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                                                                     EXHIBIT 4.2

               THIRD AMENDED AND RESTATED PARENT PLEDGE AGREEMENT


              THIRD AMENDED AND RESTATED PLEDGE AGREEMENT, dated as of July 1,
1998, made by Sybron International Corporation, a Wisconsin corporation (the
"Parent"), in favor of The Chase Manhattan Bank, as Administrative Agent (in
such capacity, the "Administrative Agent"), for the banks and other financial
institutions (the "Lenders") from time to time parties to the Second Amended
and Restated Credit Agreement, dated as of April 25, 1997 (as amended,
supplemented or otherwise modified from time to time, the "Credit Agreement"),
among the Parent, Ormco Corporation, a Delaware corporation ("Ormco"), Kerr
Corporation, a Delaware corporation ("Kerr"), Nalge Nunc International
Corporation, a Delaware corporation ("NNI"), Erie Scientific Company, a
Delaware corporation ("Erie"), Barnstead Thermolyne Corporation, a Delaware
corporation ("Barnstead"; Ormco, Kerr, NNI, Erie and Barnstead are collectively
referred to herein as the "Subsidiary Borrowers"), the Lenders, the
Administrative Agent and Chase Securities Inc., as arranger.


                             W I T N E S S E T H :


              WHEREAS, the Parent is the legal and beneficial owner of the
shares of Pledged Stock (as hereinafter defined) hereby pledged by the Parent;

              WHEREAS, the Parent is the legal and beneficial owner of each of
the Pledged Notes (as hereinafter defined) hereby pledged by the Parent; and

              NOW, THEREFORE, in consideration of the premises and to induce
the Administrative Agent and the Lenders to enter into the  Credit Agreement
and to induce the Lenders to make their respective extensions of credit to the
Parent and Subsidiary Borrowers under the Credit Agreement, the Parent hereby
agrees with the Administrative Agent, for the ratable benefit of the Lenders,
as follows:

              1.     Defined Terms.  (a)    Unless otherwise defined herein,
terms defined in the Credit Agreement and used herein shall have the meanings
given to them in the Credit Agreement.
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              (b)    The following terms shall have the following meanings:

              "Agreement":  this Third Amended and Restated Pledge Agreement,
       as the same may be amended, modified or otherwise supplemented from time
       to time.

              "Code":  the Uniform Commercial Code from time to time in effect
       in the State of New York.

              "Collateral":  the Pledged Stock, the Pledged Notes and all
       Proceeds.

              "Issuers":  the collective reference to the companies identified
       on Schedule 1 hereto as the issuers of the Pledged Stock.

              "Obligations":  (a) the unpaid principal amount of, and interest
       on (including, without limitation, interest accruing after the maturity
       of the Loans and interest accruing after the filing of any petition in
       bankruptcy, or the commencement of any insolvency, reorganization or
       like proceeding, relating to the Parent, whether or not a claim for
       post-filing or post-petition interest is allowed in such proceeding) the
       Notes and all other obligations and liabilities of the Parent to the
       Administrative Agent or to the Lenders, whether direct or indirect,
       absolute or contingent, due or to become due, or now existing or
       hereafter incurred, which may arise under, out of, or in connection
       with, the Credit Agreement (including, without limitation, all
       obligations and liabilities of the Parent under Section 9 of the Credit
       Agreement), the Notes, the other Loan Documents and any other document
       made, delivered or given in connection therewith or herewith, whether on
       account of principal, interest, reimbursement obligations, fees,
       indemnities, costs, expenses (including, without limitation, all fees
       and disbursements of counsel to the Administrative Agent or to the
       Lenders that are required to be paid by the Parent pursuant to the terms
       of the Credit Agreement) or otherwise and (b) all obligations of the
       Parent to any Lender or an Affiliate of any Lender under or in
       connection with any Interest Rate Agreement or foreign exchange
       contract.

              "Obligors":  the collective reference to the companies identified
       on Schedule 2 hereto, as such Schedule may be amended from time to time.

              "Pledged Notes":  the promissory note or notes of the Obligors
       identified on Schedule 2, together with all substitutes, replacements or
       refinancings thereto that may be issued by any Obligor to the Parent
       while this Agreement is in effect.

              "Pledged Stock":  the shares of capital stock listed on Schedule
       1 hereto, together with all stock certificates, options or rights of any
       nature whatsoever that may be issued or granted by any Issuer to the
       Parent in respect of the Pledged Stock while this Agreement is in
       effect.

