<PAGE>

                                                                   EXHIBIT 10.10

                                LICENSE AGREEMENT
                                -----------------

     This License Agreement ("Agreement"), is effective as of December 19, 1996,
by and between Gary R. Jernberg, D.D.S., M.S.D., an individual having a
principal place of business at 99 Navaho Avenue, Suite 102, Mankato, Minnesota
56001 (hereinafter referred to as "LICENSOR"), and OraPharma, Inc., a
corporation organized and existing under the laws of the State of Delaware,
having a principal place of business at 1200 Route 22 East, Suite 2000,
Bridgewater, New Jersey, 08807, (hereinafter referred to as "LICENSEE").

                                    RECITALS
                                    --------

     WHEREAS, LICENSOR is the owner of the entire right, title and interest in
the Licensed Patent (as defined below) and the Option Patents (as defined
below); and

     WHEREAS, LICENSOR represents and warrants that he has the sole right to
grant for the United States, its territories and possessions and any foreign
jurisdictions in which corresponding patents have been issued and patent
applications have been filed (collectively, the "Territory"), (i) licenses under
the Licensed Patent of the scope hereinafter granted and options and licenses
under the Option Patents of the scope hereinafter granted, and (ii) releases for
past infringement, if any, under the Licensed Patent and the Option Patents; and

     WHEREAS, LICENSEE desires to (i) develop, manufacture, use and sell
product(s) used in method(s) for local delivery of chemotherapeutic agents in
the treatment of periodontal diseases, which method(s) are covered by one or
more of the claims of the Licensed Patent, and to authorize others to do so, and
(ii) evaluate the Option Patents; and

     WHEREAS, LICENSEE desires to acquire, and LICENSOR is willing to grant, an
exclusive license under the Licensed Patent to practice and authorize others to
practice method(s) covered by one or more of the claims of the Licensed Patent
(hereinafter the "Delivery Licensed Method"); and

     WHEREAS, LICENSEE desires to obtain an option to acquire an exclusive
license under the Option Patents to develop, make, use and sell product(s) used
in methods for aiding periodontal tissue regeneration and methods for delivery
of tissue regeneration agents (the "Barrier Licensed Method") and to permit
others to do so, and the LICENSOR is willing to grant such option and exclusive
license; and

     WHEREAS, a condition precedent to the granting of any licenses herein is
the execution of a related agreement between LICENSEE and American Cyanamid
("Cyanamid Agreement").
<PAGE>

     NOW, THEREFORE, in consideration of the promises and conditions hereinafter
set forth, the parties agree as follows:

                                I. DEFINITIONS
                                ---------------

1.1  "Net invoice price" shall mean the total invoices billed, less the
     following items, to the extent to which they are paid and included in the
     total invoices billed:

     (a)  sales taxes;
     (b)  excise taxes and custom duties and other governmental charges;
     (c)  transportation and insurance on shipments to customers;
     (d)  trade, quantity and cash discounts; and
     (e)  amounts repaid, credited or otherwise allowed by reason of rebates,
          recalls, rejections of defective goods or returned goods.

     If LICENSEE or any of its Affiliates or sublicensees sells any Licensed
     Product in combination with other items which are not Licensed Products
     ("Other Items") at a single invoice price, "Net Invoice Price" for purposes
     of computing royalty payments due hereunder on the combination shall be
     determined on a country-by-country basis as follows:

     (i)   if all Licensed Products and Other Items contained in the combination
           are available separately, "Net Invoice Price" for purposes of
           computing royalty payments shall be determined by multiplying Net
           Invoice Price from sales of the combination by the fraction A/A+B,
           where A is the selling price of all Licensed Products in the
           combination and B is the selling price of all Other Items in the
           combination;

     (ii)  if the combination includes Other Items which are not sold separately
           (but all Licensed Products contained in the combination are available
           separately), "Net Invoice Price" for purposes of computing royalty
           payments shall be determined by multiplying Net Invoice Price from
           sales of the combination by the fraction A/C, where A is the selling
           price of all Licensed Products in the combination and C is the
           selling price of the combination, provided that if the fraction A/C
           is less than 50%, Net Invoice Price shall be multiplied by 50% so
           that in no event shall the Net Invoice Price of Licensed Products for
           purposes of computing royalty payments be less than 50% of the Net
           Invoice Price of Other Items; and

     (iii) if neither the Licensed Products nor the Other Items contained in the
           combination are sold separately, "Net Invoice Price" for purposes of
           computing royalty payments shall be determined by multiplying Net
           Invoice Price from sales of the combination by the fraction D/D+E,
           where D is the cost of manufacture of all Licensed Products in the
           combination and E is the cost of manufacture of all

                                       2
<PAGE>

          Other Items in the combination, all as reasonably determined by
          LICENSEE, its Affiliate or sublicensee (as applicable), provided that
          if the fraction D/D+E is less than 50%, Net Invoice Price shall be
          multiplied by 50% so that in no event shall the Net Invoice Price of
          Licensed Products for purposes of computing royalty payments be less
          than 50% of the Net Invoice Price of Other Items.

     For purposes of determining what constitutes "Other Items", a delivery
     device such as a syringe shall be included in the Net Invoice Price of the
     Licensed Product such that the Net Invoice Price of a delivery device and
     Licensed Product combination shall be deemed as Net Invoice Price of
     Licensed Product and sections i, ii, and iii shall not be utilized unless
     there are Other Items present in the combination.

1.2  "Affiliate" shall mean any corporation; e.g., subsidiary, division, etc.,
     firm, partnership, individual or other form of business organization as to
     which the control of the business shall be exercised by LICENSEE, any
     corporation in which LICENSEE owns at least fifty percent (50%) of the
     stock entitled to vote for directors, any corporation which owns fifty
     percent (50%) or more of the stock of LICENSEE, and any legal entity under
     common control with LICENSEE.

1.3  "Licensed Patent" shall mean U.S. Patent No. 4,685,883, entitled "Local
     Delivery of Chemotherapeutic Agents for the Treatment of Periodontal
     Disease" and granted on August 11, 1987, and any and all divisions,
     continuations, continuations-in-part, renewals, reissues and extensions
     thereof.

