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Type 1 · Individual ✓ Active NPI ✓ Valid NPI checksum Sole proprietor

Dr. Mark J Williamson, D.D.S.

General Practice Dentistry in Clio, MI · enumerated 2006.

Data current as of Jul 13, 2026 · sourced from CMS NPPES

National Provider Identifier

1851341945

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Registry record

Entity type Individual (Type 1)
Name Dr. Mark J Williamson
Credential D.D.S.
Sex Male
Practice address Clio, MI, 48420
Phone (810) 659-1721
Fax (810) 659-0897
Enumeration date May 11, 2006
Last updated in NPPES Dec 19, 2019

Street address withheld: NPPES sole-proprietor addresses can be home addresses. See our data policy.

Taxonomy & licenses

1223G0001X General Practice Dentistry Dental Providers · License 2901013535 (MI) Primary
DDS · Doctor of Dental Surgery: A licensed dentist; DDS and DMD are equivalent dental degrees. About the DDS credential

What is an NPI number?

A National Provider Identifier (NPI) is a unique 10-digit number that CMS assigns to every U.S. healthcare provider and organization under HIPAA. Type 1 NPIs identify individual providers; Type 2 NPIs identify organizations. The NPI appears on insurance claims, prescriptions, and credentialing paperwork, and never changes, even if the provider moves or changes specialty.

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Frequently asked questions

Where does Mark Williamson practice?
The practice location on file with NPPES is in Clio, MI. Providers can have multiple locations; NPPES lists the primary practice address.
What is the NPI number for Mark Williamson?
The National Provider Identifier (NPI) for Mark Williamson is 1851341945, a Type 1 (individual) record in the CMS NPPES registry.

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Source: CMS NPPES (public data). Snapshot 2026-07-13. Provider record last updated 2019-12-19.