<PAGE>

                                                                Exhibit 3.3


                              AMENDED AND RESTATED

                                    BY-LAWS

                                 ENAMELON, INC.
                            (A Delaware Corporation)



                                   ARTICLE I

                                    Offices

         SECTION 1. Registered Office. The registered office of the Corporation
within the State of Delaware shall be in the City of Dover, County of Kent.

         SECTION 2. Other Offices. The Corporation may also have an office or
offices other than said registered office at such place or places, either
within or without the State of Delaware, as the Board of Directors shall from
time to time determine or the business of the Corporation may require.


                                   ARTICLE II

                            Meetings of Stockholders

         SECTION 1. Place of Meetings. All meetings of the stockholders for the
election of directors or for any other purpose shall be held at any such place,
either within or without the State of Delaware, as shall be designated from
time to time by the Board of Directors and stated in the notice of meeting or
in a duly executed waiver thereof.

         SECTION 2. Annual Meeting. The Annual Meeting of the Stockholders
shall be held at such place, either within or without the State of Delaware,
and at such date and time as shall be designated by the Board of Directors from
time to time subsequent to the year of incorporation and stated in the notice
of meeting or in a duly executed waiver thereof. At such Annual Meeting, the
Stockholders shall elect, by a plurality vote, that number of Directors equal
to the number of Directors of the Class whose term expires at such meeting (or,
if fewer, the number of Directors properly nominated and qualified for
election) to hold office until the second succeeding Annual Meeting of
Stockholders after their election, and may transact such other business as may
properly be brought before the meeting.

         SECTION 3. Special Meetings. Special meetings of the stockholders,
unless otherwise prescribed by statute, may be called at any time by the Board
of Directors or the Chairman of the Board, if one shall have been elected, or
the President.


                                      16
<PAGE>


                              AMENDED AND RESTATED
                                    BY-LAWS
                                 ENAMELON, INC.
                                  (continued)

         SECTION 4. Notice of Meetings. Except as otherwise expressly required
by statute, written notice of each annual and special meeting of the
stockholders stating the date, place and hour of the meeting, and, in the case
of a special meeting, the purpose or purposes for which the meeting is called,
shall be given to each stockholder of record entitled to vote thereat not less
than ten (10) or more than sixty (60) days before the date of the meeting.
Business transacted at any special meeting of stockholders shall be limited to
the purposes stated in the notice. Notice shall be given personally or by mail
and, if by mail, shall be sent in a postage prepaid envelope, addressed to the
stockholder at his address as it appears on the records of the Corporation.
Notice by mail shall be deemed given at the time when the same shall be
deposited in the United States mail, postage prepaid. Notice of any meeting
shall not be required to be given to any person who attends such meeting,
except when such person attends the meeting in person or by proxy for the
express purpose of objecting, at the beginning of the meeting, to the
transaction of any business because the meeting is not lawfully called or
convened, or who, either before or after the meeting, shall submit a signed
written waiver of notice, in person or by proxy. Neither the business to be
transacted at, nor the purpose of, an annual or special meeting of stockholders
need be specified in any written waiver of notice.

         SECTION 5. List of Stockholders. The officer who has charge of the
stock ledger of the Corporation shall prepare and make, at least ten days
before each meeting of stockholders, a complete list of the stockholders
entitled to vote at the meeting, arranged in alphabetical order, showing the
address of and the number of shares registered in the name of each stockholder.
Such list shall be open to the examination of any stockholder, for any purpose
germane to the meeting, during ordinary business hours, for a period of at
least ten (10) days prior to the meeting, either at a place within the city,
town or village where the meeting is to be held, which place shall be specified
in the notice of meeting, or, if not specified, at the place where the meeting
is to be held. The list shall be produced and kept at the time and place of the
meeting during the whole time thereof, and may be inspected by any stockholder
who is present.

         SECTION 6. Quorum, Adjournments. The holders of a majority of the
voting power of the issued and outstanding stock of the Corporation entitled to
vote thereat, present in person or represented by proxy, shall constitute a
quorum for the transaction of business at all meetings of stockholders, except
as otherwise provided by statute or by the Certificate of Incorporation. If,
however, such quorum shall not be present or represented by proxy at any
meeting of stockholders, the stockholders entitled to vote thereat, present in
person or represented by proxy, shall have the power to adjourn the meeting
from time to time, without notice other than announcement at the meeting, until
a quorum shall be present or represented by proxy. At such adjourned meeting at
which a quorum shall be present or represented by proxy, any business may be
transacted which might have been transacted at the meeting as originally
called. If the adjournment is for more than thirty days, or, if after
adjournment a new record date is set, a notice of the adjourned meeting shall
be given to each stockholder of record entitled to vote at the meeting.

