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                                                                    EXHIBIT 10-R

                                  EXTENSION TO

                        FIRST LOAN MODIFICATION AGREEMENT

         THIS EXTENSION TO FIRST LOAN MODIFICATION AGREEMENT ("EXTENSION
AGREEMENT"), dated effective as of the 31st day of May, 2001 ("EFFECTIVE DATE"),
is entered into by and among BANK ONE, ARIZONA, NA, a national banking
association ("BANK ONE"), ZILA, INC., a Delaware Corporation ("ZILA"), and each
of the following subsidiary entities, directly or indirectly, of Zila
(collectively, the "SUBSIDIARIES"): (i) INTEGRATED DENTAL TECHNOLOGIES, INC., a
California corporation, (ii) RYKER DENTAL OF KENTUCKY, INC., a Kentucky
corporation, (iii) BIO-DENTAL TECHNOLOGIES CORPORATION, a California
corporation, (iv) ZILA PHARMACEUTICALS, INC., a Nevada corporation, (v) ZILA
TECHNOLOGIES, INC., an Arizona corporation, (vi) INTER-CAL CORPORATION, INC., an
Arizona corporation, (vii) OXYCAL LABORATORIES, INCORPORATED, an Arizona
corporation ("OXYCAL"), (viii) OXYCAL EXPORT, INC., a Virgin Islands
corporation, and (ix) ZILA SWAB TECHNOLOGIES, INC., an Arizona corporation. Zila
and the Subsidiaries are collectively referred to herein as the "DEBTORS".

                                    RECITALS:

         A. Bank One and Zila have entered into the following credit facilities
(collectively, the "LOANS", as amended from time to time): (i) a certain
revolving line of credit in the maximum principal amount of $9,000,000 ("LINE OF
CREDIT LOAN") pursuant to the Loan Agreement between Zila and Bank One dated
December 1, 2000 ("LOC LOAN AGREEMENT") as evidenced by the Promissory Note
dated December 1, 2000, in the maximum principal amount of $9,000,000 executed
by Zila in favor of Bank One ("LINE OF CREDIT PROMISSORY NOTE"); (ii) a certain
construction loan ("PROJECT LOAN"), as evidenced by a certain Project Note
executed by Oxycal in favor of Bank One in the principal amount of $5,000,000
("PROJECT NOTE"), in connection with those certain 1999A Bonds and Taxable 1999B
Bonds in the principal amount of $5,000,000 (collectively, the "BONDS") issued
pursuant to a certain Trust Indenture between The Industrial Development
Authority of the County of Yavapai, as Issuer, and Bank One, as Trustee, dated
March 1, 1999 ("BOND TRUST INDENTURE"), two Irrevocable Letters of Credit (No.
STI 13306 and No. STI 13307), each dated April 14, 1999, issued by Bank One in
favor of the owners of the Bonds in an aggregate amount of $5,061,645.00
("LETTERS OF CREDIT"), and a certain Reimbursement Agreement between Bank One
and Oxycal dated March 1, 1999 ("REIMBURSEMENT AGREEMENT"); and (iii) a certain
building loan in the initial principal amount of $450,000 ("BUILDING LOAN"), as
evidenced by a certain Promissory Note in the amount of $450,000 executed by
Zila in favor of Valley National Bank of Arizona (Bank One was formerly known as
Valley National Bank of Arizona), as subsequently amended by a certain
Modification Agreement between Zila and Bank One dated April 15, 1996, and as
further amended by a certain Promissory Note Second Modification Agreement
between Zila and Bank One dated February 26, 1998 (as amended from time to time,
the "BUILDING PROMISSORY NOTE").

         B. Bank One, Zila and the Subsidiaries have entered into a First Loan
Modification Agreement dated May 7, 2001 ("FIRST LOAN MODIFICATION AGREEMENT"),
which, in addition to other modifications with respect to the Loans, provided
for the following: (i) Bank One agreed to forbear from the date of the First
Loan Modification Agreement until May 31, 2001 ("INITIAL

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NONCOMPLIANCE PERIOD") in exercising any remedy with respect to certain covenant
defaults and/or non-compliance events under the Line of Credit Loan
("NONCOMPLIANCE EVENTS"), as set forth in more detail on Exhibit A to the First
Loan Modification Agreement; (ii) the maturity date of the Building Loan was
extended from April 1, 2001 to May 31, 2001; (iii) each of the Subsidiaries
executed documentation to provide Bank One with perfected security interests
that were intended to be provided at the time the LOC Loan Documents were
executed; (iv) the Line of Credit Loan, the Project Loan and the Building Loan
were cross-collateralized and cross-defaulted; and (v) the parties to the First
Loan Modification Agreement agreed to enter into a more comprehensive second
modification agreement to address additional issues and to provide additional
documentation for modifications set forth in the First Loan Modification
Agreement.

