Type 1 · Individual ✓ Active NPI ✓ Valid NPI checksum
Mark William Posthumus, DDS
Dentist in Grand Rapids, MI · enumerated 2007.
Data current as of Jul 13, 2026 · sourced from CMS NPPES
National Provider Identifier
1174726533
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Registry record
Entity type Individual (Type 1)
Name Mark William Posthumus
Credential DDS
Sex Male
Practice address 2300 3 Mile Rd Ne, Grand Rapids, MI, 49505
Phone (616) 363-3712
Enumeration date Jun 6, 2007
Last updated in NPPES Jul 8, 2007
Taxonomy & licenses
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.
Frequently asked questions
Is this the official NPI registry?
No. NPI Portal is a private site built on public CMS NPPES data. The official registry is npiregistry.cms.hhs.gov, operated by CMS.
What specialty is Mark Posthumus?
Mark Posthumus is registered in NPPES with the primary taxonomy of Dentist. The taxonomy code describes the provider's classification and area of specialization for claims and credentialing.
Other providers at this practice address
Browse all → David Posthumus General Practice Dentistry · Grand Rapids, MI NPI 1467803080 Posthumus Family Dentistry, PC General Practice Dentistry · Grand Rapids, MI NPI 1164068136 Sharon L Burocchi DDS Plc Dental Clinic/Center · Grand Rapids, MI NPI 1427790526 97 Smiles of Grand Rapids Dentist · Grand Rapids, MI NPI 1891654612
Source: CMS NPPES (public data). Snapshot 2026-07-13. Provider record last updated 2007-07-08.