<PAGE>

                                                                     EXHIBIT 3.1

                        THE COMMONWEALTH OF MASSACHUSETTS

                             MICHAEL JOSEPH CONNOLLY
                               Secretary of State

         ONE ASHBURTON PLACE, BOSTON MASS: 02108 FEDERAL IDENTIFICATION
         NO. 04-2762050

                        RESTATED ARTICLES OF ORGANIZATION

                     GENERAL LAWS, CHAPTER 156B, SECTION 74

      This certificate must be submitted to the Secretary of the Commonwealth
within sixty days after the date of the vote of stockholders adopting the
restated articles of organization. The fee for filling this certificate is
prescribed by General Laws chapter 156B, Section 114, Make check payable to the
Commonwealth of Massachusetts.

   We, William M. Mullahy                                   President and
        David L. Brown                                      Assistant Clerk of

                           NATIONAL DENTEX CORPORATION
                              (Name of Corporation)

located at 111 Speen Street, Framingham, Massachusetts 01701 do hereby certify
that the following restatement of the articles of organization of the
corporation was duly adopted at a meeting held on, October 8, 1993 by vote of

974,272 shares of Common Stock.... out of, 1,004,969...shares outstanding,
                                (Class of Stock)

2,855,623 shares of Class B Common Stock out of 2,978,165 shares outstanding,
                                (Class of Stock)
and ........... shares of ................out of ............shares outstanding,
                                (Class of Stock)

being at least two-thirds of each class of stock outstanding and entitled to
vote and of each class or series of stock adversely affected thereby:-

      1.    The name by which the corporation shall be known is:-
               National Dentex Corporation

      2.    The purposes for which the corporation is formed are as follows:-

            The operation of dental laboratories and the provision of laboratory
            services.
C    [ ]
P    [X]    To carry on any business and engage in any other activity, whether
M    [ ]    or not related to those in the foregoing paragraph, which may be
R.A. [ ]    permitted by the laws of the Commonwealth of Massachusetts to a
            corporation organized under Chapter 156B of the General Laws of
            Massachusetts, as the same may be amended from time to time.

12
---
P.C.

Note: If the space provided under any article or item on this form is
insufficient, additions shall be set forth separate 8 1/2 x 11 sheets of paper
leaving a left hand margin of at least on 1 inch for binding. Additions to more
than one article may be continued on a single sheet so long as each article
requiring each such addition is clearly indicated.

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The total number of shares and the par value, if any, of each class of stock
which the corporation is authorized to issue is as follows:-

<TABLE>
<CAPTION>
                     WITHOUT PAR VALUE            WITH PAR VALUE
                     -----------------            --------------
CLASS OF STOCK       NUMBER OF SHARES   NUMBER OF SHARES  PAR VALUE
--------------       -----------------  ----------------  ---------
<S>                  <C>                <C>               <C>
Preferred                                     500,000        .01

Common                                      5,000,000        .01

Class B Common                              3,000,000        .01
</TABLE>

     *4.    If more than one class is authorized, a description of each of the
            different classes of stock with, if any, the preferences, voting
            powers, qualifications, special or relative rights or privileges as
            to each class thereof and any series now established:

            See Continuation Sheet 4A

            See Continuation Sheet 4B

     *5.    The restrictions, if any, imposed by the articles of organization
            upon the transfer of shares of stock of any class are as
            follows:     None

                                  [Illegible]

     *6.    Other lawful provisions, if any, for the conduct and regulation of
            the business and affairs of the corporation, for its voluntary
            dissolution, or for limiting, defining or regulating the power of
            the corporation or of its directors or stockholders, or of any class
            of stockholders.

            See Continuation Sheet 5A

            If there are no provisions, state "None".
<PAGE>

                          NATIONAL DENTEX CORPORATION
                       RESTATED ARTICLES OF ORGANIZATION
                             CONTINUATION SHEET 4A

      The following is a description of the Preferred Stock of the Corporation
(the "Preferred Stock"), the Class B Common Stock of the Corporation (the "Class
B Common Stock") and the Common Stock of the Corporation (the "Common Stock"),
with the powers, privileges and rights, and the qualifications, limitations or
restrictions in respect thereof:

A.    PREFERRED STOCK

      1. Par Value. The par value of the Preferred Stock shall be $.01 per
      share.

      2. The Preferred Stock may be divided into one or more series of Preferred
      Stock and have such rights, preferences, voting powers qualifications and
      special or relative privileges as the Board of Directors of the
      Corporation may determine from time to time prior to issuance of such
      shares in accordance with relevant provisions of applicable law.

B.    COMMON STOCK AND CLASS B COMMONS STOCK

      1. Par Value. The par value of the Common Stock and Class B Common Stock
      shall be $.01 per share.

      2. Voting Rights.

            (a) Each share of the Common Stock of the Corporation is entitled
      to one vote, and all voting rights in the Corporation are vested in the
      holders of record of the outstanding Common Stock, except as otherwise
      required by law.

