Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Reexamination Certificate
2000-03-30
2002-10-01
Gulakowski, Randy (Department: 1746)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
C252S079100, C252S079200, C106S035000, C424S055000, C424S049000, C427S307000, C433S216000
Reexamination Certificate
active
06458869
ABSTRACT:
FIELD OF THE INVENTION
The present invention is directed to an etchant/primer composition, an etchant/primer/adhesive monomer composition, kits comprising the same and methods using the same for dental restorative applications. More particularly, the present invention is directed to an etchant/primer composition, an etchant/primer/adhesive monomer composition, kits comprising the same and methods using the same for improving the bond strength of adhesive resins bonded to dentin, enamel, bone, or other such dental structures.
BACKGROUND OF THE INVENTION
The restoration of decayed dental structures including caries, decayed dentin or decayed enamel, is often accomplished by the application of polymer based adhesives to the relevant dental structures. However, typically, polymer-based adhesive resins alone do not form strong bonds with dentin or enamel. To improve the adhesion of polymer-based resins to dentin or enamel, various pre-treatment steps are undertaken. Ordinary pre-treatment steps include an etching step followed by a priming step. Typically, after priming, the adhesive resin is applied as a polymeric adhesive resin or as polymer-forming monomer(s) polymerized on the dental structure in question.
During the etching step, an aqueous solution of inorganic or organic acids is applied to the relevant dental structure, e.g., dentin or enamel. The acid etches the enamel layer and removes the “smear layer” from dentin and demineralizes a surface layer of dentin. The “smear layer” is a coating of debris that forms on the dentin surface as a result of the cutting and grinding processes of, for example, cavity preparation. After etching, a “primer” is applied during the priming pre-treatment step. The “primer” improves the bonding between the subject dentin, enamel, or bone structure and the yet to be applied adhesive resin (or monomer(s) thereof).
The above-noted etchants, primers, resins and monomers are typically applied in a step-wise fashion. In addition to the step-wise etching, priming and polymerizing (applying and curing adhesive resins or monomers) steps, between these steps, one or more rinsing, drying, and rinsing/drying steps may be required. As a result, dental restoration involves using complex, technique-intensive, multi-step restorative procedures.
To simplify these complicated restorative procedures, it would be beneficial to provide a single composition that accomplishes at least both etching and priming. Thus, separate etching and priming steps desirably could be combined into a single step by applying a suitable combination etchant/primer composition. Additionally, it would be desirable to provide a single composition comprising an etchant, a primer, and an adhesive resin monomer. Finally, it would be desirable to provide a kit comprising the same and methods for using the same.
In an effort to formulate multi-component compositions, it was undertaken to investigate whether the addition of an acid to a primer such as N-phenyliminodiacetic acid (PIDAA) might improve the shear bond strength (SBS) of an adhesive resin such as PMDM (the reaction product of 2-hydroxyethyl methacrylate (HEMA) and pyromellitic acid dianhydride) or PMDGM (reaction product of glyceroldimethacrylate and pyromellitic acid dianhydride) bonded to dentin. A study was conducted to determine the effect on adhesive resin-dentin SBS by incorporating various acidic additives into a primer such as PIDAA.
