Ex Parte White

Board of Patent Appeals and Interferences

Aug 22, 2012

11878337 (B.P.A.I. Aug. 22, 2012)

UNITED STATES PATENT AND TRADEMARK OFFICE
UNITED STATES DEPARTMENT OF COMMERCE
United States Patent and Trademark Office
Address: COMMISSIONER FOR PATENTS
P.O. Box 1450
Alexandria, Virginia 22313-1450
www.uspto.gov
APPLICATION NO. FILING DATE FIRST NAMED INVENTOR ATTORNEY DOCKET NO. CONFIRMATION NO.
11/878,337 07/23/2007 Dennis Joseph White 7817
7590 08/23/2012
Dennis J. White
41 N Main St
Cranbury, NJ 08512
EXAMINER
SINGH, SUNIL K
ART UNIT PAPER NUMBER
3732
MAIL DATE DELIVERY MODE
08/23/2012 PAPER
Please find below and/or attached an Office communication concerning this application or proceeding.
The time period for reply, if any, is set in the attached communication.
PTOL-90A (Rev. 04/07)
UNITED STATES PATENT AND TRADEMARK OFFICE
__________

BEFORE THE BOARD OF PATENT APPEALS
AND INTERFERENCES
__________

Ex parte DENNIS JOSEPH WHITE
__________

Appeal 2011-011471
Application 11/878,337
Technology Center 3700
__________

Before ERIC GRIMES, LORA M. GREEN, and ERICA A. FRANKLIN,
Administrative Patent Judges.

GRIMES, Administrative Patent Judge.

DECISION ON APPEAL
This is an appeal under 35 U.S.C. § 134 involving claims to a method
of making a dental cast, which the Examiner has rejected for obviousness.
We have jurisdiction under 35 U.S.C. § 6(b). We reverse.
STATEMENT OF THE CASE
The Specification discloses a method of “making accurate stone dental
casts and models, which are used in the process of fabricating removable
dental appliances and indirect dental restorations” such as dentures (Spec. 1).
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Application 11/878,337

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The Specification discloses that coating a dental impression with a stone-
setting catalyst, such as dental stone that has set and been ground into a
powder, results in a dental cast that more accurately reproduces the original
tooth (id. at 12-13, 18).
Claims 1, 10, and 11 are on appeal. Claim 1 is representative and
reads as follows:
1. An improved method for producing a stone dental cast comprising the
steps of:
a. placing stone setting catalyst, onto the internal surface of an elastomeric
dental impression;
b. pouring a wet, mixed dental stone into said elastomeric dental
impression and onto said catalyst,
whereby the dental stone juxtaposed to said catalyst sets faster, and
further whereby, an accurate gypsum cast is formed by a stratified set,
thereby, producing accurate restoration or prosthesis.

The Examiner has rejected all of the claims on appeal under 35 U.S.C.
§ 103(a) as obvious based on Eisner
1
and Hamer
2
(Answer 3). The Examiner
finds that Eisner discloses “placing a thin layer of dental stone setting catalyst
(veneer) onto the internal surface of a dental impression material (column 3,
lines 15-18)” and pouring dental stone into the impression; “whereby the
dental stone juxtaposed sets faster; wherein the cast is formed by a stratified
set (layers) (column 3, lines 23-29)” (id. at 4). The Examiner finds that
Hamer “teaches that it is known to use gypsum and elastomeric impression
materials to form a dental cast (column 1, lines 15-19)” and concludes that it
would have been obvious to modify Eisner’s method to use gypsum as the

1
Eisner, US 4,243,389, issued Jan. 6, 1981.
2
Hamer, US 5,085,811, issued Feb. 4, 1992.
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Application 11/878,337

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dental stone material and to use an elastomeric dental impression based on
Hamer’s teaching (id.).
Appellant argues, among other things, that “Eisner does not first place
a catalyst before his first pour of stone. Eisner places wet mixed stone . . .
[and] wet stone does not share the chemical properties and attributes of a
catalyst” (Appeal Br. 17). Appellant also argues that Hamer “places an
impression setting catalyst onto the surface of the impression material . . . to
remove unwanted hydrogen gas, and thus, form a smoother stone cast.
Hamer’s catalyst does not influence the setting of dental stone. He does not
apply a stone setting catalyst.” (Id. at 19.)
We agree with Appellant that the Examiner has not shown that a
method meeting all the limitations of claim 1 would have been obvious to a
person of ordinary skill in the art based on Eisner and Hamer. Claim 1
requires two distinct steps: (1) placing stone setting catalyst onto the internal
surface of a dental impression, and (2) pouring dental stone into the
impression and onto the catalyst (see claim 1).
The Specification describes different ways in which the catalyst can be
applied to the impression: as powdered dental stone (Spec. 12-13), as a
liquid slurry that is allowed to evaporate to leave a thin film coating (id. at
15), or by discarding a first cast and pouring a second cast from the original
impression (id. at 16). In each case, however, the Specification describes a
catalyst-applying step that is separate from the step of pouring the dental
stone into the impression to produce the final cast.
Eisner discloses an apparatus for accurately placing a dowel pin in the
center of a tooth impression, to allow removal and repeated placement and
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Application 11/878,337