         SECTION 7. Organization. At each meeting of the stockholders, the
Chairman of the Board, if one shall have been elected, or in his absence or if
one shall not have been elected, the President shall act as chairman of the
meeting. The Secretary, or in his absence or inability to act, the person whom
the chairman of the meeting shall appoint secretary of the meeting, shall act
as secretary of the meeting and keep the minutes thereof.

         SECTION 8. Order of Business. The order of business at all meetings of
the stockholders shall be as determined by the chairman of the meeting.

         SECTION 9. Voting. Except as otherwise provided by statute or the
Certificate of Incorporation, each stockholder of the Corporation shall be
entitled at each meeting of the stockholders to one vote for each share of
capital stock of the Corporation standing in his name on the record of
stockholders of the Corporation:

         (a) on the date fixed pursuant to the provisions of Section 6 of
Article V of these By-Laws as the record date for the determination of the
stockholders who shall be entitled to notice of and to vote at such meeting; or

         (b) if no such record date shall have been so fixed, then at the close
of business on the date next


                                      17
<PAGE>


                              AMENDED AND RESTATED
                                    BY-LAWS
                                 ENAMELON, INC.
                                  (continued)

preceding the day on which notice thereof shall be given, or, if notice is
waived, at the close of business on the date next preceding the day on which
the meeting is held.

         Each stockholder entitled to vote at any meeting of the stockholders
may authorize another person or persons to act for him by a proxy signed by
such stockholder or his attorney-in fact but no proxy shall be voted after
three years from its date, unless the proxy provides for a longer period. Any
such proxy shall be delivered to the secretary of the meeting at or prior to
the time designated in the order of business for so delivering such proxies.
When a quorum is present at any meeting, the vote of the holders of a majority
of the voting power of the issued and outstanding stock of the Corporation
entitled to vote thereon, present in person or represented by proxy, shall
decide any question brought before such meeting, unless the question is one
upon which by express provision of statute or of the Certificate of
Incorporation or of these By-Laws, a different vote is required, in which case
such express provision shall govern and control the decision of such question.
Unless required by statute, or determined by the chairman of the meeting to be
advisable, the vote on any question need not be by ballot. On a vote by ballot,
each ballot shall be signed by the stockholder voting, or by his proxy, if
there be such proxy, and shall state the number of shares voted.

         SECTION 10. Inspectors. The Board of Directors may, in advance of any
meeting of stockholders, appoint one or more inspectors to act at such meeting
or any adjournment thereof. If any of the inspectors so appointed shall fail to
appear, the chairman of the meeting shall, or if inspectors shall not have been
appointed, the chairman of the meeting may, appoint one or more inspectors to
act at the meeting. Each inspector, before entering upon the discharge of his
duties shall take and sign an oath faithfully to execute the duties of
inspector at such meeting with strict impartiality and according to the best of
his ability. The inspectors shall determine the number of shares of capital
stock of the Corporation outstanding and the voting power of each, the number
of shares represented at the meeting, the existence of a quorum, the validity
and effect of proxies, and shall receive and count and tabulate all votes,
ballots or consents, hear and determine all challenges and questions arising in
connection with the right to vote, determine the results, and do such acts as
are proper to conduct the election or vote with fairness to all stockholders.
The inspectors shall determine and retain for a reasonable period of time a
record of the disposition of any challenges made to any determination by the
inspectors. The inspectors shall certify their determination as to the number
of shares represented at the meeting, and their count of all votes and ballots.
Inspectors need not be stockholders.

         SECTION 11. Action by Consent. Whenever the vote of stockholders at a
meeting thereof is required or permitted to be taken for or in connection with
any corporate action, by any provision of any applicable statute or pursuant to
or in accordance with the Corporation's Certificate of Incorporation or of
these By-Laws, the meeting and vote of stockholders may be dispensed with, and
the action taken without such a meeting, without prior notice and without a
vote, if a consent or consents in writing, setting forth the action so taken,
shall be signed by the holders of outstanding stock having not less than the
minimum number of votes that would be necessary to authorize or take such
action at a meeting at which all shares of stock of the Corporation entitled to
vote thereon were present and voted.