              "Proceeds":  all "proceeds" as such term is defined in Section 9-
       306(1) of the Uniform Commercial Code in effect in the State of New York
       on the date hereof and, in any event, shall include, without limitation,
       all dividends or other income from the Pledged Stock and the Pledged
       Notes, collections thereon or distributions with respect thereto.
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              "Securities Act":  the Securities Act of 1933, as amended.

              (c)    The words "hereof," "herein" and "hereunder" and words of
similar import when used in this Agreement shall refer to this Agreement as a
whole and not to any particular provision of this Agreement, and Section and
paragraph references are to this Agreement unless otherwise specified.

              (d)  The meanings given to terms defined herein shall be equally
applicable to both the singular and plural forms of such terms.

              2.     Pledge; Grant of Security Interest.  The Parent hereby
delivers to the Administrative Agent, for the ratable benefit of the Lenders,
all the Pledged Stock and the Pledged Notes and hereby grants to the
Administrative Agent, for the ratable benefit of the Lenders, a first security
interest in the Collateral, as collateral security for the prompt and complete
payment and performance when due (whether at the stated maturity, by
acceleration or otherwise) of the Obligations.

              3.     Stock Powers and Allonges.  (a)  Concurrently with the
delivery to the Administrative Agent of each certificate representing one or
more shares of Pledged Stock to the Administrative Agent, the Parent shall
deliver an undated stock power covering such certificate, duly executed in
blank by the Parent with, if the Administrative Agent so requests, signature
guaranteed.

              (b)    Concurrently with the delivery to the Administrative Agent
of each note representing one of the Pledged Notes, the Parent shall deliver
executed allonges endorsing such notes to "Bearer" with, if the Administrative
Agent so requests, signature guaranteed.

              4.     Representations and Warranties.  The Parent represents and
warrants that:

              (a)    except as set forth on Schedule 1, the shares of Pledged
       Stock constitute all the issued and outstanding shares of all classes of
       the capital stock of each Issuer;

              (b)    the Pledged Notes listed on Schedule 2, as such Schedule
       may be amended from time to time in accordance with the terms hereof,
       constitute all of the issued and outstanding promissory notes payable by
       the Subsidiaries of the Parent to the Parent;

              (c)  all the shares of the Pledged Stock have been duly and
       validly issued and are fully paid and nonassessable; and each of the
       Pledged Notes has been duly and validly issued and is the legal, valid
       and binding obligation of the maker thereof, enforceable in accordance
       with its terms, except as affected by bankruptcy, insolvency, fraudulent
       conveyance, reorganization, moratorium and other similar laws relating
       to or affecting creditors' rights generally, general equitable
       principles (whether considered in a proceeding in equity or at law) and
       an implied covenant of good faith and fair dealing;

              (d)    the Parent is the record and beneficial owner of, and has
       good and marketable title to, the Pledged Stock and the Pledged Notes,
       free of any and all Liens or
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       options in favor of, or claims of, any other Person, except the security
       interest created by this Agreement;

              (e)    upon delivery to the Administrative Agent of the stock
       certificates evidencing the Pledged Stock and upon delivery to the
       Administrative Agent of the Pledged Notes, the security interest created
       by this Agreement will constitute a valid, perfected first priority
       security interest in the Collateral, enforceable in accordance with its
       terms against all creditors of the Parent and any Persons purporting to
       purchase any Collateral from the Parent, except as affected by
       bankruptcy, insolvency, fraudulent conveyance, reorganization,
       moratorium and other similar laws relating to or affecting creditors'
       rights generally, general equitable principles (whether considered in a
       proceeding in equity or at law) and an implied covenant of good faith
       and fair dealing;

              (f)    on the Closing Date, all of the stock owned by the Parent
       or any of its Subsidiaries in any of their respective Subsidiaries will
       be pledged pursuant to one of the Pledge Agreements, other than 35% of
       the stock of any Controlled Foreign Corporation (or other than all of
       the stock of any Controlled Foreign Corporation which is owned directly
       by another Controlled Foreign Corporation) or other than the stock of an
       inactive corporation or a corporation in the process of liquidation;

              (g)    the Parent has obtained from each Issuer and has delivered
       to the Administrative Agent an Acknowledgement and Consent,
       substantially in the form attached hereto as Annex A, executed by each
       such Issuer; and

              (h)    no consent or authorization of, filing with or other act
       by or in respect of any Person is required in connection with the
       execution, delivery, performance, validity or enforceability of the
       Pledged Notes, and the Parent has fully performed all its obligations
       under the Pledged Notes.

