About Us
Experience Where It Matters
The Mill Street Equity team has a proven track record of success with decades of investment, research, operational, development, and leadership experience.
Robert Cartagena
31 Years In Dental Products and Medical Devices
Experience and Education
- COO and Board Member, DenMat Holdings LLC
- COO and Board Member, Discus Dental LLC | Philips
- Board Member, LED Medical
- Board Member, Children's Dental Center
- BS Business Management, Nova Southeastern Univ.
rcartagena@millstreetequity.com
Todd Tiberi
Mr. Tiberi recently was appointed by the current White House Administration to serve as the General Counsel for the United States Patent and Trademark Office ("USPTO"). As of 11/16/25, Mr. Tiberi ceased active participation in Mill Street Equity, which cessation shall be in effect for the duration of his tenure as General Counsel for the USPTO.
16 Years in Dental Products and Medical Devices
Experience and Education
- CAO and Board Member, DenMat Holdings LLC
- General Counsel, Discus Dental LLC | Philips
- Attorney, Skadden Arps Slate Meagher & Flom LLP
- BS Chemical Engineering, Carnegie Mellon Univ.
- LLM, Columbia Univ. Law School
- JD Univ. of Pittsburgh School of Law
- Judicial Clerk, U.S. District Court Judge
- Intern, Attorney General of Massachusetts
Steve Semmelmayer
45 Years in Dental Products and Medical Devices
Experience and Education
- CEO and Board Member, DenMat Holdings LLC
- CEO and Board Member, Discus Dental Inc.
- President & GM Kerr Dental Products (a div. of Sybron)
- Board Member, LED Medical
- Board Member, C3Jian
- Board Member, American Dental Partners Inc.
- Board Member, Microdental Laboratories, Inc.
- Board Member, Children’s Dental Center
- BA Business Admin, San Diego State Univ.
- MBA Pepperdine Univ.
ssemmelmayer@millstreetequity.com
Dr. Ben Wu
30 Years in Clinical Practice and Research
Experience and Education
- COO & Chief Scientific Officer, ADA Forsyth Institute
- Stanford’s World Top 2% Scientists with Career Impact
- Expert-in-Residence, Harvard Innovations Lab
- Chairman, UCLA Department of Bioengineering
- Chairman, UCLA Advanced Prosthodontics
- Board Member, Rodo Medical, Inc, Phase Diagnostic, Inc
- PhD Massachusetts Institute of Technology
- DDS Univ. of the Pacific
- Residency, Certificate in Prosthodontics Harvard Univ.