Document:

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                                                                    Exhibit 4.31

THE SECURITIES REPRESENTED BY THIS CERTIFICATE HAVE BEEN ACQUIRED FOR INVESTMENT
AND HAVE NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS AMENDED OR
STATE SECURITIES LAWS.  THESE SECURITIES MAY NOT BE SOLD OR TRANSFERRED IN THE
ABSENCE OF SUCH REGISTRATION OR AN EXEMPTION THEREFROM UNDER SAID ACT OR STATE
SECURITIES LAWS.

No.  13             Right to Purchase Shares of Common Stock of OraPharma, Inc.

                                ORAPHARMA, INC.

                         Common Stock Purchase Warrant

     This is to certify that, FOR VALUE RECEIVED, TL Ventures III Offshore L.P.
("Holder"), is entitled to purchase, subject to the provisions of this Warrant,
from OraPharma, Inc., a Delaware corporation (the "Company"), 3,728 fully paid,
validly issued and nonassessable shares of Common Stock, par value $.001 per
share, of the Company (the "Common Stock") at an exercise price of $6.46 per
share.  The number of shares of Common Stock to be received upon the exercise of
this Warrant and the price to be paid for each share of Common Stock may be
adjusted from time to time as hereinafter set forth.  The shares of Common Stock
deliverable upon such exercise, and as adjusted from time to time, are
hereinafter sometimes referred to as "Warrant Shares" and the exercise price of
a share of Common Stock in effect at any time and as adjusted from time to time
is hereinafter sometimes referred to as the "Exercise Price".

     1.   EXERCISE OF WARRANT.
          -------------------

          a.   Exercise for Cash.  This Warrant may be exercised in whole or in
part at any time or from time to time starting from a period of twelve months
and five days after issue until 5:00 p.m. Eastern Standard Time on December 23,
2006 (the "Exercise Period"). This Warrant may be exercised by presentation and
surrender hereof to the Company at its principal office, or at the office of its
stock transfer agent, if any, with the Purchase Form annexed hereto duly
executed and accompanied by payment of the Exercise Price for the number of
Warrant Shares specified in such form.  The Exercise Price may be paid by bank
check, wire transfer or cancellation of indebtedness.  As soon as practicable
after each such exercise of this Warrant, but not later than seven (7) days from
the date of such exercise, the Company shall issue and deliver to the Holder a
certificate for the Warrant Shares issuable upon such exercise, registered in
the name of the Holder.  If this Warrant should be exercised in part only, the
Company shall, upon surrender of this Warrant for cancellation, execute and
deliver a new Warrant evidencing the rights of the Holder thereof to purchase
the balance of the Warrant Shares purchasable thereunder.  Upon receipt by the
Company of this Warrant at its office, or by the stock transfer agent of the
Company at its office, in proper form for exercise, the Holder shall be deemed
to be the holder of record of the shares of Common Stock issuable upon such
exercise, notwithstanding that the stock transfer books of the Company shall
then be closed or that certificates representing such shares of Common Stock
shall not then be physically delivered to the Holder.
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          b.   Warrant Exchange.  At any time during the Exercise Period, the
Holder may, at its option, exchange this Warrant, in whole or in part (a
"Warrant Exchange"), into the number of Warrant Shares determined in accordance
with this Section 1(b), by surrendering this Warrant at the principal office of
the Company or at the office of its stock transfer agent, accompanied by a
notice stating the Holder's intent to effect such exchange, the number of
Warrant Shares to be exchanged and the date on which the Holder requests that
such Warrant Exchange occur (the "Notice of Exchange"). The Warrant Exchange
shall take place on the date specified in the Notice of Exchange or, if later,
the date the Notice of Exchange is received by the Company (the "Exchange
Date").  Certificates for the shares issuable upon such Warrant Exchange and, if
applicable, a new warrant of like tenor evidencing the balance of the shares
remaining subject to this Warrant, shall be issued as of the Exchange Date and
delivered to the Holder within seven (7) days following the Exchange Date.  In
connection with any Warrant Exchange, this Warrant shall represent the right to
subscribe for and acquire the number of Warrant Shares equal to (i) the number
of Warrant Shares specified by the Holder in its Notice of Exchange (the "Total
Number") less (ii) the number of Warrant Shares equal to the quotient obtained
by dividing (A) the product of the Total Number and the existing Exercise Price
by (B) the Fair Market Value, provided that any fractional shares determined by
this calculation shall be represented by the issuance of a new Warrant.  "Fair
Market Value" shall be determined as follows: (1) if the Common Stock is listed
on a national securities exchange or admitted to unlisted trading privileges on
such exchange or listed for trading on the Nasdaq Stock Market, the Fair Market
Value shall be the average of the last reported sale prices of the Common Stock
on such exchange or system for the twenty (20) business days ending on the last
business day prior to the date for which the determination is being made; or (2)
if the Common Stock is not so listed or admitted to unlisted trading privileges,
the Fair Market Value shall be the average of the last reported bid and asked
prices reported by the National Quotation Bureau, Inc. for the twenty (20)
business days ending on the last business day prior to the date for which the
determination is being made; or (3) if the Common Stock is not so listed or
admitted to unlisted trading privileges and bid and asked prices are not so
reported, the Fair Market Value shall be an amount, not less than book value
thereof as at the end of the most recent fiscal quarter of the Company ending
prior to the Exchange Date, determined in such reasonable manner as may be
prescribed by the Board of Directors of the Company.