              5.     Covenants.  The Parent covenants and agrees with the
Administrative Agent and the Lenders that, from and after the date of this
Agreement until the Obligations are paid in full and the Commitments are
terminated:

              (a)    If the Parent shall, as a result of its ownership of the
       Pledged Stock, become entitled to receive or shall receive any stock
       certificate (including, without limitation, any certificate representing
       a stock dividend or a distribution in connection with any
       reclassification, increase or reduction of capital or any certificate
       issued in connection with any reorganization), option or rights, whether
       in addition to, in substitution of, as a conversion of, or in exchange
       for any shares of the Pledged Stock, or otherwise in respect thereof,
       the Parent shall accept the same as the agent of the Administrative
       Agent and the Lenders, hold the same in trust for the Administrative
       Agent and the Lenders and deliver the same forthwith to the
       Administrative Agent in the exact form received, duly indorsed by the
       Parent to the Administrative Agent, if required, together with an
       undated stock power covering such certificate duly executed in blank by
       the Parent and with, if the Administrative Agent so requests, signature
       guaranteed, to be held by the Administrative Agent, subject to the terms
       hereof, as additional collateral security for the Obligations.  Any sums
       paid upon or in respect of the Pledged Stock or the Pledged Notes upon
       the
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       liquidation or dissolution of any Issuer or any Obligor, as the case may
       be, shall be paid over to the Administrative Agent to be held by it
       hereunder as additional collateral security for the Obligations, and in
       case any distribution of capital or payment of principal shall be made
       on or in respect of the Pledged Stock or the Pledged Notes or any
       property shall be distributed upon or with respect to the Pledged Stock
       or the Pledged Notes pursuant to the recapitalization or
       reclassification of the capital of any Issuer or any Obligor, as the
       case may be, or pursuant to the reorganization thereof, the property so
       distributed shall be delivered to the Administrative Agent to be held by
       it hereunder as additional collateral security for the Obligations.  If
       any sums of money or property so paid or distributed in respect of the
       Pledged Stock or the Pledged Notes shall be received by the Parent, the
       Parent shall, until such money or property is paid or delivered to the
       Administrative Agent, hold such money or property in trust for the
       Lenders, segregated from other funds of the Parent, as additional
       collateral security for the Obligations.  Notwithstanding the foregoing,
       in no event shall more than 65% of the issued and outstanding shares of
       stock, or any property distributed in respect thereof, of any Issuer
       which is a Controlled Foreign Corporation constitute collateral security
       for the Obligations of the Parent.

              (b)    Without the prior written consent of the Administrative
       Agent, the Parent will not (1) vote to enable, or take any other action
       to permit, any Issuer to issue any stock or other equity securities of
       any nature or to issue any other securities convertible into or granting
       the right to purchase or exchange for any stock or other equity
       securities of any nature of such Issuer, (2) sell, assign, transfer,
       exchange, or otherwise dispose of, or grant any option with respect to,
       the Collateral, or (3) create, incur or permit to exist any Lien or
       option in favor of, or any claim of any Person with respect to, any of
       the Collateral, or any interest therein, except for the security
       interests created by this Agreement and Liens permitted by the Credit
       Agreement.  The Parent will defend the right, title and interest of the
       Administrative Agent and the Lenders in and to the Collateral against
       the claims and demands of all Persons whomsoever.

              (c)    At any time and from time to time, upon the written
       request of the Administrative Agent, and at the sole expense of the
       Parent, the Parent will promptly and duly execute and deliver such
       further instruments and documents and take such further actions as the
       Administrative Agent may reasonably request for the purposes of
       obtaining or preserving the full benefits of this Agreement and of the
       rights and powers herein granted.  If any amount payable under or in
       connection with any of the Collateral shall be or become evidenced by
       any promissory note, other instrument or chattel paper, such note,
       instrument or chattel paper shall be immediately delivered to the
       Administrative Agent, duly endorsed in a manner satisfactory to the
       Administrative Agent, to be held as Collateral pursuant to this
       Agreement.