         C. While the second modification agreement is being negotiated and
finalized, Zila and each of the Subsidiaries now desire to enter into an
extension of the First Loan Modification Agreement (i) to extend until June 29,
2001 the Initial Noncompliance Period in which Bank One will forbear in
exercising any remedy with respect to the Noncompliance Events, (ii) to further
extend until June 29, 2001 the maturity date of the Building Loan, and (iii) to
amend the Loan Documents in certain other respects, and Bank One is willing to
agree to such forbearance, extension and amendments, provided that the Debtors
execute and deliver to Bank One the Patent Security Agreements, the Stock Pledge
Agreements (together with the related stock certificates, stock powers and power
of attorneys) and the UCC financing statements that the parties contemplate
executing under the proposed second modification agreement, and subject to the
terms and conditions set forth in this Extension Agreement.

                                   AGREEMENT:

         NOW, THEREFORE, in consideration of the foregoing premises and the
mutual covenants hereinafter stated, and for other good and valuable
consideration, the receipt and sufficiency of which are hereby acknowledged, the
parties hereto agree as follows:

1. DEFINITIONS. In addition to other defined terms as set forth in this
Extension Agreement, the following terms shall have the meanings set forth below
for purposes of this Extension Agreement:

         1.1 "BUILDING LOAN DOCUMENTS" means, collectively, the Building
Promissory Note and all of the other documents and instruments executed in
connection with the Building Loan, together with the First Loan Modification
Agreement, the Extension Agreement and the documents and instruments executed in
connection therewith, as amended from time to time.

         1.2 "LOAN DOCUMENTS" means, collectively, the LOC Loan Documents, the
Project Loan Documents and the Building Loan Documents.

         1.3 "LOANS" means, collectively, the Line of Credit Loan, the Project
Loan and the Building Loan, as amended from time to time.

         1.4 "LOC LOAN DOCUMENTS" means, collectively, the LOC Loan Agreement,
the Line of Credit Promissory Note and all of the other documents and
instruments executed in connection with the Line of Credit Loan, together with
the First Loan Modification Agreement, the


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Extension Agreement and the documents and instruments executed in connection
therewith, as amended from time to time.

         1.5 "NONCOMPLIANCE PERIOD" means the period commencing on May 7, 2001
and ending on June 29, 2001.

         1.6 "OBLIGATIONS" means, collectively, the obligations of Zila and the
Subsidiaries under the Loan Documents.

         1.7 "PROJECT LOAN DOCUMENTS" means, collectively, the Bonds, the Bond
Trust Indenture, the Letters of Credit, the Reimbursement Agreement, the Project
Note and all of the other documents and instruments executed in connection with
the Project Loan, together with the First Loan Modification Agreement, the
Extension Agreement and the documents and instruments executed in connection
therewith, as amended from time to time.

For purposes of this Extension Agreement, all terms used with initial capital
letters, but not otherwise defined in this Extension Agreement, shall have the
same meanings given such terms in the First Loan Modification Agreement, or if
not defined therein, in the LOC Loan Agreement.

2.   DEBTORS' ACKNOWLEDGMENT OF EXISTING INDEBTEDNESS.

         2.1 Each of the Debtors acknowledges and agrees that the total
outstanding amounts of each of the Loans as of June 4, 2001 are as follows: (i)
an outstanding principal balance of $6,100,000.00 with respect to the Line of
Credit Loan ("LINE OF CREDIT LOAN BALANCE"), (ii) an outstanding obligation
amount of $4,631,404.47 under the Letters of Credit issued in connection with
the Project Loan ("PROJECT LOAN BALANCE"), (iii) an outstanding principal
balance of $280,134.14 with respect to the Building Loan ("BUILDING LOAN
BALANCE"), plus (iv) any accrued and unpaid interest or fees on each of the
Loans and any other costs and expenses of Bank One to the extent due and owing
under the Loan Documents.

         2.2 Each of the Debtors acknowledges that Zila (and Oxycal in the case
of the Project Loan) is truly and justly indebted to Bank One in the amount of
the Line of Credit Loan Balance, plus the Project Loan Balance, plus the
Building Loan Balance, plus accrued and unpaid interest and fees on each of the
Loans, plus all accrued and unpaid costs and expenses that are, under the Loan
Documents, properly chargeable to Zila (or Oxycal) and that have been and in the
future may be incurred by Bank One in connection with the Loans.

         2.3 Each of the Debtors acknowledges that, as of the date hereof, it
has (i) no defense, counterclaim, offsets, cross-complaint, claim or demand of
any nature whatsoever which can be asserted as a basis to seek affirmative
relief or damages from Bank One or to reduce or eliminate all or any part of its
liability to repay the Loans, and (ii) no other claim against Bank One with
respect to any aspect of the transactions in respect of which the Loans were
made. If any such claims exist they are fully and irrevocably released as
provided in Section 10 hereof.