1.4  "Option Patents" shall mean (i) U.S. Patent No. 5,059,123, entitled
     "Periodontal Barrier and Method for Aiding Periodontal Tissue Regeneration"
     and granted on October 22, 1991, and any corresponding foreign patents and
     patent applications, (ii) U.S. Patent No. 5,197,882, entitled "Periodontal
     Barrier and Method for Aiding Periodontal Tissue and Regeneration Agents"
     and granted on March 30, 1993, and any corresponding foreign patents and
     patent applications, and (iii) any and all divisions, continuations,
     continuations-in-part, renewals, reissues and extensions of the patents and
     patent applications described in clauses (i) and (ii) above.

1.5  "Patents" shall mean (i) the Licensed Patent, and (ii) upon the exercise by
     LICENSEE of the option granted to it pursuant to paragraph 2.2 hereof, any
     of the Option Patents that LICENSEE elects to license hereunder pursuant to
     such option.

                                    II. GRANT
                                   ----------

Subject to the terms and conditions of this Agreement, LICENSOR hereby grants to
LICENSEE:

2.1  Patent License: The exclusive right and license to practice under the
     Licensed Patent and authorize others to practice the Delivery Licensed
     Method throughout the United

                                       3
<PAGE>

     States, its territories and possessions and under the Licensed Patent to
     make, have made, use, sell, have sold and otherwise commercialize Licensed
     Products throughout the United States, its territories and possessions
     (which exclusive right and license shall be exclusive even as to LICENSOR).

2.2  Option: An exclusive option to be exercised no later than January 10, 1997
     ------
     to acquire a worldwide exclusive license under the Option Patents. LICENSEE
     may exercise the option at any time prior to January 10, 1997 by giving
     written notice to LICENSOR of its election to exercise the option. Upon
     exercise of the option by LICENSEE, LICENSOR shall be deemed
     contemporaneously to have granted to LICENSEE a worldwide exclusive right
     and license to practice under the Option Patents and authorize others to
     practice under the Option Patents for which the option has been exercised
     to make, have made, use, sell, have sold and otherwise commercialize
     Licensed Products (which exclusive right and licensee shall be exclusive
     even as to LICENSOR.) If LICENSEE exercises the option as herein provided,
     the right and license granted by LICENSOR to LICENSEE with respect to the
     Option Patents shall automatically be valid, effective and binding upon
     LICENSEE and LICENSOR, without the necessity for any signatures or further
     action on the part of either of the parties hereto.

2.3  Improvement Inventions: LICENSOR's inventions in the field of oral care
     which may be invented by LICENSOR during the term of this Agreement and
     which infringe or would have infringed (if the applicable Patent was valid,
     enforceable, and unexpired) one or more claims of the Patents ("Improvement
     Inventions") shall be incorporated into this Agreement and the right and
     license granted by LICENSOR to LICENSEE with respect to such Improvement
     Inventions shall automatically be valid, effective and binding upon
     LICENSEE and LICENSOR, without the necessity for any signatures or further
     action on the part of either of the parties hereto. LICENSOR shall promptly
     disclose to LICENSEE any Improvement Inventions in the field of oral care
     during the term of this Agreement either before or after filing a patent
     application on the invention. If LICENSOR discloses such Improvement
     Inventions to LICENSEE and LICENSEE fails to file a patent application
     within sixty (60) days of such disclosure, LICENSOR has the right, at
     LICENSOR's expense, to file such application in such Improvement Invention
     and LICENSOR will be the owner of such patent rights, subject to LICENSEE's
     right and license thereunder and the other terms of this Agreement.

2.4  Right of First Refusal: A right of first refusal in accordance with the
     ----------------------
     procedures set forth below on certain of the LICENSOR's inventions in the
     field of oral care which may be invented by LICENSOR during the term of
     this Agreement. LICENSOR shall promptly disclose to LICENSEE any inventions
     in the field of oral care during the term of this Agreement either before
     or after filing a patent application on the invention. If such inventions
     qualify as Improvement Inventions then section 2.3 above shall control.
     Inventions in the field of oral care which are not Improvement Inventions,
     which utilize LICENSEE Confidential Information, or, the manufacture, use,
     or sale thereof infringe

                                       4
<PAGE>

     one or more claims of LICENSEE's patents or patents licensed from other
     third parties, whether already issued or issued in the future, shall belong
     to LICENSEE and LICENSOR hereby agrees to assign any and all such rights of
     LICENSOR in such inventions to LICENSEE. For purposes of this Section 2.4,
     "utilize" means the use by LICENSOR of Confidential Information that is or
     would have been necessary for LICENSOR to include in any patent application
     disclosure for such invention(s). Any dispute as to whether an invention by
     LICENSOR is covered by this Section 2.4 shall be resolved by arbitration in
     accordance with paragraph XXIII. For purposes of this section, LICENSEE
     Confidential Information is written information obtained from LICENSEE that
     is clearly marked and labeled as such and that would be deemed trade
     secrets as defined by the Uniform Trade Secrets Act. LICENSEE Confidential
     Information shall not include any information which LICENSOR can
     demonstrate was 1) known to LICENSOR prior to receipt from LICENSEE; 2)
     otherwise lawfully available to LICENSOR or to the public; 3) through no
     act on the part of LICENSOR becomes lawfully available to LICENSOR or the
     public; 4) corresponds in substance to any information received in good
     faith by LICENSOR from any third party with no obligation of
     confidentiality to LICENSEE; 5) communicated by LICENSEE to any third party
     without restriction as to confidentiality; or 6) independently developed by
     LICENSOR. Inventions by LICENSOR in the field of oral care which do not
     utilize LICENSEE Confidential Information and the manufacture, sale, or use
     thereof does not infringe one or more claims of LICENSEE's patents or
     patents licensed from other third parties in the field of oral care,
     whether already issued or issued in the future, shall belong to LICENSOR.
     LICENSEE shall have a period of ninety (90) days following receipt to
     evaluate any such patent application and/or invention disclosure. Upon
     written notice from LICENSEE prior to the end of such period, the parties
     shall negotiate in good faith the terms and conditions of a license
     arrangement. Should an agreement not be entered into at the end of 180
     days, LICENSOR shall be free to approach other third parties regarding
     possible interest in a license. However, LICENSOR shall disclose to
     LICENSEE the consideration offered by any third party and shall give
     LICENSEE a period of sixty (60) days to match any such offer. LICENSOR
     shall not be obligated to disclose the identity of the third party or other
     terms and conditions of the third party offer other than the consideration
     offered; namely, royalty rate, minimum guarantees, number of shares and
     price, etc.