            (b) The holders of Class B Common Stock have no right to notice of
      any meetings of stockholders of the Corporation, and no right to vote in
      the election of directors or in any other matter presented to the
      stockholders of the Corporation at any meeting, except as may otherwise be
      required by law. In the event holders of Class B Common Stock are entitled
      to vote, such holders shall be entitled to one vote for each share of
      Class B Common Stock and such holders shall vote separately as a class.

      3. Dividends.

            No dividends shall be declared and set aside for any shares of the
      Class B Common Stock except in the event that the Board of Directors of
      the Corporation shall declare a dividend (other than a stock dividend)
      payable upon the then outstanding shares of the Common Stock of the
      Corporation in which event the holders of the Class B Stock shall be
      entitled to the amount of dividends per share of Class B Stock as would be
      declared payable on the largest number of whole shares of

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      Class B Common Stock into which each share of Class B Stock held by each
      holder thereof could be exchanged into pursuant to the provisions of
      Paragraph 5 hereof, such number to be determined as of the record date for
      the determination of holders of Common Stock entitled to receive such
      dividend.

      4. Liquidation, Dissolution or Winding up.

            (a) In the event of any liquidation, dissolution or winding up of
      the Corporation, whether voluntary or involuntary, holders of each share
      of Class B Common Stock shall be entitled to be paid (provided that all
      amounts due holders of Preferred Stock on account of the liquidation,
      dissolution or winding up of the Corporation shall have been paid in full,
      or a fund shall have been set apart in trust for such purpose) out of the
      assets of the Corporation available for distribution to holders of the
      Corporation's capital stock of all classes, whether such assets are
      capital, surplus, or earnings, at the time as, and together with, the
      Common Stock, the same kind and amount of assets or securities as would
      have been issued, distributed or paid upon the largest number of whole
      shares of Common Stock into which each share of Class B Common Stock held
      by each holder thereof could have been exchanged into pursuant to the
      provisions of Paragraph 5 hereof, had such exchange occurred on the date
      immediately prior to the date of such liquidation, dissolution or winding
      up.

            (b) Whenever the distribution provided for herein shall be paid in
      property other than cash, the value of such distribution shall be the fair
      market value of such property as determined in good faith by an
      independent investment banker selected by the Board of Directors of the
      Corporation.

            (c) Neither the consolidation nor merger of the Corporation with or
      into any other corporation or entity, nor any sale, lease, exchange, or
      conveyance of all or any part of the properties, assets, or business of
      the Corporation, shall be deemed to be a liquidation, dissolution or
      winding up of the affairs of the Corporation within the meaning of this
      Paragraph 3.

            (d) No provision of this Paragraph 4 shall in any manner, prior
      to any liquidation, dissolution or winding up of the affairs of the
      Corporation, whether voluntary or otherwise, create or be deemed to create
      any restriction upon the surplus or retained earnings of the Corporation
      or prohibit the payment of dividends on the capital stock of the
      Corporation out of the funds of the Corporation legally available
      therefore, nor shall any restriction or prohibition be in any manner
      inferred from the provisions of this Paragraph 4.

                                      -2-
<PAGE>

5.    EXCHANGE RIGHTS.

      (a) Subject to and upon compliance with the provisions of this Paragraph
5, each holder of Class B Common Stock shall have the right, at its option, (the
rights of such holders being referred to herein as "Exchange Rights") at any
time to exchange any or all of the shares of Class B Common Stock now or
hereafter held by such holder for fully paid and nonassessable shares of Common
Stock (calculated as to each exchange to the nearest 1/100th of a share) at the
exchange ratio of one share of Class B Common Stock for each share of Common
Stock.

      (b) If at any time the Corporation shall be recapitalized by reclassifying
its outstanding Common Stock into shares with a different par value or by
changing its outstanding Common Stock with par value to shares without par
value, or the Corporation or a successor corporation shall consolidate or merge
with or convey all or substantially all of its or of any successor corporation's
property and assets to any other corporation or corporations, or the Corporation
or a successor corporation shall distribute Common Stock or other assets
pursuant to, without limitation, any spin-off or other distribution of assets,
each holder of Class B Common Stock shall thereafter have the right to receive
upon the basis and on the terms and conditions specified in this Paragraph 5 in
lieu of the Common Stock of the Corporation theretofore issuable upon the
exchange of Class B Common Stock, such shares, securities or assets as may be
issued or payable with respect to, or in exchange for, the number of shares of
Common Stock of the Corporation theretofore issuable upon the exchange of Class
B Common Stock had such recapitalization, consolidation, merger, conveyance or
distribution not taken place.

