<PAGE>

                                                                     Exhibit 3.1

                             AMENDED AND RESTATED
                         CERTIFICATE OF INCORPORATION
                                      OF
                          CASTLE DENTAL CENTERS, INC.

          The undersigned, Jack H. Castle, Jr., Chief Executive Officer of
Castle Dental Centers, Inc., a corporation organized and existing under the laws
of the State of Delaware (the "Corporation"), does hereby certify as follows:

          FIRST:  The name of the Corporation is Castle Dental Centers, Inc.

          SECOND: The Certificate of Incorporation of the Corporation was filed
in the Office of the Secretary of State of the State of Delaware on December 15,
1995.

          THIRD:  This Amended and Restated Certificate of Incorporation of the
Corporation (the "Restated Certificate") was duly adopted in accordance with the
provisions of Section 245 of the Delaware General Corporation Law, the Board of
Directors having duly adopted resolutions setting forth and declaring advisable
this Restated Certificate, and by the holders of a majority of the outstanding
stock of the Corporation at the regularly scheduled annual meeting of the
stockholders.

          FOURTH: The Certificate of Incorporation of the Corporation is hereby
amended and restated as follows:

                                   ARTICLE I.

          The name of the corporation is Castle Dental Centers, Inc. (the
"Corporation").

                                  ARTICLE II.

          The registered office of the Corporation in the State of Delaware is
located at 1209 Orange Street in the City of Wilmington, County of New Castle.
The name of its registered agent is The Corporation Trust Company.

                                  ARTICLE III.

          The nature of the business or purposes to be conducted or promoted by
the Corporation is to engage in any lawful act or activity for which
corporations may be organized under the General Corporation Law of the State of
Delaware.

                                       1
<PAGE>

                                  ARTICLE IV.

          The total number of shares of all classes of stock which the
Corporation shall have authority to issue is 20,000,000 shares, consisting of:
(i) 18,000,000 shares of Common Stock, par value $.001 per share (herein called
the "Common Stock");  (ii) 1,000,000 shares of Class B Nonvoting Common Stock,
par value $.001 per share (herein called the "Class B Common Stock"), and (iii)
1,000,000 shares of Preferred Stock, par value $.001 per share (herein called
the "Preferred Stock").

                               A. PREFERRED STOCK

          Shares of Preferred Stock may be issued from time to time in one or
more series as may from time to time be determined by the Board of Directors,
each of said series to be distinctly designated. The voting powers, preferences
and relative, participating, optional and other special rights, and the
qualifications, limitations or restrictions thereof, if any, of each such series
may differ from those of any and all other series of Preferred Stock at any time
outstanding, and the Board of Directors is hereby expressly granted authority to
fix or alter, by resolution or resolutions, the designation, number, voting
powers, preferences and relative, participating, optional and other special
rights, and the qualifications, limitations and restrictions thereof, of each
such series, including but without limiting the generality of the foregoing, the
following:

          (1) The distinctive designation of, and the number of shares of
Preferred Stock that shall constitute, such series, which number (except where
otherwise provided by the Board of Directors in the resolution establishing such
series) may be increased or decreased (but not below the number of shares of
such series then outstanding) from time to time by like action of the Board of
Directors;

          (2) The rights in respect of dividends, if any, of such series of
Preferred Stock, the extent of the preference or relation, if any, of such
dividends to the dividends payable on any other class or classes or any other
series of the same or other class or classes of capital stock of the corporation
and whether such dividends shall be cumulative or noncumulative;

          (3) The right, if any, of the holders of such series of Preferred
Stock to convert the same into, or exchange the same for, shares of any other
class or classes or of any other series of the same or any other class or
classes of capital stock of the corporation, and the terms and conditions of
such conversion or exchange;

          (4) Whether or not shares of such series of Preferred Stock shall be
subject to redemption, and the redemption price or prices and the time or times
at which, and the terms and conditions on which, shares of such series of
Preferred Stock may be redeemed;

                                       2
<PAGE>

          (5) The rights, if any, of the holders of such series of Preferred
Stock upon the voluntary or involuntary liquidation, dissolution or winding-up
of the corporation or in the event of any merger or consolidation of or sale of
assets by the corporation;

          (6) The terms of any sinking fund or redemption or repurchase or
purchase account, if any, to be provided for shares of such series of Preferred
Stock;

          (7) The voting powers, if any, of the holders of any series of
Preferred Stock generally or with respect to any particular matter, which may be
less than, equal to or greater than one vote per share, and which may, without
limiting the generality of the foregoing, include the right, voting as a series
of Preferred Stock as a class, to elect one or more directors of the corporation
generally or under such specific circumstances and on such conditions, as shall
be provided in the resolution or resolutions of the Board of Directors adopted
pursuant hereto, including, without limitation, in the event there shall have
been a default in the payment of dividends on or redemption of any one or more
series of Preferred Stock; and

          (8) Such other powers, preferences and relative, participating,
optional and other special rights, and the qualifications, limitations and
restrictions thereof, as the Board of Directors shall determine.