2.5  Sublicensees: A right to sublicense any or all of the inventions and/or
     Patents licensed under this Agreement.

          III. LICENSE ROYALTIES AND OTHER CONSIDERATION
          -----------------------------------------------

3.1  Royalty:  Subject to any advance or credit provided for under this
     -------
     Agreement, LICENSEE shall pay to LICENSOR, on a quarterly basis, as set
     forth in paragraph 4.1 below, a royalty which shall be based upon products
     sold by LICENSEE or its Affiliates or sublicensees for use in the practice
     of the Delivery Licensed Method and, if

                                       5
<PAGE>

     LICENSEE exercises its option under paragraph 2.2, the Barrier Licensed
     Method, and the manufacture, sale or use of which shall be covered by a
     valid, enforceable and unexpired claim of an issued Patent of the
     jurisdiction where sold (hereinafter, the "Licensed Product"). The royalty
     payable with respect to each Licensed Product sold within jurisdictions
     where a valid, enforceable and unexpired claim of an issued Patent
     continues to exist shall be [the confidential material contained herein has
     been omitted and has been separately filed with the Commission.] Upon
     expiration of the Licensed Patent, LICENSEE shall pay for a period of [the
     confidential material contained herein has been omitted and has been
     separately filed with the Commission] from the expiration of the Licensed
     Patent a royalty of [the confidential material contained herein has been
     omitted and has been separately filed with the Commission.] This reduced
     royalty is in consideration for the ongoing contributions of LICENSOR to
     LICENSEE as further provided in this Agreement. Royalties will be based on
     the Net Invoice Price resulting from any sale of Licensed Products to third
     parties by LICENSEE or any of its Affiliates or sublicensees (and not sales
     among LICENSEE, its Affiliates or sublicensees, except as otherwise
     provided in the following sentence). LICENSEE shall pay a royalty of [the
     confidential material contained herein has been omitted and has been
     separately filed with the Commission.] In those countries where the
     LICENSOR has a patent, the royalty will be [the confidential material
     contained herein has been omitted and has been separately filed with the
     Commission.] Notwithstanding anything to the contrary contained herein if a
     Licensed Product or the manufacture, sale or use thereof is covered by more
     than one Patent or claim within the Patents, LICENSEE shall be responsible
     for the payment of only one royalty.

3.2  Warrants: LICENSEE shall provide LICENSOR five (5) year warrants to
     --------
     purchase Forty Thousand (40,000) shares of LICENSEE's Common Stock, par
     value $0.01 per share, at an exercise price of five cents ($.05) per share.
     The warrants will vest according to the following schedule: Fifty percent
     (50%) of the shares (20,000) upon signing this Agreement, and the remaining
     fifty percent (50%) of the shares (20,000 shares) upon the election of
     LICENSEE to exercise its option to license exclusively one or both of the
     Option Patents. The warrants shall be substantially in the form attached as
     Exhibit A.

3.3  Milestone Payments: For any product which relies upon one of the Patents,
     ------------------
     milestone payments will be made according to the following schedule:

     A.   NDA Submission - If LICENSEE elects to submit an NDA to the U.S.
          F.D.A. for a product which requires a license on one or more of the
          Patents, then within thirty (30) days following the U.S. F.D.A.'s
          acceptance of such NDA as a complete submission (i.e., not receipt or
          final approval), LICENSEE will provide LICENSOR a payment of Fifty
          Thousand U.S. Dollars ($50,000) in either cash or an equivalent value
          in warrants to purchase LICENSEE's equity securities, calculated on
          the basis of conversion at the then fair market value for

                                       6
<PAGE>

          LICENSEE's equity securities, as of the date the NDA submission is
          accepted as a complete submission exercisable for five (5) years at
          the fair market value used for conversion. The dollar value of the
          milestone payment (i.e., $50,000 in the case of cash or warrants) will
          be treated as an advance on royalties due to LICENSOR under this
          Agreement. The election of a cash or warrant form of payment will be
          at the exclusive option of LICENSEE. LICENSOR will be notified in
          writing within five (5) days following receipt by LICENSEE of any
          notification of acceptance by the U.S. F.D.A. of an NDA Submission as
          complete and of LICENSEE's election of cash or warrants. A submission
          of an NDA relating to the same product for a new indication will not
          result in another milestone payment under this Section 3.3A.

     B.   NDA Approval - Within thirty (30) days following receipt of the
          approval and authorization of the U.S. F.D.A. to market any Licensed
          Products, LICENSEE will provide to LICENSOR a payment of One Hundred
          Thousand U.S. Dollars ($100,000) in either cash or an equivalent value
          in warrants to purchase LICENSEE's equity securities, calculated on
          the basis of conversion at the fair market value for LICENSEE's equity
          securities as of the date of such approval, exercisable for five (5)
          years at the fair market value used for conversion. The dollar value
          of the milestone payment (i.e. $100,000 in the case of cash or
          warrants) will be treated as an advance on royalties due to LICENSOR
          under this Agreement. The election of a cash or warrant form of
          payment will be at the exclusive option of LICENSEE. LICENSOR will be
          notified in writing within five (5) days following receipt by LICENSEE
          of any approvals and authorizations by the U.S. F.D.A. and of
          LICENSEE's election of cash or warrants. Approval of an NDA relating
          to the same product for a new indication will not result in another
          milestone payment under this Section 3.3B.