In particular, various acids (10% w/w H
3
PO
4
, 5% w/w ascorbic acid (AA), or 2.8% w/w CPIDAA) added to 0.3M PIDAA (dissolved in acetone:H
2
O (1:1 v/v) solution) were evaluated for their effect on SBS. Additionally, a 0.6M PIDAA (dissolved in acetone:H
2
O (1:1 v/v)) solution was evaluated as a control for its effect on SBS. The bonding protocol utilized a two-step procedure: the first step was to apply a test self-etching primer (e.g., PIDAA with 10% w/w H
3
PO
4
, 5% w/w ascorbic acid or 2.8% w/w CPIDAA, respectively) to a dentin surface for 60 seconds which was then dried with a stream of air. The H
3
PO
4
acid and ascorbic acid containing test specimens were rinsed with water and air dried. Thereafter, a 20% w/w adhesive resin of PMGDM (in acetone activated with 0.07% w/w camphorquinone (CQ; visible light photoinitiator)) was applied and light cured (LC) for 20 seconds. The light activated resin composite was then applied to the dentin previously treated with the acid modified or experimental self-etching primers and cured for 60 seconds. After 24 hours storage in H
2
O at 23° C., SBS values were measured. SBS values were measured in MPa units (SD, n=10). The results were as follows (MPa (SD)): H
3
PO
4
, 5.5 (7.9); AA, 9.1 (6.3); CPIDAA, 13.9 (6.2); and PIDAA (control), 16.9 (5.6). ANOVA indicated significant differences existed between the SBS values measured. Dunnett's multiple comparison test (p<0.05) showed that the SBS values compared as follows: H
3
PO
4
≈AA<CPIDAA≈PIDAA.
These results indicated that adding an acid to an iminodiacetic acid primer such as PIDAA weakened the shear bond strength of the adhesive resin-dentin bond. See “1997 IADR ABSTRACT FOR—ORLANDO” submitted by G. E. Shumacher and J. M. Antonucci entitled “Etchant-Modified N-phenyliminodiacetic Acid as a Self-etching Primer for Dentin Bonding” (submitted September 20, 1996).
Accordingly, one of ordinary skill in the art would have been led to believe that the addition of an acid to an iminodiacetic acid primer yields a self-etching primer that weakens (rather than strengthens) the shear bond strength of an adhesive resin bonded to dental structures such as dentin. Thus, one of ordinary skill would not have been motivated to combine acid etchants with iminodiacetic acid primers to yield a single etchant/primer composition. Consequently, until now, the need for a single self-etching primer composition (e.g., etchant/primer composition or an etchant/primer/adhesive monomer composition) remained unfulfilled.
Accordingly, there is a need in the art for a single self-etching primer composition which does not weaken the SBS between an adhesive resin and the underlying dental structure being restored.
SUMMARY OF THE INVENTION
Thus, it is an object of the present invention to provide a single composition which is a self-etching primer composition (e.g., an etchant/primer composition or an etchant/primer/adhesive monomer composition) for dental restorative purposes that does not sacrifice the SBS between the subject dental structure and the adhesive resin bonded thereto. It is a further object of the present invention to provide a kit and a method for using the same.
These and other objects are accomplished by the embodiments described below. One embodiment of the present invention comprises an etchant/primer composition comprising:
a compound having the formula:
RN(CH
2
YCO
2
M)
2
wherein R=R
1
or R
2
;
R
1
=an aromatic group;
R
2
=a conjugated unsaturated aliphatic group;
Y=a single bond, CH
2
, CHCH
3
or C═CH
2
; and
each M is independently H, an alkali metal, an alkaline earth metal, aluminum, a transition or redox metal or an alkyl group having 1 to 18 carbon atoms, with the proviso that when both M groups are alkyl groups, the compound is capable of being easily hydrolyzed, displaced, or exchanged with other reagents present in the etchant/primer composition;
a polar solvent system; and
nitric acid.
According to another embodiment, a method of preparing a dental substrate for contact with an adhesive resin or an adhesive resin monomer is provided. This method comprises the step of contacting the substrate with an etchant/primer composition that comprises:
a compound having the formula:
RN(CH
2
YCO
2
M)
2
wherein R=R
1
or R
2
;
R
1
an aromatic group;
R
2
=a conjugated unsaturated aliphatic group;
Y=a single bond, CH
2, CHCH
3
or C═CH
2
; and
each M is independently H, an alkali metal, an alkaline earth metal, aluminum, a transition or redox metal or an alkyl group having 1 to 18 carbon atoms, with the proviso that when b
Antonucci Joseph M.
Eichmiller Frederick C.
Schumacher Gary E.
Ahmed Shamim
Banner & Witcoff , Ltd.
Gulakowski Randy
National Institute of Standards of Technology
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