DURSCHANG et al.v.RITZBERGER et al.

Patent Trials and Appeals Board

Sep 29, 2016

13079861 - (J) (P.T.A.B. Sep. 29, 2016)

BoxInterferences@uspto.gov Entered: 29 September 2016
Tel: 571-272-7822

UNITED STATES PATENT AND TRADEMARK OFFICE

BEFORE THE PATENT TRIAL AND APPEALS BOARD

CHRISTIAN RITZBERGER,
RICARDO DELLAGIACOMO, MARCEL SCHWEIGER,
HARALD BURKE,
WOLFRAM HOLAND, AND
VOLKER RHEINBERGER,
JUNIOR PARTY,
(PATENTS 8,536,078, 8,557,150, 8,778,075, and 9,249,048)

V.

BERNHARD DURSCHANG,
JORN PROBST, NORBERT THIEL, JOACHIM BIBUS,
MARKUS VOLLMANN, AND
UDO SCHUSSER,
SENIOR PARTY,
(APPLICATION 14/274,235)

PATENT INTERFERENCE NO. 106,012
(TECHNOLOGY CENTER 1700)

Before SALLY GARDNER LANE, JAMES T. MOORE, and DEBORAH KATZ,
Administrative Patent Judges.

LANE, Administrative Patent Judge.

JUDGMENT - Bd. R. 127(a)

-2-

A decision granting senior party Durschang’s motion on the basis of priority 1
has been entered (Decision on Priority and Other Motions, Paper 210). In view of 2
the Decision, judgment on priority is entered against Ritzberger. 3
Order 4
It is 5
ORDERED that judgment on priority is entered against junior party 6
Ritzberger as to Count 1, the sole Count of the interference (Declaration, Paper 1, 7
at 4); 8
FURTHER ORDERED that claims 1-30 of Ritzberger patent 8,536,078, 9
which correspond to Count 1, are CANCELLED. (Declaration, Paper 1, p.4); 35 10
U.S.C. § 135(a);1 11
FURTHER ORDERED that claims 1-24 of Ritzberger patent 8,557,150, 12
which correspond to Count 1, are CANCELLED. (Redeclaration, Paper 211, p.2); 13
35 U.S.C. § 135(a); 14
FURTHER ORDERED that claims 1-45 of Ritzberger patent 8,778,075, 15
which correspond to Count 1, are CANCELLED. (Redeclaration, Paper 211, p.2); 16
35 U.S.C. § 135(a); 17
FURTHER ORDERED that claims 1-18 of Ritzberger patent 9,249,048, 18
which correspond to Count 1, are CANCELLED. (Redeclaration, Paper 211, p.2) 19
35 U.S.C. § 135(a); 20

1 Any reference to a statute in this Judgment is to the statute that was in effect
on March 15, 2013 unless otherwise indicated. See Pub. L. 112-29, § 3(n), 125
Stat. 284, 293 (2011).

-3-
FURTHER ORDERED that the parties are directed to 35 USC § 135(c) and 1
Bd. R. 205 regarding the filing of settlement agreements; 2
FURTHER ORDERED that a party seeking judicial review timely serve 3
notice on the Director of the United States Patent and Trademark Office; 4
37 C.F.R. §§ 90.1 and 104.2. See also Bd. R. 8(b). Attention is directed to Biogen 5
Idec MA, Inc., v. Japanese Foundation for Cancer Research, 785 F.3d 648, 6
654–57 (Fed. Cir. 2015) (determining that pre-AIA § 146 review was eliminated 7
for interference proceedings declared after September 15, 2012); and 8
FURTHER ORDERED that a copy of this judgment be entered into the 9
administrative records of the involved Ritzberger patents and Durschang 10
application. 11

cc (via e-mail):

Attorney for Ritzberger:

Deborah A. Sterling
Josephine J. Kim
STERNE, KESSLER, GOLDSTEIN & FOX, P.L.L.C.
dsterlin-ptab@skgf.com
joskim-ptab@skgf.com

Attorney for Durschang:

R. Danny Huntington
Seth E. Cockrum
ROTHWELL, FIGGS, ERNST & MANBECK, P.C.
dhuntington@rfem.com
scockrum@rfem.com
BoxInterferences@uspto.gov Entered: 29 September 2016
Tel: 571-272-7822

UNITED STATES PATENT AND TRADEMARK OFFICE

BEFORE THE PATENT TRIAL AND APPEAL BOARD

CHRISTIAN RITZBERGER,
RICARDO DELLAGIACOMO, MARCEL SCHWEIGER,
HARALD BURKE,
WOLFRAM HOLAND, AND
VOLKER RHEINBERGER,
JUNIOR PARTY,
(PATENT 8,536,078)

V.

BERNHARD DURSCHANG,
JORN PROBST, NORBERT THIEL, JOACHIM BIBUS,
MARKUS VOLLMANN, AND
UDO SCHUSSER,
SENIOR PARTY,
(APPLICATION 14/274,235)

PATENT INTERFERENCE NO. 106,012
(TECHNOLOGY CENTER 1700)

Before SALLY GARDNER LANE, JAMES T. MOORE, and DEBORAH KATZ,
Administrative Patent Judges.

LANE, Administrative Patent Judge.

Decision on Priority and other Motions – Bd. R. 121(a)
2

I. Introduction 1
The interference was declared under 35 USC 135(a) 1 on 3 October 2014 2
between patent 8,536,078 of junior party Ritzberger and application 14/274,235 of 3
senior party Durschang. (Declaration, Paper 1). 4
A decision on non-priority motions was entered on 12 November 2015. 5
(Decision, Paper 97; Decision on Rehearing, Paper 100). In that Decision, we 6
denied Ritzberger Motion 1 for judgment on the basis that the Durschang claims 7
are unpatentable under 35 USC 112, ¶ 1. We dismissed as moot Durschang 8
Motion 2 seeking to add a claim to its involved application noting that the motion 9
was responsive to, and contingent upon the grant of, Ritzberger Motion 1. 10
(Decision, Paper 97, p.14). Thereafter each party filed a motion for judgment on 11
the basis of priority of invention. Further senior party Durschang was authorized 12
to file (Order Authorizing Motion, Paper 139) and did file (Durschang Motion 3, 13
Paper 179), a miscellaneous motion to add additional Ritzberger patents to the 14
interference. Accordingly, the following motions are before us for decision.2 15
Junior party Ritzberger 16
1. Ritzberger motion for judgment on the basis of priority of invention. 17
(Ritzberger Priority Motion, Paper 107). Durschang filed an opposition to this 18
motion. (Durschang Opposition 2, Paper 197). Ritzberger then filed a reply. 19
(Ritzberger Reply 2, Paper 202). 20

1 Any reference to a statute in this Decision is to the statute that was in effect
on March 15, 2013 unless otherwise indicated. See Pub. L. 112-29, § 3(n), 125
Stat. 284, 293 (2011).
2 Each party requested oral argument (Ritzberger Request, Paper 201;
Durschang Request, Paper 203). We find the briefing to address fully the issues
before us and thus have determined that no oral argument is necessary.
3

Senior party Durschang 1
1. Durschang Motion 3 to add additional Ritzberger patents to the 2
interference. (Durschang Motion 3, Paper 179). Ritzberger filed an opposition to 3
this motion. (Ritzberger Opposition 3, Paper 186). Durschang then filed a reply. 4
(Durschang Reply 3, Paper 205). 5
2. Durschang motion for judgment on the basis of priority of invention. 6
(Durschang Priority Motion, Paper 180). Ritzberger filed an opposition to this 7
motion. (Ritzberger Opposition 4, Paper 187). Durschang then filed a reply. 8
(Durschang Reply 4, Paper 209). 9
10
We grant Durschang Motion 3 and the Durschang Priority Motion. We 11
dismiss as moot the Ritzberger Priority Motion. 12
13
II. Findings of Fact 14
The record supports the following findings of fact, as well as the additional 15
findings of fact set forth in the discussion portion of this decision, by a 16
preponderance of the evidence. 17
The Count 18
1. The sole count of the interference, Count 1 (Count), is: 19
Claim 3 or claim 6 of Ritzberger (8,536,078) 20
or 21
Claim 1 of Durschang (14/274,235). 22
23
(Declaration, Paper 1, 4). 24
2. Claim 3 of Ritzberger depends on claim 1, which is: 25
Lithium silicate glass ceramic, which comprises at least 6.1 wt.-% ZrO2 and 26
which comprises more than 10 vol.-% of lithium metasilicate crystals. 27
4

1
(Ritzberger clean copy of claims, Paper 9). 2
3
3. Claim 3 of Ritzberger is: 4
Lithium silicate glass ceramic of claim 1, which comprises more than 30 5
vol.-% of lithium metasilicate crystals. 6
7
(Ritzberger clean copy of claims, Paper 9). 8
9
4. Claim 6 of Ritzberger depends on claim 4 which is: 10
Lithium silicate glass ceramic, which comprises at least 6.1 wt.-% ZrO2 and 11
which comprises more than 10 vol.-% of lithium disilicate crystals. 12
13
(Ritzberger clean copy of claims, Paper 9). 14
15
5. Claim 6 of Ritzberger is: 16
Lithium silicate glass ceramic of claim 4, which comprises more than 30 17
vol.-% of lithium disilicate crystals. 18
19
(Ritzberger clean copy of claims, Paper 9). 20
6. Claim 1 of Durschang is: 21
A lithium silicate glass ceramic comprising at least 10 wt. % ZrO2 and 22
having a main crystal phase, wherein said main crystal phase is selected from the 23
group consisting of lithium metasilicate crystal and lithium disilicate crystal. 24
25
(Durschang clean copy of claims, Paper 6). 26
7. Each party’s specification indicates that the composition of the Count 27
is for dental applications and is used in dental restorations. (Ritzberger involved 28
patent, Ex 1005, 2:10-20 and Durschang involved application, Ex 1001, p.1-2). 29
8. According to the parties’ specifications, the lithium silicate glass 30
5

ceramics of the involved claims provide benefits such as improved mechanical 1
properties, translucence and chemical stabilities. (Ritzberger involved patent, Ex 2
1005, col. 4:3-32 and Durschang involved application, Ex 1001, p.3). 3
4
Claim correspondence 5
9. Claims 1-30 of Ritzberger correspond to the Count. (Declaration, 6
Paper 1, p.5). 7
10. Claims 1-3 of Durschang correspond to the Count. (Declaration, Paper 8
1, p.5). 9
10
Benefit 11
11. The involved Ritzberger patent, 8,536,078 (’078), issued 17 12
September 2013 from application 13/079,861, filed 5 April 2011. 13
12. Ritzberger was accorded priority benefit of the following: 14
EP 10160222.5, filed 16 April 2010 15
(Declaration, Paper 1, p.5). 16
13. The involved Durschang application, 14/274,235, was filed 9 May 17
2014. 18
14. Durschang was accorded priority benefit of the following: 19
US 13/518,765, filed 15 August 2012 20
PCT/EP10/07918, filed 23 December 2010 21
DE 102009 060 274.7, filed 23 December 2009 22
(Declaration, Paper 1, p.5). 23
24
6