         2.4 Each of the Debtors agrees that Bank One has fully performed all
obligations that it may have had or now has to Zila and the Subsidiaries with
respect to the Loans, and that except as expressly set forth herein, Bank One's
obligation to make additional Advances under the Line


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of Credit Loan is conditioned upon the satisfaction of all conditions precedent
for such Advances as set forth in the LOC Loan Agreement, as amended by the
First Loan Modification Agreement and as further amended by this Extension
Agreement.

3. AMENDMENTS TO FIRST LOAN MODIFICATION AGREEMENT. Each of the parties hereto
agrees that the First Loan Modification Agreement is amended as set forth below
and that the other Loan Documents are deemed amended in all respects to the
extent necessary to accomplish the following changes:

         3.1 Extension of Noncompliance Period. The definition of "Noncompliance
Period" in Section 1.5 of the First Loan Modification Agreement is hereby
amended in its entirety to read as follows:

                  1.5 "NONCOMPLIANCE PERIOD" means the period commencing on May
         7, 2001 and ending on June 29, 2001.

         3.2 Extension of Maturity Date of Building Loan. Section 4.1 of the
First Loan Modification Agreement is hereby amended by substituting "June 29,
2001" for "May 31, 2001" as the maturity date of Building Loan.

         3.3 Committed Sum. Section 4.2(a) of the First Loan Modification
Agreement is hereby amended in its entirety to read as follows:

                  (a) The "Committed Sum" as defined in the LOC Loan Agreement
         shall be $7,250,000.00 beginning on the Effective Date.

         3.4 Permanent Reduction of Line of Credit Loan on Sale of Office
Building. The clause beginning with "provided, however" in the last sentence of
Section 4.5 of the First Loan Modification Agreement is hereby amended to read
as follows:

         provided, however, Bank One agrees to release its lien with respect to
         the building securing the Building Loan (as such building is more
         specifically described on Exhibit "A" to the Deed of Trust dated March
         8, 1991 executed by Zila, the "BUILDING") upon either: (i) the
         repayment in full of all amounts due under the Building Loan and the
         Line of Credit Loan with no further commitment of Bank One to advance
         under the Line of Credit Loan, or (ii) the refinance, sale or
         sale/leaseback of the Building in which (A) the proceeds of such
         refinance, sale or sale/leaseback are paid to Bank One to be applied to
         the repayment of the Building Loan in full with any excess to be
         applied to pay down the Line of Credit Loan and to permanently reduce
         by $500,000.00 the "Committed Sum" as defined in the LOC Loan
         Agreement, as amended from time to time, and (B) if a refinance, the
         amount of such refinance is at least 75% of the appraised valued of the
         Building based upon an appraisal acceptable to Bank One, or if a sale
         or sale/leaseback, the amount of such sale is at least the amount of
         the appraised value of the Building based upon such an appraisal.


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4.   REAFFIRMATION OF EXISTING SECURITY INTERESTS AND GRANT OF SECURITY
     INTERESTS.

         4.1 Reaffirmation of Existing Security Interests. Each of the Debtors
hereby confirms and agrees that Bank One's security interests in the assets of
Zila and the Subsidiaries and all of the collateral previously pledged to Bank
One pursuant to the Loan Documents shall continue to secure the payment and
performance of all of the Obligations to Bank One.

         4.2 Grant of Security Interests in Intellectual Property Rights.
Without affecting any security interests previously granted to Bank One with
respect to the Loans, each of the Debtors hereby grants to Bank One, to secure
the Line of Credit Loan as well as all of the other Obligations under the Loan
Documents, a security interest in all of such Debtor's right, title and interest
in and to the personal property described on EXHIBIT A, attached hereto and
incorporated herein by this reference. Zila and each of the Subsidiaries
represent and warrant to Bank One that the listing of patents and patents
pending set forth on EXHIBIT B, attached hereto and incorporated herein by this
reference, sets forth all material patents and patents pending of the Debtors
currently registered or pending in the United States Patent and Trademark
Office. Each of the Debtors agrees to execute and deliver to Bank One such
documents and instruments as are necessary to document and perfect the security
interests granted to Bank One under this Section 4.2, including, without
limitation, all UCC-1 financing statements, patent assignment agreements,
documents for filing with the U.S. Patent and Trademark Office, if any, and
other documents and instruments requested by Bank One. Further, each of the
Debtors agrees to deliver to Bank One the information necessary to identify and
describe all patents, patents pending, copyrights, trade names, trademarks and
other intellectual property of the Debtors registered, filed, issued or obtained
in the future within thirty (30) days after such Debtor becomes aware of such
additional intellectual property rights, and, upon Bank One's request, to
promptly execute and deliver to Bank One such additional documents and
instruments as are necessary to document and perfect the security interests in
such future intellectual property rights.