3.4  Special Advisor: LICENSEE will retain LICENSOR for the term of this
     ---------------
     Agreement as a Special Advisor to LICENSEE, for an annual retainer of [the
     confidential material contained herein has been omitted and has been
     separately filed with the Commission] paid quarterly on the first day of
     the second month of each quarter. The first quarter payment shall be
     payable on a pro-rata basis. LICENSEE and LICENSOR will execute a
     confidentiality agreement, attached as Exhibit B, as a part of this
     arrangement. It is expected that LICENSEE will have regular meetings with
     LICENSOR at which time progress on the development of products, etc.
     relating to LICENSOR's technology will be presented to LICENSOR. Reasonable
     expenses relating to LICENSOR's travel in connection with meetings that
     LICENSEE requests LICENSOR attend, will be reimbursed upon submission of a
     written invoice and copies of all receipts therefor. In addition, new ideas
     or suggestions that LICENSOR may have regarding LICENSEE's existing or
     proposed projects may be discussed at these meetings. [the confidential
     material contained herein has been omitted and has been separately filed
     with the Commission]. However, such LICENSOR's consulting services shall be

                                       7
<PAGE>

     limited to a maximum of ten (10) days per year. Consulting services
     requiring travel by LICENSOR shall be limited to no more than [the
     confidential material contained herein has been omitted and has been
     separately filed with the Commission] trips per year with a maximum of [the
     confidential material contained herein has been omitted and has been
     separately filed with the Commission] per month and no more than [the
     confidential material contained herein has been omitted and has
     beenseparately filed with the Commission] days per trip. Additional
     consulting services shall be provided by LICENSOR only upon LICENSOR's
     approval.

3.5  Sublicenses: In the event that LICENSEE enters into corporate relationships
     involving product(s) which require a sublicense of one or more of the
     Patents, LICENSEE will provide LICENSOR the same consideration set forth in
     paragraphs 3.1 through 3.4 as if the product(s) were developed and
     commercialized by LICENSEE itself.

                    IV. PAYMENTS, REPORTS, BOOKS AND RECORDS
                    -----------------------------------------

4.1  Payments and Reports: Within sixty (60) days after the end of each calendar
     --------------------
     quarter (e.g., the quarters ending on March 31, June 30, September 30 and
     December 31) during which LICENSEE is obligated to pay royalties to
     LICENSOR, LICENSEE shall provide a written report to LICENSOR setting forth
     the sale of Licensed Products broken down by drug type or product class
     within the Territory during such calendar quarter, provided that if
     LICENSEE shall not have received from its Affiliates or any sublicensee a
     report of sales of Licensed Products, then such sales may be included in
     the next quarterly report. If no Licensed Products have been sold during
     any calendar quarter, a statement to that effect shall be made by LICENSEE
     to LICENSOR within said sixty (60) day period. At the time each report is
     made, LICENSEE shall pay to LICENSOR the royalties shown by such report to
     be payable thereunder. Interest shall accrue at the rate of [the
     confidential material contained herein has been omitted and has been
     separately filed with the Commission] with respect to any payment which is
     not received when it is due and payable.

4.2  Books and Records: LICENSEE shall keep books and records in such reasonable
     -----------------
     detail as will permit the reports provided for in paragraph 4.1 above to be
     made and the royalties payable hereunder to be determined. LICENSEE further
     agrees to permit the books and records related to any such report to be
     inspected or audited, not more than once per year, at the expense of
     LICENSOR upon reasonable advance notice during reasonable business hours by
     a certified public accountant acceptable to LICENSEE to verify such
     reports. LICENSEE shall not unreasonably refuse acceptance of a certified
     public accountant selected by LICENSOR to perform such an audit. The
     expense of any such inspection or audit shall be borne by LICENSOR, except
     that if as a result of such inspection or audit, it is determined that
     LICENSEE has underpaid the royalties due

                                       8
<PAGE>

     LICENSOR by [the confidential material contained herein has been omitted
     and has been separately filed with the Commission], the expense of such
     inspection or audit shall be paid by LICENSEE, or if already paid, LICENSEE
     shall reimburse LICENSOR for the cost thereof. The accountant shall
     transmit to LICENSOR only that information necessary to verify the sales
     figures and LICENSOR shall require the accountant to maintain all other
     information in strict confidence. LICENSOR may perform the audits set forth
     above to cover a period of three (3) years from the date a report is due
     LICENSEE. However, if a material shortfall in payment of royalties is
     discovered during an audit, LICENSOR may perform the audits set forth above
     to cover a period of five (5) years from the date a report is due LICENSEE.

4.3  Periodic Status Reports: LICENSOR shall be provided on a semi-annual basis
     -----------------------
     (every six (6) months) with an overall status review of all research and
     development and marketing efforts to develop and market products covered by
     the invention.

4.4  Payment of Royalties: Payment shall be made by delivery of a check to the
     --------------------
     LICENSOR's address noted above or such other address as designated in
     writing by LICENSOR. Payment shall be deemed made upon date of deposition
     in the mail if mailed, or personal delivery if personally delivered.

4.5  Accounting; Foreign Currency: Royalty payments shall be paid in United
     ----------------------------
     States dollars. If a currency conversion shall be required in connection
     with the payment of royalties hereunder, the conversion shall be made by
     using the exchange rate quoted in The Wall Street Journal (eastern edition)
     on the last business day of the calendar quarter reporting period to which
     such royalty payments relate. Where royalties are due from sales in a
     country where by reason of currency regulations of any kind or otherwise it
     is impossible to make royalty payments for such sales in accordance with
     this Agreement, such royalties shall be deposited in whatever currency is
     allowable for the benefit or credit of LICENSOR in any bank in that country
     as shall be acceptable to LICENSOR.

4.6  Withholding Taxes: LICENSOR acknowledges and agrees that there may be
     -----------------
     deducted from any payments or royalties otherwise due and payable hereunder
     any taxes or other payments required to be withheld under applicable law
     with respect to such payments or royalties or otherwise relating to
     Licensed Products.