ARTICLE III

                               Board of Directors

         SECTION 1. General Powers. The business and affairs of the Corporation
shall be managed by or under the direction of the Board of Directors. The Board
of Directors may exercise all such authority and powers of the Corporation and
do all such lawful acts and things as are not by statute or the Certificate of
Incorporation directed or required to be exercised or done by the stockholders.

         SECTION 2. Number, Qualifications, Election and Term of Office. The
number of Directors may be fixed, from time to time, by the affirmative vote of
a majority of the entire Board of Directors. Any decrease in the number of
Directors in any Class shall be effective at the time of the next succeeding
Annual Meeting of Stockholders at which that Class shall next stand for
election. Directors need not be stockholders. The Directors shall be classified


                                      18
<PAGE>

                              AMENDED AND RESTATED
                                    BY-LAWS
                                 ENAMELON, INC.
                                  (continued)

with respect to the time for which they shall severally hold office into two
classes as nearly equal in number as possible. Except as hereinafter otherwise
provided for the filling of vacancies, the Class I Directors shall hold office
for an initial term expiring at the 2000 Annual Meeting of Stockholders, and
the Class II Directors shall hold office for an initial term expiring at the
1999 Annual Meeting of Stockholders, with the members of each Class of
Directors to hold office until their respective successors have been duly
elected and qualified or until their earlier death, resignation or removal.
Thereafter, at each Annual Meeting of Stockholders, the successors to the Class
of Directors whose term expires at that meeting shall be elected to hold office
for a term expiring at the Annual Meeting of Stockholders held in the second
year following the year of their election and until their respective successors
have been duly elected and qualified or until their earlier death, resignation
or removal. Increases and decreases in the number of Directors shall be
apportioned between the Classes to make each Class as nearly equal as possible.

         SECTION 2A. Nominations for the Board. Nominations for the election of
directors may be made by the Board of Directors or by a stockholder entitled to
vote in the election of directors. A stockholder entitled to vote in the
election of directors, however, may make such a nomination only if written
notice of such stockholder's intent to do so has been given, either by personal
delivery or by United States mail, postage prepaid, and received by the
Corporation with respect to an election to be held at an annual meeting of
stockholders, not later than 120 nor more than 180 days prior to the first
anniversary of the preceding year's annual meeting (or, if the date of the
annual meeting is changed by more than twenty (20) days from such anniversary
date, within ten (10) days after the date the Corporation mails or otherwise
gives notice of the date of such meeting).

         Each stockholder's notice of intent to make a nomination shall set
forth: (i) the name(s) and address(es) of the stockholder who intends to make
the nomination and of the person or persons to be nominated; (ii) a
representation that the stockholder (a) is a holder of record of stock of the
Corporation entitled to vote at such meeting, (b) will continue to hold such
stock through the date on which the meeting is held, and (c) intends to appear
in person or by proxy at the meeting to nominate the person or person specified
in the notice; (iii) a description of all arrangements or understandings
between the stockholder and each nominee and any other person or persons
(naming such person or persons) pursuant to which the nomination is to be made
by the stockholder; (iv) such other information regarding each nominee proposed
by such stockholder as would be required to be included in a proxy statement
filed pursuant to Regulation 14A promulgated under Section 14 of the Securities
Exchange Act of 1934, as amended, as now in effect or hereafter modified, had
the nominee been nominated by the Board of Directors; and (v) the consent of
each nominee to serve as director of the Corporation if so elected. The
Corporation may require any proposed nominee to furnish such other information
as may reasonably be required by the Corporation to determine the
qualifications of such person to serve as a director.

         SECTION 3. Place of Meetings. Meetings of the Board of Directors shall
be held at such place or places, within or without the State of Delaware, as
the Board of Directors may from time to time determine or as shall be specified
in the notice of any such meeting.

         SECTION 4. Annual Meeting. The Board of Directors shall meet for the
purpose of organization, the election of officers and the transaction of such
other business, as soon as practicable after each annual meeting of the
stockholders, on the same day and at the same place where such annual meeting
shall be held. Notice of such meeting need not be given. In the event such
annual meeting is not so held, the annual meeting of the Board of Directors may
be held at such other time or place (within or without the State of Delaware)
as shall be specified in a notice thereof given as hereinafter provided in
Section 7 of this Article III.

