Exhibit 99.1

American Dental Partners, Inc.

401 Edgewater Place, Suite 430

Wakefield, MA 01880

For Immediate Release

AMERICAN DENTAL PARTNERS

ANNOUNCES END OF “GO-SHOP” PERIOD

WAKEFIELD, MASSACHUSETTS – December 15, 2011 – American Dental Partners, Inc. (Nasdaq: ADPI) (“American Dental Partners” or the “Company”) today announced the expiration of the 40-day “go-shop” period during which the Company solicited alternative proposals to the proposed acquisition of the Company by funds affiliated with JLL Partners, Inc. (“JLL”), a leading private equity fund. The “go-shop” process was expressly contemplated by the previously announced Agreement and Plan of Merger, dated as of November 4, 2011, that the Company entered into with JLL Crown Holdings, LLC, a Delaware limited liability company, and JLL Crown Merger Sub, Inc.

After a broad solicitation of financial and strategic parties during the go-shop period, which ended at 11:59 p.m. (Eastern time) on December 14, 2011, the Company did not receive any acquisition proposals.

The Company expects the transaction to close in the first quarter of 2012, subject to satisfaction of the closing conditions described in the merger agreement, including receipt of stockholder approval.

Greenhill & Co, LLC is the financial advisor to the special committee of the Company’s board of directors, and BofA Merrill Lynch is the financial advisor to the Company’s board of directors.

About American Dental Partners

American Dental Partners is one of the nation’s leading business partners to dental group practices. The Company is affiliated with 27 dental group practices, which have 282 dental facilities with approximately 2,404 operatories located in 21 states.

About JLL

JLL Partners is a New York-based leading private equity investment firm with approximately $4 billion of capital under management. JLL’s investment philosophy is to partner with outstanding management teams and invest with them in companies that they can continue to grow into market leaders. JLL has invested in a variety of industries, with special focus on healthcare services, financial services and business services. More information on JLL can be found on the website www.jllpartners.com.

Forward-Looking Statements:

Certain statements herein are “forward-looking statements” pursuant to the safe harbor provisions of the Private Securities Litigation Reform Act of 1995. Such forward-looking statements reflect the Company’s current expectations or beliefs concerning future events and actual results of operations may differ materially from historical results or current expectations. Any such forward-looking statements are subject to various risks and uncertainties, including but not limited to risks associated with overall or regional economic conditions, dependence upon affiliated dental practices, contracts the affiliated practices have with third-party payors, government regulation of the dental industry, the impact of health care reform, dependence upon service agreements and the impact of any terminations or potential terminations of such contracts, business interruptions, the outcome of pending litigation, the Company’s acquisition and affiliation strategy, the parties’ ability to consummate the proposed acquisition of the Company on the contemplated timeline and other factors that are set forth in the Company’s Form 10-K and in all filings with the SEC made by the Company subsequent to the filing of the Form 10-K. The Company does not undertake to publicly update or revise its forward-looking statements, whether as a result of new information, future events or otherwise.

Additional Information and Where to Find It:

This communication may be deemed to be solicitation material in respect of the proposed merger. In connection with the proposed transaction, the Company has filed a preliminary proxy statement with the SEC related to the merger on November 29, 2011. When completed, a definitive proxy statement and a form of proxy will be mailed to the stockholders of the Company. INVESTORS AND SECURITY HOLDERS OF THE COMPANY ARE URGED TO READ CAREFULLY AND IN THEIR ENTIRETY ALL RELEVANT MATERIALS FILED WITH THE SECURITIES AND EXCHANGE COMMISSION, INCLUDING THE PROXY STATEMENT, WHEN THEY BECOME AVAILABLE, BECAUSE THESE MATERIALS WILL CONTAIN IMPORTANT INFORMATION ABOUT THE PROPOSED TRANSACTION. Investors and security holders may obtain a free copy of the proxy statement and other documents filed by the Company with the Securities and Exchange Commission (when available) at the Securities and Exchange Commission’s website at http://www.sec.gov or at the Company’s website at http://www.amdpi.com. The proxy statement and other relevant materials (when available) may also be obtained for free from the Company by directing a request to American Dental Partners, Inc., 401 Edgewater Place, Suite 430, Wakefield, Massachusetts 01880, telephone (781) 224- 0880. The contents of the websites referenced above are not deemed to be incorporated by reference into the proxy statement.

Participants in Solicitation:

The Company and its directors, executive officers and other members of its management and employees may be deemed to be participants in the solicitation of proxies from the Company’s stockholders in connection with the proposed merger. Information concerning the interests of the Company’s participants in the solicitation is, and will be, set forth in the Company’s proxy statements and Annual Reports on Form 10-K, previously or in the future filed with the Securities and Exchange Commission, and in the proxy statements relating to the proposed transaction when it becomes available. Each of these documents is, or will be, available free of charge at the Securities and Exchange Commission’s website at http://www.sec.gov and from the Company at http://www.amdpi.com, or by directing a request to American Dental Partners, Inc., 401 Edgewater Place, Suite 430, Wakefield, Massachusetts 01880, telephone (781) 224-0880.