                             V. TERM AND TERMINATION
                             -----------------------

5.1  Term:  Excepted as provided in Section 3.1 relative to certain ongoing
     ----
     royalties for [the confidential material contained herein has been omitted
     and has been separately filed with the Commission] following expiration of
     the Licensed Patent, the term of this Agreement shall commence on the
     effective date of the Agreement and continue for the entire remaining term
     of the Patents (including as the term of any Patent that may be

                                       9
<PAGE>

     extended pursuant to the Patent Term Restoration Act or foreign
     equivalent), unless earlier terminated, pursuant to the provisions of
     paragraphs 5.2 or 5.3 below.

5.2  Termination by LICENSOR:
     -----------------------

     (a)  Default by LICENSEE: LICENSOR at his option may terminate this
          -------------------
          Agreement by written notice to LICENSEE if LICENSEE shall:

          i.   default in the payment of any royalties or any other amount
               required to be paid by LICENSEE to LICENSOR hereunder and such
               default shall continue for a period of sixty (60) days after
               LICENSOR shall have given to LICENSEE written notice of such
               default; or

          ii.  default in the making of any reports required to be made by
               LICENSEE to LICENSOR hereunder and such default shall continue
               for a period of sixty (60) days after LICENSOR shall have given
               LICENSEE written notice of such default; or

          iii. default in the performance of any other material provision
               contained in this Agreement to be performed and such default
               shall continue for a period of sixty (60) days after LICENSOR
               shall have given LICENSEE written notice of such default.

     (b)  Effect of Failure to Terminate: Failure or delay by LICENSOR to
          ------------------------------
          exercise its right of termination by reason of any default of LICENSEE
          in carrying out any obligation imposed upon it by this Agreement shall
          not operate to prejudice LICENSOR's right of termination for any other
          or subsequent default by LICENSEE.

     (c)  Cyanamid Agreement: LICENSOR at his option may terminate this
          ------------------
          Agreement by giving at least ten (10) days' prior written notice to
          LICENSEE in the event LICENSEE does not enter into the Cyanamid
          Agreement within thirty (30) days after the effective date of this
          Agreement (unless LICENSEE enters into the Cyanamid Agreement during
          such ten (10) day period.)

5.3  Termination by LICENSEE:
     -----------------------

     (a) Patent Validity:  LICENSEE shall have the right to terminate this
         ---------------
     Agreement with respect to any Patent in the event that all of the claims of
     such Patent are held invalid by a court of last resort or by a lower
     tribunal from whose action no appeal has been taken within the period
     allowed therefor.  In the event that LICENSEE exercises its right under
     this paragraph to terminate, said termination shall affect

                                       10
<PAGE>

          only payment of any future royalties due, and there shall be no
          obligation by LICENSOR to refund past royalties paid or due to
          LICENSOR.

     (b)  Termination by LICENSEE: LICENSEE shall have the right to terminate
          -----------------------
          this Agreement, with or without cause, as of the end of any calendar
          month by giving actual notice to LICENSOR at least sixty (60) days
          prior to the date of which LICENSEE shall elect to have such
          termination become effective. Such termination shall discharge
          LICENSEE from any and all obligations not yet due as of the effective
          date of such termination, but shall not release LICENSEE from the
          payment of any and all royalties earned and unpaid as of the effective
          date of such termination.

5.4  Termination by Either Party: Termination of this Agreement by either party
     ---------------------------
     shall be a remedy in addition to any other rights and/or remedies which a
     party may have against the other as of the occurrence which brought about
     such termination. Termination shall not relieve LICENSEE of any of its
     obligations to pay royalties which accrued prior to the effective date of
     termination, or to comply with any other of its obligations to perform
     which arose prior to the effective date of termination. In the event this
     Agreement is terminated prior to the expiration hereof, LICENSEE, its
     Affiliates and its sublicensees may continue the manufacture of any work-
     in-progress and retain and continue to sell all inventory of Licensed
     Products then on hand or in production for a period of one hundred and
     eighty (180) days from the effective date of termination provided that
     royalties are paid to LICENSOR in the amounts and in the manner provided in
     this Agreement as if this Agreement had not been terminated.

5.5  Patent Term Restoration Act: LICENSEE has the duty and right to seek
     ---------------------------
     extension of the patent term under the Patent Term Restoration Act and
     shall endeavor to obtain the maximum extension possible. LICENSEE will keep
     LICENSOR informed as to any opportunities for such extensions and will
     promptly forward to LICENSOR copies of all correspondence by and between
     LICENSEE and the Patent Office. LICENSOR shall cooperate with LICENSEE in
     providing whatever information and assistance is required including signing
     any necessary documents without any charge to LICENSEE. LICENSEE shall
     notify LICENSOR when extension under the Patent Term Restoration Act and
     applicable foreign equivalents is possible. LICENSOR shall have the right
     to seek extension of the patent term, if available, under the Patent Term
     Restoration Act and applicable foreign equivalents if LICENSEE chooses not
     to do so. LICENSEE shall pay all expenses for such process.

                                    VI. TITLE
                                    ---------

     Title to the Licensed Patent and the Option Patents and all rights therein
shall remain with LICENSOR, except for the rights and licenses granted to
LICENSEE under this Agreement.

                                       11
<PAGE>

                         VII. TRANSFERABILITY OF LICENSE
                        --------------------------------

     The rights granted by this Agreement to LICENSEE shall not be assigned,
transferred or sold by LICENSEE without the prior written consent of LICENSOR
(which consent shall not be unreasonably withheld or delayed), except that
LICENSEE may, without obtaining the consent of LICENSOR, (i) grant sublicenses
hereunder, and (ii) assign its rights hereunder to any Affiliate of LICENSEE or
to the successor of LICENSEE's business or all or substantially all of its
assets related to the licenses granted hereunder or capital stock (by purchase,
merger, operation of law or otherwise), provided that such successor agrees to
assume all of the obligations provided herein.

                 VIII. DOCUMENTATION AND SUPPLEMENTAL ASSISTANCE
                 -----------------------------------------------

     LICENSOR shall have no on-going obligation to provide additional
documentation, technology, or assistance to LICENSEE beyond the disclosure in
the Patents, except for duties as Special Advisor as described in Paragraph 3.4
of this Agreement and LICENSEE's rights under paragraphs 2.3 and 2.4.