         SECTION 5. Regular Meetings. Regular meetings of the Board of
Directors shall be held at such time and place as the Board of Directors may
fix. If any day fixed for a regular meeting shall be a legal holiday at the
place where the meeting is to be held, then the meeting which would otherwise
be held on that day shall be held at the same hour on the next succeeding
business day. Notice of regular meetings of the Board of Directors need not be
given except as otherwise required by statute or these By-Laws.

         SECTION 6. Special Meetings. Special meetings of the Board of
Directors may be called by the Chairman of the Board, if one shall have been
elected, or by two or more directors of the Corporation or by the President.


                                      19
<PAGE>

                             AMENDED AND RESTATED
                                    BY-LAWS
                                ENAMELON, INC.
                                  (continued)

         SECTION 7. Notice of Meetings. Notice of each special meeting of the
Board of Directors (and of each regular meeting for which notice shall be
required) shall be given by the Secretary as hereinafter provided in this
Section 7, in which notice shall be stated the time and place of the meeting.
Except as otherwise required by these By-Laws, such notice need not state the
purpose of such meeting. Notice of each such meeting shall be mailed, postage
prepaid, to each director, addressed to him at his residence or usual place of
business, by first-class mail, at least two days before the day on which such
meeting is to be held, or shall be sent addressed to him at such place by
telegraph, cable, telex, telecopier or other similar means, or be delivered to
him personally or be given to him by telephone, or other similar means, at
least twenty-four hours before the time at which such meeting is to be held.
Notice of any such meeting need not be given to any director who shall, either
before or after the meeting, submit a signed waiver of notice or who shall
attend such meeting, except when he shall attend for the express purpose of
objecting, at the beginning of the meeting, to the transaction of any business
because the meeting is not lawfully called or convened.

         SECTION 8. Quorum and Manner of Acting. A majority of the entire Board
of Directors shall constitute a quorum for the transaction of business at any
meeting of the Board of Directors, and, except as otherwise expressly required
by statute or the Certificate of Incorporation or these By-Laws, the act of a
majority of the directors present at any meeting at which a quorum is present
shall be the act of the Board of Directors. In the absence of a quorum at any
meeting of the Board of Directors, a majority of the directors present thereat
may adjourn such meeting to another time and place. Notice of the time and
place of any such adjourned meeting shall be given to the directors unless such
time and place were announced at the meeting at which the adjournment was
taken, in which case such notice shall only be given to the directors who were
not present thereat. At any adjourned meeting at which a quorum is present, any
business may be transacted which might have been transacted at the meeting as
originally called. The directors shall act only as a Board and the individual
directors shall have no power as such.

         SECTION 9. Organization. At each meeting of the Board of Directors,
the Chairman of the Board, if one shall have been elected, or, in the absence
of the Chairman of the Board or if one shall not have been elected, the
President (or, in his absence, another director chosen by a majority of the
directors present) shall act as chairman of the meeting and preside thereat.
The Secretary, or, in his absence, any person appointed by the chairman shall
act as secretary of the meeting and keep the minutes thereof.

         SECTION 10. Resignations. Any director of the Corporation may resign
at any time by giving written notice of his resignation to the Corporation. Any
such resignation shall take effect at the time specified or, if the time when
it shall become effective shall not be specified therein, immediately upon its
receipt. Unless otherwise specified therein, the acceptance of such resignation
shall not be necessary to make it effective.

         SECTION 11. Vacancies. Any vacancy in the Board of Directors, whether
arising from death, resignation, removal, an increase in the number of
Directors or any other cause, may be filled by the vote of a majority of the
Directors then in office, though less than a quorum, or the sole remaining
Director. Each Director so elected shall hold office until the next Annual
Meeting of Stockholders at which the term of the Class to which such Director
has been elected expires and until his successor shall have been elected and
qualified, or until his earlier death, resignation or removal.

         SECTION 12. Removal of Directors. The Stockholders may remove a
Director only for cause, such removal to be effected at a Special Meeting of
Stockholders called for that purpose. A Director may not be removed by the
Board of Directors.