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fitting of the tooth model during fabrication (Eisner, col. 1, ll. 5-28). Eisner
states that its device is used to position an indicator showing where the dowel
pin should be placed (id. at col. 3, ll. 2-15) relative to a “dental impression
. . . taken in the usual manner” (id. at col. 3, ll. 1-2). Eisner’s process
continues as follows:
Casting material is subsequently deposited within the impression
and subjected to vibration in the usual manner. During such
vibration, base 1 is held firmly in place by the impression
material and stop 6. Prior to setting of the plaster, dowel pin P,
in its holder 7, is set back into place on base member 1 in
abutment with indicator 10.
Upon setting of the impression deposited dental stone, all
components of the present apparatus are removed leaving the
partially exposed dowel pin in place. A second pour is then
made with the jaw reproduction being removed from the
impression after setting of the second pour. Subsequent removal
of the tooth model and prosthetic fitting is all thereafter done in
the conventional manner.
(Id. at col. 3, ll. 15-30.)
Hamer discloses that “curable vinyl polysiloxane compositions are
used to make negative impressions of teeth, which serve as molds for casting
the positive model, the positive model being a cured epoxy or gypsum
material” (Hamer, col. 1, ll. 15-19). Hamer discloses that hydrogen gas
escaping from the mold can cause pits in the casting material (id. at col. 1,
ll. 21-23), and that finely divided palladium can prevent this problem (id. at
col. 1, ll. 24-34). Hamer does not disclose any stone-setting catalysts.
We agree with Appellant that neither Eisner nor Hamer discloses the
first step recited in claim 1: placing a stone-setting catalyst on the internal
surface of an impression before pouring dental stone onto it. The Examiner
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has not persuasively explained why such a step would have been obvious to a
skilled worker despite the references’ silence on this point.
The Examiner argues that “the claims are broadly claiming a catalyst
in which Eisner discloses a stone that sets. Therefore, the initial layer must
inherently have a catalyst that causes or initiates the material to set.”
(Answer 5.) The Examiner has not, however, pointed to any evidence
showing that dental stone does not set in the absence of a catalyst, and
therefore has not shown that a skilled worker would have understood Eisner’s
process to require a catalyst.
The Examiner also argues that
Appellant has not claimed any specific properties/characteristic
of the catalyst to differentiate from the prior art. The
Appellant[’]s specification states that the catalyst is a dental
stone material that is hydrated. The Examiner points out, that
the initial dental stone that is poured in the impression material
is a paste like substance and therefore must be hydrated in order
to have the flowing property of a paste/puddy [sic].
(Answer 5.)
As we understand it, the Examiner’s reasoning is that the Specification
states that dental stone material that is hydrated is a catalyst and, since
Eisner’s process uses wet dental stone, it is also a catalyst. This reasoning is
also unpersuasive. The Examiner has pointed to no passage in the
Specification to support the position that wet dental stone itself is a catalyst,
and our review of the Specification did not reveal one. In addition, as
discussed above, claim 1 requires two separate steps: placing a catalyst onto
an impression, and then pouring wet dental stone onto the catalyst. The
claim does not read on a single step of pouring wet dental stone that is also a
catalyst into a dental impression.
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Finally, the Examiner argues that “dental stone is a plaster type
material and will form a porous layer upon setting. Therefore, once a second
layer of plaster is poured on top of the first layer, some of the dental[ ] stone
will be seeped into the first porous layer causing the second stone to set at a
slower rate.” (Answer 5.)
This argument is also unpersuasive. First, the Examiner has pointed to
no evidence in the record to show that the asserted effect actually occurs.
Second, the Specification describes the effect of a catalyst layer as speeding
the hardening of the dental stone in contact with it, not causing subsequently
applied stone to set at a slower rate. (See Spec. 13: “Any errant set stone
particle from a previous stone mix would detrimentally serve as a catalyst to
start the setting of wet dental stone at a site away from the impression surface
. . . [and] compete with the desired setting of wet stone juxtaposed to the
surface of the impression” (emphasis added).)
SUMMARY
We reverse the rejection of claims 1, 10, and 11 as obvious based on
Eisner and Hamer.
REVERSED

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