Dental cavity varnish composition

Dental cavity varnish compositions comprising a solution of nitrocellulose and toluene sulfonamide which wet and precisely conform to each "peak" and "valley" of the extensive microundercuts generated during cavity preparation. The varnish compositions are compatible with composite resin restorative materials.

STATEMENT OF THE INVENTION 
This invention relates to dental cavity varnish compositions which 
precisely conform to dental cavity walls and are compatible with composite 
resin restorative materials. 
BACKGROUND AND SUMMARY OF THE INVENTION 
In the removal of the enamel shell which protects the underlying structure, 
the more permeable dentin is exposed to thus render the remaining tooth 
structure more susceptible to dental decay as well as creating an entrance 
for harmful stimuli to the vital pulp beneath. 
A common practice prior to restoring the missing structure with a filling 
material or cement is to apply a thin layer of cavity varnish over the 
entire exposed dentin area in order to (1) provide a barrier to moisture 
penetration, (2) serve as insulation against external stimuli, and (3) 
reduce marginal leakage around a restoration. 
Cavity preparation generates extensive microundercuts throughout the cavity 
walls. These microundercuts serve to promote good retention of a closely 
packed restoration. In order to benefit from these microundercuts, a 
cavity varnish should precisely conform to each "peak" and "valley" of the 
microundercuts with no concomitant loss of definition thereof caused by 
the varnish. Thus, the varnish must be capable of fully wetting the dentin 
surfaces while spreading uniformly over their general topography, and yet 
not swamping the microundercuts. Conventional cavity varnishes have been 
only mildly successful in fulfilling the above requirements. 
Additionally, a dental cavity varnish should be compatible with composite 
resin restorative materials, such as bisphenol-A resin, for example, 
currently in wide usage by the dental profession. 
It is well known that composite materials can irritate underlying tooth 
structures. The use of a protective varnish therefore is appropriate. 
Unfortunately, traditional varnishes were developed, in the main, for 
compatible use with amalgams and silicates, both widely used prior to 
composite resin restorative materials. For example, a widely used prior 
art copal-containing cavity varnish caused an unpolymerized mushy layer to 
form when the composite was applied over the varnish film. This unreacted 
layer permitted ready access to the dentin area, or seepage thereinto, of 
harmful stimuli. 
The present invention substantially satisfies the abovementioned 
requirements, i.e., complete wetting of the dentin surfaces while 
providing a thin but uniform film over the microundercuts without 
obstructing the peaks and valleys thereof; and complete compatibility with 
composite resin restorative materials, as well as amalgams and silicates. 
In addition thereto, the present varnish is fast drying, hydrophobic when 
dry, simple to use, and possesses long shelf life and good sealing ability 
.

DETAILED DESCRIPTION OF THE INVENTION 
The present invention resides in compositions of matter illustrated by the 
following non-limiting examples tabulated below: 
TABLE I 
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EXAMPLES 
1 2 3 4 5 6 
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*Nitrocellulose (A), parts 
7.5 5.0 5.0 -- -- -- 
*Nitrocellulose (B), parts 
-- -- -- 7.0 -- -- 
*Nitrocellulose (C), parts 
-- -- -- -- 6.5 -- 
**Nitrocellulose (D), parts 
-- -- -- -- -- 6.5 
Toluene Sulfonamide parts 
3.5 5.0 5.0 4.0 4.5 4.5 
Ethyl Acetate parts 
50.0 40.0 50.0 50.0 50.0 50.0 
Ether parts 50.0 40.0 50.0 40.0 50.0 50.0 
Ethyl Alcohol parts 
-- 20.0 -- 10.0 -- -- 
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*Nitrocellulose (A), (B), and (C), each dissolved in a 25% solution of 
ethyl alcohol 25%, toluene 55%, and ethyl acetate 20%; the resulting 
nitrocellulose solutions having viscosities of 3 to 4 seconds, 4 to 5 
seconds, and 6 to 8 seconds respectively, in accordance with ASTM D301-56 
**Nitrocellulose (D) dissolved in a 20% solution, in lieu of the 25% 
solution abovedescribed, to yield a viscosity of 6 to 8 seconds, in 
accordance with ASTM D301-56. 
With the solvents of Examples 1 through 6 above tabulated, i.e., ethyl 
acetate, ether and ethyl alcohol, the effective ranges of the 
nitrocellulose and toluene sulfonamide were determined to fall between 
about 3 to 10 parts and 0.5 to 6.0 parts respectively, preferably 
respectively 5.0 to 7.5 parts and 3.5 to 5.0 parts. Below about 3 parts 
nitrocellulose, and above about 10 parts nitrocellulose, the resultant 
varnish film is undesirably thin and thick respectively. Below about 0.5 
parts toluene sulfonamide, the varnish fails to spread satisfactorily, 
whereas above about 6.0 parts, the resultant film is not sufficiently 
water-repellent. 
Nitrocellulose imparts film forming properties to the composition. The 
resultant film is tough and water-repellant. Toluene sulfonamide is highly 
compatible with the nitrocellulose and with composite restorative resin 
materials. It spreads well and assists the cavity varnish composition in 
wetting the dentin surfaces. In combination, the nitrocellulose and 
toluene sulfonamide form a sealing film which chemically bonds to the 
dentin and to the resin or composite restorative while yet satisfying the 
requirements set forth and described hereinabove.