                                B. COMMON STOCK

          Except as otherwise provided herein, all shares of Common Stock and
Class B Common Stock will be identical and will entitle the holders thereof to
the same rights and privileges.

          1.  Voting Rights.  The holders of Common Stock will be entitled to
              -------------
one vote per share on all matters to be voted on by the corporation's
stockholders, and except as otherwise required by law, the holders of Class B
Common Stock will have no right to vote their shares of Class B Common Stock on
any matters to be voted on by the corporation's stockholders.

          2.  Dividends.  When and as dividends are declared thereon, whether
              ---------
payable in cash, property or securities of the corporation, the holders of
Common Stock and the holders of Class B Common Stock will be entitled to share
ratably according to the number of shares of Common Stock or Class B Common
Stock held by them, in such dividends; provided, that if dividends are declared
which are payable in shares of Common Stock or Class B Common Stock, dividends
will be declared which are payable at the same rate on both classes of Common
Stock, and the dividends payable in shares of Common Stock will be payable to
holders of Common Stock, and the dividends payable in shares of Class B Common
Stock will be payable to the holders of Class B Common Stock.

          3.  Liquidation Rights.  In the event of any liquidation, dissolution
              ------------------
or winding up of the corporation, whether voluntary or involuntary, after
payment shall have been made to the holders of any Preferred Stock pursuant to
this Article IV, the holders of Common Stock and Class B Common Stock shall be
entitled, to

                                       3
<PAGE>

the exclusion of the holders of Preferred Stock, to share ratably according to
the number of shares of Common Stock or Class B Common Stock held by them in the
remaining assets of the corporation available for distribution to its
stockholders.

          4.  Conversion of Class B Common Stock.
              ----------------------------------

               (a) At any time and from time to time, each record holder of
          Class B Common Stock will be entitled to convert any and all of the
          shares of such holder's Class B Common Stock into the same number of
          shares of Common Stock at such holder's election; provided, that each
          holder of Class B Common Stock shall only be entitled to convert any
          share or shares of Class B Common Stock to the extent that after
          giving effect to such conversion such holder or its affiliates shall
          not directly or indirectly own, control or have power to vote a
          greater quantity of securities of any kind issued by the corporation
          than such holder and its affiliates are permitted to own, control or
          have power to vote under any law or under any regulation, rule or
          other requirement of any governmental authority at any time applicable
          to such holder and its affiliates.

               (b) Each conversion of shares of Class B Common Stock into shares
          of Common Stock will be effected by the surrender of the certificate
          or certificates representing the shares to be converted at the
          principal office of the corporation (or such other office or agency of
          the corporation as the corporation may designate by notice in writing
          to the holder or holders of the Class B Common Stock) at any time
          during normal business hours, together with a written notice by the
          holder of such Class B Common Stock stating that such holder desires
          to convert the shares, or a stated number of the shares, of Class B
          Common Stock represented by such certificate or certificates into
          Common Stock and a written undertaking that upon such conversion such
          holder and its affiliates will not directly or indirectly own, control
          or have the power to vote a greater quantity of securities of any kind
          issued by the corporation than such holders and its affiliates are
          permitted to own, control or have the power to vote under any
          applicable law, regulation, rule or other governmental requirement
          (and such statement will obligate the corporation to issue such Common
          Stock). Such conversion will be deemed to have been effected as of the
          close of business on the date on which such certificate or
          certificates have been surrendered and such notice has been received,
          and at such time the rights of the holder of the converted Class B
          Common Stock as such holder will cease and the person or persons in
          whose name or names the certificate or certificates for shares of
          Common Stock are to be issued upon such conversion will be deemed to
          have become the holder or holders of record of the shares of Common
          Stock represented thereby.

               (c) Promptly after such surrender and the receipt of such written
          notice, the corporation will issue and deliver in accordance with the
          surrendering holder's instructions

                                       4
<PAGE>

     (i) the certificate or certificates for the Common Stock issuable upon such
     conversion and (ii) a certificate representing any Class B Common Stock
     which was represented by the certificate or certificates delivered to the
     corporation in connection with such conversion but which was not converted.

          (d) If the corporation in any manner subdivides or combines the
     outstanding shares of one class of either Common Stock or Class B Common
     Stock, the outstanding shares of the other class will be proportionately
     subdivided or combined.