         SECTION 13. Committees. The Board of Directors may, by resolution
passed by a majority of the entire Board of Directors, designate one or more
committees, including any executive committee, each committee to consist of one
or more of the directors of the Corporation. The Board of Directors may
designate one or more directors as alternate members of any committee, who may
replace any absent member at any meeting of the committee. Except to the extent
restricted by statute or the Certificate of Incorporation, each such committee,
to the extent provided in the resolution creating it, shall have and may
exercise all the authority of the Board of Directors. Each such committee shall
serve at the pleasure of the Board of Directors and have such name as may be
determined from time to time by resolution adopted by the Board of Directors.
Each committee shall keep regular


                                      20
<PAGE>

                              AMENDED AND RESTATED
                                    BY-LAWS
                                 ENAMELON, INC.
                                  (continued)

minutes of its meetings and report the same to the Board of Directors.

         SECTION 14. Action by Consent. Unless restricted by the Certificate of
Incorporation, any action required or permitted to be taken by the Board of
Directors or any committee thereof may be taken without a meeting if all
members of the Board of Directors or such committee consent in writing to the
adoption of a resolution authorizing the action. The resolution and the written
consents thereto by the members of the Board of Directors or such committee
shall be filed with the minutes of the proceedings of the Board of Directors or
such committee.

         SECTION 15. Telephonic Meeting. Unless restricted by the Certificate
of Incorporation, any one or more members of the Board of Directors or any
committee thereof may participate in a meeting of the Board of Directors or
such committee by means of a conference telephone or similar communications
equipment allowing all persons participating in the meeting to hear each other
at the same time. Participation by such means shall constitute presence in
person at a meeting.

                                   ARTICLE IV

                                    Officers

                  SECTION 1. Number and Qualifications. The officers of the
Corporation shall be elected by the Board of Directors and shall include the
Chief Executive Officer, President, one or more Vice-Presidents, the Secretary,
the Treasurer, and the Chairman of the Board of Directors. If the Board of
Directors wishes it may also elect other officers (including one or more
Assistant Treasurers and one or more Assistant Secretaries), as may be
necessary or desirable for the business of the Corporation. Any two or more
offices may be held by the same person. Each officer shall hold office until
the first meeting of the Board of Directors following the next annual meeting
of the stockholders, and until his successors shall have been elected and shall
have qualified, or until his death, or until he shall have resigned or have
been removed, as hereinafter provided in these By-Laws.

         SECTION 2. Resignations. Any officer of the Corporation may resign at
any time by giving written notice of his resignation to the Board of Directors
or the Chairman of the Board or the President or the Chief Executive officer or
the Secretary. Any such resignation shall take effect at the time specified
therein or, if the time when it shall become effective shall not be specified
therein, immediately upon its receipt. Unless otherwise specified therein, the
acceptance of any such resignation shall not be necessary to make it effective.

         SECTION 3. Removal. Any officer of the Corporation may be removed,
either with or without cause, at any time, by the Board of Directors at any
meeting thereof.

         SECTION 4. Chairman of the Board. The Chairman of the Board, if one
shall have been elected, shall be a member of the Board, an officer of the
Corporation and, if present, shall preside at each meeting of the Board of
Directors or of the stockholders. He shall advise and counsel with the
President, and in his absence with other executives of the Corporation, and
shall perform such other duties as may from time to time be assigned to him by
the Board of Directors.

         SECTION 5. The President. The President shall be the chief operating
officer of the Corporation. He shall, in the absence of the Chairman of the
Board or if a Chairman of the Board shall not have been elected, preside at
each meeting of the Board of Directors or the stockholders. He shall perform
all duties incident to the office of President and chief executive officer and
such other duties as may from time to time be assigned to him by the Board of
Directors.

         SECTION 6. Chief Executive Officer. The Chief Executive Officer shall
be a principal executive officer of the corporation with overall responsibility
for all of the Corporation's activities. He shall perform all duties incident
to the office of Chief Executive Officer and such other duties as may from time
to time be assigned to him by the Board of Directors.