         4.3 Grant of Security Interests in Stock of Subsidiaries. Without
affecting any security interests previously granted to Bank One with respect to
the Loans, each of the Debtors, to the extent applicable, hereby grants to Bank
One, to secure the Line of Credit Loan as well as all of the other Obligations
under the Loan Documents, a security interest in all of such Debtor's right,
title and interest in and to the stock and other personal property described on
EXHIBIT C, attached hereto and incorporated herein by this reference. Zila
agrees to deliver to Bank One copies of the stock certificates representing 100%
of the common stock of each Debtor. Each of the Debtors, to the extent
applicable, agrees to execute such documents and instruments as are necessary to
document and perfect the security agreements granted to Bank One under this
Section 4.3, including, without limitation, all UCC-1 financing statements,
stock powers, stock pledge agreements and other documents and instruments
requested by Bank One.

         4.4 Collateral Secures All Loans. Each of the Debtors hereby confirms
and agrees that Bank One's security interest in the collateral granted under
this Section 4 secures all of the Loans and all of the Obligations under the
Loan Documents. Further, each of the Debtors hereby confirms and agrees that an
event of default (subject to applicable notice and cure periods) under any of
the Loan Documents shall be deemed to be an event of default under all of the
Loan Documents entitling Bank One to pursue any and all remedies available under
the Loan Documents as well as any and all other legal and equitable remedies
available to Bank One under


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applicable law. The release provisions of Section 4.5 of the First Loan
Modification Agreement, as amended from time to time, shall be applicable to all
security interests granted under this Section 4, and to all security documents
related thereto, subject to the terms of this Extension Agreement.

5. ADDITIONAL AGREEMENTS. As material inducements to Bank One to enter into this
Extension Agreement, the parties hereto agree as follows:

         5.1 Amendment of Current Ratio Calculation. In calculating the current
ratio for the quarters ended April 30, 2001 and July 31, 2001 in accordance with
the section of the Addendum to the LOC Loan Agreement entitled "ADDITIONAL
AFFIRMATIVE COVENANT - - CURRENT RATIO", the outstanding amount of the Project
Loan will not be included in "current liabilities".

         5.2 Amendment of Working Capital Calculation. In calculating working
capital for the quarters ended April 30, 2001 and July 31, 2001 in accordance
with the section of the Addendum to the LOC Loan Agreement entitled "ADDITIONAL
AFFIRMATIVE COVENANT - - WORKING CAPITAL", the outstanding amount of the Project
Loan will not be included in "current liabilities".

         5.3 Accounts Receivable/Inventory Review. Zila and the Subsidiaries
agree to comply with and assist Bank One, or a company designated by Bank One,
to perform a review of the accounts receivable and inventory of Zila and the
Subsidiaries and the calculation of the Borrowing Base. Zila agrees to reimburse
Bank One for all of its out-of-pocket costs and expenses with respect to such
review, including, without limitation, the reasonable travel expenses of Bank
One's representatives.

         5.4 Monthly Financial Statements. Borrower agrees to deliver to Bank
One as soon as available, but in no event later than 30 days after the end of
each fiscal month (starting with the month of May 2001), the monthly financial
statements of Borrower and each of the Subsidiaries on a consolidating basis
certified by an officer of Borrower, all in accordance with the provisions of
the section of the Addendum to the LOC Loan Agreement entitled "ADDITIONAL
AFFIRMATIVE COVENANT - - CONSOLIDATING INTERIM FINANCIAL STATEMENTS", except
that such financial statements are to be delivered monthly instead of quarterly.

         5.5 Ratification of Loan Documents. All terms, conditions and
provisions of the First Loan Modification Agreement and the other Loan Documents
are hereby reaffirmed, ratified and continued in full force and effect and shall
remain unaffected and unchanged except as specifically amended by this Extension
Agreement and the other documents and instruments executed in connection
herewith.

6. REPRESENTATIONS, WARRANTIES, ACKNOWLEDGEMENTS AND AGREEMENTS OF DEBTORS. As
material inducements to Bank One to enter into this Extension Agreement, and
acknowledging Bank One's reliance upon the truth and accuracy thereof, each of
the Debtors represents, warrants, acknowledges and agrees that:


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         6.1  The recitals set forth above are true and correct.

         6.2 All financial statements and other information delivered to Bank
One by or on behalf of Zila or the Subsidiaries in connection with this
Extension Agreement were true and correct in all material respects as of the
respective dates thereof and as of the date of this Extension Agreement.

         6.3  The Loans are just and owing.

         6.4 The obligation of Zila to repay the Loans, together with all
accrued and unpaid interest thereon, and all other amounts properly chargeable
to the Debtors under the Loan Documents, is absolute and unconditional, each of
the guaranties of the Subsidiaries with respect to the indebtedness owed to Bank
One is absolute and unconditional, and there exists no claim, right of set off
or recoupment, counterclaim or defense of any nature whatsoever to the payment
and performance of the Obligations nor the Subsidiaries' guaranties with respect
to the Obligations. The Loan Documents, including, without limitation, the Line
of Credit Promissory Note, the Building Promissory Note, the Project Note, the
Reimbursement Agreement and the guaranties of the Subsidiaries, represent valid,
enforceable and collectible obligations of the Debtors, subject to general
principles of equity and bankruptcy, insolvency, reorganization, moratorium and
similar laws relating to or affecting the rights of creditors generally.