     2.   RESERVATION OF SHARES.  The Company shall at all times reserve for
issuance and/or delivery upon exercise of this Warrant such number of shares of
its Common Stock as shall be required for issuance and delivery upon exercise of
this Warrant.

     3.   FRACTIONAL SHARES.  No fractional shares of Common Stock shall be
issued upon the exercise of this Warrant.  With respect to any fraction of a
share called for upon any exercise hereof, the Company shall pay to the Holder
an amount in cash equal to such fraction multiplied by the Fair Market Value of
a share of Common Stock.

     4.   ANTIDILUTION PROVISIONS.  In the event the Common Stock is changed by
reason of a stock split, reverse stock split, stock dividend or recapitalization
or is converted into or exchanged for other securities as a result of a merger,
consolidation or reorganization in which the Company is the surviving
corporation, appropriate adjustments shall be made in the terms of this Warrant,
or additional warrants shall be granted to the Holder as shall be equitable and
appropriate, or an adjustment in the number and class of shares allocated to,
and the Exercise Price of, this Warrant shall likewise be made.

     5.   CERTAIN EXTRAORDINARY TRANSACTIONS.  In the event the Common Stock is

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exchanged for securities, cash or other property of any other corporation or
entity as the result of a reorganization, merger or consolidation in which the
Company is not the surviving corporation, the dissolution or liquidation of the
Company, or the sale of all or substantially all the assets of the Company, the
Board of Directors of the Company or the board of directors of any successor
corporation or entity may, in its discretion, as to the unexercised portion of
this Warrant, (a) provide for payment of an amount equal to the excess of the
fair market value of the Warrant Shares, as determined by the Board of Directors
of the Company or such board, over the Exercise Price of such Warrant Shares as
of the date of the transaction, in exchange for the surrender of the right to
exercise this Warrant, or (b) provide for the assumption of this Warrant, or the
substitution therefor of new warrants, by the successor corporation or entity.

     6.   LOSS OF WARRANT.  Upon receipt by the Company of evidence satisfactory
to it of the loss, theft, destruction or mutilation of this Warrant, and (in the
case of loss, theft or destruction) of reasonably satisfactory indemnification,
and upon surrender and cancellation of this Warrant, if mutilated, the Company
will execute and deliver a new warrant of like tenor and date.

     7.   NO RIGHTS AS STOCKHOLDER.  The Holder shall not, as holder of this
Warrant, be entitled to vote, if applicable, or to receive dividends or to be
deemed the holder of Common Stock that may at any time be issuable upon exercise
of this Warrant for any purpose whatsoever, nor shall anything contained herein
be construed to confer upon the Holder, as such, any of the rights of a
stockholder of the Company or, if applicable, any right to vote for the election
of directors or upon any matter submitted to stockholders at any meeting
thereof, or to give or withhold consent to any corporate action (whether upon
any recapitalization, issue or reclassification of stock, change of par value or
change of stock to no par value, consolidation, merger or conveyance or
otherwise), or to receive notice of meetings, or to receive dividends or
subscription rights, until such holder shall have exercised the Warrant and been
issued the Warrant Shares in accordance with the provisions hereof.