                                      21
<PAGE>

                              AMENDED AND RESTATED
                                    BY-LAWS
                                 ENAMELON, INC.
                                  (continued)

         SECTION 7. Vice-Presidents. Each Vice-President shall perform all such
duties as from time to time may be assigned to him by the Board of Directors,
the Chief Executive Officer or the President. At the request of the Chief
Executive Officer or President or in their absence or in the event of their
inability or refusal to act, the Vice-President, or if there shall be more than
one, the Vice-Presidents in the order determined by the Board of Directors (or
if there be no such determination, then the Vice-Presidents in the order of
their election), shall perform the duties of the President, and, when so
acting, shall have the powers of and be subject to the restrictions placed upon
the President in respect of the performance of such duties.

         SECTION 8.  Treasurer.  The Treasurer shall:

         (a) have charge and custody of, and be responsible for, all the funds
and securities of the Corporation;

         (b) keep full and accurate accounts of receipts and disbursements in
books belonging to the Corporation;

         (c) deposit all moneys and other valuables to the credit of the
Corporation in such depositories as may be designated by the Board of Directors
or pursuant to its direction;

         (d) receive, and give receipts for, moneys due and payable to the
Corporation from any source whatsoever;

         (e) disburse the funds of the Corporation and supervise the
investments of its funds, taking proper vouchers therefor;

         (f) render to the Board of Directors, whenever the Board of Directors
may require, an account of the financial condition of the Corporation; and

         (g) in general, perform all duties incident to the office of Treasurer
and such other duties as from time to time may be assigned to him by the Board
of Directors.

         SECTION 9.  Secretary.  The Secretary shall:

         (a) keep or cause to be kept in one or more books provided for the
purpose, the minutes of all meetings of the Board of Directors, the committees
of the Board of Directors and the stockholders;

         (b) see that all notices are duly given in accordance with the
provisions of these By-Laws and as required by law;

         (c) be custodian of the records and the seal of the Corporation and
affix and attest the seal to all certificates for shares of the Corporation
(unless the seal of the Corporation on such certificates shall be a facsimile,
as hereinafter provided) and affix and attest the seal to all other documents
to be executed on behalf of the Corporation under its seal;

         (d) see that the books, reports, statements, certificates and other
documents and records required by law to be kept and filed are properly kept
and filed; and

         (e) in general, perform all duties incident to the office of Secretary
and such other duties as from time to time may be assigned to him by the Board
of Directors.

         SECTION 10. The Assistant Treasurer. The Assistant Treasurer, or if
there shall be more than one, the Assistant Treasurers in the order determined
by the Board of Directors (or if there be no such determination, then in the
order of their election) , shall, in the absence of the Treasurer or in the
event of his inability or refusal to act, perform the duties and exercise the
powers of the Treasurer and shall perform such other duties as from time to
time may be assigned by the Board of Directors.


                                      22
<PAGE>

                              AMENDED AND RESTATED
                                    BY-LAWS
                                 ENAMELON, INC.
                                  (continued)

         SECTION 11. The Assistant Secretary. The Assistant Secretary, or if
there shall be more than one, the Assistant Secretaries in the order determined
by the Board of Directors (or if there be no such determination, then in the
order of their election), shall, in the absence of the Secretary or in the
event of his inability or refusal to act, perform the duties and exercise the
powers of the Secretary and shall perform such other duties as from time to
time may be assigned by the Board of Directors.

         SECTION 12. Compensation. The compensation of the officers of the
Corporation for their services as such officers shall be fixed from time to
time by the Board of Directors. An Officer of the Corporation shall not be
prevented from receiving compensation by reason of the fact that he is also a
director of the Corporation.


                                   ARTICLE V

                     Stock Certificates and their Transfer

         SECTION 1. Stock Certificates. Each holder of stock of the Corporation
shall be entitled to have a certificate, in such form as shall be approved by
the Board of Directors, certifying the number of shares of the Corporation
owned by him. The certificates representing shares shall be signed in the name
of the Corporation by the Chairman of the Board or the President or a
Vice-President and by the Secretary, an Assistant Secretary, the Treasurer or
an Assistant Treasurer and sealed with the seal of the Corporation (which seal
may be a facsimile, engraved or printed); provided, however, that where any
such certificate is countersigned by a transfer agent, or is registered by a
registrar (other than the corporation or one of its employees), the signatures
of the Chairman of the Board, President, Vice President, Secretary, Assistant
Secretary, Treasurer or Assistant Treasurer upon such certificates may be
facsimiles, engraved or printed. In case any officer who shall have signed any
such certificate shall have ceased to be such officer before such certificate
shall be issued, it may nevertheless be issued by the Corporation with the same
effect as if such officer were still in office at the date of their issue.