      (c) In the event (i) the Corporation shall issue any shares of Common
Stock, options or rights to subscribe for shares of Common Stock, or any
securities convertible into or exchangeable for shares of Common Stock, (ii) the
Corporation shall take a record of the holders of its Common Stock for the
purpose of entitling them to receive a dividend payable otherwise than in cash
or any other distribution in respect of the Common Stock pursuant to, without
limitation, any spin-off, split-off or distribution of the Corporation's assets,
or (iii) the Corporation shall take a record of the holders of its Common Stock
for the purpose of entitling them to subscribe for or purchase any shares of any
class or to receive any other rights, or (iv) of any classification,
reclassification or other reorganization or recapitalization of the shares which
the Corporation is authorized to issue, consolidation or merger of the
Corporation with or into another corporation, or conveyance of all or
substantially all of the assets of the Corporation; or (v) of the voluntary or

                                     - 3 -
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involuntary dissolution, liquidation on winding up of the Corporation; then, and
in such event, the Corporation shall mail to each holder of Class B Common
Stock, at least fifteen (15) days prior thereto, a notice stating the date or
expected date on which such event is to take place. Such notice shall also
specify the date or expected date, if any is to be fixed, as of which holders of
Common Stock of record shall be entitled to exchange their Common Stock for
securities or other property deliverable upon such reclassification,
reorganization, consolidation, merger, conveyance, dissolution, liquidation or
winding up, as the case may be.

      (d) The Corporation will at all times reserve and keep available out of
authorized shares, solely for issuance upon the exercise of the Exchange Rights,
such number of shares of Common Stock as from time to time shall be issuable
upon the exercise of the Exchange Rights.

      (e) In order to exchange shares of Class B Common Stock for Common Stock,
the holder thereof shall surrender at the principal office of the Corporation
the certificate or certificates therefor, duly endorsed to the Corporation or in
blank, and give written notice to the Corporation that it elects to exchange
such shares and shall state in writing therein the number of such shares it
wishes to exchange and the name or names (with addresses) in which it wishes the
certificate(s) for Common Stock to be issued.

      (f) in case only a portion of a holder's shares of Class B Common Stock
are exchanged, upon such exchange the Corporation shall issue and deliver to the
holder thereof, at the expense of the Corporation, a new certificate for the
number of shares of Class B Common Stock equal to the number of unexchanged
shares covered by the certificate(s) surrendered to the Corporation for
exchange.

      (g) As promptly as practicable (and in any event within ten (10) days)
after the receipt of such notice and the surrender of the shares of Class B
Common Stock, the Corporation shall issue, at its expense, and shall deliver to
such holder, or on its written order, at the principal office of the Corporation
(i) certificate(s) for the number of full shares of Common Stock issuable upon
the exchange of such shares (or specified portion thereof), and (ii) cash in
lieu of scrip as provided herein.

      (h) Such exchange shall be deemed to have been effected immediately prior
to the close of business on the date (the "Exchange Date") on which the
Corporation shall have received both such notice and the surrendered shares, and
at such time the rights of the holder of such shares as to such shares shall
cease and the person or persons in whose name or names any certificate or
certificates for shares of Common Stock

                                      -4-
<PAGE>

shall be issuable upon such exchange shall be deemed to have become the holder
of holders of record of the shares of Common Stock represented thereby.

      (i) Upon exchange of any shares of Class B Common Stock, unpaid accrued
dividends, if any to the Exchange Date shall be paid to the holder of such
shares with respect to the number of shares of Class B Common Stock exchanged.
No payment or adjustment shall be made by or on behalf of the Corporation on
account of any dividends on the Common Stock issued upon such exchange which
were declared fox payment to holders of Common Stock of record as of any dare
prior to the Exchange Date.

      (j) No fractional shares of Common Stock shall be issued upon any exchange
of shares of Class B Common Stock. In lieu of any fraction of a share of Common
Stock to which any holder of Class B Common Stock would otherwise be entitled
upon exchange of any shares of Class B Common Stock, the Corporation shall pay a
cash adjustment for such fraction in an amount equal to the same fraction of the
market value of a share of Common Stock (as determined in good faith by the
Board of Directors of the Corporation), at the close of business on the Exchange
Date.

