The origins are older than the acronym
The trade association traces the model to 1975, when Affordable Care supported its first denture practice.2 Several of today’s platforms are survivors of that pre-acronym era rather than post-2010 creations: Gentle Dental (now 42 North Dental) began in Boston around 1980; Pacific Dental Services was founded in 1994; the company that became Aspen Dental was assembled from two upstate New York groups and renamed in 1998; Heartland Dental was founded by Dr. Rick Workman in Effingham, Illinois in 1997.3The first public wave, and the OCA collapse
The 1990s produced publicly traded “dental practice management companies.” Their contracts, failures, and litigation influenced later DSO structures. Orthodontic Centers of America went public in December 1994 and more than tripled its center count in two years.4 Its 20-to-40-year Business Services Agreements gave the company control of offices, equipment, staff, billing, and bank accounts in exchange for a share of practice economics. Then, in sequence: accounting errors forced a restatement of its 2004 quarterly financials in 2005, the stock collapsed and was delisted, and OCA filed Chapter 11 in March 2006 while fighting affiliated orthodontists in dozens of lawsuits over whether its agreements were void as the unlicensed corporate practice of dentistry.5 Courts in Texas, Washington, Colorado, and South Carolina held they were; the Fifth Circuit affirmed in 2008 and later held OCA could not even recover money from the dentists once the contracts were declared illegal.6 The case law page covers the decisions in full. The same period saw the physician practice management crash, including FPA Medical, MedPartners, and eventually PhyCor. Public-market interest in clinical roll-ups then receded for years.7 The 1990s model exposed problems in economics, clinician relations, and legal structure. Later DSO agreements responded with dentist-owned professional entities, clearer clinical reservations, shorter terms, and revised fee formulas, among other changes.The private equity era
The next wave combined management companies with private capital and dentist equity:- Ontario Teachers’ Pension Plan took a majority stake in Heartland Dental in November 2012, when it had 397 supported practices; KKR acquired a majority interest in 2018, by which point supported-practice revenue was roughly $$1.3 billion.8 Heartland reported more than 1,800 supported offices across 39 states in 2025.9
- Aspen Dental’s ownership passed from Ares (2006) to Leonard Green & Partners (2010, reported around $$500 million) to an American Securities-led recapitalization (2015).10
- Private-equity transactions involving dental practices ran at fewer than 20 per year from 2004 to 2015, then climbed to 96 in 2021. The share of dentists affiliated with PE increased from 6.6% in 2015 to 12.8% in 2021.11 In 2025, roughly 95% of tracked dental PE deals were add-ons to existing platforms rather than new platform formations.12
The market today
The ADA Health Policy Institute’s workforce series is the authoritative measure:1
The distribution varies substantially by age and state:
- By career stage (2024): 26.5% of dentists up to ten years out of school; 14.4% at 11–25 years; 9.1% beyond 25 years.
- By state (2024): Nevada and Colorado were around 27%, Oklahoma 26%, and Arizona, Texas, and Georgia 25%. Hawaii was at 2% and North Dakota at 3%.
- Ownership is occurring later. Practice ownership fell from 84.7% of dentists in 2005 to 72.5% in 2023, and ownership among dentists under 30 fell from 25.4% to 8.8%. HPI’s cohort analysis nevertheless finds recent cohorts reaching roughly 90% ownership by late career.13 Many young dentists begin in DSO employment and buy later. Some DSOs respond with the equity-participation structures covered in DSO economics.
Who the major platforms are
Counts are company-reported and move constantly; treat them as order-of-magnitude, with as-of dates.14
One useful distinction is branded versus affiliated. Aspen and Affordable Dentures use a common consumer brand, while Heartland, MB2, and DCA generally retain local practice names. Branding can matter to the corporate-practice analysis because it affects who appears to provide care. It can also signal a growth model, although both branded and affiliated groups may use acquisitions and de novos.
The association and the name
The industry’s trade association is the Association of Dental Support Organizations (ADSO). It began as the Dental Group Practice Association in 2007, with thirteen members including Affordable Care, Aspen, Heartland, and Pacific Dental Services, and adopted the ADSO name in 2014. The association reports more than 80 DSO members supporting over 8,500 practices.2 The association and the ADA use “dental support organization,” while industry media and some state statutes use “dental service organization.” This wiki uses “support.”What the research says about effects on care
The evidence base is early, and an honest summary points in more than one direction:15- Medicaid participation was higher in one analysis. The Health Affairs study found PE-affiliated dental practices more likely to participate in Medicaid than unaffiliated practices, which may reflect scale in claims administration.
- Pricing is neutral-to-cautionary. A 2025 Health Services Research study of 2015–2021 acquisitions found post-acquisition charges rose 3.3% but allowed (negotiated) prices were statistically unchanged, while the service mix shifted from diagnostic and preventive toward higher-reimbursement restorative, specialty, and surgical procedures.
- Quality-outcome research remains limited, as the researchers note. The enforcement history, much of it involving Medicaid pediatric chains in earlier years, is a different evidence base from peer-reviewed outcome studies. See the enforcement tracker.
Sources
- ADA Health Policy Institute, The U.S. Dentist Workforce (August 2025 edition).
- ADSO, About ADSO; Group Dentistry Now, ADSO history (DGPA formed 2007; renamed ADSO 2014).
- OTPP/KKR release (n.8) on Heartland’s 1997 founding; Aspen Dental history; 42 North Dental; Dental Care Alliance history.
- FundingUniverse, Orthodontic Centers of America company history.
- Securities litigation summary of the 2005 restatement, bigclassaction.com; In re OCA, Inc., 552 F.3d 413 (5th Cir. 2008), opinion (Chapter 11 filed March 2006, Bankr. E.D. La. No. 06-10179).
- Penny v. OrthAlliance, Inc., 255 F. Supp. 2d 579 (N.D. Tex. 2003), opinion; In re OCA (n.5); Packard v. OCA, Inc., 624 F.3d 726 (5th Cir. 2010), opinion.
- Tampa Bay Times, Doctors regain control of clinics (2000); PhyCor.
- OTPP/KKR, KKR to acquire majority interest in Heartland Dental (announced March 7, 2018; closed April 30, 2018).
- Heartland Dental, company growth release, August 5, 2025 (via PRNewswire; company-reported figures).
- Aspen Dental ownership history (Ares 2006; Leonard Green 2010; American Securities 2015).
- Nasseh, LoSasso & Vujicic, Percentage of Dentists and Dental Practices Affiliated With Private Equity Nearly Doubled, 2015–21, Health Affairs 43(8) (August 2024); ADA News summary.
- Private Equity Stakeholder Project, PE healthcare deals: 2025 in review (deal counts; PESP is an advocacy organization).
- ADA HPI, Practice Ownership Trends in Dentistry: A New Look at Old Data (June 2025).
- Company sources: Heartland Dental release (n.9); MB2 year-end 2025 release; Smile Brands; DCA; Affordable Care; Smile Doctors; 42 North Dental.
- Health Affairs (n.11); Nasseh, LoSasso, Vujicic & Downey, Financial Incisors: Cutting Through the Effects of Private Equity on Dentistry Market Dynamics and Care Delivery, Health Services Research (published December 2025).