Sentinel sells Metro Dentalcare to American Dental Partners, Inc.

Transaction Combines Two Leading Dental Companies

NEW YORK, September 26, 2007 - Sentinel Capital Partners, a private equity firm that invests in promising, smaller middle-market companies, announced today the sale of Metropolitan Dental Holdings, Inc. (dba "Metro Dentalcare") to American Dental Partners, Inc. (NASDAQ: ADPI).

Minneapolis-St. Paul based Metro Dentalcare is a multi-specialty dental group with more than 90 dentists, 33 dental facilities and a dental lab that has provided quality dental care since 1968. Generating approximately $70 million in patient revenue annually, Metro Dentalcare provides a complete range of services including routine, cosmetic and specialized dental health services including preventative care, whitening, crowns, veneers, dental implants, oral surgery, endodontics, periodontics, children's dentistry and orthodontics.

"We are grateful to have had the opportunity to work with and support Metro Dentalcare's talented management team in significantly growing the business, improving operations and financial performance, and transforming the company into a leading dental care provider in the Twin Cities," said Paul Murphy, a partner at Sentinel. "This is a great business and we are proud to have positioned it for future success with ADPI, where there is a strong strategic fit."

"This transaction brings together two leading dental companies, and we are confident that we are better positioned now than ever before to provide high quality patient care," said Dr. David Milbrath, Co-Founder and Chairman of Metro Dentalcare. "It has truly been a pleasure working closely with the team at Sentinel, and we thank them for their invaluable counsel and support."

"The Sentinel team's knowledge of and prior success in the dental industry coupled with their experience helping businesses grow made them the ideal partner for Metro Dentalcare; with Sentinel's support, we expanded from 64 doctors in 2005 to more than 90 doctors today providing care to more than 220,000 patients annually," said Dr. Marcus Gustafson, Co-Founder and CEO of Metro Dentalcare. "We look forward to continued growth under our new affiliation with ADPI."

"This transaction is a testament to the great progress Metro Dentalcare has made under the leadership of Dr. David Milbrath and Dr. Marcus Gustafson," said Jim Coady, a partner at Sentinel. "Part of Sentinel's strategy is to back strong management teams in industry sectors where Sentinel has experience and has enjoyed success. Including Metro Dentalcare, we have successfully completed two dental care investments and four healthcare investments. Metro Dentalcare is also one of six recent Sentinel investments in the Minneapolis-St. Paul region, a market we intently follow and like a great deal."

Sentinel's healthcare related investments include Castle Dental Centers, Inc., a leading dental services provider the firm sold in 2004; Interim Healthcare Holdings, Inc., the nation's largest provider of home healthcare and supplemental healthcare staffing services; and Strategic Partners, a leading supplier of medical uniforms for healthcare professionals. Sentinel has also made six investments in Minneapolis-St. Paul ­ Border Foods, Inc., the leading franchisor of Taco Bell restaurants in Minnesota; Buffets, Inc., the largest operator of buffet-style restaurants in the U.S.; LTI Flexible Products, a leader in designing and manufacturing specialty sealing systems for industrial applications; Trussbilt, LLC, a manufacturer of steel security products for the detention and corrections market; and, most recently, Inscape Publishing, Inc., a leading provider of corporate training solutions for employee assessment and development.