration and assures appropriate contact of the restoration with adjacent dentition. The current art in achieving the desired packable viscosity of resin based products uses higher filler loading and/or fillers with beneficial sizes and shapes. The problem associated with this approach is that those materials often appear dry and tend to be crumbly when handled. Another approach is to increase resin viscosity to create heavy body material. The material from this approach may be too sticky for optimal use, and also may be dry and crumbly.
SUMMARY OF THE INVENTION
Dental materials are provided that exhibit unique handling characteristics based on the hydrogen bonding properties of components of the material. More specifically, dental materials are provided comprising Component i), which is a hydrogen bondable compound that is a polymer having a molecular weight greater than about 10,000, and Component ii), which is a hydrogen bondable bridging compound. One of Components i) and ii) contains 2 or more hydrogen-bond donor sites per compound, and the other of Components i) or ii) contains 2 or more hydrogen-bond acceptor sites per compound, which hydrogen-bond acceptor sites are not capable of also acting as hydrogen-bond donor sites. Components i) and ii) are present in an amount sufficient to exhibit at least 10% higher Relative Viscosity, and optionally at least one of i) or ii) is polymerizable. If the material contains any additional compounds having only one hydrogen-bond donor site or hydrogen-bond acceptor site per compound, the ratio of hydrogen-bond donor sites on compounds having only one hydrogen-bond donor site to hydrogen-bond donor sites on compounds having 2 or more hydrogen-bond donor sites per compound is less than 0.25, and the ratio of hydrogen-bond acceptor sites on compounds having only one hydrogen-bond acceptor site to hydrogen-bond acceptor sites on compounds having 2 or more hydrogen-bond acceptor sites per compound is less than 0.25.
For purposes of the present invention, the term “compound” means any chemical entity, including monomer, oligomer, polymer or filler particle.
“Relative Viscosity,” for purposes of the present invention, is a comparison of a subject composition, which is an uncured desired composition of the present invention, with the viscosity of a comparative composition that is identical in composition to the subject composition except that the hydrogen bond donor sites have been functionalized so that they are no longer capable of donating hydrogen. For example, hydrogen bond donor sites that are hydroxy functionalities may be functionalized by reacting with acetic anhydride or acetyl chloride to form the ester or acetate. The appropriate functionalization to perform this evaluation is selected based on the ability to carry out the reaction with the compound, while adding only the additional chemical entity necessary to eliminate the hydrogen donor sites. It is contemplated that functionalization to form acetate esters or methyl or ethyl ethers or their equivalents depending on the starting hydrogen bond donor sites will provide appropriate comparisons to show the effect of the hydrogen bond interaction between Components i) and ii).
The present invention provides unique handling characteristics over a broad spectrum of dental material classes. The specific class of dental materials selected for preparation by the artisan is determined by incorporation of ingredients specific to that class of materials, or otherwise formulating to provide the specific physical property characteristic required for that class, such as initial viscosity. Thus, improved properties may be observed for dental restoratives that are in the categories as defined herein as packable, shapeable or flowable composites, as well as for less viscous dental materials such as sealants and adhesives.
DETAILED DESCRIPTION OF THE INVENTION
A novel method of modifying and controlling the rheology of dental materials, and particularly those for dental composite materials, has been developed utilizing hydrogen bonding between materials that act as hydrogen-bond acceptors and materials that act as hydrogen-bond donors. Without being bound by theory, it is believed that the selection of the specific components as described herein provides for creation of a hydrogen bonded matrix when the material is in the uncured state. This matrix exhibits unusual structural behavior when the material is undisturbed or when force is applied to a large surface of the material. However, the material exhibits dramatically different rheological properties when the material is under bulk or localized shear force. Thus, the material will tend to stay where it is desired to stay due to the presence of the hydrogen bonded matrix, and will move easily when it is desirable to do so simply by applying force in a manner that disrupts the hydrogen bonded matrix.
Using this novel approach, we have created dental materials that have excellent rheological properties beneficial to the handling and ease-of-use aspects of dental procedures. In one aspect of the present invention, the rheology of dental composite material (i.e. dental restorative materials made from polymerizable components and filler materials) are significantly improved as compared to prior dental composite materials.
In one embodiment of the present invention, dental composites may exhibit heavy body characteristics that offer a “packable” composite. A “packable” composite is a material that can be placed in the cavity and which when compressed by a dental probe will exert enough lateral force to distort a matrix band and additionally will tend to hold the matrix band out essentially in this distorted position after the dental probe has been removed from the composite material. Preferably, the packable material is defined as a material having a 2.5 kg Consistency Value as described herein between 9.5 mm and 28 mm and a Placement Force Value as described herein between 400 and 1200 grams.
Most preferably, composites of the present invention will exhibit an unusual behavior in that it will exhibit an ability to be formed in the shape of an arch as defined by the Arch Test described herein, and will hold that position without slumping or deformation.
The non-slumping and non-sticky characteristics make the material easy to handle and manipulate. Composites of the present invention also may be sculpted and shaped to create anatomy on the occlusal surface, thereby savin
Kuehn Robert D.
Mitra Sumita B.
Shen Byron Ciping
Zhang Xiaodong
3M Innovative Properties Company
Bumgarner Melba
Wilson John J.
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