EXHIBIT 10.1

SUPPLEMENT TO AMENDED AND RESTATED PLEDGE AND SECURITY AGREEMENT

THIS SUPPLEMENT TO AMENDED AND RESTATED PLEDGE AND SECURITY AGREEMENT, dated as
of April 19, 2006 (this “Supplement”), is between:

(i) PDHC, LTD., a Minnesota corporation (the “PDHC”); and

(ii) KEYBANK NATIONAL ASSOCIATION, a national banking association, as
administrative agent (in such capacity as administrative agent, the
“Administrative Agent”), for the benefit of the Secured Creditors:

PRELIMINARY STATEMENTS:

(1) PDHC, the other Grantors named therein and the Administrative Agent are
parties to the Amended and Restated Pledge and Security Agreement, dated as of
February 22, 2005 (the “Pledge and Security Agreement”), which Pledge and
Security Agreement was made pursuant to the Amended and Restated Credit
Agreement, dated as of February 22, 2005 (as may be further amended or otherwise
modified, restated, replaced or amended and restated from time to time, the
“Credit Agreement”), among American Dental Partners, Inc., the financial
institutions named as lenders therein, and the Administrative Agent.

(2) PDHC and the Administrative Agent desire to supplement the Pledge and
Security Agreement, as required by Section 4.15 thereof, to grant the
Administrative Agent a security interest in a certain Commercial Tort Claim held
by PDHC.

(3) It is a condition precedent to the continued making of Loans and the
continued issuance of, and participation in, Letters of Credit, under the Credit
Agreement that PDHC shall have executed and delivered to the Administrative
Agent this Supplement.

(4) PDHC has obtained, and will continue to obtain, benefits from the Credit
Agreement and, accordingly, desires to execute this Supplement in order to
satisfy the condition described in the preceding paragraph and to induce the
Secured Creditors to continue to extend credit pursuant to the Credit Agreement
and the other Credit Documents.

(5) Capitalized terms used in this Supplement and not otherwise defined herein
shall have the meanings given to such terms in the Credit Agreement or the
Pledge and Security Agreement, as applicable.

NOW, THEREFORE, in consideration of the benefits accruing to PDHC, the receipt
and sufficiency of which is hereby acknowledged, PDHC hereby covenants and
agrees with the Administrative Agent, for the benefit of itself and the Secured
Creditors, as follows:

 

1.

Grant of Security Interest. As security for the prompt and complete payment and
performance when due of the Secured Obligations, PDHC does hereby pledge, sell,
assign and transfer unto the Administrative Agent, and does hereby grant to the
Administrative Agent, for the benefit of the Secured Creditors, a continuing
security interest in, all of its right, title and interest in and to the
Commercial Tort Claim relating to Court File No: 27-CV-06-2500, PDG, P.A. and
Dental Specialists of Minnesota, P.A. v. PDHC, Ltd., filed in the State of
Minnesota District Court,

--------------------------------------------------------------------------------

 

Fourth Judicial District, and all Proceeds of the foregoing. PDHC hereby
authorizes the Administrative Agent to file the financing statement attached
hereto as Exhibit A.

 

2. Representations and Warranties. PDHC, by signing below, hereby represents and
warrants to the Administrative Agent and the Secured Creditors that: (a) PDHC
has the legal power and authority to execute and deliver this Supplement;
(b) the officer executing this Supplement has been duly authorized to execute
and deliver the same and bind PDHC with respect to the provisions hereof; (c) no
Default or Event of Default exists under the Pledge and Security Agreement, nor
will any occur immediately after the execution and delivery of this Supplement
or by the performance or observance of any provision hereof; (d) PDHC has no
claim or offset against, or defense or counterclaim to, any obligations or
liabilities of PDHC under any Credit Document; (e) this Supplement constitutes a
valid and binding obligation of PDHC in every respect, enforceable in accordance
with its terms, except as the enforceability thereof may be limited by
bankruptcy, insolvency or other similar laws of general application affecting
the enforcement of creditors’ rights or by general principles of equity limiting
the availability of equitable remedies; and (f) each of the representations and
warranties set forth in the Pledge and Security Agreement is true and correct as
of the date hereof, except to the extent that any thereof expressly relate to an
earlier date, in which case such representations and warranties were true and
correct as of such earlier date.

 

3. Pledge and Security Agreement Unaffected. Each reference to the Pledge and
Security Agreement in any Credit Document shall hereafter be construed as a
reference to the Pledge and Security Agreement as supplemented hereby.

 

4. Waiver. PDHC, by signing below, hereby waives and releases the Administrative
Agent and each of the Secured Creditors and their respective directors,
officers, employees, attorneys, affiliates and subsidiaries from any and all
claims, offsets, defenses and counterclaims of which PDHC is aware, such waiver
and release being with full knowledge and understanding of the circumstances and
effect thereof and after having consulted legal counsel with respect thereto.

 

5. Governing Law. THIS SUPPLEMENT AND THE RIGHTS AND OBLIGATIONS OF THE PARTIES
HEREUNDER SHALL BE CONSTRUED IN ACCORDANCE WITH AND BE GOVERNED BY THE INTERNAL
LAWS OF THE STATE OF OHIO WITHOUT ANY EFFECT GIVEN TO THE CONFLICTS OF LAW
PRINCIPLES THEREOF.

[Remainder of page intentionally left blank]

 

- 2 -

--------------------------------------------------------------------------------

IN WITNESS WHEREOF, the PDHC has caused this Agreement to be executed and
delivered by a duly authorized officer as of the date first above written.

 

PDHC, LTD.

By:   

/s/ Breht T. Feigh

Name: 

 

Breht T. Feigh

Title: 

 

Vice President

Accepted by:

 

KEYBANK NATIONAL ASSOCIATION,

as Administrative Agent

By:  

/s/ J. T. Taylor

Name:  

J. T. Taylor

Title:

 

Senior Vice President