              (d)  The Parent shall pay, and save the Administrative Agent and
       the Lenders harmless from, any and all liabilities with respect to, or
       resulting from any delay in paying, any and all stamp, excise, sales or
       other taxes which may be payable or determined to be payable with
       respect to any of the Collateral or in connection with any of the
       transactions contemplated by this Agreement.

              (e)    The Parent will not (i) amend, modify, terminate or waive
       any provision of
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       any Pledged Note in any manner materially adverse to the interests of
       the Administrative Agent or the Lenders, (ii) fail to exercise promptly
       and diligently each and every material right which it may have under any
       Pledged Note where such failure could reasonably be expected to have an
       adverse affect on the interests of the Administrative Agent or the
       Lenders or (iii) fail to deliver to the Administrative Agent a copy of
       each material demand, notice or document received by it relating in any
       way to any Pledged Note.

              (f)    Without the prior written consent of the Administrative
       Agent, the Parent will not grant any extension (other than, so long as
       no Default or Event of Default shall exist, extensions granted in
       accordance with prudent business judgment) of the time of payment of any
       Pledged Note, compromise, compound or settle the same for less than the
       full amount thereof, release, wholly or partially, any Person liable for
       the payment thereof, or allow any credit or discount whatsoever thereon.

              (g)    The Parent shall deliver to the Administrative Agent, in
       the exact form received, to be held by the Administrative Agent, subject
       to the terms hereof, as additional collateral security for the
       Obligations any additional promissory notes made by any Obligor for the
       benefit of the Parent or other securities, options or rights received by
       it in substitution or exchange for, or as a conversion of, or in
       addition to, any of the Pledged Notes, or otherwise in respect thereof,
       together with an undated endorsement or power, as the case may be, duly
       executed to the order of "Bearer" or in blank, as the case may be, by
       the Parent and with, if the Administrative Agent reasonably requests,
       signature guaranteed.

              6.     Cash Dividends; Voting Rights; Interest and Principal
Payments.  (a)  Unless an Event of Default shall have occurred and be
continuing and the Administrative Agent shall have given notice to the Parent
of the Administrative Agent's intent to exercise its corresponding rights
pursuant to Section 7 below, the Parent shall be permitted to receive all cash
dividends paid in the normal course of business and consistent with past
practice, to the extent permitted in the Credit Agreement, in respect of the
Pledged Stock and to exercise all voting and corporate rights with respect to
the Pledged Stock; provided, however, that no vote shall be cast or corporate
right exercised or other action taken which, in the Administrative Agent's
reasonable judgment, would impair the Collateral or which would be inconsistent
with or result in any violation of any provision of the Credit Agreement, the
Notes, this Agreement or any other Loan Document.

              (b)    Unless an Event of Default shall have occurred and be
continuing and the Administrative Agent shall have given notice to the Parent
of the Administrative Agent's intent to exercise its corresponding rights
pursuant to Section 7 hereof, the Parent shall be permitted to receive and
retain all scheduled interest and principal payments on account of the Pledged
Notes.

              7.     Rights of the Lenders and the Administrative Agent.  (a)
If an Event of Default shall occur and be continuing and the Administrative
Agent shall give notice of its intent to exercise such rights to the Parent,
(1) the Administrative Agent shall have the right to receive any and all cash
dividends paid in respect of the Pledged Stock and any and all interest,
principal or other payments paid in respect of the Pledged Notes and make
application thereof to the Obligations in such order as the Administrative
Agent may determine, (2) all shares of the Pledged Stock shall be registered in
the name of the Administrative Agent or its nominee, and the
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Administrative Agent or its nominee may thereafter exercise (A) all voting,
corporate and other rights pertaining to such shares of the Pledged Stock at
any meeting of shareholders of any Issuer or otherwise and (B) any and all
rights of conversion, exchange, subscription and any other rights, privileges
or options pertaining to such shares of the Pledged Stock as if it were the
absolute owner thereof (including, without limitation, the right to exchange at
its discretion any and all of the Pledged Stock upon the merger, consolidation,
reorganization, recapitalization or other fundamental change in the corporate
structure of any Issuer, or upon the exercise by the Parent or the
Administrative Agent of any right, privilege or option pertaining to such
shares of the Pledged Stock, and in connection therewith, the right to deposit
and deliver any and all of the Pledged Stock with any committee, depositary,
transfer agent, registrar or other designated agency upon such terms and
conditions as the Administrative Agent may determine) and (3) the
Administrative Agent or its nominee may thereafter exercise all rights
pertaining to the Pledged Notes (including without limitation, any and all
rights of conversion, exchange, subscription and any other rights, privileges
or options pertaining thereto) as if it were the absolute owner thereof, all
without liability except to account for property actually received by it, but
the Administrative Agent shall have no duty to the Parent to exercise any such
right, privilege or option and shall not be responsible for any failure to do
so or delay in so doing.