                        IX. TRADEMARKS AND ADVERTISEMENTS
                        ---------------------------------

9.1  Except as otherwise provided in this Agreement, LICENSEE and LICENSOR each
     agree that it shall not use, make reference to, or display any trademarks,
     service marks, trade names, symbols or logos owned or used by the other,
     including the use of the other's name, and further agrees that no
     advertisement in any form, whether by publication, television, radio, data
     sheet or by any other mode or medium, shall make any use of the names,
     trademarks, trade names, logos or service marks of the other, unless prior
     written permission is obtained from the other, except that LICENSEE may
     state that it is licensed by LICENSOR under one or more of the Patents and
     LICENSEE may comply with disclosure requirements under any applicable law.

9.2  LICENSEE shall endeavor to acknowledge Gary R. Jernberg, D.D.S., M.S.D., as
     the inventor of the Patents on all LICENSEE materials identifying advisors
     of the Company.

                         X. ENFORCEMENT OF PATENT RIGHTS
                         -------------------------------

10.1 Notice of Infringement: Each party hereto shall promptly notify the other
     ----------------------
     of any alleged infringement by a third party of the Patents and of any
     available evidence of such infringement.

10.2 Suit by LICENSEE: LICENSEE shall have the right, but not the obligation, to
     ----------------
     take any action, including, without limitation, to commence a suit or other
     legal proceedings, against third parties to prosecute any infringement of
     any of the Patents in its own name or in the name of LICENSOR as party
     plaintiff. LICENSOR shall join as a party to any

                                       12
<PAGE>

     such suit or other legal proceedings if required by law or procedure, and
     otherwise cooperate and assist LICENSEE in any action undertaken by
     LICENSEE. All damages and other amounts recovered by LICENSEE as a result
     of any suit or other legal proceedings commenced by LICENSEE (whether
     pursuant to a final judgment, by settlement or otherwise) shall be applied
     first to all of the out of pocket expenses of LICENSEE and LICENSOR, if
     LICENSOR is required by law or procedure to join in such suit or other
     legal proceedings, to prosecute and/or settle such suit or other legal
     proceedings (including, without limitation, attorneys fees and the fees of
     consultants and experts), and the remaining balance of any such recovery or
     payment shall be distributed [the confidential material contained herein
     has been omitted and has been separately filed with the Commission] to
     LICENSEE and [the confidential material contained herein has been omitted
     and has been separately filed with the Commission] to LICENSOR. LICENSOR
     may, at its sole expense, participate in any suit or other legal
     proceedings commenced by LICENSEE if not otherwise required by law or
     procedure to join in such suit or other legal proceedings.

10.3 Suit by LICENSOR: If, within ninety (90) days after notice by either party
     ----------------
     of any alleged infringement, LICENSEE has been unsuccessful in persuading
     the alleged infringer to desist and has not commenced a suit or other legal
     proceedings, or if LICENSEE notifies LICENSOR at any time of its intention
     not to bring suit or other legal proceedings against an alleged infringer,
     the LICENSOR shall have the right, but not the obligation, to commence suit
     or other legal proceedings for such infringement. The total cost of any
     such infringement action commenced solely by LICENSOR shall be borne by
     LICENSOR, and LICENSOR shall retain any recovery of damages awarded in such
     action, except that [the confidential material contained herein has been
     omitted and has been separately filed with the Commission] of any such
     recovery or damages, after deducting all costs and expenses to prosecute
     and/or settle such suits or other legal proceedings (including, without
     limitation, attorneys fees and the fees of consultants and experts) shall
     be credited against all royalties payable hereunder. LICENSEE may, at its
     sole expense, participate in any suit or other legal proceedings commenced
     by LICENSOR.

                     XI. PATENT PROSECUTION AND MAINTENANCE
                     --------------------------------------

     LICENSEE shall, during the term of this Agreement, prosecute all patent
applications included within the Patents, and maintain all issued patents
included within the Patents in force by duly filing all necessary papers and
paying any fees required by the patent laws of the particular country in which
such Patents were issued provided that LICENSEE shall be entitled to credit the
following amounts against any future royalties: [the confidential material
contained herein has been omitted and has been separately filed with the
Commission] for each application filed in the United States and a total of [the
confidential material contained herein has been omitted and has been separately
filed with the Commission] to cover all foreign filings. Upon request LICENSOR
shall promptly provide to LICENSEE copies of all

                                       13
<PAGE>

applications and correspondence and other documents related to the Patents that
are reasonably necessary to allow LICENSEE to prosecute and maintain such
Patents provided LICENSOR is reimbursed for all costs reasonably related to
providing such assistance.

                                XII. DISCLAIMERS
                                -----------------

     Nothing contained in this Agreement shall be construed as:

     (a)  conferring any license or other right, by implication, estoppel or
          otherwise, under any patent application, patent or patent right,
          except as herein expressly granted under this Agreement; or

     (b)  except as otherwise set forth in paragraph XIV, a warranty or
          representation by LICENSOR that any manufacture, use, sale or other
          disposition of Licensed Products under the license granted in this
          Agreement is fit for use or will be free from claims of infringement
          of any patent, other than the Licensed Patent or the Option Patents,
          as the case may be; or

     (c)  imposing on either party any obligation to file any patent application
          or to secure any patent or maintain any patent in force, except the
          Patents.

                    XIII. INDEMNIFICATION; PRODUCTS LIABILITY
                    -----------------------------------------

     LICENSEE agrees to defend, indemnify and hold LICENSOR harmless from any
and all claims, demands, loss, liability, expense or damage (including
investigative costs, court costs and reasonable attorneys' fees) arising out of
or otherwise related to (i) any claim of injury or damage by any third party
arising out of any theory of product liability based upon usage of any Licensed
Product or based upon any claim that any Licensed Product is defective in
material, design or workmanship, or that the use or sale of such Licensed
Product constituted a breach of warranty, either express or implied, (ii) the
breach of any representation or warranty made by LICENSEE herein or (iii) the
default by LICENSEE in the performance or observance of any of its obligations
to be performed or observed hereunder. LICENSEE will assume control of the
defense of any such claim or action; provided, however, that (i) LICENSOR shall
be entitled to participate therein (through counsel of his own choosing) at
LICENSOR's sole cost and expense, and (ii) LICENSEE shall not settle or
compromise any such claim or action without the prior written consent of
LICENSOR (which consent shall not be unreasonably withheld or delayed) unless
such settlement or compromise includes a general release of LICENSOR from any
and all liability with respect thereto.