Real parties 1
15. Ritzberger identifies its real party in interest as Ivoclar Vivident AG. 2
(Ritzberger Notice of Real Party, Paper 8). 3
16. Durschang identifies its real parties in interest as DeguDent GmbH, 4
Vita Zahnfabrik H. Rauter GmbH & Co. KG, and Fraunhofer-Gesellschaft Zur 5
Forderung Der Angewandten Forschung E.V. (Durschang Notice of Real Party, 6
Paper 4). 7
8
Durschang Motion 3 (to add Ritzberger patents to the interference) 9
17. During ex parte prosecution of its involved application, Durschang 10
requested interference under Bd. R. 202(a). (Request for Interference, Ex 1053). 11
18. In its Request for Interference, Durschang asserted that its claims 12
interfere with the involved Ritzberger patent as well as Ritzberger patent 8,557,150 13
(’150), issued 15 October 2013 (Ex 1016) and Ritzberger patent 8,778,075 (’075) 14
issued 15 July 2014 (Ex 1017). (Request for Interference, Ex 1053). 15
19. The interference was declared involving only one Ritzberger patent, 16
i.e., the involved ’078 patent. (Declaration, Paper 1). 17
20. Durschang was authorized to file a miscellaneous motion to add the 18
’150 patent and the ’075 patent as well as a patent issued after the interference was 19
declared, i.e., patent 9,249,048 (’048) (Ex 1018). (Order Setting Times, Paper 17, 5 20
and Order Authorizing Motion, Paper 139). 21
21. The ’048 patent issued 02 February 2016 from a child application of 22
the application that issued as the ’150 patent. 23
22. Consideration of whether to add additional Ritzberger patents was 24
deferred until the priority phase of the interference. (Order Setting Times, Paper 25
7

17, p.5 and Order Authorizing Motion, Paper 139). 1
23. Claims 1 and 6 of the ’150 patent, below, are illustrative of the 2
claimed subject matter: 3
1. A process for preparing a dental restoration comprising 4
shaping of a lithium silicate glass ceramic or a lithium silicate 5
glass by 6
(i) pressing or 7
(ii) machining 8
to the dental restoration, wherein the glass ceramic or the glass comprises 9
60.0 to 71.0wt.-% Si02 and 10.1 to 20.0wt.-% Zr02 . 10
11
6. The process according to claim 1, wherein the glass 12
ceramic is selected from lithium metasilicate glass ceramic 13
and lithium disilicate glass ceramic. 14
15
(’150, Ex 1016, cols. 14 and 15). 16
17
24. Claims 1, 6 and 7 of the ’075 patent, below, are illustrative of the 18
claimed subject matter: 19
1. Dental restoration, which is coated with a lithium silicate 20
glass ceramic, wherein the lithium silicate glass ceramic comprises 21
at least 6.1 wt.-% Zr02. 22
23
6. Dental restoration according to claim 1, wherein the 24
lithium silicate glass ceramic comprises lithium metasilicate 25
as a main crystal phase. 26
27
7. Dental restoration according to claim 1, wherein the 28
lithium silicate glass ceramic comprises lithium disilicate as 29
a main crystal phase. 30
31
8

(’075, Ex 1017 at col. 13). 1
2
25. Claim 1 of the ’048 patent, below, is illustrative of the claimed subject 3
matter: 4
1. A process for preparing a dental restoration comprising shaping of a 5
lithium silicate glass ceramic by 6
(i) pressing or 7
(ii) machining to the dental restoration, 8
wherein the glass ceramic comprises at least 8.0 wt.-% Zr02, 9
wherein the glass ceramic comprises lithium metasilicate as main crystal 10
phase and comprises more than 10 vol.-% of lithium metasilicate crystals. 11
12
(’048, Ex 1018, col. 14). 13
14
26. In support of Durschang Motion 3, Durschang relies upon the 15
testimony of Dr. Himanshu Jain. (Second Jain Declaration, Ex 1051).3 16
27. Dr. Jain is the T.L. Diamond Distinguished Chair in Engineering and 17
Applied Science and a Professor in the Department of Materials Science and 18
Engineering at Lehigh University in Bethlehem, Pennsylvania. (Jain Declaration, 19
Ex 1009, ¶1). 20
28. Dr. Jain received a B.Sc. in Chemistry, Physics and Mathematics from 21
Christ Church College, Kanpur University, a M.Sc. in Physics from Banaras Hindu 22
University, and a M.Tech. in Materials Science from the Indian Institute of 23
Technology, and an Eng.Sc.D. in Materials Science and Engineering from 24
Columbia University and was a Post-Doctoral Appointee in the Basic Ceramics 25

3 Durschang filed a corrected version of the Second Jain Declaration on 18
March 2016. (See Order authorizing filing of the corrected exhibit, Paper 184). It
is this corrected version that we are referring to in this Decision.
9

Group at Argonne National Laboratory in Argonne, Illinois. (Jain Declaration, Ex 1
1009, ¶2). 2
29. Based on his education, professional and research experience as set 3
forth above and further in his declaration testimony (Jain Declaration, Ex 1009, 4
¶¶3-8) and curriculum vitae (Ex 1010), we find Dr. Jain to be qualified to testify 5
regarding the technical subject matter involved in the interference. 6
30. As further discussed below, Dr. Jain testified to his opinion that all of 7
the claims of the Ritzberger patents Durschang seeks to have added to the 8
interference would have been obvious in view of the Count. (Second Jain 9
Declaration, Ex 1051, ¶¶32-47). 10
31. Dr. Jain testified that, in forming his opinion, he considered whether 11
one skilled in the art would have had a reasonable expectation of successfully 12
carrying out the claimed invention based on the combined teachings of the prior art 13
references. (Second Jain Declaration, Ex 1051, ¶7) 14
32. Dr. Jain refers to claim charts which are attached to his declaration as 15
Appendices A-C. 16
33. In Dr. Jain’s declaration, the claim chart, and Durschang Motion 3, 17
the two following prior art references are relied upon to show obviousness: 18
Patent 7,316,740 (ʼ740) (Ex 1004), issued January 8, 2008, is said to 19
describe a process whereby lithium silicate materials “can be easily processed 20
by machining to dental products without undue wear of the tools and which 21
subsequently can be converted into lithium silicate products showing high 22
strength.” (Second Jain Declaration, Ex 1051, ¶13, quoting from the Abstract of 23
the ’740 patent). 24
25
10

Patent 6,420,288 (ʼ288) (Ex 1019) issued 16 July 2002, is said to be directed 1
to “a process…for the preparation of shaped translucent lithium disilicate glass 2
ceramic products which are characterized by high strength and good chemical 3
stability and may be processed by pressing in the plastic state or milling to finished 4
glass ceramic products which may be used in particular as dental restorations.” (Ex 5
1019, Abstract). (Second Jain Declaration, Ex 1051, ¶24, quoting from the 6
Abstract of the ’288 patent). 7
34. In support of its position that the additional Ritzberger patents should 8
not be added to the interference Ritzberger directs us to the declaration testimony 9
of Dr. Richard K. Brow. (Second Brow Declaration, Ex 2053). 10
35. According to Dr. Brow he is the Curators’ Professor of Ceramic 11
Engineering in the Department of Materials Science and Engineering at Missouri 12
S&T, a Senior Investigator in the Materials Research Center, and a Research 13
Investigator in the Center for Biomedical Science and Engineering. (Brow 14
Declaration, Ex 2017, II.¶¶1 and 2). 15
36. Dr. Brow testified that his research at Missouri S&T involves 16
characterizing the structure and properties of oxide glasses and glass-ceramic 17
materials for a wide range of engineering applications, including dental 18
applications. (Brow Declaration, Ex 2017, II.¶¶1 and 2). 19
37. Dr. Brow testifies that he has experience directly related to the use of 20
glass ceramics as dental materials and that he has worked with dental ceramics 21
companies in the characterization of glass-ceramic materials for dental 22
applications. (Second Brow Declaration, Ex 2053, ¶4). 23
38. Dr. Brow testified that he has taught an undergraduate lab in which 24
students make lithium silicate glasses and then study the effects of composition 25
11

and heat-treatment conditions on the formation of lithium metasilicate and lithium 1
disilicate glass-ceramics. (Second Brow Declaration, Ex 2053, ¶4). 2
39. Based on his education, professional and research experience as set 3
forth above and further in his declaration testimony (Brow Declaration, Ex 2017, 4
II.¶¶1-6), we find Dr. Brow to be qualified to testify regarding the technical subject 5
matter involved in the interference. 6
40. Dr. Brow generally testified to the following regarding the issue of 7
whether additional Ritzberger patents should be added to the interference: 8
A person of ordinary skill in the art would not have been motivated to 9
combine the subject matter of the Count with the teachings of the ’288 or 10
’740 patents; and 11
A person of ordinary skill in the art would not have had a reasonable 12
expectation of success in obtaining the inventions claimed in the ’150, ’075 13
or ’048 patents by combining the subject matter of the Count with the 14
teachings of the ’288 or ’740 patents. 15
(Second Brow Declaration, Ex 2053, ¶6). 16
17
Testimony and other evidence on priority 18
41. Durschang inventors Dr. Bernard Durschang and Dr. Jörn Probst have 19
presented testimony to support the Durschang priority showing as further discussed 20
below. (Durschang Declaration, Ex 1050 and Probst Declaration, Ex 1049). 21
42. In addition to inventor testimony Durschang relies upon the testimony 22
of Mr. Peter Michel (Michel Declaration, Ex 1046), Dr. Martin Kilo (Kilo 23
Declaration, Ex 1048), Mr. Richard Olsowski (Olsowski Declaration, Ex 1045), 24
Ms. Gudrun Leopoldsberger (Leopoldsberger Declaration, Ex 1047) and Dr. 25
12