              (b)    Anything herein to the contrary notwithstanding, the
Parent shall remain liable under the Pledged Notes to observe and perform all
the conditions and obligations to be observed and performed by it thereunder
all in accordance with the terms and provisions of the Pledged Notes.  Neither
the Administrative Agent nor the Lenders shall have any obligation or liability
under any Pledged Note by reason of or arising out of this Agreement or the
receipt by the Administrative Agent or the Lenders of any payment relating to
such Pledged Note pursuant hereto (other than to account for monies actually
received by it), nor shall the Administrative Agent or any of the Lenders be
obligated in any manner to perform any of the obligations of the Parent under
or pursuant to any Pledged Note, to make any payment, to make any inquiry as to
the nature or the sufficiency of any payment received by it or as to the
sufficiency of any performance by any party under any Pledged Note, to present
or file any claim, to take any action to enforce any performance or to collect
the payment of any amounts which may have been assigned to it or to which it
may be entitled at any time or times.

              (c)    The rights of the Administrative Agent and the Lenders
hereunder shall not be conditioned or contingent upon the pursuit by the
Administrative Agent or any Lender of any right or remedy against any Issuer or
any Obligor or against any other Person which may be or become liable in
respect of all or any part of the Obligations or against any collateral
security therefor, guarantee thereof or right of offset with respect thereto.
Neither the Administrative Agent nor any Lender shall be liable for any failure
to demand, collect or realize upon all or any part of the Collateral or for any
delay in doing so, nor shall the Administrative Agent be under any obligation
to sell or otherwise dispose of any Collateral upon the request of the Parent
or any other Person or to take any other action whatsoever with regard to the
Collateral or any part thereof.

              8.     Remedies.  If an Event of Default shall occur and be
continuing, the Administrative Agent, on behalf of the Lenders, may exercise,
in addition to all other rights and remedies granted in this Agreement and in
any other instrument or agreement securing, evidencing or relating to the
Obligations, all rights and remedies of a secured party under the Code.
Without limiting the generality of the foregoing, the Administrative Agent,
without demand of performance
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or other demand, presentment, protest, advertisement or notice of any kind
(except any notice required by law referred to below) to or upon the Parent,
any Issuer, any Obligor or any other Person (all and each of which demands,
defenses, advertisements and notices are hereby waived), may in such
circumstances forthwith collect, receive, appropriate and realize upon the
Collateral, or any part thereof, and/or may forthwith sell, assign, give option
or options to purchase or otherwise dispose of and deliver the Collateral or
any part thereof (or contract to do any of the foregoing), in one or more
parcels at public or private sale or sales, in the over-the-counter market, at
any exchange, broker's board or office of the Administrative Agent or any
Lender or elsewhere upon such terms and conditions as it may deem advisable and
at such prices as it may deem best, for cash or on credit or for future
delivery without assumption of any credit risk.  The Administrative Agent or
any Lender shall have the right upon any such public sale or sales, and, to the
extent permitted by law, upon any such private sale or sales, to purchase the
whole or any part of the Collateral so sold, free of any right or equity of
redemption in the Parent, which right or equity is hereby waived or released.
The Administrative Agent shall apply any Proceeds from time to time held by it
and the net proceeds of any such collection, recovery, receipt, appropriation,
realization or sale, after deducting all reasonable costs and expenses of every
kind incurred in respect thereof or incidental to the care or safekeeping of
any of the Collateral or in any way relating to the Collateral or the rights of
the Administrative Agent and the Lenders hereunder, including, without
limitation, reasonable attorneys' fees and disbursements of counsel to the
Administrative Agent, to the payment in whole or in part of the Obligations, in
such order as the Administrative Agent may elect, and only after such
application and after the payment by the Administrative Agent of any other
amount required by any provision of law, including, without limitation, Section
9-504(1)(c) of the Code, need the Administrative Agent account for the surplus,
if any, to the Parent.  To the extent permitted by applicable law, the Parent
waives all claims, damages and demands it may acquire against the
Administrative Agent or any Lender arising out of the exercise by them of any
rights hereunder, except such claims and damages arising out of the gross
negligence or willful misconduct of the Administrative Agent or any such
Lender.  If any notice of a proposed sale or other disposition of Collateral
shall be required by law, such notice shall be deemed reasonable and proper if
given at least 10 days before such sale or other disposition.  The Parent shall
remain liable for any deficiency if the proceeds of any sale or other
disposition of Collateral are insufficient to pay the Obligations and the fees
and disbursements of any attorneys employed by the Administrative Agent or any
Lender to collect such deficiency.

