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                                                             Exhibit 10.15

                               AMENDMENT AGREEMENT

         AMENDMENT AGREEMENT, dated as of January 17, 1997, by and between
ENAMELON, INC., a Delaware corporation, having its principal place of business
at 15 Kimball Avenue, Yonkers, New York 10704 (the "Company"), and ANTHONY E.
WINSTON, residing at 42 Tall Oak Drive, East Brunswick, New Jersey 08816 (the
"Employee").

                                    RECITALS

         The Company and the Employee are parties to an Employment Agreement,
dated January 17,1995 (the "Employment Agreement"), and have agreed to amend the
Employment Agreement to extend the term of the Employment Agreement, to increase
the Employee's compensation thereunder, and to make certain other changes as
herein provided. Capitalized terms used herein shall have the meanings set forth
in the Employment Agreement unless otherwise defined herein.

         NOW, THEREFORE, in consideration of the mutual covenants and agreements
herein set forth, and for other good and valuable consideration, the receipt and
sufficiency of which are hereby acknowledged, the parties hereto hereby agree as
follows:

         1 . Section 1 of the Employment Agreement is hereby deleted in its
entirety and the following new Section 1is hereby inserted in lieu thereof:

                  1. Employment.

                  The Company agrees to employ the Employee and the Employee
         accepts employment upon the terms and conditions set forth herein for a
         term commencing on the date hereof and ending on January 17, 2000,
         unless earlier terminated in accordance with the terms of this
         Agreement.

         2.       Section  3(a) of the  Employment  Agreement is hereby
deleted in its entirety and the  following new Section 3(a) is hereby inserted
in lieu thereof.

                  (a)      The Company  shall pay the  Employee an annual base
         salary  ("Base  Salary") as follows:

                  (i)      commencing  January 18, 1997, and ending January 17,
         1998, a Base Salary at the rate of $143,000 per year;

                  (ii)     commencing  January 18, 1998, and ending January 17,
         1999, a Base Salary at the rate of $151,000 per year; and

                  (iii)    commencing January 18, 1999, and ending January 17,
         2000, a Base Salary at the rate of $160,000 per year.


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                                                             Exhibit 10.15

         The Employee's Base Salary shall be paid at such times and in such
         manner as is consistent with the Company's prevailing payroll practices
         for other senior executives of the Company.

         3. Sections 3(c) and 3(d) of the Employment Agreement are hereby
deleted in their entirety and the following new Sections 3(c) and 3(d) are
inserted in lieu thereof:

                  (c) The Employee shall participate in an executive
         compensation plan to be established by the Board of Directors of the
         Company. The Employee shall be entitled to 10% of any amounts allocated
         by the Board of Directors each year during the term hereof to such plan
         for the purpose of providing an incentive to key employees. In no
         event, however, shall the Employee receive more than two times his base
         salary. In addition, in the event the term hereof is not commensurate
         with the fiscal year of the Company or the Employee is not employed
         hereunder for a full fiscal year, any such amounts due to the Employee
         hereunder pursuant to the terms of any executive compensation plan
         shall be pro-rated for any such fiscal year during which the Employee
         was not employed for the full twelve-month period thereof.

                  (d) The Employee acknowledges that he has been granted as of
         the commencement of this Agreement 150,000 ten-year incentive stock
         options (after giving effect to a 3 for 1 stock split) in accordance
         with the terms of the Company's Stock Option Plan (the "Plan"). The
         Employee shall hereafter have the right to receive additional stock
         options under the Plan or any other stock option plan adopted by the
         Company at such times and on such terms as are consistent with options
         granted to other senior executives of the Company.

         4.       Section  4(a) of the  Employment  Agreement is hereby
deleted in its entirety and the  following new Section 4(a) is inserted in
lieu thereof:

                  (a) During the term of this Agreement, the Employee shall have
         the right to participate in the Company's group health insurance plan
         and such other employee benefit plans as are offered to other senior
         executives of the Company.

         5.       Section  4(c) of the  Employment  Agreement is hereby
deleted in its entirety and the  following new Section 4(c) is inserted in
lieu thereof.

                  (c) The Employee shall be entitled to five (5) weeks of paid
         vacation and twelve(12)personal days per calendar year ("Vacation
         Allotments"). The Vacation Allotments are non-cumulative and if the
         Employee fails to use any or all of his Vacation Allotments during a
         particular calendar year, such Vacation Allotments shall be deemed
         forfeited forever.

