Type 1 · Individual ✓ Active NPI ✓ Valid NPI checksum
Dr. William Joseph O'Brien, DDS
Prosthodontics in Milwaukee, WI · enumerated 2006.
Data current as of Jul 13, 2026 · sourced from CMS NPPES
National Provider Identifier
1285657957
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Registry record
Entity type Individual (Type 1)
Name Dr. William Joseph O'Brien
Credential DDS
Sex Male
Practice address 5900 N Port Washington Rd, Suite B262, Milwaukee, WI, 53217
Phone (414) 332-7450
Enumeration date Jul 25, 2006
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
Where does William O'Brien practice?
The practice location on file with NPPES is in Milwaukee, WI. Providers can have multiple locations; NPPES lists the primary practice address.
What is the NPI number for William O'Brien?
The National Provider Identifier (NPI) for William O'Brien is 1285657957, a Type 1 (individual) record in the CMS NPPES registry.
Other providers at this practice address
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Source: CMS NPPES (public data). Snapshot 2026-07-13. Provider record last updated 2007-07-08.