Himanshu Jain. (Second Jain Declaration, Ex 1051). 1
43. Mr. Michel is employed as a technical employee at Fraunhofer ISC 2
since 1994. (Michel Declaration, Ex 1046, ¶2). 3
44. Mr. Michael testified that, on 28 May 2009 and at the direction of Dr. 4
Durschang, he produced 637_Z, a lithium silicate glass having 12% zirconium 5
oxide. (Michael Declaration, Ex 1046, ¶¶16-21 referring to May 2009 Melt 6
Record, Ex 1042). 7
45. X-ray diffraction (XRD) is an analytical technique capable of 8
detecting crystalline material in a sample where a portion of a sample is milled into 9
a powder and then analyzed in the powder form. XRD involves directing a beam 10
into the sample, recording the diffraction pattern of the sample, and comparing the 11
obtained pattern with a known standard. (Durschang Priority Motion, SMF4s 31-12
33, citing Second Jain Declaration, Ex 1051, ¶58, and admitted in Ritzberger 13
Opposition 4 at Appendix B-5). 14
46. According to Durschang, sometime between mid-June and early July 15
of 2009, samples of 637_Z were given to Mr. Schömig so they could be 16
crystallized, and subsequently analyzed via XRD. (Ex 1050, ¶¶66 and 67). 17
47. Mr. Schömig has not testified in the interference. 18
48. Dr. Kilo is employed at Fraunhofer ISC as the head of as the head of 19
group glass and mineral materials and testified that as head of this group he would 20
regularly discuss the results of ongoing projects with the project leaders such as 21
Dr. Durschang. (Kilo Declaration, Ex 2017, II.¶¶2 and 3). 22
49. Dr. Kilo testified that he recalls reviewing and discussing with Dr. 23

4 Statement of Material Fact.
13

Durschang the results of various testing of a sample 637_Z. (Kilo Declaration, Ex 1
1048, ¶¶11-20). 2
50. Among other things, Dr. Kilo specifically recalls discussing the 3
results of XRD analysis of 637_Z by 19 June 2009, the last day he was at the office 4
prior to leaving for a summer vacation. (Kilo Declaration, Ex 1048, ¶¶11-20, 5
referring to study results, Ex 1035/Ex 1036)5. 6
51. Differential thermal analysis (DTA) is a technique commonly used by 7
those of skill in the art to detect crystallization events. It can detect a 8
crystallization event that occurs in a glass sample and will record that event as a 9
peak in the thermal curve of the sample. (Durschang Priority Motion, SMF 24 and 10
25, citing, e.g., Second Jain Declaration, Ex 1051, ¶50 and admitted by Ritzberger, 11
Ritzberger Opposition 4 at Appendix B-4). 12
52. Mr. Olsowski has been employed as physical technical assistant at 13
Fraunhofer ISC since 2006. (Olsowski Declaration, Ex 1045, ¶2). 14
53. Mr. Olsowski testified that on 23 June 2009 he conducted DTA of 637 15
Z_1 at the request of Dr. Durschang and that it was his practice to give the results 16
of any analysis to the requester as soon as results became available. (Olsowski 17
Declaration, Ex 1045, ¶¶7-9, referring to DTA results dated 23 June 2009, Ex 18
1043). 19
54. Dr. Kilo testified that he recalls reviewing the DTA results after he 20
returned from vacation (on 06 July 2009) and that the results confirmed the XRD 21
results and showed no unexpected crystallization such as the crystallization of 22

5 Exhibit 1036 is the certified English translation of Ex 1035. We will refer to
the translation, i.e., Exhibit 1036, in this Decision.

14

zirconium in the sample. (Kilo Declaration, Ex 1048, ¶¶16-18, referring to DTA 1
results dated 23 June 2009, Ex 1043). 2
55. Scanning electron microscopy (SEM) is a technique that uses a 3
focused beam of electrons to image a sample and requires that the sample be 4
ground and polished, etched with a strong acid, coated with a conductive material, 5
and then fixed on a sample holder. (Durschang Priority Motion, SMFs 40 and 42, 6
citing, e.g., Second Jain Declaration, Ex 1051, ¶¶67 and 68 and admitted by 7
Ritzberger, Ritzberger Opposition 4 at Appendix B-6). 8
56. Dr. Kilo testified that he recalls that after seeing the XRD and DTA 9
results he agreed with Dr. Durschang that SEM analysis should be conducted and 10
recalls viewing the results of the SEM analysis that confirmed the XRD and DTA 11
results. (Kilo Declaration, Ex 1048, ¶19). 12
57. Ms. Leopoldsberger has been employed as a technical employee at 13
Fraunhofer ISC since 1989. (Leopoldsberger Declaration, Ex 1047, ¶2). 14
58. Ms. Leopoldsberger testified that she conducted SEM at the request of 15
Dr. Durschang for certain benchmark testing on, inter alia, a sample known as 16
637_12 on 18 May 2009, further discussed herein, and then on the sample 637_Z 17
beginning on 25 June 2009 and that it was her practice to give the results of any 18
analysis to the requester as soon as results became available. (Leopoldsberger 19
Declaration, Ex 1047, ¶¶12, 13, 15, 16, 21-29, referring to Project Outline, Ex 20
1033/10346 and study results, Ex 1036). 21
59. Benchmark testing results referred to in Ms. Leopoldsberger’s 22
testimony, are said to have been reported at the 20 May 2009 meeting and to be 23

6 Exhibit 1034 is the certified English translation of Ex 1033. We will refer to
the translation, i.e., Exhibit 1034, in this Decision
15

illustrated in a project outline document for the development of a high strength 1
glass ceramic. (Probst Declaration, Ex 1049, ¶30; Durschang Declaration, Ex 2
1050, ¶60, Project Outline, Ex 1034). 3
60. Dr. Jain, whose credentials and qualifications are discussed above, 4
also presented testimony in support of the Durschang Priority Motion 5
61. Dr. Jain testified that, based on his review of Project Outline results he 6
concluded that heat treatment of samples (e.g., 637_12) tested at 650 degrees C for 7
20 minutes resulted in a lithium metasilicate main crystal phase and the samples 8
that had been heat treated at 650 degrees C for 20 minutes followed by a second 9
heat treatment of 850 degrees C for 10 minutes resulted in a lithium disilicate main 10
crystal phase. (Second Jain Declaration, Ex 1051, ¶77). 11
62. The results of the 637_Z1 testing were compiled into a presentation 12
that was said to have been given on 30 July 2009. (Probst Declaration, Ex 1049, 13
¶¶34-36; Durschang Declaration, Ex 1050, ¶¶101-103, referring to e.g., study 14
results, Ex 1036 and meeting minutes, Ex 1039/Ex 1040)7. 15
63. Dr. Jain reviewed the study results and, for reasons discussed in detail 16
in his testimony, agrees that the results show a lithium silicate glass falling within 17
the scope of the Count. (Second Jain Declaration, Ex 1051, ¶¶79-100). 18
64. Regarding XRD testing, Ritzberger expert witness Dr. Brow testified 19
that “[i]n order to determine what type of crystalline phase has formed, a person of 20
ordinary skill in the art would need to perform XRD analysis.” (Second Brow 21
Declaration, Ex 2053, ¶17). 22

7 Exhibit 1040 is the certified English translation of Ex 1039. We will refer to
the translation, i.e., Exhibit 1040, in this Decision.

16

65. Dr. Jain testified that the XRD data was confirmatory, but not 1
necessary, to conclude that the Durschang inventors has actually produced a 2
lithium silicate glass-ceramic with at least 10% zirconium oxide. (Second Jain 3
Declaration, Ex 1051, ¶95). 4
66. Dr. Kilo, when asked if he could tell which crystals formed based on 5
the DTA diagram, testified that “XRD work” would have to be done to tell which 6
glass crystals were formed. (Kilo Deposition, Ex 2055 at 37:4-7.) 7
67. Additional testing of 637_Z1 occurred during the week leading up to 8
the 30 July 2009 presentation. 9
68. Flexural strength testing, said to have taken about a week to complete, 10
was reported on 27 July 2009 and is said to have shown that sample 637_Z1 was of 11
sufficiently high strength to serve as a dental restoration. (Bending strength tests 12
dated 27 July 2009, Ex 1044; Kilo Declaration, Ex 1048, ¶21; Durschang 13
Declaration, Ex 1050, ¶100). 14
69. Dr. Durschang also directed Ms. Leopoldsberger to conduct an SEM 15
analysis on a sample of 637_Z1 that was not subjected to any heat treatments and 16
Ms. Leopoldsberger testified that she completed that analysis on 29 July 2009. 17
(Leopoldsberger Declaration, Ex 1047, ¶¶27-29; Durschang Declaration, Ex 1050, 18
¶101). 19
20
III. Discussion 21
A. Durschang Motion 3 (to add additional Ritzberger patents) 22
When it requested an interference during ex parte prosecution Durschang 23
requested that the interference be declared with three Ritzberger patents said to 24
contain subject matter interfering with the now involved Durschang claims. 25
17