         6.5 To such Debtor's knowledge, the execution, delivery and performance
of this Extension Agreement (and the documents related hereto) by the Debtors do
not and will not (i) violate any law, rule, regulation or court order to which
any Debtor is subject, (ii) conflict with or result in a breach of the articles
of incorporation or bylaws of any Debtor or any agreement or instrument to which
any Debtor is a party or by which its properties are bound, or (iii) result in
the creation or imposition of any lien, security interest or encumbrance on any
property of any Debtor, whether now owned or hereafter acquired, other than
liens in favor of Bank One.

         6.6 Such Debtor has consulted with counsel and with such other experts
and advisors as it has deemed necessary in connection with the negotiation,
execution and delivery of this Extension Agreement and the related documents.
This Extension Agreement and the related documents shall be construed without
regard to any presumption or rule requiring that it be construed against the
party causing this Extension Agreement or any part hereof to be drafted.

7. COSTS AND EXPENSES OF LOAN MODIFICATION. Zila agrees to pay to Bank One
all costs and expenses incurred by Bank One in connection with this Extension
Agreement, including, without limitation, reasonable attorneys' fees, recording
fees, filing fees and all other costs and expenses incurred.

8. CONDITIONS PRECEDENT TO EFFECTIVENESS. The effectiveness of this Extension
Agreement is subject to the full and complete satisfaction of all of the
following conditions precedent:

         8.1 Bank One shall have received this Extension Agreement duly executed
by each of the Debtors.


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         8.2 Bank One shall have received patent security agreements, in form
and substance acceptable to Bank One, duly executed by each of the Debtors
listed on EXHIBIT B as owning patents.

         8.3 Bank One shall have received stock pledge agreements, in form and
substance acceptable to Bank One, duly executed by each of the applicable
Debtors with respect to the stock of entities listed on EXHIBIT C, together with
all original stock certificates pledged thereunder and stock powers related
thereto executed in blank by Zila and the Subsidiaries, as applicable.

         8.4 Bank One shall have received all of the UCC-1 financing statements
requested by Bank One to perfect and give notice to third parties as to the
security interests granted under Section 4 of this Extension Agreement, duly
executed by each of the applicable Debtors.

         8.5 All documents described in this Section 8 must be executed and
delivered to Bank One on or before June 14, 2001.

9. NO WAIVER OF DEFAULTS. This Extension Agreement in no way acts as a waiver of
any default of any Debtor (other than the Noncompliance Events during the
Noncompliance Period) or as a release or relinquishment of any of the existing
liens, security interests, rights or remedies securing payment and performance
of the Obligations or the enforcement thereof. Such liens, security interests,
rights and remedies are hereby ratified, confirmed, preserved, renewed and
extended by each of the Debtors in all respects.

10. RELEASE OF ALL CLAIMS AND WAIVER. Each of the Debtors hereby releases,
remises, acquits and forever discharges Bank One and Bank One's employees,
agents, representatives, consultants, attorneys, fiduciaries, servants,
officers, directors, partners, predecessors, successors and assigns, subsidiary
corporations, parent corporations, and related corporate divisions (all of the
foregoing hereinafter called the "RELEASED PARTIES"), from any and all actions
and causes of action, judgments, executions, suits, debts, claims, demands,
liabilities, obligations, damages and expenses of any and every character, known
or unknown, direct and/or indirect, at law or in equity, of whatsoever kind or
nature, whether heretofore or hereafter arising, for or because of any matter or
things done, omitted or suffered to be done by any of the Released Parties prior
to and including the date and execution hereof, arising out of or in any way
connected with the Loans, this Extension Agreement or the other Loan Documents
(all of the foregoing hereinafter called the "RELEASED MATTERS"). Each of the
Debtors acknowledges that the agreements herein are intended to be in full
satisfaction of all or any alleged injuries or damages arising in connection
with the Released Matters. Each of the Debtors represents and warrants to Bank
One that it has not purported to transfer, assign or otherwise convey any of its
right, title or interest in any Released Matter to any other person and that the
foregoing constitutes a full and complete release of all Released Matters.