     8.   NON-TRANSFERABILITY.  Neither this Warrant nor any Warrant Shares
shall be registered under the Securities Act of 1933, as amended, and applicable
state securities laws.  Therefore, the Company shall require, as a condition of
allowing the transfer or exchange of this Warrant or such Warrant Shares, that
the Holder of this Warrant or such Warrant Shares, as the case may be, furnish
to the Company an opinion of counsel reasonably acceptable to the Company to the
effect that such transfer or exchange will be exempt from the registration and
prospectus delivery requirements under the Securities Act of 1933, as amended,
and applicable state securities laws.  The certificates evidencing the Warrant
Shares shall bear a legend to the effect that the Warrant Shares evidenced by
such certificate have not been registered under the Securities Act of 1933, as
amended, and applicable state securities laws and are, therefore, subject to
restrictions on transfer.

     9.   INVESTMENT REPRESENTATIONS AND WARRANTIES.  The Holder hereby
represents and warrants to the Company that (a) it has knowledge and experience
in financial and business matters sufficient to enable it to evaluate the merits
and risks of an investment in the Company; (b) it has assets sufficient to
enable it to bear the economic risk of its investment in this Warrant and the
Warrant Shares and is an "accredited investor" as defined in Rule 501 under the
Securities Act of 1933, as amended; (c) it is acquiring this Warrant and, upon
exercise, will acquire the Warrant Shares, for its own account, and not with a
view to, or for sale in connection with, any distribution thereof; (d) it or its
representatives have received from the Company such information with respect to
the Company as it has deemed necessary and relevant in connection with this
Warrant and the Warrant Shares and it has had the

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opportunity, directly or through such representatives, to ask questions of and
receive answers from persons acting on behalf of the Company necessary to verify
the information so obtained; and (e) it and its officers, directors, employees
and agents have not employed any broker or finder or incurred any liability for
any brokerage or finder's fees or commissions or similar payments in connection
with this Warrant and the Warrant Shares.

     10.  GOVERNING LAW.   This Agreement and all amendments, modifications,
alterations, or supplements hereto shall be construed under and governed by the
laws of the State of New Jersey and the United States of America, without regard
to the principles of conflicts of law thereof.

     11.  MISCELLANEOUS.  Except as provided in Sections 4 and 5 hereof, this
Warrant and any term hereof may be changed, waived, discharged or terminated
only by an instrument in writing signed by the party against which enforcement
of such change, waiver, discharge or termination is sought.  The headings in
this Warrant are for purposes of reference only and shall not limit or otherwise
affect any of the terms hereof.  The invalidity or unenforceability of any
provision hereof shall in no way affect the validity or enforceability of any
other provision.

     12.  EXPIRATION.  The right to exercise this Warrant shall expire at 5:00
P.M. Eastern Standard Time on December 23, 2006.

     This Warrant is executed as of the date and year first written above.

Witness:                            ORAPHARMA, INC.

                                    By: /s/ Michael Kishbauch
---------------------------            ----------------------------
                                       Michael Kishbauch, President

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                             FORM OF SUBSCRIPTION
                  (To be signed only on exercise of Warrant)

TO: OraPharma, Inc.

     The undersigned, the holder of the within Warrant, hereby irrevocably
elects to exercise this Warrant for, and to purchase thereunder _______ shares
of Common Stock, $.001 par value per share, of OraPharma, Inc. and herewith
makes payment of $__________ therefor, and requests that the certificates for
such shares be issued in the name of, and delivered to the undersigned at
_____________________________.