                       XIV. REPRESENTATIONS AND WARRANTIES
                       -----------------------------------

14.1 By LICENSEE.  LICENSEE hereby represents and warrants to LICENSOR that (i)
     -----------
     LICENSEE has full legal right, power and authority to execute, deliver and
     perform its

                                       14
<PAGE>

     obligations under this Agreement, and (ii) the execution, delivery and
     performance by LICENSEE of this Agreement does not contravene or constitute
     a default under any provision of applicable law or of its certificate of
     incorporation or by-laws (or equivalent governing documents) or of any
     agreement, judgment, injunction, order, decree or other instrument binding
     upon it.

14.2 By LICENSOR. LICENSOR hereby represents and warrants to LICENSEE that (i)
     -----------
     LICENSOR has full legal right, power and authority to execute, deliver and
     perform his obligations under this Agreement, (ii) the execution, delivery
     and performance by LICENSOR of this Agreement do not contravene or
     constitute a default under any provision of applicable law or any
     agreement, judgment, injunction, order, decree or other instrument binding
     upon LICENSOR or otherwise relating to the Licensed Patent or the Option
     Patents, (iii) LICENSOR is the exclusive owner of all legal and beneficial
     right, title and interest in and to the Licensed Patent and the Option
     Patents, free and clear of any lien, claim or encumbrance or other rights
     of any other person or entity, and he has the right to license and grant
     rights under the Licensed Patent and the Option Patents to LICENSEE, (iv)
     LICENSOR has not granted to any other person or entity any license or other
     rights with respect to the Licensed Patent or the Option Patents that are
     currently in effect, and (v) to the best knowledge of LICENSOR, neither the
     practice of the Patents as contemplated hereby, nor the development,
     manufacture, use, sale or commercialization of any Licensed Product shall
     infringe or violate any patent or other right of any person or entity.

                                XV. GOVERNING LAW
                                -----------------

     This Agreement is deemed entered into in Minnesota for purposes of
jurisdiction and venue and shall be governed by, and construed in accordance
with, the laws of the State of Minnesota and the United States.

                                  XVI. MARKING
                                  ------------

     LICENSEE agrees to have all Licensed Products and the product literature
and advertisements for the Licensed Products made, used or sold under this
Agreement herein granted marked with the appropriate patent notice; e.g.:

                   LICENSED UNDER U.S. PATENT NO. 4,685,883 or
                       LICENSED UNDER U.S. PAT. 4,685,883

                                 XVII. DILIGENCE
                                 ---------------

     LICENSEE agrees to use commercially reasonable efforts to develop
(including NDA submission within four (4) years), and bring to market, within
six (6) years from the date hereof, a Licensed Product the manufacture, sale or
use of which is subject to any claim contained in the

                                       15
<PAGE>

Licensed Patent. If LICENSEE exercises the option pursuant to paragraph 2.2,
LICENSEE shall use commercially reasonable efforts to develop (including NDA
submission within eight (8) years), and bring to market, within ten (10) years
from the date hereof, a Licensed Product the manufacture, use or sale of which
is subject to any claim contained in any of the Option Patents. Licensee may,
but shall have no obligation, to develop additional Licensed Products. If the
Licensed Patent or Option Patents are not commercialized and brought to market
within the periods provided for above, then the parties shall meet and consider
the status of LICENSEE's development efforts and agree upon the reasonable
efforts LICENSEE shall utilize to develop and bring such Licensed Products to
market. If the parties are unable to agree upon such efforts within forty-five
(45) days, the matter shall be resolved by arbitration in accordance with
paragraph XXIII hereof. If LICENSEE thereafter fails to use efforts agreed to by
the parties or determined by arbitration, the license granted herein with
respect to the Licensed Patent or Option Patents, as the case may be shall be
converted to a nonexclusive license. For the purposes of this paragraph, the
efforts of an Affiliate, sublicensee or collaborator of LICENSEE shall
constitute the efforts of LICENSEE hereunder.


                             XVIII. ENTIRE AGREEMENT
                             -----------------------

     This Agreement shall constitute the entire Agreement between the parties,
and there will be no other representations, warranties, undertakings, or
conditions, express or implied, except as set forth in this Agreement. This
Agreement supersedes all prior agreements, understandings or negotiations,
written or otherwise.

                          XIX. LIMITATION OF LIABILITY
                          ----------------------------

     UNDER NO CIRCUMSTANCES SHALL EITHER PARTY BE LIABLE TO THE OTHER PARTY OR
ANY OTHER PERSON OR ENTITY FOR ANY LOSS OF PROFITS OR SPECIAL, CONSEQUENTIAL OR
INDIRECT DAMAGES OF ANY KIND WHATSOEVER.
     No party shall be liable for failure or delay in performing any of its
obligations hereunder if such failure or delay is occasioned by circumstances
beyond the reasonable control of the party so failing or delaying, including
without limitation, Acts of God, war, insurrection, fire, flood, etc.

                                XX. MODIFICATIONS
                                -----------------

     This Agreement may not be modified, amended or supplemented except by an
instrument in writing signed by both parties.

                                   XXI. WAIVER
                                   -----------

                                       16
<PAGE>

     The failure of either party to require the performance of any term of this
Agreement, or the waiver by either party of any breach under this Agreement,
shall not prevent any subsequent enforcement of such term, nor be deemed a
waiver of any subsequent breach.

                                XXII. SUCCESSORS
                                ----------------

     All of the terms, provisions and conditions of this Agreement shall be
binding upon and inure to the benefit of the parties hereto and their respective
heirs, and permitted successors, transferees and assigns.