(Durschang Request for Interference, Ex 1053). The interference was declared with 1
only the Ritzberger involved (’078) application and the Board deferred 2
consideration of whether additional Ritzberger patents would be added to the 3
interference. (Order Setting Times, Paper 17, 5 and Order Authorizing Motion, 4
Paper 139). 5
We now consider whether it is appropriate to add additional Ritzberger 6
patents in light of the briefing of the parties. The issue before us is whether it is 7
appropriate to add the following three Ritzberger patents to the interference: 8
8,557,150 (’150), issued 15 October 2013 (Ex 1016) 9
8,778,075 (’075), issued 15 July 2014 (Ex 1017) 10
9,249,048 (’048), issued 02 February 2016 (Ex 1018). 11
Durschang provides argument, testimony from Dr. Jain and claim charts 12
comparing the claims of the patents sought to be added to the Count in support of 13
its position that the three patents should be added. Ritzberger on the other hand 14
relies upon the testimony of Dr. Brow and argues that the three Ritzberger patents 15
should not be added to the interference since Durschang has not met its burden to 16
show that the claims Durschang seeks to add correspond to the Count. (Ritzberger 17
Opposition 3, Paper 186 p.1:4-6, citing 37 CFR §41.121(b) and Standing Order, 18
¶ 203.2). In particular Ritzberger argues that “[t]he claims Durschang seeks to add 19
are neither anticipated by, nor obvious in view of, the subject matter of the Count, 20
alone or in combination with any prior art.” (Ritzberger Opposition 3, Paper 186, 21
p.1:6-9). 22
We have reviewed the claims of the patents Durschang seeks to add as they 23
compare to the Durschang involved claims and the Count (which includes 24
Durschang claim 1) of the interference as well as the briefing from each party and 25
18

evidence relied upon in this briefing. We determine that it is appropriate to add the 1
three additional Ritzberger patents and designate all the claims of each as 2
corresponding to the Count. 3
The 8,557,150 patent 4
Claim 6 of the ’150 patent for example is directed to a process for preparing 5
a dental restoration by shaping a lithium silicate glass ceramic or a lithium silicate 6
glass by (1) pressing or (ii) machining to the dental restoration, wherein the glass 7
ceramic or the glass comprises 60.0 to 71.0 wt.% SiO2 and 10.1 to 20.0 wt.% ZrO2 8
wherein the glass ceramic is selected from lithium metasilicate glass ceramic 9
and lithium disilicate glass ceramic. These process steps are not recited in the 10
Count. However, as Dr. Jain explains, the process steps claimed in the ’150 patent 11
were known in the art and are described, for example, in the prior art in the cited 12
’740 and ’288 patents. (Second Jain Declaration, Ex 1051, at ¶¶34-36, referring 13
also to claim chart, Appendix A). We are persuaded that one skilled in the art 14
would have had reason to use the dental restoration composition of the Count in 15
the known process for preparing a dental restoration to obtain the benefits of that 16
composition. 17
We refer the reader to the claim chart and the discussion about such in Dr. 18
Jain’s testimony, which we find convincing, regarding why the remaining claims 19
of the ’150 patent correspond to the Count. Ex 1051, passim. 20
The 8,778,075 patent 21
Claim 6 of the ’075 patent for example is directed to a dental restoration, 22
which is coated with a lithium silicate glass ceramic, wherein the lithium silicate 23
glass ceramic comprises at least 6.1 wt.-% Zr02. and wherein the lithium silicate 24
glass ceramic comprises lithium metasilicate as a main crystal phase. Claim 7 is 25
19

the same as claim 6 but specifies lithium disilicate as a main crystal phase. Dr. 1
Jain explains that the use of a lithium silicate glass-ceramic to coat a dental 2
restoration, and processes for coating the dental restoration, were well known in 3
the art as evidenced by the ’740 and ’288 patents. (Second Jain Declaration, Ex 4
1051, at ¶¶38-41, referring also to claim chart, Appendix B). We are persuaded 5
that one skilled in the art would have had reason to use the dental restoration 6
composition of the Count in known dental restoration coatings to obtain benefits of 7
that composition. 8
We refer the reader to the claim chart and the discussion about such in Dr. 9
Jain’s testimony, which we find convincing, regarding why the remaining claims 10
of the ’075 patent correspond to the Count. Ex 1051, passim. 11
The 9,249,048 patent 12
Claim 1 of the ’048 for example is directed to a process for preparing a 13
dental restoration comprising shaping of a lithium silicate glass ceramic by 14
(i) pressing or (ii) machining to the dental restoration, wherein the glass ceramic 15
comprises at least 8.0 wt.-% Zr02, wherein the glass ceramic comprises lithium 16
metasilicate as the main crystal phase and comprises more than 10 vol.-% of 17
lithium metasilicate crystals. Dr. Jain explains that processes for using lithium 18
silicate glass-ceramics to form dental restoration by machining or pressing were 19
well known in the art as shown in the ’740 patent. (Second Jain Declaration, Ex 20
1051, ¶¶42-46 referring also to claim chart, Appendix C). We are persuaded that 21
one skilled in the art would have had reason to use the dental restoration 22
composition of the Count in a known method of preparing a dental restoration 23
process to obtain benefits of that composition. 24
We refer the reader to the claim charts and the discussion about such in Dr. 25
20

Jain’s testimony, which we find convincing, regarding why the remaining claims 1
of the ’048 patent correspond to the Count. Ex 1051, passim. 2
Ritzberger arguments 3
Ritzberger argues against the addition of the three patents on the basis that 4
the claims of these patents do not correspond to the Count, i.e., would not have 5
been anticipated or rendered obvious by the Count. (Bd. R. 207(b) stating that a 6
claim corresponds to the Count if the subject matter of the Count, taken as prior art 7
to the claim, “would have anticipated or rendered obvious the subject matter of the 8
claim.”) Because we conclude that the claims of the three additional Ritzberger 9
patents would have been obvious in view of the Count, we do not consider the 10
arguments of either party regarding anticipation. 11
Obviousness results “if the differences between the subject matter sought to 12
been patented and the prior art are such that the subject matter as a whole would 13
have been obvious at the time the invention was made to a person having ordinary 14
skill in the art to which said subject matter pertains.” 35 USC. § 103. If each 15
element of a claim is found in a combination of prior art references then we 16
consider, inter alia, whether the prior art would have suggested to those of 17
ordinary skill in the art that they should make the claimed composition or carry out 18
the claimed process and whether it “would also have revealed that in so making or 19
carrying out, those of ordinary skill would have a reasonable expectation of 20
success.” Medichem, S.A. v. Rolabo, S.L., 437 F.3d 1157, 1164 (Fed. Cir. 2006). 21
This obviousness analysis “need not seek out precise teachings directed to the 22
specific subject matter of the challenged claim, for a court can take account of the 23
inferences and creative steps that a person of ordinary skill in the art would 24
employ.” KSR Intern, Co., v. Teleflex, Inc., 550 U.S. 398, 418 (2007). 25
21

Ritzberger argues that its claims would not have been rendered obvious by 1
the subject matter of the Count for the reasons that: (1) one skilled in the art would 2
not have had a reason or motivation to combine the prior art to arrive at the claims 3
and (2) one skilled in the art would not have had a reasonable expectation of 4
success because of unpredictability that results when altering the amount of ZrO2 5
(3) the prior art provided no guidance regarding how to adjust the level of other 6
components when increasing ZrO2 to maintain properties suitable for a dental 7
restoration, and (4) the subject matter of the Count achieved unexpected results 8
when used to prepare dental restorations. (Ritzberger Opposition 3, Paper 186). 9
We consider these arguments below: 10
1. One skilled in the art would not have had a reason or motivation to combine 11
the prior art to arrive at the claims. 12
13
Ritzberger argues that Durschang has not articulated a reason why one 14
skilled in the art would have combined the Count with the asserted prior art 15
references to arrive at the inventions claimed by the ’150, ’075, and ’048 patents. 16
Ritzberger argues that Dr. Jain admitted that he simply added limitations from the 17
prior art to the Count to see whether, in his judgment, that would render the 18
additional claims obvious and that Dr. Jain therefore engaged in hindsight. 19
(Ritzberger Opposition 3, Paper 186 p.5:15-23, citing InTouch Techs., Inc. v. VGO 20
Comms., Inc., 751 F.3d 1327, 1348-49 (Fed. Cir. 2014) for the proposition that 21
expert testimony is impermissible hindsight where expert opines that all of the 22
elements of the claims disparately existed in the prior art, but failed to explain what 23
reason or motivation one of ordinary skill in the art at the time of the invention 24
would have to put the separate pieces of prior art together). Ritzberger argues that 25
the ’288 patent teaches using a lesser quantity of ZrO2 to achieve translucency but 26
22

does not detail how one could predict when increased amounts of ZrO2 would 1
improve or impair translucency. (Ritzberger Opposition 3, Paper 186 at 6:5-19). 2
We do not find this argument persuasive. We are convinced that one skilled 3
in the art would have had reason to combine the conventional methods and 4
processing steps shown in the cited prior art with the dental restoration 5
composition of the Count to obtain the benefits provided by that composition 6
including improved translucence or the other reported benefits of improved 7
mechanical properties and chemical stabilities. (See FF8 7, referring to Ritzberger 8
involved patent, Ex 1005, 2:10-20 and Durschang involved application, Ex 1001, 9
p.1-2). Ritzberger’s arguments that a person skilled in the art would have had no 10
reason to increase the amount of ZrO2 in the dental restorations and processes of 11
making and using such ignores the Count. The Count, which is to be taken as prior 12
art in analyzing claim correspondence, provides for an increased amount of ZrO2 13
such that one skilled in the art would have had an expectation that the increased 14
amount works for dental restoration purposes. 15
2. One skilled in the art would not have had a reasonable expectation of 16
success because of unpredictability that results when altering the amount of 17
ZrO2. 18
19
Ritzberger, relying upon the testimony of Dr. Brow, argues that the effect of 20
increasing the amount of ZrO2 is unpredictable and therefore one skilled in the art 21
would not have had a reasonable expectation that combining the prior art would 22
yield a successful result, e.g., appropriate optical and mechanical properties for a 23
dental restoration. (Ritzberger Opposition 3, Paper 186, p. 10, citing Second Brow 24

8 Finding of fact.
23

Declaration, Ex 2053, ¶¶ 41, 51, 59). Ritzberger directs us also to testimony from 1
Durschang witnesses indicating their opinion that they could not know with 2
certainty what the effect of increasing the ZrO2 concentration would have been 3
until it was tried. (Ritzberger Opposition 3, Paper 186, p. 11, citing, e.g., Jain 4
Deposition, Ex. 2056, 50:6-8). On this point and to the extent the Ritzberger 5
claims require any particular optical or mechanical property (most of them do not), 6
we credit the testimony of Dr. Jain over the testimony of Dr. Brow to the extent 7
there is conflict on whether there was a reasonable expectation of success. 8
We are convinced that one skilled in the art would have had a reasonable 9
expectation of success when using a lithium silicate ceramic glass composition 10
containing ZrO2 that is said to be useful in dental restorations, in known methods 11
and processes that are useful for dental restorations composed of lithium silicate 12
ceramic glass but contain a lesser amount of ZrO2. 13
What is required for obviousness is a reasonable, not an absolute, expectation 14
of success. While we agree that one cannot know with certainty what result will be 15
achieved until the combination is actually made or performed, absolute 16
predictability is not required for there to be a reasonable expectation of success. In 17
re Merck & Co., 800 F.2d 1091, 1097 (Fed. Cir. 1986) (“Obviousness does not 18
require absolute predictability.”) Further the evidence suggested that one skilled in 19
the art would have known how to vary parameters, e.g., heating conditions, to 20
achieve the desired result of a dental restoration. (Durschang Reply, Paper 205, p. 21
3:13-20, citing Brow Deposition, Ex 1055, 30:6-15, 33:9-34:15, 88:22-89:8). 22
3. The prior art provided no guidance regarding how to adjust the level of other 23
components when increasing ZrO2 to maintain properties suitable for a 24
dental restoration. 25
26
24