Dated:                        _____________________________________________
                              (Signature must conform to name of holder as
                              specified on the face of the Warrant)

                              __________________________________
                                         (Address)

                              __________________________________<PAGE>

                                                                    Exhibit 4.32

THIS WARRANT AND THE SECURITIES TO BE ISSUED UPON EXERCISE HEREOF HAVE NOT BEEN
REGISTERED UNDER THE SECURITIES ACT OF 1933, AS AMENDED, OR THE SECURITIES LAWS
OF ANY STATE AND MAY NOT BE OFFERED, SOLD, TRANSFERRED, PLEDGED, HYPOTHECATED OR
OTHERWISE DISPOSED OF UNLESS REGISTERED PURSUANT TO SUCH ACT AND ANY APPLICABLE
STATE SECURITIES LAW OR UNLESS AN EXEMPTION FROM SUCH REGISTRATION IS AVAILABLE.

                                ORAPHARMA, INC.
                            STOCK WARRANT AGREEMENT
                            -----------------------

                    GRANTEE:            Mucosal Therapeutics LLC

                    DATE OF GRANT:      December 28, 1999

                    NUMBER OF SHARES:   82,305

                    EXERCISE PRICE:     $2.43 per share

                    EXPIRATION DATE:    December 27, 2004

     Pursuant to the License Agreement dated as of December 14, 1998 (the
"License Agreement") by and between Mucosal Therapeutics LLC ("Mucosal") and
OraPharma, Inc. (the "Company"), the Company has agreed to grant to Mucosal, as
of the Date of Grant set forth above, a warrant (the "Warrant") to purchase up
to the aggregate number of shares of Common Stock, par value $.001 per share
(the "Common Stock"), of the Company set forth herein at the price per share set
forth herein, all upon the terms and conditions hereof.  This Stock Warrant
Agreement is hereinafter referred to as either the "Agreement" or this
"Warrant".

                             TERMS AND CONDITIONS
                             --------------------

     1.  Grant and Exercise of Warrant.  (a)  The Company hereby grants to
Mucosal, and Mucosal is entitled, upon the terms and subject to the conditions
hereinafter set forth, to purchase, from the Company, 82,305 shares of the
Company's Common Stock (the "Warrant Shares") at a purchase price of $2.43 per
share (the "Exercise Price").  This Warrant shall be fully vested as of the date
hereof.  This Warrant may not be exercised after the Expiration Date set forth
above.

         (b)  This Warrant may not be exercised at a time when the exercise
thereof or the issuance or transfer of shares upon such exercise would, in the
opinion of the Board of
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Directors of the Company, constitute a violation of any law, federal, state,
local or foreign, or any regulations thereunder, or the requirements of the New
York Stock Exchange or any other national securities exchange or market.

     2.  Procedure for Exercise.  (a) This Warrant may be exercised, in whole or
part, by Mucosal by delivering a written notice (the "Notice") to the Secretary
of the Company.  This Warrant may not be exercised for any fractional share.
The Notice shall (i) state that Mucosal elects to exercise the Warrant; (ii)
state the number of Warrant Shares with respect to which the Warrant is being
exercised; and (iii) include the reaffirmation of the representations and
warranties of Mucosal set forth in Section 3 below.  This Warrant may not be
exercised unless and until Mucosal shall have entered into a Restricted Stock
Agreement with the Company in substantially the form of Exhibit A hereto with
respect to the Warrant Shares as to which this Warrant is being exercised.

         (b)  Payment of the aggregate Exercise Price for such Warrant Shares
shall be made in cash or by certified check payable to the Company in an amount
equal to the aggregate Exercise Price of the Warrant Shares with respect to
which this Warrant is being exercised.

         (c)  The Company shall issue a stock certificate in the name of Mucosal
for such Warrant Shares as soon as practicable after receipt of the Notice and
payment of the aggregate Exercise Price for such Warrant Shares.  Mucosal shall
not have any privileges as a stockholder of the Company with respect to any
Warrant Shares until such Warrant Shares shall be registered on the books of the
Company in the name of Mucosal.

     3.  Representations and Warranties.  Mucosal acknowledges, represents and
warrants to the Company as follows:

         (a)  In connection with its exercise of the Warrant, it will consult
with such independent legal counsel or other advisors considered appropriate to
it to assist it in evaluating its proposed investment in the Company.  Without
limiting the foregoing, Mucosal acknowledges that there may be certain adverse
tax consequences to it in connection with its exercise of the Warrant and the
Company has advised Mucosal to seek the advice of experts in such areas prior to
exercising the Warrant.