              9.     Registration Rights; Private Sales.  (a)  If the
Administrative Agent shall determine to exercise its right to sell any or all
of the Pledged Stock pursuant to paragraph 8 hereof, and if in the opinion of
the Administrative Agent it is necessary or advisable to have the Pledged
Stock, or that portion thereof to be sold, registered under the provisions of
the Securities Act, the Parent will cause the Issuer thereof to (1) execute and
deliver, and cause the directors and officers of such Issuer to execute and
deliver, all such instruments and documents, and do or cause to be done all
such other acts as may be, in the opinion of the Administrative Agent,
necessary or advisable to register the Pledged Stock, or that portion thereof
to be sold, under the provisions of the Securities Act, (2) to use its best
efforts to cause the registration statement relating thereto to become
effective and to remain effective for a period of one year from the date of the
first public offering of the Pledged Stock, or that portion thereof to be sold
and (3) to make all amendments thereto and/or to the related prospectus which,
in the opinion of the Administrative Agent, are necessary or advisable, all in
conformity with the requirements of the Securities Act and the rules and
regulations of the Securities and Exchange Commission applicable thereto.  The
Parent agrees
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to cause such Issuer to comply with the provisions of the securities or "Blue
Sky" laws of any and all jurisdictions which the Administrative Agent shall
designate and to make available to its security holders, as soon as
practicable, an earnings statement (which need not be audited) which will
satisfy the provisions of Section 11(a) of the Securities Act.

              (b)    The Parent recognizes that the Administrative Agent may be
unable to effect a public sale of any or all the Pledged Stock, by reason of
certain prohibitions contained in the Securities Act and applicable state
securities laws or otherwise, and may be compelled to resort to one or more
private sales thereof to a restricted group of purchasers which will be obliged
to agree, among other things, to acquire such securities for their own account
for investment and not with a view to the distribution or resale thereof.  The
Parent acknowledges and agrees that any such private sale may result in prices
and other terms less favorable than if such sale were a public sale and,
notwithstanding such circumstances, agrees that any such private sale shall be
deemed to have been made in a commercially reasonable manner.  The
Administrative Agent shall be under no obligation to delay a sale of any of the
Pledged Stock for the period of time necessary to permit the Issuer thereof to
register such securities for public sale under the Securities Act, or under
applicable state securities laws, even if such Issuer would agree to do so.

              (c)    The Parent further agrees to use its best efforts to do or
cause to be done all such other acts as may be necessary to make such sale or
sales of all or any portion of the Pledged Stock pursuant to this Section valid
and binding and in compliance with any and all other applicable Requirements of
Law.  The Parent further agrees that a breach of any of the covenants contained
in this Section will cause irreparable injury to the Administrative Agent and
the Lenders, that the Administrative Agent and the Lenders have no adequate
remedy at law in respect of such breach and, as a consequence, that each and
every covenant contained in this Section 9 shall be specifically enforceable
against the Parent, and the Parent hereby waives and agrees not to assert any
defenses against an action for specific performance of such covenants except
for a defense that no Event of Default has occurred under the Credit Agreement.

              10.    Irrevocable Authorization and Instruction to Issuer and
Obligor.  The Parent hereby authorizes and instructs each Issuer and Obligor to
comply with any instruction received by it from the Administrative Agent in
writing that (a) states that an Event of Default has occurred and (b) is
otherwise in accordance with the terms of this Agreement, without any other or
further instructions from the Parent, and the Parent agrees that each Issuer
and each Obligor shall be fully protected in so complying.

