Adhesive securing of dental filling materials

Details Adhesive securing of dental filling materials Adhesive securing of dental filling materials

1999-02-16

2001-06-12

Pezzuto, Helen L. (Department: 1714)

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

Polymers from only ethylenic monomers or processes of...

C526S274000

Reexamination Certificate

active

06245872

ABSTRACT:

The present invention relates to the use of a mixture of ethylenically unsaturated acid group-containing monomers in a suitable solvent in a process for the adhesive securing of dental filling materials in only one step.
According to the current state of the art, the work steps passed through by the person carrying out the treatment in order to secure dental filling materials to the hard tooth substance are the following:
1.) Etching of the hard tooth substance by an acid (total-etch-technique),
2.) Application of a so-called primer, which penetrates into the tooth substance at the surface,
3.) Application of a so-called bonding, which together with the primer forms a hybrid layer,
4.) Polymerization of the bonding (e.g. by irradiation with light or by redox reaction),
5.) Application of the filling material.
Depending on the type and composition of these adhesive systems, the primer or the bonding consists of one or two liquids (to be mixed prior to use) which are applied once or twice by the person carrying out the treatment and in between have to be polymerized e.g. by irradiation with light. More-over, these adhesive systems are generally moisture-sensitive and may be used only if accompanied by absolute drainage (coffer dam). The whole procedure for the securing of dental filling materials is thus much more costly and time-intensive for the dentist than was the case with amalgam.
In order to reduce the number of constituents to be used, the primer and the bonding were combined into one component (so-called single-bottle bondings, e.g. Prime & Bond 2.1®, Dentsply/Detrey, Dreieich). But etching must still be carried out first, followed by the application of the single-bottle bonding at least once and then polymerization, before the filling material is used. There are indications in the literature that the efficiency of these adhesives that are to be used in a simplified way is to be questioned (R. Frankenberger, N. Krämer, J. Sindel; Dtsch Zahnärztl Z 51 (1996), 556-560).
Another simplification of the process described above for the adhesive securing of filling materials is to combine the primer and the etching product into one component (so-called auto-etching primers; e.g. Etch & Prime 3.0® Degussa; Clearfil-Linerbond 2.0®, Kuraray, Osaka). Although these only have to be applied and no longer rinsed off, they are followed by either the bonding, still to be polymerized, of the process described at the outset (e.g. Clearfil-Linerbond 2.0®, Kuraray, Osaka) or else at least a crosslinking step for the polymerization of the auto-etching primer before the filling material can be used.
Auto-etching mixtures of phosphoric acid hemaesters with a photoinitiator in acetone as solvent are disclosed in DE-A-34 14 163. However, this document also teaches that, in order to be able to produce an adhesive join to the hard tooth substance, a further adhesion promoter, which has to be polymerized first, is to be applied before the actual filling material.
Auto-etching adhesive mixtures which no longer need to be polymerized prior to the application of the filling material are described in EP-A-0 183 027. However, they require an additional catalyst in the form of a sulphinic acid and/or its salt in order to achieve an adequate adhesion to the dentine. The document does not provide any evidence that a good enamel adhesion is achieved without a previous etching step.
Auto-etching mixtures are likewise disclosed in EP-A-0 088 527, but must contain as an acid component phosphoric acid esters that are relatively complicated to produce and thus comparatively costly. These compounds bear at least three ethylenically unsaturated groups and contain no other initiator component. The quoted adhesion values for dentine and enamel are low compared with those which can be achieved through preliminary treatment of the hard tooth substance by etching and bonding.
Mixtures are described in U.S. Pat. No. 5,264,513 which, in addition to water, an unsaturated polymerizable acid and a catalyst, must also contain unsaturated polymerizable hydroxyl group-containing monomers in order to guarantee an adequate dentine and enamel adhesion. These hydroxyl group-containing monomers, in particular the preferred 2-HEMA, have a high sensitization potential and thus pose a threat to those who use these mixtures.
Adhesives on the basis of polymerizable phosphoric acid halides, which also lead to an adequate adhesive join to the dentine without previous etching, are described in U.S. Pat. No. 5,304,585. However, in order to achieve optimum adhesion forces at the enamel, a previous separate etching step is necessary.
Also described in the literature is a series of other adhesive mixtures which, although they have an auto-etching action, must either be applied repeatedly and/or polymerized before the filling material is used.
The object of the present invention is to provide adhesive mixtures for securing dental filling materials which are applied in one step and coated without further aftertreatment with polymerizable filling material and at the same time lead to good adhesion values to dentine and to very good adhesion values to enamel. These adhesive mixtures should consist of as few components as possible, be accessible at a favourable price and be able to be used by the user without risk.
This object is achieved by the use of a mixture which comprises
i) 10 to 90 parts by weight of at least one singly or repeatedly ethylenically unsaturated phosphoric acid ester,
ii) 5 to 85 parts by weight of a solvent,
iii) 0.01 to 5 parts by weight of an initiator which can form free radicals, and
iv) 0 to 10 parts by weight of customary auxiliaries and additives,
coating with polymerizable filling material being carried out immediately after the application of the mixture to the hard tooth substance.
Surprisingly, it was found that such mixtures already lead, merely through single application to untreated dentine or untreated enamel and without an intermediate polymerization step, to adhesive joins with dental filling materials which are as good as when hard tooth substance is previously treated with an etching product, primer and bonding. The advantage for the user is a saving of several work steps and an associated saving in time, which also makes the treatment less unpleasant for the patient. Although the procedure is clearly shortened, the outstanding adhesion values, in particular to the tooth enamel, show that the quality of the restorations is not poorer than with conventional securing processes.
The invention is described in more detail in the following:
The adhesive mixture which features the described advantages when used according to the invention contains as constituent i) 10 to 90 parts by weight, preferably 30 to 85 parts by weight, of at least one singly or repeatedly unsataurated phosphoric acid ester. Suitable monomers containing phosphoric acid groups are known and described e.g. in U.S. Pat. No. 4,182,035, U.S. Pat. No. 4,222,780, U.S. Pat. No. 4,235,633, U.S. Pat. No. 4,259,117 and U.S. Pat. No. 4,368,043 and also in EP-A-0 084 407. Ethylenically unsaturated phosphoric acid esters according to the following formula are preferably used in the adhesive mixture:
in which R
1
and R
2
stand independently of each other for a hydrogen atom or for
where R
3
represents hydrogen or C
1
- to C
3
-alkyl and n is a whole number ≧1, on condition that at least one of the radicals R
1
or R
2
does not equal hydrogen.
Constituent ii) of the adhesive mixture is a solvent which is capable of completely dissolving constituents i) and iii). Suitable solvents are those which are sufficiently volatile and can be employed without posing a threat to the user. Examples of these are readily volatile alcohols such as ethanol, propanol or isopropanol, as well as liquid, not very toxic ketones, such as e.g. acetone. Water is particularly preferred as solvent. Constituent ii) is contained in the adhesive mixtures at the rate of 5 to 85 parts by weight, preferably 10 to 80 parts by weight.
Radical-forming catalysts according to constitu

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