                               XXIII. ARBITRATION
                               ------------------

     Any controversy or dispute arising out of or in connection with this
Agreement, its interpretation, performance, or termination including any
questions of fraud or questions concerning the validity or enforceability of the
Agreement, but not the validity of the claims of the Patents, which the parties
are unable to resolve within forty-five (45) days after written notice by one
party to the other of the existence of such controversy or dispute, may be
submitted to arbitration by either party, and if so submitted by either party,
shall be finally settled by arbitration conducted in accordance with the
Commercial Arbitration Rules of the American Arbitration Association in effect
on the date hereof. Any such arbitration shall take place in Minneapolis,
Minnesota. The law applicable to the subject matter of the dispute shall be the
laws of the State of Minnesota.

     The institution of any arbitration proceeding hereunder shall not relieve
LICENSEE of its obligation to make payments accrued hereunder to LICENSOR during
the continuance of such proceeding. The decision by the arbitrators shall be
binding and conclusive upon the parties, their successors, and assigns and they
shall comply with such decision in good faith, and each party hereby submits
itself to the jurisdiction of the courts of the place where the arbitration is
held but only for the entry of judgment with respect to the decision of the
arbitrators hereunder. Notwithstanding the foregoing, judgment upon the award
may be entered in any court where the arbitration takes place, or any court
having jurisdiction. Notwithstanding anything to the contrary contained herein,
either party shall have the right to apply to a court of competent jurisdiction
for a temporary restraining order, a preliminary injunction or other equitable
relief to prevent irreparable harm or to preserve the status quo.

                               XXIV. COUNTERPARTS
                               ------------------

     This Agreement may be executed in two or more counterparts, each of which
shall be deemed an original and all of which shall constitute one instrument,
and, in making proof hereof, it shall not be necessary to produce or account for
more than one such counterpart.

                                  XXV.  NOTICE
                                  ------------

                                       17
<PAGE>

     Any notice and reports with respect to this Agreement shall be given in
writing, by mail, postage prepaid, or by prepaid telegram, by reputable
overnight courier (receipt requested) or personally delivered to the principal
place of business of the parties, as set forth above, or such other address as
shall be designated in writing by either party. Unless otherwise expressly
provided in this Agreement, any notice to be given shall be deemed to have been
given and shall be effective, three days after the date of deposit in the mail
if mailed or upon receipt if sent by overnight courier or personally delivered.
Copies of all notices sent to LICENSEE shall be addressed to the attention of
the President of LICENSEE.

                          XXVI. RELATIONSHIP OF PARTIES
                          -----------------------------

     It is expressly agreed by the parties hereto that LICENSOR and LICENSEE are
independent contractors and nothing in this Agreement is intended to create an
employer relationship, joint venture, or partnership between the parties. No
party has the authority to bind the other.

                            XXVII. FURTHER ASSURANCES
                            -------------------------

     Without limiting the generality of any provision of this Agreement, each
party agrees that upon request of any other party, it shall, from time to time,
do any and all other acts and things as may reasonably be required to carry out
its obligations hereunder, to consummate the transactions contemplated hereby,
and to effectuate the purposes hereof. For any consulting services provided by
LICENSOR above and beyond the ten (10) days required under Section 3.4, LICENSEE
agrees to reimburse LICENSOR for any travel and subsistence expenses reasonably
incurred to provide any assistance requested by LICENSEE and to compensate
LICENSEE at a rate of [the confidential material contained herein has been
omitted and has been separately filed with the Commission.]

                              XXVIII. SEVERABILITY
                              --------------------

     Any term or provision of this Agreement which is invalid or unenforceable
in any jurisdiction shall, as to such jurisdiction, be ineffective to the extent
of such invalidity or unenforceability without rendering invalid or
unenforceable the remaining terms and provisions of this Agreement or affecting
the validity or enforceability of any of the terms or provisions hereof in any
other jurisdiction.

                                 XXIX. HEADINGS
                                 --------------

     The headings used in this Agreement are for convenience of reference only
and shall not affect the meaning or construction of this Agreement.

                           XXX. RESERVATION OF RIGHTS
                           --------------------------

                                       18
<PAGE>

     LICENSOR retains any and all rights to applications of LICENSOR inventions
outside the field of oral care and LICENSOR shall be free to license or exploit
any such inventions for use outside the field of oral care as LICENSOR chooses.

                                       19
<PAGE>

     IN WITNESS WHEREOF, the parties have executed this Agreement:

                              LICENSOR

                              Gary R. Jernberg, D.D.S., M.S.D.
                              --------------------------------

Date:  12/19/96               By:
     -------------------         -----------------------------
                              Name: /s/ Gary R. Jernberg
                                   ---------------------------
                              Title:
                                    --------------------------

                              LICENSEE

                              OraPharma, Inc.
                              ---------------

Date:  12/24/96               By: MICHAEL D. KISHBAUCH
    --------------------         -----------------------------
                              Name: /s/ Michael Kishbauch
                                   ---------------------------
                              Title:  PRESIDENT/CEO
                                    --------------------------

                                       20
<PAGE>

     IN TESTIMONY WHEREOF, I have hereunto set my had this 19 day of
                                                          ----
 December , 1996.
----------    --
                                               Dawn Renner
                                    --------------------------------------------
                                    Name:


STATE OF Minnesota  )
                    )ss.
COUNTY OF Hennepin  )

     On this 19 day of December, 1996  before me personally appeared
             --        --------    --
 Gary R. Jernberg , to me known to be the person described in and who
------------------
acknowledged to me that he executed the same for the uses and purposes therein
set forth.



  /s/ Dawn Renner                                  [seal]
-----------------------------------
Notary Public

     IN TESTIMONY WHEREOF, I have hereunto set my hand this 24 day of
                                                           ----
 December ,1996.
----------   --
                                          Richard A. Charlton
                                    --------------------------------------------
                                    Name:


STATE OF New Jersey )
                    )ss.
COUNTY OF           )

     On this  24 day of  December , 1996  before me personally appeared
             ----       ----------    --
 Michael Kishbauch , to me known to be the person described in and who
-------------------
acknowledged to me that he executed the same for the uses and purposes therein
set forth.



   /s/ Richard Charlton                            [seal]
-----------------------------------

                                       21