11.  COMPLETE AGREEMENT;  NO FUTURE FORBEARANCE OR MODIFICATION GRANTED.

         11.1 Complete Agreement. Notwithstanding anything to the contrary
contained herein or in any other instrument executed by the parties and
notwithstanding any other action or conduct undertaken by the parties on or
before the date hereof, the agreements, covenants and provisions contained
herein and in the First Loan Modification Agreement shall constitute the


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only evidence of Bank One's agreement to forbear or to modify the Loan
Documents. Accordingly, no express or implied consent to any further
forbearances or modifications shall be inferred or implied by Bank One's
execution of this Extension Agreement. The Loan Documents and this Extension
Agreement, together with any documents executed in connection herewith,
constitute the entire agreement and understanding among the parties relating to
the subject matter hereof, and supersedes all prior proposals, negotiations,
agreements and understandings relating to such subject matter. In entering into
this Extension Agreement, each of the Debtors acknowledges that it is relying on
no statement, representation, warranty, covenant or agreement of any kind made
by Bank One or any employee or agent of Bank One, except for the agreements of
Bank One set forth herein.

         11.2 No Future Forbearance or Modification Granted. Further, Bank One's
execution of this Extension Agreement shall not constitute a waiver (either
express or implied) of the requirement that any future forbearance under or
modification of any Loan Document shall require the express written approval of
Bank One. No such approval (either express or implied) has been given as of the
date hereof.

12. EFFECT AS A MODIFICATION AGREEMENT. Other than as specifically set forth
herein, the remaining terms of the Loan Documents shall remain in full force and
effect, including, without limitation, all guaranties executed by the
Subsidiaries in favor of Bank One. Notwithstanding anything to the contrary
contained in the Loan Documents, in the event of a conflict between the terms of
this Extension Agreement (on the one hand) and any Loan Document (on the other
hand), the terms of this Extension Agreement shall control. Nothing contained in
this Extension Agreement is intended to or shall be construed as relieving any
person or entity, whether a party to this Extension Agreement or not, of any of
such person's or entity's obligations to Bank One.

13. CONSENT AND RATIFICATION BY GUARANTORS. Each of the Subsidiaries
acknowledges that, on or about December 1, 2000 (or subsequent thereto), it
executed and delivered to Bank One a Commercial Guaranty for the benefit of Bank
One pursuant to which it absolutely and unconditionally guaranteed payment of
all indebtedness of Zila to Bank One, whether then existing or later incurred or
created, and Oxycal acknowledges that on or about March 1, 1999, it executed and
delivered to Bank One an Unconditional Guarantee of Payment with respect to its
obligations under the Reimbursement Agreement. Each of the Subsidiaries
acknowledges, agrees and warrants that: (i) Bank One's rights under such
guaranties shall not be adversely affected by the execution of this Extension
Agreement or the other documents related hereto; (ii) such guaranties shall
remain in full force and effect, and all references in such guaranties to the
Loan Documents (regardless of the precise form of such references) are deemed
amended to refer to the Loan Documents as amended; and (iii) such Subsidiary's
guaranty, as amended, is hereby ratified and reaffirmed by such Subsidiary.

14. FACSIMILE AND COUNTERPART EXECUTION. Any signature delivered by a party by
facsimile transmission shall be deemed an original signature hereto, and this
Extension Agreement may be executed in counterparts, all of which shall
constitute one agreement.

15. BENEFIT OF AGREEMENT. This Extension Agreement shall be binding upon and
inure to the benefit of and be enforceable by the parties hereto and their
respective successors and assigns.


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No other person or entity is entitled to claim any right or benefit hereunder,
including, without limitation, the status of a third-party beneficiary of this
Extension Agreement.


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         IN WITNESS WHEREOF, the parties hereto have executed this Extension
Agreement effective as of the day, month and year first above written.

                         "ZILA":          ZILA, INC.,
                                          a Delaware corporation

                                          By: /s/ Joseph Hines
                                          Name: Joseph Hines
                                          Title: President

                         "SUBSIDIARIES":  Integrated Dental Technologies, Inc.,
                                          a California corporation

                                          By: /s/ Bradley C. Anderson
                                          Name: Bradley C. Anderson
                                          Title: Treasurer

                                          Ryder Dental of Kentucky, Inc.,
                                          a Kentucky corporation

                                          By: /s/ Bradley C. Anderson
                                          Name: Bradley C. Anderson
                                          Title: Treasurer

                                          Bio-Dental Technologies Corporation,
                                          a California corporation

                                          By: /s/ Bradley C. Anderson
                                          Name: Bradley C. Anderson
                                          Title: Treasurer

                                          Zila Pharmaceuticals, Inc.,
                                          a Nevada corporation

                                          By: /s/ Bradley C. Anderson
                                          Name: Bradley C. Anderson
                                          Title: Treasurer

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<PAGE>   12
                         "SUBSIDIARIES":  Zila Technologies, Inc.,
                              (Cont'd)    an Arizona corporation

                                          By: /s/ Bradley C. Anderson
                                          Name: Bradley C. Anderson
                                          Title: Treasurer

                                          Inter-Cal Corporation, Inc.,
                                          an Arizona corporation