              11.    Administrative Agent's Appointment as Attorney-in-Fact.
(a)  The Parent hereby irrevocably constitutes and appoints the Administrative
Agent and any officer or agent of the Administrative Agent, with full power of
substitution, as its true and lawful attorney-in-fact with full irrevocable
power and authority in the place and stead of the Parent and in the name of the
Parent or in the Administrative Agent's own name, from time to time in the
Administrative Agent's discretion, for the purpose of carrying out the terms of
this Agreement, to take any and all appropriate action and to execute any and
all documents and instruments which may be necessary or desirable to accomplish
the purposes of this Agreement, including, without limitation, any financing
statements, endorsements, assignments or other instruments of transfer.

              (b)    The Parent hereby ratifies all that said attorneys shall
lawfully do or cause to
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be done pursuant to the power of attorney granted in paragraph 11.(a).  All
powers, authorizations and agencies contained in this Agreement are coupled
with an interest and are irrevocable until the Obligations are paid in full and
the Commitments are terminated.

              12.    Duty of Administrative Agent.  The Administrative Agent's
sole duty with respect to the custody, safekeeping and physical preservation of
the Collateral in its possession, under Section 9-207 of the Code or otherwise,
shall be to deal with it in the same manner as the Administrative Agent deals
with similar securities and property for its own account.  Neither the
Administrative Agent, any Lender nor any of their respective directors,
officers, employees or agents shall be liable for failure to demand, collect or
realize upon any of the Collateral or for any delay in doing so or shall be
under any obligation to sell or otherwise dispose of any Collateral upon the
request of the Parent or any other Person or to take any other action
whatsoever with regard to the Collateral or any part thereof.

              13.    Execution of Financing Statements.  Pursuant to Section 9-
402 of the Code, the Parent authorizes the Administrative Agent to file
financing statements with respect to the Collateral without the signature of
the Parent in such form and in such filing offices as the Administrative Agent
reasonably determines appropriate to perfect the security interests of the
Administrative Agent under this Agreement.

              14.    Authority of Administrative Agent.  The Parent
acknowledges that the rights and responsibilities of the Administrative Agent
under this Agreement with respect to any action taken by the Administrative
Agent or the exercise or non-exercise by the Administrative Agent of any
option, voting right, request, judgment or other right or remedy provided for
herein or resulting or arising out of this Agreement shall, as between the
Administrative Agent and the Lenders, be governed by the Credit Agreement and
by such other agreements with respect thereto as may exist from time to time
among them, but, as between the Administrative Agent and the Parent, the
Administrative Agent shall be conclusively presumed to be acting as agent for
the Lenders with full and valid authority so to act or refrain from acting, and
neither the Parent, any Issuer nor any Obligor shall be under any obligation,
or entitlement, to make any inquiry respecting such authority.

              15.    Notices.  All notices, requests and demands to or upon the
Administrative Agent, the Parent, any Issuer or any Obligor to be effective
shall be in writing (or by telex, fax or similar electronic transfer confirmed
in writing) and shall be deemed to have been duly given or made (1) when
delivered by hand or (2) if given by mail, three days after being deposited in
the mail, postage prepaid, or (3) if by telex, fax or similar electronic
transfer, when sent and receipt has been confirmed, addressed to the
Administrative Agent or the Parent at its address or transmission number for
notices provided in the Credit Agreement and to each Issuer and each Obligor at
its address set forth in its Acknowledgment and Consent.  The Parent, any
Issuer and any Obligor may change their addresses and transmission numbers for
notices by written notice to the Administrative Agent.

              16.    Severability.  Any provision of this Agreement which is
prohibited or unenforceable in any jurisdiction shall, as to such jurisdiction,
be ineffective to the extent of such prohibition or unenforceability without
invalidating the remaining provisions hereof, and any such prohibition or
unenforceability in any jurisdiction shall not invalidate or render
unenforceable such provision in any other jurisdiction.
<PAGE>   11
                                                                              11


              17.    Amendments in Writing; No Waiver; Cumulative Remedies.
(a)  None of the terms or provisions of this Agreement may be waived, amended,
supplemented or otherwise modified except by a written instrument executed by
the Parent and the Administrative Agent, provided that any provision of this
Agreement may be waived by the Administrative Agent and the Lenders in a letter
or agreement executed by the Administrative Agent or by telex or facsimile
transmission from the Administrative Agent.