Ritzberger argues that, as the Count does not recite a complete composition, 1
one skilled in the art would not know how to adjust the other components of the 2
glass to arrive at the preferred range of components recited in the claims of the 3
three patents. While the ’288 and ’740 patent appear to disclose ranges for each 4
component that encompasses or overlap the claimed ranges, Ritzberger argues that 5
there is no guidance in the prior art for how to adjust the ranges when a higher 6
concentration of ZrO2 is being used. (Ritzberger Opposition 3, Paper 186, p.12). 7
On this point the testimony of Dr. Brow appears to be consistent with that of 8
Dr. Jain. Dr. Brow agreed that the particular components and their amounts are 9
known in the prior art, and identified in the ʼ740 and ʼ288 patents. (Deposition of 10
Brow, Ex 1055, 41:3-43:14). Dr. Brow also acknowledged that a person of 11
ordinary skill in the art would know that when one component is increased by a 12
given amount, then there must be a corresponding percentage reduction in the 13
amounts of the other components and Dr. Brow agreed that “a typical way to 14
design materials” is to vary the amount of a component, and then characterize the 15
resulting composition to make sure the results are satisfactory. (Deposition of 16
Brow, Ex 1055, 45:2-21). We are convinced after weighing the testimony of both 17
Dr. Jain and Dr. Brow as well as the other evidence pointed to by the parties, that 18
adjusting the other components to account for an increased amount of ZrO2 would 19
have been within the skill of the art particularly where the claimed amounts fall 20
within the ranges disclosed by the prior art. 21
4. The subject matter of the Count achieved unexpected results when 22
used to prepare dental restorations. 23
24
Ritzberger argues that “both Parties agree that the subject matter of the 25
Count achieved unexpected results” and that [a]ccordingly, the evidence of 26
25

surprising results strongly suggests that the inventions embodied in the ’150, ’075, 1
and ’048 patent claims would not have been obvious to a POSA in light of the 2
Count and the cited prior art.” (Ritzberger Opposition 3, Paper 186, p.13-15). This 3
argument is not convincing as it ignores that the Count is taken as prior art in 4
determining obviousness. On this point we agree with Durschang that “when 5
unexpected results are used as evidence of nonobviousness, the results must be 6
shown to be unexpected compared with the closest prior art.” Durschang Reply 3, 7
Paper 205, p. 4:20-22) citing In re Baxter Travenol Labs., 952 F.2d 388, 392 (Fed. 8
Cir. 1991). 9
Here the closest prior art, i.e., the Count, includes the feature that is said to 10
yield unexpected results. We agree with we Durschang that “Ritzberger cannot 11
rely on evidence of unexpected results that are attributable to a feature in the prior 12
art, i.e., a feature of the Count.” (Durschang Reply 3, Paper 205, p. 4:22-23). 13
We have considered the remaining arguments in Ritzberger Opposition 3 but 14
do not find them persuasive. We GRANT Durschang Motion 3. The interference 15
will be redeclared in a separate paper to reflect that all of the claims of each of 16
Ritzberger patents ’150, ’075 and ’048 correspond to the Count. 17
B. Priority 18
Ritzberger argues that it conceived and reduced to practice an invention of 19
the Count earlier than 23 December 2009, Durschang’s earliest accorded benefit 20
date. In particular, Ritzberger alleges a simultaneous conception and reduction to 21
practice of an embodiment of the Count by 23 July 2009 with additional 22
embodiments reduced to practice by 28 September 2009. (Ritzberger Priority 23
Motion, Paper 107, p. 3 and 9). Ritzberger does not assert an earlier conception 24
coupled with diligence. 25
26

Durschang argues that it conceived and reduced to practice embodiments of 1
the Count before the dates alleged by Ritzberger. In particular, Durschang alleges 2
reductions to practice by 19 June 2009, 23 June 2009 or 21 July 2009. (Durschang 3
Priority Motion, Paper 180, p. 13, 16, and 18). Alternatively Durschang argues 4
that it was the first to conceive an invention of the Count and then was diligent in 5
reducing to practice this invention by 30 July 2009. (Durschang Priority Motion, 6
Paper 180, p. 22). 7
“Priority is generally awarded to the applicant who was first to reduce the 8
invention to practice; however, an applicant who was first to conceive the 9
invention but last to reduce it to practice will be awarded priority if he 10
demonstrates reasonable diligence in his reduction to practice.” Cooper v. 11
Goldfarb, 240 F.3d 1378, 1382 (Fed. Cir. 2001) (citing 35 U.S.C. § 102(g)). 12
The Board may take up motions for decision in any order and may take such 13
other action appropriate to secure the just, speedy, and inexpensive determination 14
of the interference. Bd. R. 125(a). The party filing the motion has the burden of 15
proving that it is entitled to relief requested in the motion. Bd. R. 121(b). 16
We first consider the Durschang priority motion because, if Durschang shows that 17
it reduced to practice an invention of the Count prior to the earliest date alleged in 18
the Ritzberger priority motion, then Ritzberger cannot prevail on priority. 19
Alternatively if Durschang shows that it first conceived and then diligently reduced 20
to practice an invention of the Count, then Ritzberger cannot prevail on priority. 21
1. Durschang Priority Motion 22
Durschang has shown by a preponderance of the evidence, as discussed in 23
greater detail below, that the following sequence of events occurred: 24
By 28 May 2009, the inventors has an idea to form a lithium silicate glass 25
27

containing 12% zirconium oxide. That is when Dr. Durschang directed Mr. Michel 1
to melt the sample known as 637_Z1. Dr. Durschang directed testing of 637_Z1. 2
In mid-June XRD analysis results showed 637_Z1 to be a lithium silicate glass-3
ceramic comprising at least 10 wt. % ZrO2 and having a main crystal phase, 4
wherein said main crystal phase is selected from the group consisting of lithium 5
metasilicate crystal and lithium disilicate crystal, i.e., a one falling within the scope 6
of the Count. Additional testing of 637_Z1 was undertaken and that testing 7
confirmed the XRD analysis. DTA analysis, performed by Mr. Olsowski, was 8
completed on 23 June 2009. On 21 July 2009 SEM analysis, undertaken by Ms. 9
Leopoldsberger was completed. Flexural strength testing and additional SEM 10
testing occurred in the week thereafter. The results of testing, including the XRD, 11
DTA and SEM testing, were presented by the inventors at meeting held on 30 July 12
2009. 13
We conclude that the above events led to an actual reduction to practice of 14
an embodiment of the Count by 21 July 2009, a date prior to Ritzberger’s earliest 15
alleged conception and reduction to practice date of 23 July 2009. Alternatively 16
we conclude that these events show a conception prior to 23 June 2009 and that a 17
reduction to practice occurred when the totality of the above discussed testing 18
results was presented at a meeting held on 30 July 2009. We find that Durschang 19
was diligent from before 23 July 2009, Ritzberger’s earliest alleged conception and 20
reduction to practice date, until 30 July 2009. 21
Reduction to practice no later than 21 July 2009 22
In order to establish an actual reduction to practice, the inventor must prove 23
that the inventor: (1) constructed an embodiment or performed a process that met 24
all the limitations of the interference count; and (2) determined that the invention 25
28

would work for its intended purpose. Cooper v. Goldfarb, 154 F.3d 1321, 1327 1
(Fed. Cir. 1998). An inventor’s testimony alone cannot establish an actual 2
reduction to practice. That testimony must be corroborated by independent 3
evidence. Reese v. Hurst, 661 F.2d 1222, 1225, 211 USPQ 936, 940 (CCPA 4
1981). It is not necessary “to produce an actual over-the-shoulder observer to 5
satisfy the corroboration requirement; rather, sufficient circumstantial evidence of 6
an independent nature can satisfy the corroboration rule.” Knorr v. Pearson, 671 7
F.2d 1368, 1373 (CCPA, 1982), citing Berges v. Gottstein, 618 F.2d 771, 776, 8
(CCPA, 1980). “Additionally, oral testimony of someone other than the alleged 9
inventor may corroborate.” Trovan Ltd. v. Sokymat SA, 299 F.3d 1292, 1303 (Fed. 10
Cir. 2002). The rule of reason “requires the Patent and Trademark Office to 11
examine, analyze, and evaluate reasonably all pertinent evidence when weighing 12
the credibility of an inventor's story.” Holmwood v. Sugavanam, 948 F.2d 1236, 13
1238-98 (Fed. Cir. 1991). 14
According to Durschang its inventors set out to produce a novel lithium 15
silicate glass-ceramic that could be used as a dental restoration. (Probst 16
Declaration, Ex 1049, ¶13-16; Durschang Declaration, Ex 1050, ¶18). The 17
testimony of Drs. Durschang and Probst indicates that they believed that such a 18
glass-ceramic would have to first have a lithium metasilicate main crystal phase so 19
that it could be easily machined. (Probst Declaration, Ex 1049, ¶22; Durschang 20
Declaration, Ex 1050, ¶¶20, 61). The testimony also indicates a belief that the 21
glass-ceramic also would have to be capable of being converted to a glass-ceramic 22
with a lithium disilicate main crystal phase so that it would be strong enough to 23
serve as a dental restoration. (Durschang Priority Motion, Paper 180, p.11:11-17; 24
Probst Declaration, Ex 1049, ¶22; Durschang Declaration Ex 1050, ¶¶20, 61). Dr. 25
29