                                      -5-
<PAGE>

                           NATIONAL DENTEX CORPORATION

                        RESTATED ARTICLES OF ORGANIZATION

                              CONTINUATION SHEET 4B

      Each outstanding share of Common stock, $.01 par value, of the Corporation
and each outstanding share of Class B Common Stock, $.01 par value, of the
Corporation, respectively, is changed, on the effective date of these Restated
Articles of Organization, into one-half share of Common Stock, with a par value
of $.01 per share, or one-half share of Class B Common Stock with a par value of
$.01 per share (as the case may be), all without decreasing the total number of
authorized shares of Common Stock and Class B Common Stock; provided, however,
that in lieu of issuing any fractional shares, there shall be paid to each
stockholder who, according to the foregoing provisions, would otherwise be
entitled to hold as a result of such change a fractional share of Common Stock
or Class B Common Stock (whether or not additional to one or more full shares) a
cash payment for such fractional share calculated at a price of $8.00 for each
post-split share; and that by virtue of the aforesaid change of Common Stock and
Class B Common Stock, respectively, from and after the effective date of these
Restated Articles of Organization, each outstanding certificate for Common Stock
and Class B Common Stock, respectively, until surrendered in exchange for
certificate(s) for the number of shares (or payment in lieu of fractional
shares) determined in accordance with such change, shall evidence ownership of
that amount of shares of Common Stock or Class B Common Stock, respectively (or
right to receive payment in lieu of fractional shares), into which such shares
have been changed.

<PAGE>

                           NATIONAL DENTEX CORPORATION

                        RESTATED ARTICLES OF ORGANIZATION

                              CONTINUATION SHEET 6A

1.    The Board of Directors of the Corporation may make, amend, or repeal the
      By-Laws of the Corporation, in whole or in part, except with respect to
      any provision thereof which, by law, the Articles of Organization, or the
      By-Laws, require action exclusively by the stockholders entitled to vote
      thereon; but any By-Law adopted by the Board of Directors may be amended
      or repealed by the stockholders.

2.    All meetings of stockholders of the Corporation may be held within the
      Commonwealth of Massachusetts or elsewhere within the United States. The
      place of such meetings shall be fixed in, or determined in the manner
      provided in the By-Laws.

3.    The Corporation may be a partner, general or limited, in any business
      enterprise which it would have the power to conduct by itself.

4.    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, notwithstanding any provision of law
      imposing such liability, except for liability (i) for any breach of the
      director's duty of loyalty to the Corporation or stockholders, (ii) for
      acts or omissions not in good faith or which involve intentional
      misconduct or a knowing violation of law, (iii) under Section 61 or
      Section 62 of the Massachusetts Business Corporation Law, or (iv) for any
      transaction from which the director derived an improper personal benefit.

            Any repeal or modification of the foregoing paragraph by the
            stockholders of the Corporation shall not adversely affect any right
            or protection of a director of the corporation existing at the time
            of such repeal or modification.

5.    The provisions of Massachusetts General Laws Chapter 110D shall not apply
      to Control Share Acquisitions of the Corporation (as such term is defined
      in Massachusetts General Laws Chapter 110D, Section 1(c)(i), as now in
      effect).

6.    A majority stockholder vote of each class of stock entitled to vote
      thereon, instead of a two-thirds stockholder vote of each class of stock
      entitled to vote thereon, is required to approve consolidations, mergers,
      sales of substantially all of the Corporation's assets, and any amendment
      to the Articles of

<PAGE>

      Organization of the Corporation, except where a greater or different vote
      is expressly required by law.

<PAGE>
      We further certify that the foregoing restated articles of organization
effect no amendments to the articles of organization of the corporation as
heretofore amended except amendments to the following articles 4, 6

      {* If there are no such amendments, state "None".}

                   Briefly describe amendments in space below:

1.    Article 4 was amended to provide for a change in the description of the
      outstanding shares of Common Stock and Class B Common Stock.

2.    Article 6 was amended to provide that the provisions of Massachusetts
      General Laws Chapter 110D shall not apply to the Corporation.

                                  [ILLEGIBLE]

IN WITNESS WHEREOF AND UNDER THE PENALTIES OF PERJURY we have hereto signed
our names this 14th day of October in the Year 1993.

                                 /s/  William M. Mullahy, President

                                 /s/  David L. Brown, Assistant Clerk

<PAGE>

                       THE COMMONWEALTH OF MASSACHUSETTS

                       RESTATED ARTICLES OF ORGANIZATION
                    (General Laws, Chapter 156B, Section 74)

      I hereby approve the within restated articles of organization and, the
filling fee in the amount of $400 having been paid, said articles are deemed to
have been filed with me this 14th day of OCTOBER, 1993.

                                                     /s/ MICHAEL JOSEPH CONNOLLY
                                                     ---------------------------
[SEAL]                                               MICHAEL JOSEPH CONNOLLY
                                                        Secretary of State

A TRUE COPY ATTEST

/s/ WILLIAM FRANCIS GALVIN
-------------------------------
WILLIAM FRANCIS GALVIN
SECRETARY OF THE COMMONWEALTH

DATE 3.16.05 CLERK A65

                         TO BE FILLED IN BY CORPORATION

           PHOTO COPY OF RESTATED ARTICLES OF ORGANIZATION TO BE SENT

                         TO:  Irene A. Halpin, Esq.
                              Posternak, Blankstein & Lund
                              100 Charles River Plaza
                              Boston, MA 02114