         (b)  Mucosal shall own the Warrant, and shall purchase the Warrant
Shares, for its own account for investment, and not with a view to or for resale
in connection with the distribution thereof, nor with any present intention of
selling or otherwise disposing of all or any part of the Warrant or Warrant
Shares.  Mucosal agrees that it must bear the economic risk of its investment
for an indefinite period of time because, among other reasons, any Warrant
Shares purchased by it upon exercise of the Warrant may not be registered under
the Securities Act of 1933, as amended (the "Act") or under the securities laws
of certain states and, therefore, cannot be Transferred unless they are
subsequently registered under the Act

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and under applicable securities laws of such states or an exemption from such
registration is available. Mucosal understands that the Company is under no
obligation to register this Warrant and/or the Warrant Shares on Mucosal's
behalf or to assist it in complying with any exemption from such registration
under the Act or any state securities laws. Furthermore, Mucosal hereby
acknowledges and agrees that it will not Transfer, either publicly or privately,
the Warrant or the Warrant Shares without registration thereof under the Act or
an exemption therefrom. For purposes of this Agreement, the term "Transfer"
means to directly or indirectly sell, assign, transfer, pledge (other than a
pledge to the Company), hypothecate or to otherwise encumber or dispose of any
record or beneficial ownership of the Warrant or Warrant Shares (or contract to
do any of the foregoing).

         (c)  Mucosal understands that the Warrant and the Warrant Shares are
speculative investments which involve a high degree of risk of loss of its
entire investment in the Company.  Mucosal can afford (i) to hold unregistered
securities for an indefinite period of time; and (ii) to sustain a complete loss
of the entire amount of its investment in the Company and, at the same time,
bear any tax liability which may result if its investment in the Company is
lost.  Mucosal has determined that the Warrant (and, upon exercise of the
Warrant, will determine with respect to the Warrant Shares) is a suitable
investment and it has the financial ability to bear the economic risk of its
investment in the Company (including its possible total loss), has adequate
means for providing for its current needs and personal contingencies and has no
need for liquidity with respect to its investment in the Company.

         (d)  Mucosal is an "accredited investor", as defined in Rule 501 under
the Act.

         (e)  Mucosal has such knowledge and experience in financial and
business matters as to be capable of evaluating the merits and risks of an
investment in the Warrant and the Warrant Shares and making an informed and
reasoned investment decision, and has obtained, in its judgment, sufficient
information from the Company to evaluate the merits and risks of an investment
in the Company.

         (f)  Mucosal has been given the opportunity to ask questions of, and
receive answers from, the Company concerning the Company and other matters
pertaining to this investment, and to obtain any additional information
necessary to verify the accuracy of any information provided, and has not been
furnished any offering literature or prospectus and has not received any general
solicitation or general advertising regarding the purchase of any Common Stock.
Mucosal has been furnished with all additional documents and information
requested by it.

         (g)  Mucosal is aware that there is no assurance as to the future
performance of the Company.  No representations or warranties of any kind have
been made to Mucosal by the Company or any officer, employee, agent or affiliate
of the Company.

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         (h)  Mucosal understands that the Warrant is, and the Warrant Shares
will be, issued pursuant to a specific exemption under the provisions of the Act
and exemptions under various state securities laws, which exemptions may depend,
among other things, upon Mucosal's investment intent.  Mucosal understands that
the availability of such exemptions is in part dependent upon the truthfulness
and accuracy of the representations made by it herein and that the Company will
rely on such representations in issuing the Warrant and the Warrant Shares to
Mucosal.

Mucosal acknowledges and agrees that each time it exercises the Warrant and
purchases Warrant Shares, and as a condition to such purchase, it shall re-state
and reaffirm all of the representations and warranties set forth above, unless
the Warrant Shares shall then be subject to an effective registration statement
under the Act and applicable state securities laws. Notwithstanding the
foregoing, even if Mucosal does not so re-state and reaffirm as required, upon
each exercise of the Warrant it will automatically be deemed to have so re-
stated and reaffirmed.