                                          By: /s/ Bradley C. Anderson
                                          Name: Bradley C. Anderson
                                          Title: Treasurer

                                          Oxycal Laboratories, Incorporated,
                                          an Arizona corporation

                                          By: /s/ Bradley C. Anderson
                                          Name: Bradley C. Anderson
                                          Title: Treasurer

                                          Oxycal Export, Inc.,
                                          a Virgin Islands corporation

                                          By: /s/ Bradley C. Anderson
                                          Name: Bradley C. Anderson
                                          Title: Treasurer

                                          Zila Swab Technologies, Inc.,
                                          an Arizona corporation

                                          By: /s/ Bradley C. Anderson
                                          Name: Bradley C. Anderson
                                          Title: Treasurer

                         "BANK ONE"       Bank One, Arizona, NA,
                                          a national banking association

                                          By: /s/ Hope Levin
                                          Name: Hope Levin
                                          Title: Vice President


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                                    EXHIBIT A

                      DESCRIPTION OF SECTION 4.2 COLLATERAL

         All right, title and interest of Debtors, now owned or hereafter
acquired, whether now existing or hereafter arising, and wherever located, in
and to the following:

                  (1) All patentable inventions, patent rights, shop rights,
         letter patent of the United States or any other country, all right,
         title and interest therein and thereto, and all registrations and
         recordings thereof, including all patent registrations and recordings
         in the Patent and Trademark Office or in any similar office or agency
         of the United States, any state thereof or any foreign country or
         political subdivision thereof (collectively, the "PATENTS");

                   (2) All copyrights including all original works of authorship
         fixed in any tangible medium of expression, all right, title and
         interest therein and thereto, and all registrations and recordings
         thereof, including, without limitation, all applications, registrations
         and recordings in the Copyright Office or in any similar office or
         agency of the United States, any state thereof, or any foreign country
         or any political subdivision thereof (collectively, the "COPYRIGHTS");

                   (3) All trademarks, trade names, trade styles and service
         marks, and all prints and labels on which said trademarks, trade names,
         trade styles and service marks have appeared or appear, and all designs
         and general intangibles of like nature, now existing or hereafter
         adopted or acquired, all right, title and interest therein and thereto,
         all registrations and recordings thereof, including, without
         limitation, all applications, registrations and recordings in the
         Patent and Trademark Office or in any similar office or agency of the
         United States, any state thereof, or any foreign country or any
         political subdivision thereof (collectively, the "TRADEMARKS").

                  (4) All information, including formulas, patterns,
         compilations, programs devices, methods, techniques or processes, that
         desires independent economic value, actual or potential, from not being
         generally known to, and not being readily ascertainable by proper means
         by other persons who can obtain economic value from its disclosure or
         use (collectively, the "TRADE SECRETS");

                  (5) All claims by Debtors against any person or entity for
         past, present or future infringement of the Patents, Copyrights,
         Trademarks or Trade Secrets;

                  (6) together with all of the following, whether now owned or
         hereafter acquired, whether now existing or hereafter arising, and
         wherever located:

                           (a) all attachments, accessions, accessories, tools,
                  parts, supplies, increases, and additions to and all
                  replacements and substitutions for any property described
                  above;

                           (b) all products and produce of any of the property
                  described above;


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                           (c) all proceeds from the sale, lease, destruction,
                  loss, or other disposition of any of the property described
                  above (including, without limitation, whatever is receivable
                  or received when any of the above property or proceeds is
                  sold, licensed, collected, exchanged, returned, substituted or
                  otherwise disposed of, whether such disposition is voluntary
                  or involuntary, including rights to payment and return
                  premiums and insurance proceeds under insurance with respect
                  to any of the above property, and all rights to payment with
                  respect to any cause of action affecting or relating to the
                  above property); and

                           (d) all records and data relating to any of the
                  property described above, whether in the form of a writing,
                  photograph, microfilm, microfiche, or electronic media,
                  together with all of such Debtors' right, title and interest
                  in and to all computer software required to utilize, create,
                  maintain, and process any such records or data on electronic
                  media.


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                                    EXHIBIT B

              LISTING OF PATENTS OF ZILA, INC. AND ITS SUBSIDIARIES

                                 ISSUED PATENTS

OWNED BY ZILA PHARMACEUTICALS, INC.

