AMENDMENT NO. 7 TO AMENDED AND RESTATED CREDIT AGREEMENT

Exhibit 10.1

AMENDMENT NO. 7 TO AMENDED AND RESTATED CREDIT AGREEMENT

This Amendment No. 7 to Amended and Restated Credit Agreement (this “ Amendment ”) is dated as of October 24, 2008, by and among AMERICAN DENTAL PARTNERS, INC., a Delaware corporation (the “ Borrower ”), the Subsidiaries of the Borrower party hereto (collectively, the “ Subsidiary Guarantors ” and together with the Borrower, the “ Credit Parties ”), the lending institutions party to the Credit Agreement, as hereinafter defined (the “ Lenders ”), and KEYBANK NATIONAL ASSOCIATION, a national banking association, as administrative agent for the Lenders (the “ Administrative Agent ”).

WHEREAS, the Borrower, the Administrative Agent and the Lenders are parties to that certain Amended and Restated Credit Agreement, dated as of February 22, 2005, as amended by the Omnibus Amendment Agreement and Waiver, dated as of January 26, 2007, Amendment No. 2 to Amended and Restated Credit Agreement, dated February 21, 2007, Amendment No. 3 to Amended and Restated Credit Agreement, dated as of September 25, 2007, Amended and Restated Forbearance Agreement and Amendment No. 4 to Credit Agreement, dated as of January 11, 2008, Amendment No. 5 to Amended and Restated Credit Agreement and Waiver, dated as of February 21, 2008, Amendment No. 6 to Amended and Restated Credit Agreement, dated as of June 11, 2008, which provides, among other things, for revolving loans, letters of credit and other financial accommodations, all upon certain terms and conditions stated therein (as amended and as the same may be further amended, restated or otherwise modified from time to time, the “ Credit Agreement ”);

WHEREAS, the Credit Parties have requested, and the Administrative Agent and the Lenders have agreed, to amend the Credit Agreement to modify certain provisions thereof;

NOW, THEREFORE, in consideration of the premises and of the mutual covenants herein contained and for other valuable considerations, the Credit Parties, the Administrative Agent and the Lenders hereby agree as follows:

Section 1. Definitions . Each capitalized term used herein and not otherwise defined in this Amendment shall be defined in accordance with the Credit Agreement.

Section 2. Amendments to Credit Agreement .

2.1 New Definitions . Section 1.1 of the Credit Agreement is hereby amended to add the following new definitions thereto in the appropriate alphabetical order:

““ Amendment No. 7 Effective Date ” shall mean the date upon which the conditions specified in Section 3.1 of Amendment No. 7 to Amended and Restated Credit Agreement are satisfied.”

““ Amendment No. 7 to Amended and Restated Credit Agreement ” shall mean Amendment No. 7 to Amended and Restated Credit Agreement, dated as of October 24, 2008, by and among the Borrower, the Subsidiary Guarantors, the Lenders and the Administrative Agent.”

““ Term Loan Agreement Amendment No. 3 ” shall mean Amendment No. 3 to Term Loan Agreement, dated as of October 24, 2008, by and among the Borrower, the subsidiary guarantors signatory thereto, the lenders signatory thereto and KBCM Bridge LLC, as a lender and as administrative agent.”

SOLICITORS, 068999, 000002, 102522951.1, Amendment No 7 to Credit Agr - Conformed

2.2 Amendment to Section 1.1 . Section 1.1 of the Credit Agreement is hereby amended to amend and restate the definitions of “Applicable Margin,” “Base Rate” and “Facility Termination Date” in their entirety as follows:

““ Applicable Margin ” shall mean:

(i) As of the Amendment No. 7 Effective Date, until changed hereunder in accordance with the following provisions, the Applicable Margin shall be (A) 450.00 basis points for Base Rate Loans, and (B) 450.00 basis points for Eurodollar Loans;

(ii) Commencing with the fiscal quarter of the Borrower ended on December 31, 2008, and continuing with each fiscal quarter thereafter, the Administrative Agent shall determine the Applicable Margin in accordance with the following matrix, based on the Leverage Ratio:

(iii) Changes in the Applicable Margin based upon changes in the Leverage Ratio shall become effective on the third Business Day following the receipt by the Administrative Agent pursuant to Section 8.1(a) or (b) of the financial statements of the Borrower, accompanied by the certificate and calculations referred to in Section 8.1(c), demonstrating the computation of the Leverage Ratio, based upon the Leverage Ratio in effect at the end of the applicable period covered (in whole or in part) by such financial statements. Notwithstanding the foregoing provisions, during any period when (A) the Borrower has failed to timely deliver its consolidated financial statements referred to in Section 8.1(a) or (b), accompanied by the certificate and calculations referred to in Section 8.1(c), (B) a Default under Section 10.1(a) has occurred and is continuing, or (C) an Event of Default has occurred and is continuing, the Applicable Margin shall be the highest rate per annum indicated therefor in the above matrix, regardless of the Leverage Ratio at such time. Any changes in the Applicable Margin shall be determined by the Administrative Agent in accordance with the provisions set forth in this definition and the Administrative Agent will promptly provide notice of such determinations to the Borrower and the Lenders. Any such determination by the Administrative Agent shall be conclusive and binding absent manifest error.”

““ Base Rate ” shall mean, for any day, a fluctuating interest rate per annum as shall be in effect from time to time which rate per annum shall at all times be equal to the greatest of: (i) the rate of interest established by KeyBank in Cleveland, Ohio, from time to time, as its “prime rate,” whether or not publicly announced, which interest rate may or may not be the lowest rate charged by it for commercial loans or other extensions of credit; (ii) the Federal Funds Effective Rate in effect from time to time, determined one Business Day in arrears, plus  ¹ / 2 of 1.00% per annum; and (iii) the Adjusted Eurodollar Rate for one month interest periods that would be applicable had the Borrower submitted on such day a Notice of Borrowing, Co