     4.  Stock Dividends, Splits, Etc.  In the event the Common Stock is
changed by reason of a stock split, reverse stock split, stock dividend or
recapitalization (exclusive of any public or private sales of Capital Stock of
the Company), or is converted into or exchanged for other securities as a result
of a merger, consolidation or reorganization in which the Company is the
surviving corporation, appropriate adjustments shall be made in the terms of
this Warrant, or additional warrants shall be granted to Mucosal as shall be
equitable and appropriate, or an adjustment in the number and class of shares
allocated to, and the Exercise Price of, the Warrant shall be made.

     5.  Certain Extraordinary Transactions.  In the event the Common Stock is
exchanged for securities, cash or other property of any other corporation or
entity as the result of a reorganization, merger or consolidation in which the
Company is not the surviving corporation, the dissolution or liquidation of the
Company, or the sale of all or substantially all the assets of the Company, the
Board of Directors of the Company or the board of directors of any successor
corporation or entity shall, as to the unexercised portion of this Warrant, (a)
provide for payment of an amount equal to the excess of the fair market value of
the Warrant Shares, as determined by the Board of Directors of the Company or
such board, over the Exercise Price of such Warrant Shares as of the date of the
transaction, in exchange for the surrender of the right to exercise the Warrant,
or (b) provide for the assumption of the Warrant, or the substitution therefor
of new warrants, by the successor corporation or entity.

     6.  Restriction on Transfer of Warrant.  The Warrant may not be
Transferred in any way by Mucosal.  The Warrant shall not be subject to
execution, attachment or similar process.  Any attempted Transfer of the Warrant
contrary to the provisions hereof, and the levy of any execution, attachment or
similar process upon the Warrant, shall result in the immediate termination of
the Warrant.  If requested in writing by the managing underwriters, if any, of
any public offering, Mucosal shall not offer, sell, contract to sell or
otherwise

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dispose of any of the Warrant Shares except as part of such public offering
within 30 days before or 180 days after the effective date of the registration
statement filed with respect to said offering.

     7.  Right of First Offer.  (a) If, prior to the date of the initial public
offering of shares of the Common Stock, Mucosal desires to Transfer to any
third-party all or any part of the Warrant Shares pursuant to the terms of a
bona fide offer received from a third party, Mucosal shall first submit a
written offer (the "Offer") to sell such Warrant Shares (the "Offered Shares")
to the Company on terms and conditions, including price, not less favorable to
the Company then those on which Mucosal proposes to sell such Warrant Shares to
such third party.  The Offer shall disclose the identity of the proposed
purchaser, specify the number of Offered Shares proposed to be sold, the total
number of Offered Shares owned by Mucosal, and the agreed terms and conditions
of the sale and any other material facts relating to the sale.

         (b)  The Company shall have the right to purchase all or any portion of
the Offered Shares on the same terms and conditions specified in the Offer.

         (c)  If the Company desires to purchase all or any portion of the
Offered Shares, the Company shall communicate in writing its election to
purchase (an "Acceptance") to Mucosal, which Acceptance shall be delivered to
Mucosal within 30 days of the Company's receipt of  the Offer.

         (d)  If the Company elects to purchase all or any of the Offered
Shares, sale of the Offered Shares to be so purchased pursuant to this Section
shall be made at the offices of the Company on the 30th day following the
expiration of the 30-day period applicable pursuant to paragraph (c) of this
Section (or if such 30th day is not a business day, then on the next succeeding
business day).  Such sales shall be effected by Mucosal's delivery to the
Company of a certificate or certificates evidencing the Offered Shares to be
purchased by it, duly endorsed for Transfer to the Company, which Offered Shares
shall be delivered free and clear of all liens, charges, claims and encumbrances
of any nature whatsoever, against payment to Mucosal of the purchase price
therefor by the Company.  Payment for the Offered Shares shall be made as
provided in the Offer or by wire transfer or certified check.

         (e)  If the Company does not elect to purchase all of the Offered
Shares, then the Offered Shares not so purchased may be sold by Mucosal at any
time within 150 days after the Company's receipt of  the Offer.  Any such sale
shall be upon terms and conditions, including price, not less favorable to
Mucosal than those specified in the Offer, and the purchaser or transferee (and
all subsequent purchasers or transferees) shall be subject to all the terms of
this Agreement.  Any Offered Shares not sold within such 150-day period shall
continue to be subject to the requirements of a first offer by the Company
pursuant to this Section.