              (b)    Neither the Administrative Agent nor any Lender shall by
any act (except by a written instrument pursuant to paragraph 17.(a) hereof),
delay, indulgence, omission or otherwise be deemed to have waived any right or
remedy hereunder or to have acquiesced in any Default or Event of Default or in
any breach of any of the terms and conditions hereof.  No failure to exercise,
nor any delay in exercising, on the part of the Administrative Agent or any
Lender, any right, power or privilege hereunder shall operate as a waiver
thereof.  No single or partial exercise of any right, power or privilege
hereunder shall preclude any other or further exercise thereof or the exercise
of any other right, power or privilege.  A waiver by the Administrative Agent
or any Lender of any right or remedy hereunder on any one occasion shall not be
construed as a bar to any right or remedy which the Administrative Agent or
such Lender would otherwise have on any future occasion.

              (c)    The rights and remedies herein provided are cumulative,
may be exercised singly or concurrently and are not exclusive of any other
rights or remedies provided by law.

              18.    Section Headings.  The Section headings used in this
Agreement are for convenience of reference only and are not to affect the
construction hereof or be taken into consideration in the interpretation
hereof.

              19.    Successors and Assigns.  This Agreement shall be binding
upon the successors and assigns of the Parent and shall inure to the benefit of
the Administrative Agent and the Lenders and their successors and assigns.

              20.    Governing Law.  This Agreement shall be governed by, and
construed and interpreted in accordance with, the law of the State of New York.
<PAGE>   12
                                                                              12


              IN WITNESS WHEREOF, the undersigned has caused this Agreement to
be duly executed and delivered as of the date first above written.

                                          SYBRON INTERNATIONAL CORPORATION

                                          By:
                                             ---------------------------------
                                          Title:
                                                ------------------------------
<PAGE>   13
                                                                      SCHEDULE 1
                                                             TO PLEDGE AGREEMENT



                          DESCRIPTION OF PLEDGED STOCK


<TABLE>
<CAPTION>
                                                                         No. of Shares    Total No. of Shares
                                     Class of      Stock Certificate        Pledged           Outstanding
              Issuer                   Stock              No.
<S>                                  <C>           <C>                   <C>              <C>
</TABLE>
<PAGE>   14
                                                                      SCHEDULE 2
                                                             TO PLEDGE AGREEMENT



                                 PLEDGED NOTES


<TABLE>
<CAPTION>
                                                                   Original
                              Date of                              Principal
 Obligor                      Note                                 Amount   
 -------                      -------                              ---------
<S>                           <C>                                  <C>
                                                                   $         
                                                                    ---------
</TABLE>
<PAGE>   15
                          ACKNOWLEDGEMENT AND CONSENT


              Each of the undersigned is an Issuer referred to in the foregoing
Pledge Agreement, and each of the undersigned hereby acknowledges receipt of a
copy of the Pledge Agreement, dated July 1, 1998, made by Sybron International
Corporation for the benefit of The Chase Manhattan Bank, as Administrative
Agent (as amended, supplemented or otherwise modified from time to time, the
"Pledge Agreement").  The undersigned agrees for the benefit of the
Administrative Agent and the Lenders as follows:

              1.  The undersigned will be bound by the terms of the Pledge
       Agreement and will comply with such terms insofar as such terms are
       applicable to the undersigned.

              2.  The undersigned will notify the Administrative Agent promptly
       in writing of the occurrence of any of the events described in paragraph
       5.(a) of the Pledge Agreement.

              3.  The terms of paragraph 9.(c) of the Pledge Agreement shall
       apply to it, mutatis mutandis, with respect to all actions that may be
       required of it under or pursuant to or arising out of Section 9 of the
       Pledge Agreement.



                                           SYBRON DENTAL SPECIALTIES, INC.
                                           SYBRON TRANSITION CORP.
                                           MEXOSERV COMPANY
                                           SYBRON LABORATORY PRODUCTS
                                             CORPORATION
                                           NATIONAL SCIENTIFIC COMPANY
                                           LRS ACQUISITION CORP.

                                                                           
                                           --------------------------------
                                           By:    John J. Buono, Assistant
                                                  Treasurer


                                           Address for Notices:

                                           c/o Sybron International Corporation
                                           411 East Wisconsin Avenue, 24th Floor
                                           Milwaukee, Wisconsin  53202
                                           Fax:  (414) 274-6561