Exhibit 3.1(b)

AMENDED AND RESTATED

CERTIFICATE OF INCORPORATION

OF

AMERICAN DENTAL PARTNERS, INC.

American Dental Partners, Inc. (the “Corporation”), a corporation organized and existing under the General Corporation Law of the State of Delaware (the “DGCL”), does hereby certify as follows:

FIRST: The name of the corporation is American Dental Partners, Inc. The original Certificate of Incorporation of the Corporation was filed with the Secretary of State of the State of Delaware on December 22, 1995, amended January 12, 1996 and November 7, 1996. An amended and restated certificate of incorporation was filed with the Secretary of State of the State of Delaware on December 31, 1996, amended October 31, 1997, amended and restated November 26, 1997, and restated February 9, 2012.

SECOND: This Amended and Restated Certificate of Incorporation was duly adopted by the board of directors of the Corporation and by the sole stockholder of the Corporation in accordance with Sections 228, 242 and 245 of the DGCL.

The text of the Certificate of Incorporation of the Corporation is hereby amended and restated in its entirety to read as follows:

FIRST: The name of the corporation (which is hereinafter referred to as the “Corporation”) is American Dental Partners, Inc.

SECOND: The name and address of the registered agent in the State of Delaware is The Corporation Trust Company, 1209 Orange Street, Wilmington, New Castle County, Delaware 19801.

THIRD: The purpose of 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, as from time to time amended.

FOURTH: The total number of shares of stock which the Corporation shall have authority to issue is one thousand (1,000) shares of common stock, par value $0.01 per share.

FIFTH: In furtherance and not in limitation of the powers conferred by law, subject to any limitations contained elsewhere in this certificate of incorporation, bylaws of the Corporation may be adopted, amended or repealed by a majority of the board of directors of the Corporation, but any bylaws adopted by the board of directors may be amended or repealed by the stockholders entitled to vote thereon. Election of directors need not be by written ballot.

SIXTH: (a) No director shall 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; provided, however, that, to the extent provided by applicable law, this provision shall not eliminate the liability of a director i) for any breach of a director’s duty of loyalty to the Corporation or its stockholders, ii) for acts or omissions not in good faith or which involve intentional misconduct or a knowing violation of law, iii) under Section 174 of the General Corporation Law of Delaware, or iv) for any transaction from which the director derived an improper personal benefit. No amendment to or repeal of this provision shall apply to or have any effect on the liability or alleged liability of any director for or with respect to any acts or omissions of such director occurring prior to such amendment or repeal.

(b) The Corporation shall indemnify and hold harmless any person who was or is a party or is threatened to be made a party to, or testifies in, any threatened, pending or completed action, claim, suit or proceeding, whether civil, criminal, administrative or investigative, by reason of the fact that such person is or was a director or officer of the Corporation, or is or was serving at the request of the Corporation as a director, officer, employee or agent of another corporation, partnership, joint venture, employee benefit plan, trust or other enterprise, against all claims, losses, liabilities, expenses (including attorneys’ fees and disbursements), damages, judgments, fines and amounts paid in settlement actually and reasonably incurred by such person in connection with such action, suit or proceeding to the fullest extent permitted under the General Corporation Law of the State of Delaware, and the Corporation may adopt bylaws or enter into agreements with any such person for the purpose of providing for such indemnification.

(c) To the extent that a director or officer of the Corporation has been successful on the merits or otherwise in defense of any action, suit or proceeding referred to in paragraph (b) of this Article SIXTH, or in defense of any claim, issue or matter therein, such person shall be indemnified against expenses (including attorneys’ fees) actually and reasonably incurred by such person in connection therewith.

(d) Expenses (including attorneys’ fees) incurred by an officer or director in defending or testifying in a civil, criminal, administrative or investigative action, claim, suit or proceeding by reason of the fact that such person is or was an officer or director of the Corporation (or is or was serving at the request of the Corporation as a director, officer, employee or agent of another corporation, partnership, joint venture, employee benefit plan, trust or other enterprise) shall be paid by the Corporation in advance of the final disposition of such action, claim, suit or proceeding within ten business days of the Corporation’s receipt of a request for advancement of such expenses from such director or officer and, to the extent required by law, upon receipt of an undertaking by or on behalf of any such director or officer to repay such amount if it shall ultimately be determined that such director or officer is not entitled to be indemnified by the Corporation against such expenses as authorized by the relevant sections of the General Corporation Law of the State of Delaware, and the Corporation may adopt bylaws or enter into agreements with such persons for the purpose of providing for such advances.

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(e) The indemnification permitted by this Article SIXTH shall not be deemed exclusive of any other rights to which any person may be entitled under any agreement, vote of stockholders or disinterested directors or otherwise, both as to action in such person’s official capacity and as to action in another capacity while holding an office, and 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 person.

(f) The Corporation shall have power to 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, employee or agent of another corporation, partnership, joint venture, employee benefit plan 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 the provisions of this Article SIXTH or otherwise.

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IN WITNESS WHEREOF, the Corporation has caused this Amended and Restated Certificate of Incorporation to be executed on its behalf this 9^th day of February, 2012.

[Signature Page to the Amended and Restated Certificate of Incorporation of American Dental Partners, Inc.]