Drug – bio-affecting and body treating compositions – Enzyme or coenzyme containing – Hydrolases
Reexamination Certificate
2002-01-15
2004-06-22
Witz, Jean C. (Department: 1651)
Drug, bio-affecting and body treating compositions
Enzyme or coenzyme containing
Hydrolases
Reexamination Certificate
active
06752989
ABSTRACT:
The present invention concerns a process for improving the adhesive fastening of dental materials on the dental hard substance by modifying the collagen layer present after preparation or etching.
The following steps are performed by the treatment provider for fastening dental materials on the prepared dental hard substance according to the current state of the art:
1 Slightly etching the overall dental hard substance using an acid (“total etching technique”).
2 Applying a so-called primer, which superficially penetrates into the dental hard substance.
3 Application of a so-called bonding, which together with the primer forms a hybrid layer.
4 Polymerization of the bonding (for example by irradiation with light and/or through a redox reaction).
5 Application of the dental material.
In order to diminish the number of components to be applied, the primer and the bonding—or also sealant—were combined into one component (so-called onebottle bonding products, for example Prime & Bond 2.1, Dentsply/Detray company, Dreieich, Germany). Nonetheless, the area must first be etched and rinsed in order to free the smear layer, which has arisen in connection with the preparation (and represents a mixture, which basically consists of hydroxyl apatite and collagen), from hydroxyl apatite so that subsequently the onebottle bonding product can be applied at least once and subsequently be polymerized before the dental material is used. References are found in the literature which question the efficiency of this easily applied adhesive (R. Frankenberger, N. Krämer, J. Sindel, Dtsch. Zahnärztl. Z (German Dentist Magazine), 51: 556-560 (1996). In particular, the lifetime of the adhesive connection declines sharply with this simplified procedure.
Another simplification of the procedure described above for the adhesive fastening of dental materials consists of combining the primer and etching agent into one component (so-called self-etching primers; for example, Etch & Prime 3.0, Degussa company; Clearfill-Liner Bond 2.0, Kuraray company, Osaka, Japan). These need only be applied and no longer need to be rinsed—so-called “modification of the smear layer.” This is followed by either the bonding to be polymerized (for example, Clearfill Liner Bond 2.0, Kuraray company, Osaka) or at least a reticulation step for polymerization of the self-etching primer before the dental material can be used.
After the first step (etching the dental hard substance), a network of exposed collagen fibers is present on the dentine. After polymerization has taken place, a so-called hybrid layer arises by the subsequent application of the primer or the bond (onebottle variant), initiated by exposure to light and/or a redox reaction. This hybrid layer consists of collagen fibers, which, together with the hardened monomers of the primer and/or bond, form an interpenetrating network. According to current theory, this hybrid layer is chiefly responsible for the adhesion between the dental hard substance and the dental materials (N. Nakabayashi et al., J. Biomed. Mater. Res., 1982, 16, 265-273; R. L. Erikson, Am. J. Dent. 1989, 2, 117-123; D. H. Pashley, Trans. Acad. Dent. Mater., 1990, 3, 55-73; B. v. Meerbek, dissertation 1993, Catholic University of Louvain). Furthermore, the hybrid layer acts as an elastic “buffer” between dental hard substance and dental material, as the modulus of elasticity lies approximately between both materials. Overall the hybrid layer is thus a basic component, which decisively contributes to the success of the preparation and the health of the remaining dental hard substance.
There are also studies, which show that not-impregnated partial areas of the collagen layer weaken the connection between the dental hard substance and dental material and possibly lead to an accelerated weakening of this connection (J. D. Eick, Proc. Fin. Dent. Soc., 1992, 88 (First supplement), 225-242; N. Nakabayashi et al.; Dent. Mater., 1992, 8, 125-130).
In order to obtain a good hybrid layer on the dentine, a complete wetting of all collagen fibers and therewith the observation of and pedantic compliance with the manufacturer's specifications are necessary (B. v. Meerbek et al., Dtsch. Zahnärztl. Z. 1994, 49, 977-984). Wetting the collagen fibers with the various bonding materials is, however, dependent upon various factors, such as, for example, the thickness and dryness of the collagen layer, the fiber length and the hydrophilicity of the bonding monomer matrix. In addition, the proportion of collagen in the dental hard substance is different or variable according to the individual characteristics of the patient. Establishing a good adhesive connection is therewith an extremely technique- and substance-sensitive process in dental practice, which but seldom leads to predictable results (J. Perdigao et al., Dent. Mater., 1997, 13, 218-227; B. v. Meerbek et al., Philip Journal, 1997, 9-10, 313-315).
U.S. Pat. No. 5,762,502 describes a method where either the smear layer arising after preparation can be removed by treatment with metalloproteinases or collagenases (substituting of the etching step) or the exposed collagen can be completely removed by these enzymes following the etching.
The task of the invention consists of avoiding problems known from the state of the art and making an improved surface treatment agent for hard tissues available.
The object of the present invention is solved by making available a surface treatment agent for hard tissues, including at least one enzyme and an agent restricting the enzyme activity. By using the agent, this remains on the hard tissue, whereby the enzyme activity is restricted temporarily and/or locally.
As a function of the concrete embodiment, the surface treatment agent of the present invention is first formed by mixing the individual components, especially the enzyme and the agent restricting the enzyme activity, immediately before the application or while applying the individual components on the surface to be treated.
A non-definitive enumeration of features is introduced with the term “include” and “contain.” The circumstance that the word “one” is used before naming a feature does not rule out that the features mentioned can be present several times in the sense of “at least one.”
The surface treatment agents from the invention can, for example, be used in bonding formulations in combination with an activity-terminating mechanism so that the enzyme or enzymes can remain on the dental hard substance without damaging it.
The surface treatment agents from the invention have, among other things, the following advantages.
In contrast with the state of the art, the enzyme solution does not have to be separately applied and rinsed each time. This saves the dentist and the patient three additional steps (applying the enzyme solution, allowing it to act, and subsequent rinsing). The treatment is shortened and simplified (it is recognized that the complexity of the classic four-step bonding procedure very often led to mistakes and poor clinical results).
A further advantage in comparison with the state of the art is retention of the hybrid layer, which is important for sealing and for the adhesion on the dental hard substance, which also has an essential function as an elastic buffer between tooth and dental material. One must imagine that the structure of the layers of mineralized dentine-hybrid layer-bonding-dental material takes place through hardness gradients, where the hybrid layer has assumed basically a “mediator role.”
Finally, there is no longer the danger with the surface treatment of the invention that, if the enzyme solution used is not completely rinsed off, it remains at least partially on the tooth and there damages the dental hard substance by degradation of the collagen present in the adjacent dentine, even under the applied bonding.
The fact that the juncture is in fact severely damaged when collagenase remains too long on the exposed dentine is shown in the present invention by the comparison examples and illustration 1.
The invention furthermore makes a
Frey Oliver
Häberlein Ingo
Hecht Reinhold
Luchterhandt Thomas
3M ESPE AG
Crowell & Moring LLP
Witz Jean C.
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