          (e) In the case of, and as a condition to, any capital reorganization
     of, or any reclassification of the capital stock of, the corporation (other
     than a subdivision or combination of shares of Common Stock or Class B
     Common Stock into a greater or lesser number of shares (whether with or
     without par value) or a change in the par value of Common Stock or Class B
     Common Stock or from par value to no par value, or from no par value to par
     value) or in the case of, and as a condition to, the consolidation or
     merger of the corporation with or into another corporation (other than a
     merger in which the corporation is the continuing corporation and which
     does not result in any reclassification of outstanding shares of Common
     Stock or Class B Common Stock), each share of Class B Common Stock shall be
     convertible into the number of shares of stock or other securities or
     property receivable upon such reorganization, reclassification,
     consolidation or merger by a holder of the number of shares of Common Stock
     of the corporation into which such share of Class B Common Stock was
     convertible immediately prior to such reorganization, reclassification,
     consolidation or merger; and, in any such case, appropriate adjustment
     shall be made in the application of the provisions set forth in this
     paragraph 4 with respect to the rights and interests thereafter of the
     holders of Class B Common Stock to the end that the provisions set forth in
     this paragraph 4 (including provisions with respect to the conversion rate)
     shall thereafter be applicable, as nearly as they reasonably may be, in
     relation to any shares of stock or other securities or property thereafter
     deliverable upon the conversion of the shares of Class B Common Stock.

          (f) Shares of Class B Common Stock which are converted into shares of
     Common Stock as provided herein shall not be reissued.

          (g) The corporation will at all times reserve and keep available out
     of its authorized but unissued shares of Common Stock or its treasury
     shares, solely for the purpose of issue upon the conversion of the Class B
     Common Stock as provided in this paragraph 4, such number of shares of
     Common Stock as shall then be issuable upon the conversion of all then
     outstanding shares of Class B Common Stock (assuming that all such shares
     of Class B Common Stock are held by persons entitled to convert such shares
     into Common Stock).

                                       5
<PAGE>

               (h) The issuance of certificates for Common Stock upon the
          conversion of Class B Common Stock will be made without charge to the
          holders of such shares for any issuance tax in respect thereof or
          other cost incurred by the corporation in connection with such
          conversion and the related issuance of Common Stock. The corporation
          will not close its books against the transfer of Class B Common Stock
          or of Common Stock issued or issuable upon the conversion of Class B
          Common Stock in any manner which would interfere with the timely
          conversion of Class B Common Stock.

                                   ARTICLE V.

          In furtherance and not in limitation of the powers conferred by the
laws of the State of Delaware, the Board of Directors is expressly authorized
and empowered to adopt, amend and repeal the Bylaws of the Corporation, subject
to the power of the stockholders of the Corporation to adopt, amend or repeal
any bylaw made by the Board of Directors.

                                  ARTICLE VI.

          Unless and except to the extent that the bylaws of the corporation
shall so require, the election of directors of the corporation need not be by
written ballot.

                                  ARTICLE VII.

          A director of the Corporation shall not be personally liable to the
Corporation or its stockholders for monetary damages for breach of fiduciary
duty as a director, except to the extent such exemption from liability or
limitation thereof is not permitted under the General Corporation Law of the
State of Delaware as the same exists or may hereafter be amended. Any amendment,
modification or repeal of the foregoing sentence shall not adversely affect any
right or protection of a director of the Corporation existing hereunder with
respect to any act or omission occurring prior to such amendment, modification
or repeal.

                                 ARTICLE VIII.

          The Corporation shall provide indemnification to certain persons as
provided below.

          A.  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, suit or proceeding whether civil, criminal, administrative or
investigative (collectively, a "Proceeding") (other than a Proceeding by or in
the right of the Corporation) by reason of the fact that the person is or was a
director or officer of the Corporation (which, for purposes hereof, includes any
constituent corporation absorbed by the Corporation in a consolidation or
merger), or while serving as such a director or officer, is or was serving at
the request of the Corporation as a director, officer, partner, joint venturer,
trustee, employee or agent of another corporation, partnership,

                                       6
<PAGE>

joint venture, trust or other enterprise (including service with respect to
employee benefit plans), against expenses (including attorneys' fees),
judgments, fines and amounts paid in settlement actually and reasonably incurred
by the person in connection with such Proceeding if the person acted in good
faith and in a manner the person 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 the person's conduct was
unlawful. The termination of any Proceeding by judgment, order, settlement,
conviction, or upon a plea of nolo contendere or its equivalent, shall not, of
itself, create a presumption that the person did not act in good faith and in a
manner which the person 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 reasonable cause to believe that the person's conduct was
unlawful.