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                                                           Exhibit 10.15

         6. The introductory paragraph of Section 6 and Section 6(a) of the
Employment Agreement are hereby deleted in their entirety and the following new
introductory paragraph and Section 6(a) are hereby inserted in lieu thereof:

                  6.       Covenants and Restrictions.

                  The Employee covenants that, except in carrying out his duties
         hereunder, during the term of his employment and for the period
         consisting of the Remainder Term (as defined in section 9(b) hereof),
         if any, and two (2) years following the date on which this term of this
         Agreement is scheduled to expire under Section 1 hereof (such two-year
         period being referred to herein as the "Restricted Period"),
         irrespective of the reasons for termination of the Employee's
         employment and unless such longer period of time is specifically set
         forth herein:

                  (a) The Employee will not directly or indirectly own any
         interest in, participate or engage in, assist, render any services
         (including advisory services) to, become associated with, work for,
         serve (in any capacity whatsoever, including, without limitation, as an
         employee, consultant, advisor, agent, independent contractor, officer
         or director) or otherwise become in any way or manner connected with
         the ownership, management, operation, or control of, any business,
         firm, corporation, partnership or other entity (collectively referred
         to herein as a "Person") that (i) during the Remainder Term, if any,
         engages in, or assists others in engaging in or conducting any
         business, which deals, directly or indirectly, in products or services
         competitive with the Company's product line or services, as described
         below, anywhere in the world and (ii) during the Restricted Period
         engages in, or assists others in engaging in or conducting any
         business, which deals, directly or indirectly, in products or services
         competitive with the Company's product line or services anywhere in the
         world whereby the Employee will make use of the Enamelon Technology, as
         defined hereinafter; provided, however, that the above restriction
         shall not be deemed to exclude the Employee from acting as a director
         of a corporation for the benefit of the Company with the consent of the
         Company's Board of Directors; and provided, further, that during the
         Restricted Period, the Employee may engage in the above business
         activity involving the research and development, manufacture, marketing
         or sale of any dentifrice, chewing gum, food, confection, spray,
         professional gel, or mouth rinse that uses currently accepted
         technology which, for example, makes use of fluoride, in the prevention
         of cavities, and may directly result in the remineralization of teeth
         so long as the Employee, in such a capacity, does not make use of the
         Enamelon Technology, as defined hereinafter. For purposes hereof,
         "products or services competitive with the Company's product line or
         services" shall mean any products or services which have as their
         primary purpose or function or which are marketed, promoted or sold as
         having the effect of repairing, remineralizing, rebuilding,
         desensitizing teeth or preventing or retarding tooth decay and/or

         cavities. For purposes hereof, the

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                                                              Exhibit 10.15

         "Enamelon Technology" shall mean any scientific know-how or methods
         developed by the Company or any of its employees with the aim to
         further develop the Products. Enamelon Technology includes but is not
         limited to its development of Amorphous Calcium Phosphate technology
         ("ACPT").

         7.       Section  9(b) of the  Employment  Agreement is hereby
deleted in its entirety and the  Following new Sections 9(b), 9(c) and 9(d)
are inserted in lieu thereof:

                  (b) Not withstanding any provisions in this Agreement to the
         contrary, the Company may terminate the employment of the Employee
         hereunder without Cause at anytime. If the Company terminates the
         employment of the Employee hereunder without Cause or if either the
         Employee or the Company terminate the employment of the Employee for
         any reason at any time within six months after a Change of Control (as
         hereinafter defined), then the Company shall be obligated to pay the
         Employee's Base Salary for a period equal to the longer of (i) the
         remainder of the term of this Agreement or (ii) six months after the
         date of the Employee's termination (such period being referred to
         herein as the "Remainder Term"), and the Company shall also continue
         for the Remainder Term to permit the Employee to receive or participate
         in all fringe benefits available to him pursuant to Section 4 above;
         provided, however, that during the Remainder Term any amounts payable
         to the Employee pursuant to this Section 9(b) and any fringe benefits
         that he receives or in which he participates pursuant to this Section
         9(b) shall be reduced by any payments or fringe benefits the Employee
         shall receive during the Remainder Term from any other source of
         employment that is unaffiliated with the Company. All amounts payable
         during the Remainder Term shall be paid at such times and in such
         manner as shall be consistent with the Company's prevailing payroll
         practices.

                  (c) For purposes of this Agreement, a "change of control"
         shall be deemed to occur when any Person or group of Persons directly
         or indirectly (through a subsidiary or otherwise), (A) acquires or is
         granted the right to acquire, directly or through a merger or similar
         transaction, a majority of Company's outstanding voting securities, or
         (B) acquires all or substantially all of the Company's assets.

                  (d) The Company shall pay the Employee, as severance pay upon
         expiration of this Agreement as provided in Section 1, his Base Salary
         for a period of six (6) months after the date of expiration, unless (i)
         the term of this Agreement shall have been extended or the Employee
         shall otherwise be employed by the Company after the expiration of the
         term of this Agreement or (ii) this Agreement shall have been

         terminated prior to such expiration date. All such severance payments
         shall be paid at such time and in such manner as shall be consistent
         with the Company's prevailing payroll practices.

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                                                          Exhibit 10.15

         8. The terms "this Agreement," "hereof," "hereunder" and words of like
meaning appearing in the Employment Agreement shall mean and refer to the
Employment Agreement as amended hereby.

         9. Except as otherwise amended by this Amendment Agreement, the
Employment Agreement shall remain in full force and effect, and the Company and
the Employee each hereby reaffirm each of their respective agreements, covenants
and obligations set forth therein.

         IN WITNESS WHEREOF, the parties hereto have executed this Amendment
Agreement as of the date above written.

                                 ENAMELON, INC.

                                        By:   /s/ Steven R. Fox
                                              -----------------------
                                              Steven R. Fox, Chairman

                                              /s/ Anthony E. Winston
                                              -----------------------
                                              Anthony E. Winston

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