Durschang and Dr. Probst envisioned a high zirconium oxide in the glass believing 1
that would result in increased flexural strength. The testimony indicates that they 2
settled upon the idea of greater than 10% because a lithium silicate glass ceramic 3
having a zirconium oxide concentration “in excess of 10% had not been reported in 4
the literature, and [was] not covered by any patents.” (Durschang Priority Motion, 5
Paper 180, p.11:20-12:5, citing to Project Outline, Ex 1034, p.14; Probst 6
Declaration, Ex 1049, ¶24; and Durschang Declaration, Ex 1050, ¶25). 7
Part of the production process involved what are referred to by Durschang as 8
“benchmark tests”. In these tests samples of lithium silicate glass ceramics 9
containing up to 4% ZrO2 were used, e.g., a sample known as 637_12. (Durschang 10
Declaration, Ex 1050, ¶¶28-29 and April 2009 Melt Record, Ex 1041). The 11
purpose of these tests was to identify heat treatments that could consistently 12
produce a glass-ceramic with a lithium metasilicate as the main crystal phase and 13
then result in a glass-ceramic with lithium disilicate as the main crystal phase. 14
(Durschang Declaration, Ex 1050, ¶36). According to Durschang the examples 15
used in the benchmark tests exhibited lithium disilicate as the main crystal phase 16
following the first heat treatment of 650° C for 20 minutes, and the second heat 17
treatment of 850° C for 10 minutes. (Ex 1034, p.24; Durschang Declaration, Ex 18
1050, ¶¶49-50; Leopoldsberger Declaration, Ex 1047, ¶¶12-16; Second Jain 19
Declaration, Ex 1051, ¶¶64-66). The results were confirmed through DTA, XRD, 20
and SEM analysis. 21
These benchmark results are said to have been reported at the 20 May 2009 22
meeting and to be illustrated in a project outline document for the development of 23
a high strength glass ceramic. (Probst Declaration, Ex 1049, ¶30; Durschang 24
Declaration, Ex 1050, ¶60, Project Outline, Ex 1034). Ms. Leopoldsberger 25
30

testified that she took the micrographs included in the Project Outline on 18 May 1
2009 using the same heat treatment of 650 degrees Celsius for 20 minutes followed 2
by 850 degrees Celsius for 10 minutes using, e.g., 637_12. (Leopoldsberger 3
Declaration, Ex 1047, ¶¶12-15, Project Outline, Ex 1034, p.26-29). 4
Dr. Jain testified that, based on his review of Project Outline results of the 5
benchmark samples, e.g., 637_12, he concluded that heat treatment at 650 degrees 6
C for 20 minutes resulted in a lithium metasilicate main crystal phase and a sample 7
that had been heat treated at 650 degrees C for 20 minutes followed by a second 8
heat treatment of 850 degrees C for 10 minutes resulted in a lithium disilicate main 9
crystal phase. (Second Jain Declaration, Ex 1051, ¶77). 10
Dr. Durschang testified that he began developing a new composition 11
immediately after the 20 May 2009 meeting using a greater concentration, i.e., 12
12%, of zirconium oxide. Durschang alleges that its inventors conceived an 13
invention of the Count by 28 May 2009 when, at the instruction of Dr. Durschang, 14
Mr. Michel melted a sample known as 637_Z1, said to contain the components of a 15
lithium silicate glass containing 12% zirconium oxide. Mr. Michel’s testimony 16
and documentation referenced in that testimony are consistent with, and 17
corroborative of, Dr. Durschang’s testimony regarding the production of sample 18
637_Z1. (Durschang Priority Motion, Paper 180, p.12:6-11 and 18-23, citing to 19
Michel Declaration, Ex 1046, ¶¶16-21 and Durschang Declaration, Ex 1050, ¶65, 20
May 2009 Melt Records, Ex 1042). 21
The inventors testified that after 637_Z1 was produced they set about 22
characterizing it. XRD, DTA and SEM analysis were undertaken, in that order, 23
according to Dr. Durschang. (Durschang Declaration, Ex 1050, ¶¶66 and 84). 24
31

The sample was provided to Mr. Schömig by Dr. Durschang so that it could 1
be crystallized and then analyzed XRD. Dr. Durschang testified that “[t]o the best 2
of my recollection, I believe the XRD characterization was conducted between 3
mid-June and early-July” but was unable to remember the exact date. (Durschang 4
Declaration, Ex 1050, ¶67). 5
The results of the XRD testing, as well as the DTA and SEM testing, are 6
said to be shown in Exhibit 1036. Exhibit 1036, said to have been presented at the 7
30 July 2009 meeting, appears to include a compilation of the 637_Z1 XRD, DTA 8
and SEM results. (FF 62). Mr. Schömig did not provide testimony in the 9
interference regarding the tests he undertook or when they were completed. Thus, 10
unlike with the DTA and SEM testing, the technician performing the XRD testing 11
did not provide testimony to corroborate the details, including the date of, the XRD 12
testing. 13
According to Dr. Durschang the XRD testing was said to have been 14
conducted using the heating treatments established during the benchmark phase. 15
In particular the XRD analysis was of three samples: (1) a non-crystallized sample 16
of the 637_Z1 glass, (2) a sample that had been treated at 650 degrees C for 20 17
minutes (subjected to only one heat treatment), and (3) a sample that had been heat 18
treated at 650 degrees C for 20 minutes followed by a second heat treatment of 850 19
degrees C for 10 minutes (subjected to both heat treatments). (Durschang Priority 20
Motion, Paper 180, p.13:11-18, citing to Second Jain Declaration, Ex 1051, ¶¶57 21
and 67). 22
The results of the XRD analysis are said to have shown that lithium 23
metasilicate was the only crystal present, i.e., it was present in the main crystal 24
phase, in the sample that was subjected to only one heat treatment while lithium 25
32

disilicate was the only crystal present in the sample that was subjected to both heat 1
treatments. (Durschang Priority Motion at 14:14-16). 2
Durschang relies upon Dr. Kilo to corroborate Dr. Durschang’s testimony 3
regarding the XRD testing. Dr. Kilo testified that he recalls that the XRD analysis 4
was conducted before 19 June 2009 specifically because he recalls having a 5
discussion about the project, including the results of the XRD analysis, on his last 6
day at the office before leaving for summer vacation on 21 June 2009. (Kilo 7
Declaration, Ex 1048, ¶¶11, referring to study results, Ex 1036). 8
Dr. Kilo testified that he recalls Dr. Durschang showing him the results of 9
the XRD analysis of sample 637_Z1 that followed the first heat treatment of 650 10
degrees for 20 minutes. He also testified that he recalls agreeing with Dr. 11
Durschang that the peaks from the sample were a good match to the peaks from the 12
lithium metasilicate standard and that he recalls being very happy with this result 13
because it confirmed that lithium metasilicate was present in the main crystal 14
phase. 15
Dr. Kilo testified that he recalls Dr. Durschang showing him the results of 16
the XRD analysis of sample 637_Z1 that followed the first heat treatment of 650 17
degrees for 20 minutes, and the second heat treatment of 850 degrees for 10 18
minutes and that he recalls agreeing with Dr. Durschang that the peaks from the 19
sample were a good match to the peaks from the lithium disilicate standard, a 20
result he was happy with because it confirmed that lithium disilicate was present in 21
the main crystal phase. 22
Dr. Kilo testified that he recalls that the XRD analysis confirmed production 23
of a lithium silicate glass-ceramic with 12% zirconium oxide with a main crystal 24
phase of lithium metasilicate after the first heat treatment, and a main crystal phase 25
33

of lithium disilicate after the second heat treatment, a result that made him happy 1
because it confirmed that the glass group had developed a product with a 12% 2
zirconium content that could be easily machined due to the presence of lithium 3
metasilicate as the main crystal phase, but that could be subsequently strengthened 4
with a second heat treatment that formed lithium disilicate crystals. (Kilo 5
Declaration, Ex 1048, ¶¶10-15, referring to study results, Ex 1035, p. 9 and 12). 6
Dr. Durschang testified that he thereafter asked Mr. Olsowski to conduct a 7
DTA analysis on 637_Z1. (Olsowski Declaration, Ex 1045, ¶5; Durschang 8
Declaration, Ex 1050, ¶78). Mr. Olsowski recalls Dr. Durschang informing him of 9
the temperature profile to use in the DTA analysis. (Olsowski Declaration, Ex 10
1045, ¶6; Durschang Declaration, Ex 1050, ¶78). Mr. Olsowski completed that 11
analysis, the result of which he testified are shown in Exhibit 1043 (DTA results), 12
on 23 June 2009. (Olsowski Declaration, Ex 1045, ¶¶7 and 8). Dr. Durschang 13
testified that he recalls reviewing these test results with Dr. Kilo and that they 14
agreed that the DTA analysis showed that lithium metasilicate formed as the main 15
crystal phase at around 650 degrees Celsius, and lithium disilicate formed as the 16
main crystal phase at around 850 degrees Celsius. (Durschang Declaration, Ex 17
1050, ¶78). 18
Dr. Kilo testified that that he recalls reviewing the DTA results after he 19
returned from vacation (on 06 July 2009), and that the results confirmed the XRD 20
results and showed no unexpected crystallization event such as the crystallization 21
of zirconium in the sample. (Kilo Declaration, Ex 1048, ¶¶16-18). Dr. Kilo 22
testified that he recalls that after the XRD and DTA results had shown the desired 23
crystal phases, he agreed with Dr. Durschang that SEM analysis should be 24
34

conducted to better examine the microstructure of the glass-ceramics. (Kilo 1
Declaration, Ex 1048, ¶19, referring to DTA results, Ex 1043). 2
Dr. Durschang testified that he then directed Ms. Leopoldsberger to conduct 3
SEM analysis of 637_Z1. (Leopoldsberger Declaration, Ex 1047, ¶¶17 and 23; 4
Durschang Declaration, Ex 1050, ¶84). Ms. Leopoldsberger testified that she 5
conducted the SEM analysis on sample 637_Z1 on 21 July 2009, the results of 6
which are shown within her declaration as well as at Exhibit 1036. 7
(Leopoldsberger Declaration, Ex 1047, ¶¶17, 19, 24, 25). Dr. Durschang testified 8
that the SEM results confirmed the results of the XRD and DTA analysis. Dr. 9
Durschang recalls discussing these results with Dr. Probst and Dr. Kilo. (Probst 10
Declaration, Ex 1049, ¶34; Durschang Declaration, Ex 1050, ¶¶98-99). 11
Dr. Kilo testifies that he recalls reviewing the SEM results and he agreed 12
that they confirmed the XRD and DTA results. (Kilo Declaration, Ex 1048, ¶20, 13
referring to study results, Ex 1036, p.7 and 10). 14
Dr. Jain testified that, based on his review of the study results shown at 15
Exhibit 1036, which include the XRD, DTA and SEM results discussed above, he 16
agrees that the Durschang inventors had actually produced a lithium silicate glass-17
ceramic with at least 10% zirconium oxide and a main crystal phase consisting of 18
lithium metasilicate or lithium disilicate at least by 30 July 2009. (Second Jain 19
Declaration, Ex 1051, ¶¶78-98). 20
We conclude that by 19 June 2009 Durschang had confirmed through XRD 21
analysis that it had produced a lithium silicate glass-ceramic falling within the 22
scope of the Count, i.e., one comprising at least 10 wt. % ZrO2 and having a main 23
crystal phase, wherein said main crystal phase is selected from the group consisting 24
of lithium metasilicate crystal and lithium disilicate crystal. 25
35