         344-P-7  "COMPOSITIONS AND IN SITU METHODS FOR FORMING FILMS ON BODY
                  TISSUES" (COMPOSITIONS OF ZILACTIN PLUS CORTICOSTEROIDS)

                  USA                       5,081,157              ISSUED 2/6/91

         344-P-8  "COMPOSITIONS AND IN SITU METHODS FOR FORMING FILMS ON BODY
                  TISSUES" (BASIC "ZILACTIN" COMPOSITIONS)

                  USA                       5,081,158            ISSUED 2/6/91


OWNED BY ZILA, INC

         344-P-10 "BIOLOGICAL STAIN COMPOSITION AND METHODS OF PREPARATION AND
                  USE" (BASIC ORATEST FORMULATIONS - ACQUIRED FROM CTM)

                  USA                       5,372,801            ISSUED 12/13/94


         344-P-14 "METHODS AND COMPOSITIONS FOR IN-VIVO DETECTION OF ORAL
                  CANCERS AND PRECANCEROUS CONDITIONS" (ALTERNATE DYES)

                  USA                       5,882,627            ISSUED  3/16/99


         344-P-17 "IN VIVO STAIN COMPOSITION, PROCESS OF MANUFACTURE AND METHODS
                  OF USE TO IDENTIFY DYSPLASTIC TISSUE" (NEW ZILA MANUFACTURING
                  PROCESS AND NEWLY CHARACTERIZED TOLUIDINE BLUE DRUG SUBSTANCE,
                  METHODS OF USE)

                  USA                       6,086,852            ISSUED 7/11/00


         344-P-19 "IMPROVED PROCESS FOR MANUFACTURE OF TOLUIDINE BLUE O" (HIGH
                  YIELD MANUFACTURING PROCESS)

                  USA                       6,194,573            ISSUED 2/27/01


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         344-P-21 "METHOD FOR DETECTING CANCER" (THE "MASHBERG PATENT" - NOT
                  OWNED, BUT EXCLUSIVELY LICENSED TO ZILA BY NATIONAL INSTITUTES
                  OF HEALTH)

                  USA                       4,321,251            ISSUED  3/23/82


         344-P-38 "DRY HANDLE SWAB ASSEMBLY AND UNIT" (ACQUIRED FROM NATIONAL
                  HEALTH)

                  USA                       4,952,204            ISSUED  8/28/90



OWNED BY OXYCAL LABORATORIES, INCORPORATED.

         478-P-3  "COMPOSITIONS AND METHODS FOR ADMINISTERING VITAMIN C" (BASIC
                  ESTER-C PATENT)

                  USA                       4,822,816            ISSUED  4/18/89

         478-P-5  "COMPOSITION AND METHOD FOR ADMINISTERING THERAPEUTICALLY
                  ACTIVE COMPOUNDS" (ESTER-C USED TO IMPROVE
                  ABSORPTION/RETENTION OF OTHER MEDICAMENTS)

                  USA                       4,968,716            ISSUED  11/6/90

         478-P-7  "COMPOSITIONS AND METHODS FOR ADMINISTERING THERAPEUTICALLY
                  ACTIVE COMPOUNDS" (BASIC ESTER C COMPOSITION AND USE TO
                  IMPROVE ABSORPTION RETENTION OF VITAMIN C AND OTHER
                  MEDICAMENTS)

                  USA                       5,070,085            ISSUED  12/3/91


         478-P-9  "STABLE LIQUID MINERAL ASCORBATE COMPOSITIONS AND METHODS OF
                  MANUFACTURE AND USE" (ESTER-C "TOPICAL")

                  USA                       6,197,813            ISSUED   3/6/01



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                                    EXHIBIT C

                      DESCRIPTION OF SECTION 4.3 COLLATERAL

         All of Debtors' right, title and interest in the outstanding stock of
each of the following subsidiaries, whether now owned or hereafter acquired,
whether now existing or hereafter arising, and wherever located:

                  (1) Integrated Dental Technologies, Inc., a California
         corporation;

                  (2) Ryker Dental of Kentucky, Inc., a Kentucky corporation;

                  (3) Bio-Dental Technologies Corporation, a California
         corporation;

                  (4) Zila Pharmaceuticals, Inc., a Nevada corporation;

                  (5) Zila Technologies, Inc., an Arizona corporation;

                  (6) Inter-Cal Corporation, Inc., an Arizona corporation;

                  (7) Oxycal Laboratories, Incorporated, an Arizona corporation;

                  (8) Oxycal Export, Inc., a Virgin Islands corporation;

                  (9) Zila Swab Technologies, Inc., an Arizona corporation;

                  (10) together with all of the following, whether now owned or
         hereafter acquired, whether now existing or hereafter arising, and
         wherever located:

                           (a) all accessions, increases, and additions to and
                  all replacements and substitutions for any property described
                  above;

                           (b) all products and produce of any of the property
                  described above (including, without limitation, all cash
                  dividends, stock dividends and other distributions related
                  thereto);

                           (c) all proceeds (including, without limitation,
                  insurance proceeds) from the sale, lease, destruction, loss,
                  or other disposition of any of the property described above;
                  and

                           (d) all records and data relating to any of the
                  property described above, whether in the form of a writing,
                  photograph, microfilm, microfiche, or electronic media,
                  together with all of such Subsidiary's right, title and
                  interest in and to all computer software required to utilize,
                  create, maintain, and process any such records or data on
                  electronic media.

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