                                      -5-
<PAGE>

     8.  Restrictive Legends.  Stock certificates representing the Warrant
Shares shall bear such legend or legends as the Board of Directors of the
Company shall deem appropriate.

     9.  Miscellaneous.

         (a)  Jurisdiction.  Each party hereby submits itself for the sole
purpose of this Agreement and any controversy arising hereunder to the exclusive
jurisdiction of the courts located in the State of New York, and any courts of
appeal therefrom, and waives any objection (on the grounds of lack of
jurisdiction, or forum non conveniens or otherwise) to the exercise of such
jurisdiction over it by any such courts.

         (b)  Governing Law.  This Agreement and all amendments, modifications,
alterations, or supplements hereto, and the rights of the parties hereunder,
shall be construed under and governed by the laws of the State of New York and
the United States of America, without regard to the principles of conflicts of
law thereof.

         (c)  Notices.  All notices, consents and other communications required
or which may be given under this Agreement shall be deemed to have been duly
given (i) when delivered by hand, (ii) three (3) days after being mailed by
registered or certified mail, return receipt requested, or (iii) when received
by the addressee, if sent by facsimile transmission (with acknowledgment of
complete transmission) or by Express Mail, Federal Express or other express
delivery service (receipt requested), in each case addressed to the Company at
its principal place of business and to Mucosal its address as listed on the
books and records of the Company (or in either case to such other address as
such party may hereafter designate as to itself by notice to the other party
hereto).

         (d)  Successors and Assigns.  This Agreement shall be binding upon and
inure to the benefit of the parties hereto and their respective legal
representatives, successors and permitted assigns.

         (e)  Entire Agreement.  This Agreement constitutes the entire agreement
between the Company and Mucosal with respect to the subject matter hereof and
shall not be modified, amended or terminated except as herein provided or except
by another agreement in writing executed by the parties hereto.

         (f)  Headings.  The Section headings are for convenience only and are
not a part of this Agreement.

         (g)  Severability.  All rights and restrictions contained herein may be
exercised and shall be applicable and binding only to the extent that they do
not violate any applicable laws and are intended to be limited to the extent
necessary so that they will not render this Agreement illegal, invalid or
unenforceable.  If any provision or portion of any provision of this Agreement
not essential to the commercial purpose of this Agreement shall be

                                      -6-
<PAGE>

held to be illegal, invalid or unenforceable by a court of competent
jurisdiction, it is the intention of the parties that the remaining provisions
or portions thereof shall constitute their agreement with respect to the subject
matter hereof, and all such remaining provisions or portions thereof shall
remain in full force and effect. To the extent legally permissible, any illegal,
invalid or unenforceable provision of this Agreement shall be replaced by a
valid provision agreeable to the parties hereto which will implement the
commercial purpose of the illegal, invalid or unenforceable provision. In the
event that any provision essential to the commercial purpose of this Agreement
is held to be illegal, invalid or unenforceable and is not replaced by a valid
provision which will implement the commercial purpose of this Agreement and
which is agreed to the parties hereto in writing within 30 days following such
holding, this Agreement and the rights granted herein shall terminate.

         (h)  Waiver; Remedies.  The failure of any party hereto to require
performance hereunder, or the written waiver by any party hereto of any breach
of this Agreement, shall not prevent the subsequent enforcement thereof nor be
deemed a waiver of any subsequent breach.

         (i)  Counterparts.  This agreement may be executed in counterparts,
each of which shall be deemed an original and both of which together shall
constitute one instrument.

         (j)  Expenses; Further Assurances.  Unless otherwise provided herein,
all costs and expenses incurred in connection with this Agreement and the
transactions contemplated hereby shall be paid by the party which shall have
incurred the same, and the other party shall have no liability relating thereto.
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.

                                      -7-
<PAGE>

     IN WITNESS WHEREOF, the parties have executed this Stock Warrant Agreement
as of the 28th day of December, 1999.

                         MUCOSAL THERAPEUTICS LLC

                         By:___________________________________
                            Name:
                            Title:

                         ORAPHARMA, INC.

                         By:__________________________________
                            Name:
                            Title:

                                      -8-

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