         SECTION 2. Books of Account and Record of Stockholders. There shall be
kept correct and complete books and records of account of all the business and
transactions of the Corporation. There shall also be kept, at the office of the
Corporation or at the office of its transfer agent, a record containing the
names and addresses of all stockholders of the Corporation, the number of
shares of stock held by each, and the dates when they became the holders of
record thereof.

         SECTION 3. Transfer of Shares. Transfer of shares of the Corporation
shall be made on the records of the Corporation only upon authorization by the
registered holder thereof, or by his attorney thereunto authorized by power of
attorney duly executed and filed with the Secretary or with a transfer agent,
and on surrender of the certificate or certificates for such shares properly
endorsed or accompanied by a duly executed stock transfer power and the payment
of all taxes thereon. The person in whose names shares shall stand on the
record of stockholders of the Corporation shall be deemed the owner thereof for
all purposes as regards the Corporation. Whenever any transfer of shares shall
be made for collateral security and not absolutely and written notice thereof
shall be given to the Secretary or to a transfer agent, such fact shall be
noted on the records of the Corporation.

         SECTION 4. Transfer Agents and Registrars. The Board of Directors may
appoint, or authorize any officer or officers to appoint, one or more transfer
agents and one or more registrars and may require all certificates for shares
of stock to bear the signature of any of them.

         SECTION 5. Regulations. The Board of Directors may make such
additional rules and regulations, not inconsistent with these By-Laws, as it
may deem expedient concerning the issue, transfer and registration of
certificates for shares of the Corporation.

         SECTION 6. Fixing of Record Date. The Board of Directors may fix, in
advance, a date not more than sixty (60) nor less than ten (10) days before the
date then fixed for the holding of any meeting of the stockholders of record of
voting shares of stock at such time, and no others, shall be entitled to notice
of and to vote at such

                                      23
<PAGE>

                              AMENDED AND RESTATED
                                    BY-LAWS
                                 ENAMELON, INC.
                                  (continued)

meeting. The Board of Directors may fix, in advance, a date not more than sixty
(60) days preceding the date fixed for the payment of any dividend or the
making of any distribution or the allotment of any rights in respect of any
change, conversion or exchange of stock, as the record date for the
determination of the stockholders entitled to receive any such dividend,
distribution, or allotment, and in such case only the stockholders of record at
the time so fixed shall be entitled to receive such dividend, distribution, or
allotment.

         SECTION 7. Lost, Destroyed or Mutilated Certificates. The holder of
any certificate representing shares of the Corporation shall immediately notify
the Corporation of any loss, destruction or mutilation of such certificate, and
the Corporation may issue a new certificate in the place of any certificate
theretofore issued by it which the owner thereof shall allege to have been lost
or destroyed or which shall have been mutilated. The Board of Directors may, in
its discretion, require such owner of his legal representatives to give to the
Corporation a bond in such sum, limited or unlimited, and in such form and with
such surety or sureties as the Board of Directors in its absolute discretion
shall determine, to indemnify the Corporation against any claim that may be
made against it on account of the alleged loss of destruction of any such
certificate, or the issuance of such new certificate.





                                   ARTICLE VI

                                Indemnification

         SECTION 1. General. The Corporation shall indemnify and hold harmless,
to the fullest extent permitted by applicable law as it presently exists or may
hereafter be amended, any person who was or is a party or is threatened to be
made a party to any threatened, pending or completed action, suit or
proceeding, whether civil, criminal, administrative or investigative (other
than an action by or in the right of the Corporation) by reason of the fact
that he is or was a director, officer, employee or agent of the Corporation, or
is or was serving at the request of the Corporation as a director, officer,
employee or agent of another corporation, partnership, joint venture, trust or
other enterprise, against expenses (including attorneys' fees), judgments,
fines and amounts paid in settlement actually and reasonably incurred by him in
connection with such action, suit or proceeding if he acted in good faith and
in a manner he reasonably believed to be in or not opposed to the best
interests of the Corporation, and, with respect to any criminal action or
proceeding, had no reasonable cause to believe his conduct was unlawful. The
termination of any action, suit or proceeding by judgment, order, settlement,
conviction, or upon a plea of nolo contendre or its equivalent, shall not, of
itself, create a presumption that the person did not act in good faith and in a
manner which he reasonably believed to be in or opposed to the best interests
of the Corporation, and, with respect to any criminal action or proceeding, had
reasonable cause to believe that his conduct was unlawful.