          B.  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
Proceeding by or in the right of the Corporation to procure a judgment in its
favor by reason of the fact that the person is or was a director or officer of
the Corporation (which, for purposes hereof, includes any constituent
corporation absorbed by the Corporation in a consolidation or merger), or while
serving as such a director or officer is or was serving at the request of the
Corporation as a director, officer, partner, joint venturer, trustee, employee
or agent of another corporation partnership, joint venture, trust or other
enterprise (including service with respect to employee benefit plans) against
expenses (including attorney's fees) actually and reasonably incurred by the
person in connection with the defense or settlement of such action or suit if
the person acted in good faith and in a manner the person 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 the person shall have been adjudged to be liable to the Corporation unless
and only to the extent that the Delaware Court of Chancery 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,
the person is fairly and reasonably entitled to indemnity for such expenses
which the Delaware Court of Chancery or such other court shall deem proper.

          C.  Any indemnification under Section A or Section B of this Article
VIII (unless ordered by a court) shall be made by the Corporation only as
authorized in the specific case upon a determination that indemnification of the
director or officer is proper in the circumstances because such person has met
the applicable standard of conduct set forth in Section A or Section B of this
Article VIII. Such determination shall be made (i) by the Board of Directors by
a majority vote of a quorum consisting of directors who were not parties to such
Proceeding, or (ii) if such a quorum is not obtainable, or, even if obtainable,
a quorum of disinterested directors so directs, then by independent legal
counsel in a written opinion, or (iii) by a majority vote of the stockholders,
except that shares owned by or voted under the control of directors who are at
the time parties to such Proceeding may not be voted in the determination.

          D.  Expenses (including attorney's fees) incurred by a director or
officer in defending any Proceeding shall be paid by the Corporation in advance
of the final disposition of such Proceeding but only

                                       7
<PAGE>

(i) upon receipt of an undertaking by or on behalf of such director or officer
to repay such amount if it shall ultimately be determined that such person is
not entitled to be indemnified by the Corporation as authorized by this Article
VIII or otherwise and (ii) in the case of Proceedings brought by or in the right
of the Corporation, only if a determination shall not have been made within 90
days after receipt of any written request for such advance by such director or
officer that indemnification of the director or officer is not proper in the
circumstances because the director or officer has not met the applicable
standard of conduct set forth in Section B. of this Article VIII. This
determination shall be made (a) by the Board of Directors by a majority vote of
a quorum consisting of directors who are not parties to such proceeding or (b)
if such quorum is not obtainable, or, even if obtainable, a quorum of
disinterested directors so directs, then by independent legal counsel in a
written opinion, or (c) by a majority vote or the stockholders, but shares owned
by or voted under the control of directors who are at the time parties to such
Proceeding may not be voted in the determination (collectively, the
"Authority"). Such determination as to whether indemnification is proper may be
challenged by the director or officer in any court of competent jurisdiction and
it shall not be a defense to any claims for advances, nor shall it create a
presumption that advances are not proper. The burden of proving that
indemnification is not proper shall be on the Corporation. Any such
determination may be reexamined at any time by the Authority.

          E.  The indemnification and advancement of expense provided by, or
granted pursuant to, the other Sections of this Article VIII shall not be deemed
exclusive of any other rights to which those seeking indemnification or
advancement or expenses may be entitled under any bylaw, agreement, vote of
disinterested stockholders or disinterested directors or otherwise, both as to
action in any persons' official capacity and as to action in another capacity
while holding such office.

          F.  The Corporation, upon authorization of the Board of Directors, may
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, partner, joint venturer,
trustee, employee or agent of another corporation, partnership, joint venture,
trust or other enterprise against any liability asserted against such person and
incurred by such person in any such capacity, or arising out of such person's
status as such, whether or not the Corporation would have the power to indemnify
such person against such liability under this Article VIII.

          G.  The indemnification and advancement of expenses provided by, or
granted pursuant to, this Article VIII shall continue as to a person who has
ceased to be a director or officer and shall inure to the benefit of the heirs,
executors and administrators of such a person.

          H.  The Corporation may, by action of the Board of Directors, provide
indemnification and advance expenses to employees and agents of the Corporation
upon such terms and conditions as the Board of Directors deems appropriate.

                                  ARTICLE IX.

                                       8
<PAGE>

          Subsequent to a firm commitment underwritten public offering of the
Corporation's Common Stock in which gross proceeds equal or exceed $25 million
before deducting underwriters' discounts and other expenses of the offering, any
action required or permitted to be taken by the Stockholders must be effected at
a duly called annual or special meeting of Stockholders and may not be effected
without such a meeting by any consent in writing by such holders.

          IN WITNESS WHEREOF, the undersigned has executed this Amended and
Restated Certificate of Incorporation on behalf of the Corporation and has
attested such execution and does verify and affirm, under penalty of perjury,
that this Amended and Restated Certificate of Incorporation is the act and deed
of the Corporation and that the facts stated herein are true as of this 27th day
of June, 2000.

                              Castle Dental Centers, Inc.

                              By:____________________________________________
                              Jack H. Castle, Jr., Chief Executive Officer


                                       9