The additional testing, i.e., the DTA and SEM testing, undertaken 1
subsequent to the XRD analysis confirmed that a lithium silicate glass-ceramic 2
within the scope of the Count had been reduced to practice. The corroborated 3
evidence shows that these tests were completed by 23 June 2009 and 21 July 2009 4
respectively. These additional, confirmatory tests provided additional evidence of 5
a reduction to practice occurring by 21 July 2009, which also is prior to the earliest 6
date alleged in the Ritzberger priority motion. 7
Ritzberger arguments against Durschang reduction to practice 8
Ritzberger argues that Dr. Durschang did not know until after he received 9
the XRD results that he possessed the limitation of a lithium metasilicate or lithium 10
disilicate as the main crystalline phase as required by the Count Ritzberger argues 11
that the earliest corroborated date showing when Dr. Durschang had the XRD 12
results is 30 July 2009 and that is, according to Ritzberger, the earliest date 13
Durschang has shown that there was either a conception or a reduction to practice 14
of an invention of the Count. (Ritzberger Opposition 4, Paper 189, p.1:23-2:18). 15
Ritzberger argues that Durschang cannot rely on DTA or SEM results to 16
show possession of the main crystal phases required by the Count. According to 17
Ritzberger both it and Durschang agree that DTA testing evaluates whether a 18
crystallization event has occurred, not the nature of that event. (Ritzberger 19
Opposition 4, Paper 189, p. 9:18, citing Kilo Deposition, Ex 2055 at 37:4-7.) 20
Ritzberger argues SEM is unable to indicate which crystalline phases are present 21
and instead only provides a visual display of the physical crystal to evaluate 22
morphology, i.e. the size and shape of the crystals. (Ritzberger Opposition 4, Paper 23
189, p.9:23-10:4, citing Kilo Deposition, Ex 2055, p.49:12-16.) 24
36

Ritzberger relies upon the testimony of Dr. Brow in support of its argument 1
that XRD analysis was needed to show an actual reduction to practice of an 2
embodiment of the Count. Dr. Brow testified that “[i]n order to determine what 3
type of crystalline phase has formed, a person of ordinary skill in the art would 4
need to perform XRD analysis.” (Second Brow Declaration, Ex 2053, ¶17). Dr. 5
Brow’s testimony is in conflict with Dr. Jain’s testimony on this point. Dr. Jain 6
testified that the XRD data was confirmatory, but not necessary, to conclude that 7
the Durschang inventors has actually produced a lithium silicate glass-ceramic 8
with at least 10% zirconium oxide. (Second Jain Declaration, Ex 1051, ¶95). 9
We credit Dr. Brow’s testimony over that of Dr. Jain on this point. Dr. 10
Brow’s testimony is consistent with that of Dr. Kilo who testified that “XRD 11
work” would have to be done to tell which glass crystals were formed. (Kilo 12
Deposition, Ex 2055 at 37:4-7.) Further Dr. Jain’s testimony indicates only that 13
one could surmise with some degree of confidence, relying on the benchmark test 14
results and the literature, what crystals were formed based on SEM and DTA 15
testing. In this case, we determine that an actual reduction to practice requires the 16
assurance provided by the XRD testing. 17
Ritzberger argues that Dr. Durschang was unable to pinpoint the date of the 18
XRD testing (stating that it was “sometime “between mid-June and early July” and 19
before SEM testing). (Ritzberger Opposition 4 at 8:24-9:7 and Durschang 20
Declaration, Ex 1050, ¶67). Ritzberger points out that there are no date stamps on 21
the XRD graphs themselves nor is there other evidence, such as documentation 22
referring to the graphs, or testimony from the technician that conducted the XRD 23
tests. Thus, argues Ritzberger “[t]he XRD [data] needed to appreciate every 24
37

element of the Count only appears in a July 30, 2009 presentation.” (Ritzberger 1
Opposition 4, Paper 189, p.8:21-24). 2
Durschang though relies upon the testimony of Dr. Kilo who stated that he 3
recalls reviewing the XRD data on or before 19 June 2009, his last day in the office 4
before he left for vacation. (FF 50). Ritzberger argues that the testimony of Dr. 5
Kilo on this matter is not credible. Ritzberger notes that Dr. Kilo works with Dr. 6
Durschang and for an assignee of the involved Durschang application and that 7
there are no other witnesses supporting Dr. Kilo’s testimony as to the date the 8
conversation with Dr. Durschang took place. (Ritzberger Opposition 4 at 11:3-18). 9
Ritzberger asserts that Dr. Kilo’s testimony is “anecdotal at best, unsupported by 10
documentary or other evidence, and wholly dependent on his memory of an event 11
nearly seven years earlier.” Further Ritzberger argues that Dr. Durschang himself 12
testified that although he keeps notes and records of his projects, he was unable to 13
determine the specific dates the XRD testing was performed and testified that he 14
“can’t remember what day it was” that he saw the XRD testing” [testifying that it 15
was mid-June to early July] such that, according to Ritzberger, “there is no 16
inventor testimony for Dr. Kilo to corroborate here”. (Ritzberger Opposition 4 at 17
10:7-16, citing Durschang Deposition Ex 2054 at 39:3-7 and 11:2-3, 11:6-7, 34:1-18
7.) 19
We credit the testimony of Dr. Kilo regarding the date on which he reviewed 20
the XRD results with Dr. Durschang. Dr. Kilo’s testimony is consistent with Dr. 21
Durschang’s testimony that XRD testing occurred in mid-June to early July and 22
before SEM testing. Dr. Kilo provides credible reasons why he remembers the 23
specific date by which he had reviewed the results with Dr. Durschang, i.e., this 24
was Dr. Kilo’s first vacation since starting his job at Fraunhofer ISC, and he was 25
38

nervous about taking vacation so soon and because of this, he wanted to know the 1
status of all the ongoing projects, and what work had been successfully completed 2
(Kilo Deposition, Ex 2055, p.69:11-70:4); Dr. Durschang’s happiness with the 3
apparent success of the project stood out in Dr. Kilo’s memory prior to his 4
departing on his vacation (Kilo Deposition, Ex 2055, p.59:13-16); Dr. Kilo was 5
pleased because it was a successful result on a project for which he was the group 6
leader, and it had occurred before his summer vacation (Kilo Declaration, Ex 1048, 7
¶¶11-15); and Dr. Kilo’s recollection that the reason he went on summer vacation 8
in June of 2009 was because his daughter was starting school that year and he 9
needed to be back before school began. (Kilo Deposition, Ex 2055, p.69:11-70:4). 10
Nor are we convinced that Dr. Kilo’s testimony is not credible because he is 11
and was a co-worker of Dr. Durschang and is employed by an assignee of the 12
Durschang involved application. First we note that frequently the best and 13
possibly only source of corroboration of an inventor’s testimony is from someone 14
working with or for the inventor who has an opportunity to observe the work being 15
done. While we consider Dr. Kilo’s relationship with Dr. Durschang and his 16
employer in evaluating Dr. Kilo’s testimony, here we find the testimony to be 17
credible especially given Dr. Kilo’s detailed and reasonable explanation of why he 18
was able to remember the conversation with Dr. Durschang regarding the test 19
results, including the XRD results. Woodland Trust v. Flower tree Nursery Inc., 20
148 F.3d 1368, 1371 (Fed. Cir. 1998) (listing “the relationship between the 21
corroborating witness and the alleged prior user” and “the interest of the 22
corroborating witness in the subject matter in suit” but also “the extent and details 23
of the corroborating testimony” as factors to be considered in assessing 24
corroboration.) 25
39

The Transweb case, cited by Ritzberger, notes that the Court has “generally 1
been most skeptical of oral testimony that is supported only by testimonial 2
evidence of other interested persons.” However, the Court also stated that “there 3
are no hard and fast rules as to what constitutes sufficient corroboration, and each 4
case must be decided on its own facts.” (Ritzberger Opposition 4, Paper 187, 5
citing Transweb, LLC v. 3M Innovative Properties Co., 812 F.3d 1295, 1302 (Fed. 6
Cir. 2016)). In this case, as we noted above, Dr. Kilo provided a detailed and 7
reasonable basis for why his discussion with Dr. Durschang regarding the XRD 8
results stood out in his memory. As a new project manager Dr. Kilo was anxious 9
about leaving to go on a vacation. Before leaving he checked the status of Dr. 10
Durschang’s project and was happy to learn of a successful result right before he 11
went on vacation. 12
We also are not persuaded by Ritzberger’s argument that the testimony lacks 13
credibility because it is not confirmed by another witness. Ritzberger has not 14
directed us to case law or other controlling authority for the proposition that a 15
corroborator’s testimony also must be corroborated. Instead, as noted in the 16
Durschang Reply, case law indicates that only an inventor’s testimony needs 17
corroboration. (Durschang Reply 4, Paper 209, p.9:6-11, citing Holmwood v. 18
Sugavanam, 948 F.2d 1236, 1239 (Fed. Cir. 1991) (“Only an inventor’s testimony 19
needs corroboration.”) 20
Ritzberger’s argument that Dr. Kilo’s testimony is not persuasive because 21
there are no documents, such as emails between Dr. Durschang and Dr. Kilo, to 22
support it is also unpersuasive. Again Ritzberger has not directed us to case law or 23
other controlling authority for the proposition that a corroborator’s testimony must 24
be corroborated by documentation. Further Dr. Kilo testified that he and Dr. 25
40