         SECTION 2. Derivative Actions. The Corporation shall indemnify any
person who was or is a party or is threatened to be made a party to any
threatened, pending or completed action or suit by or in the right of the
Corporation to procure a judgment in its favor by reason of the fact that he is
or was a director, officer, employee or agent of the Corporation, or is or was
serving at the request of the Corporation as a director, officer, employee or
agent of another corporation, partnership, joint venture, trust or other
enterprise against expenses (including attorneys' fees) actually and reasonably
incurred by him in connection with the defense or settlement of such action or
suit if he acted in good faith and in a manner he reasonably believed to be in
or not opposed to the best interests of the Corporation and except that no
indemnification shall be made in respect of any claim, issue or matter as to
which such person shall have been adjudged to be liable to the Corporation
unless and only to the extent that the Court of Chancery of the State of
Delaware or the court in which such action or suit was brought shall determine
upon application that, despite the adjudication of liability but in view of all
the circumstances of the case, such person is fairly and reasonably entitled to
indemnity for such expenses which the Court of Chancery or such other court
shall deem proper.

         SECTION 3. Prepayment of Expenses. The Corporation shall pay the
expenses incurred in defending any


                                      24
<PAGE>

                              AMENDED AND RESTATED
                                    BY-LAWS
                                 ENAMELON, INC.
                                  (continued)

proceeding in advance of its final disposition, provided, however, that the
payment of expenses incurred by a director or officer in advance of the final
disposition of the proceeding shall be made only upon receipt of an undertaking
by the director or officer to repay all amounts advanced if it should be
ultimately determined that the director or officer is not entitled to be
indemnified under this Article or otherwise.

         SECTION 4. Non-Exclusivity of Rights. The rights conferred on any
person by this Article VI shall not be exclusive of any other rights which such
person may have or hereafter acquire under any statute, provision of the
Certificate of Incorporation, these By-Laws, agreement, vote of stockholders or
disinterested directors or otherwise.

         SECTION 5. Amendment or Repeal. Any repeal or modification of the
foregoing provisions of this Article VI shall not adversely affect any right or
protection hereunder of any person in respect of any act or omission occurring
prior to the time of such repeal or modification.

         SECTION 6. Insurance. The Corporation shall have power to purchase and
maintain insurance on behalf of any person who is or was a director, officer,
employee or agent of the Corporation, or is or was serving at the request of
the Corporation as a director, officer, employee or agent of another
corporation, partnership, joint venture, trust or other enterprise against any
liability asserted against him and incurred by him in any such capacity, or
arising out of his status as such, whether or not the Corporation would have
the power to indemnify him against such liability under the provisions of this
Article VI.


                                  ARTICLE VII

                               General Provisions

         SECTION 1. Seal. The seal of the Corporation shall bear the name of
the Corporation and shall be in such form as shall be approved by the Board of
Directors.

         SECTION 2. Fiscal Year. The fiscal year of the Corporation shall
commence January 1, but may thereafter be changed by resolution of the Board of
Directors.

         SECTION 3. Checks, Notes, Drafts, Etc. All checks, notes, drafts or
other orders for the payment of money of the Corporation shall be signed,
endorsed or accepted in the name of the corporation by such officer, officers,
person or persons as from time to time may be designated by the Board of
Directors or by an officer or officers authorized by the Board of Directors to
make such designation.

         SECTION 4. Execution of Contracts, Deeds, Etc. The Board of Directors
may authorize any officer or officers, agent or agents, in the name and on
behalf of the Corporation to enter into or execute and deliver any and all
deeds, bonds, mortgages, contracts and other obligations or instruments, and
such authority may be general or confined to specific instances.


                                  ARTICLE VIII

                                   Amendments

         These By-Laws may be amended or repealed or new By-Laws adopted (a) by
action of the stockholders entitled to vote thereon at any annual or special
meeting of stockholders or (b) by action of the Board of Directors at a regular
or special meeting thereof. Any By-Law made by the Board of Directors may be
amended or repealed by action of the stockholders at any annual or special
meeting of stockholders.


                                       25