Durschang shared an office and that it was where their conversations would occur. 1
Thus it is not unexpected that emails or other notes regarding the discussion 2
between Dr. Durschang and Dr. Kilo do not exist as Durschang points out in its 3
Reply. (Durschang Reply 4, Paper 209, p.9:18-22, citing Kilo Deposition, Ex 2055, 4
p.31:11-18). 5
We note Ritzberger’s reliance on Blicharz v. Hays, 496 F.2d 603 (C.C.P.A. 6
1974) to argue that Dr. Kilo’s testimony should be rejected. In Blicharz the Court 7
discussed the Board’s determination that the corroborator’s testimony was not 8
credible, considering it was “nothing short of phenomenal” that the corroborator 9
could, from memory only, distinguish a particular experiment from all the 10
others. The Court determined that, when considered in light of the totality of the 11
other details of his testimony, the witness provided corroborative testimony. 12
(“Contrary to the position of the board and arguments of appellee, we find the 13
[corroborator’s] testimony to constitute significant corroboration in other respects 14
also.”), Blicharz v. Hays, 496 F.2d at 606. Here we consider Dr. Kilo’s testimony 15
in light of the totality of the other details of his testimony and in view of the other 16
evidence of record. 17
In addition to reasons stated above, we find Dr. Kilo’s testimony to be 18
credible because it is consistent with other non-inventor testimony. Dr. Kilo 19
testified that he reviewed the XRD results by 19 June 2009 and before he reviewed 20
the DTA and SEM results. This testimony is consistent with Mr. Olsowski’s 21
testimony that he conducted DTA analysis on 23 June 2009. (Olsowski 22
Declaration, Ex 1045, ¶¶7-9) and Ms. Leopoldsberger’s testimony that she 23
conducted SEM analysis on 21 July 2009. (Leopoldsberger Declaration, Ex 1047, 24
¶¶23-26). Dr. Kilo’s testimony is consistent with SEM testing occurring after the 25
41

XRD testing for the further reason that evidence of record indicates that SEM 1
testing requires significant effort such that it would be performed only after other 2
analysis confirmed the desired crystals were present in the glass-ceramic. (SMF 42, 3
admitted at Ritzberger Opposition 4, Paper 187, Appendix B-6; Durschang 4
Declaration, Ex 1050, ¶¶17, ¶24, 51-52, Second Jain, Declaration, Ex 1051, ¶68). 5
Ms. Leopoldsberger testified that SEM analysis was conducted on 21 July 2009. 6
Thus there is further reason to believe that the XRD testing would have occurred at 7
the time asserted by Dr. Kilo and at least before 21 July 2009. 8
Earliest conception coupled with reasonable diligence 9
As noted above we conclude that Durschang reduced to practice an 10
invention of the Count no later than 21 July 2009 when SEM testing was 11
completed. Alternatively, to the extent Dr. Kilo’s testimony is insufficient to 12
corroborate the XRD results and XRD results were necessary to a reduction to 13
practice, we consider whether Durschang has shown at least a conception by the 21 14
July 2009 date. 15
Proof of conception requires a showing that the inventors formed a definite 16
and permanent idea of the complete and operative invention as it is to be applied in 17
practice. Coleman v. Dines, 754 F.2d 353 at 359. Each and every feature or 18
limitation of the Count must be present in order to establish a conception. Kridl v. 19
McCormick, 105 F.3d 1446, 1449 (Fed. Cir. 1997). 20
By 28 May 2009 Dr. Durschang had directed the production of a lithium 21
silicate glass having 12% zirconium oxide and had performed benchmark tests 22
sufficient to show the heating steps that would enable the Durschang inventors to 23
work out the heat treatments that would produce a glass-ceramic having a lithium 24
metasilicate main crystal phase and capable of being converted to a glass-ceramic 25
42

with a lithium disilicate main crystal phase. (FFs 44, 58, 59 and 61). These 1
activities, combined with the 637_Z1 DTA and SEM test results, which were 2
consistent and indicative of a glass-ceramic falling within the Count, convince us 3
that the Durschang inventors had at least conceived of an embodiment of the Count 4
by 21 July 2009. 5
As acknowledged by Ritzberger the results of the XRD (and other) testing 6
were reported on 30 July 2009. (Ritzberger Opposition 4, Paper 187, at p. 8:21-24 7
and 14:24-15:3). At that time, even disregarding Dr. Kilo’s testimony regarding the 8
date Dr. Durschang shared the results of the XRD testing, a reduction to practice 9
occurred. (FF 64 and 66). 10
If a party is first to conceive but last to reduce to practice, that party may still 11
prevail on priority if it exercised reasonable diligence from a time before the other 12
party's conception date to its own reduction to practice date. See 35 USC 13
§ 102(g) (in determining priority “there shall be considered ... the reasonable 14
diligence of one who was first to conceive and last to reduce to practice, from a 15
time prior to conception by the other”); Mahurkar v. C.R. Bard, Inc., 79 F.3d 16
1572, 1578 (Fed.Cir.1996) (a party that is first to conceive but second to reduce to 17
practice “must demonstrate reasonable diligence toward reduction to practice”). 18
In this case Durschang must account for diligence during the “critical period, 19
i.e., the period from before 23 July 20099 to 30 July 2009. Thus, Durschang must 20

9 We use this date assuming that Ritzberger is able to show a conception by its
earliest alleged date of 23 July 2009. Because we grant the Durschang Priority
Motion even assuming the 23 July 2009 date, we have not evaluated whether
Ritzberger actually has made such a showing.
43

show diligence for a period of about one week, two days of which were weekend 1
days. Durschang provides the following diligence chart: 2
3
Date Exhibit No./Page Description of Activity Motion Citation
(Page:Line)
July 21, 2009 1035, pgs. 7, 10 SEM micrograph of
heat treated 637_Z1
22:11-12
July 27, 2009 1044, pgs. 1-3 Bending Strength Tests
of 637_Z1
22:21-23:2
July 29, 2009 1035, pg. 5 Preparation of SEM
micrograph of non-heat
treated 637_Z1
23:2-5
July 30, 2009 1035 Actual Reduction to
Practice
23:6-12
4
Durschang Priority Motion, Paper 180, Appendix 3). 5
The evidence shows additional testing of 637_Z1 during the week leading up 6
to the 30 July 2009 presentation. Flexural strength testing was said to have taken 7
about a week to conduct and was completed on 27 July 2009. The results of the 8
flexural strength testing and is said to have shown that sample 637_Z1 was of 9
sufficiently high strength to serve as a dental restoration. (Bending strength tests 10
dated 27 July 2009, Ex 1044; Kilo Declaration, Ex 1048, ¶21; Durschang 11
Declaration, Ex 1050, ¶100). Dr. Durschang also directed Ms. Leopoldsberger to 12
conduct an SEM analysis on a sample of 637_Z1 that was not subjected to any heat 13
treatments. (Leopoldsberger Declaration, Ex 1047, ¶¶27-29; Durschang 14
Declaration Ex 1050, ¶101). Ms. Leopoldsberger testified that she completed that 15
analysis on 29 July 2009. Based on these activities, we determine that Durschang 16
has shown that it was reasonably diligent during the critical period. 17
Ritzberger arguments against conception coupled with diligence 18
Ritzberger argues that Durschang was not reasonably diligent in reducing to 19
practice an invention of the Count because the flexural strength testing and SEM 20
44

images of uncrystallized glass are not connected to any reduction to practice of an 1
embodiment within the scope of the Count. (Ritzberger Opposition 4, Paper 187, 2
p. 16:7-17:8). 3
“The basic inquiry [for determining diligence] is whether, on all of the 4
evidence, there was reasonably continuing activity to reduce the invention to 5
practice [and] [t]here is no rule requiring a specific kind of activity in determining 6
whether the applicant was reasonably diligent in proceeding toward an actual or 7
constructive reduction to practice.” Brown v. Barbacid, 436 F.3d 1376, 1380 (Fed. 8
Cir. 2006). 9
We also refer to the Bell case cited by Ritzberger which states: 10
It is doubtless true that work quite unconnected with the 11
reduction of an invention to practice cannot be considered. [footnote 12
omitted]. But whether particular work is sufficiently connected with 13
the invention to be considered to be in the area of reducing it to 14
practice must be determined in the light of the particular 15
circumstances of the case which may be as varied as the mind of man 16
can conceive. It is thus peculiarly a question of fact for the finder of 17
the facts to determine in the light of those circumstances. 18
19
Bell Tel. Labs., Inc. v. Hughes Aircraft Co., 564 F.2d 654, 656 (3d Cir. 1977). 20
We agree with Durschang that the flexural strength testing was sufficiently 21
connected with reducing the invention to practice since flexural strength testing 22
was used to confirm that the lithium metasilicate and lithium disilicate phases were 23
sufficiently strong enough to serve as a dental restoration, which was the purpose 24
of the invention. (Durschang Reply 4, 13:21-14:3, citing Bending strength tests 25
dated 27 July 2009, Ex 1044; Kilo Declaration, Ex 1048, ¶21; Durschang 26
Declaration, Ex 1050, ¶100). As to the SEM testing of the uncrystallized glass, 27
45

Durschang argues that it “provides an important comparator for the subsequently 1
crystallized glass-ceramics”. (Durschang Reply 4, p.13:23-14:3). The SEM 2
testing may be less directly connected to the reduction to practice than the flexural 3
strength tests but shows work related to evaluating 637_Z1. When we consider the 4
SEM testing in concert with the flexural strength testing we are convinced that the 5
inventors acted with reasonable diligence toward reducing the invention to practice 6
for the approximately one week critical period. 7
2. Ritzberger Priority Motion 8
We conclude that Durschang reduced to practice an invention of the Count 9
by 21 July 2009. Alternatively we conclude that Durschang conceived an 10
invention of the Count by 21 July 2009 and then exercised reasonable diligence in 11
reducing to practice the invention by 30 July 2009. 12
Because Ritzberger’s earliest alleged date of simultaneous conception and 13
reduction to practice is 23 July 2009, Ritzberger cannot prevail on priority. We 14
dismiss as moot the Ritzberger Priority Motion. 15
16
IV. Order 17
Upon consideration of the record, it is 18
ORDERED that Durschang Motion 3 to add additional Ritzberger patents to 19
the interference is GRANTED; 20
FURTHER ORDERED that the interference will be redeclared in a separate 21
paper to reflect the addition of the Ritzberger patents; 22
FURTHER ORDERED that Durschang Motion for judgment on the basis of 23
priority is GRANTED; 24
FURTHER ORDERED that the Ritzberger Motion for judgment on the basis 25
of priority is DISMISSED as moot; and 26
46

FURTHER ORDERED that judgment adverse to Ritzberger shall be entered 1
in a separate paper. 2

Attorney for Ritzberger:
Deborah A. Sterling
Josephine J. Kim
STERNE, KESSLER, GOLDSTEIN & FOX, P.L.L.C.
dsterlin-ptab@skgf.com
joskim-ptab@skgf.com

Attorney for Durschang:
R. Danny Huntington
Seth E. Cockrum
ROTHWELL, FIGGS, ERNST & MANBECK, P.C.
dhuntington@rfem.com
scockrum@rfem.com