Type 1 · Individual ✓ Active NPI ✓ Valid NPI checksum

Dr. Gregory James Nielsen, D.D.S.

Endodontics in Billings, MT · enumerated 2007.

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

National Provider Identifier

1578600318

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Registry record

Entity type Individual (Type 1)

Name Dr. Gregory James Nielsen

Credential D.D.S.

Sex Male

Practice address 2225 Broadwater Ave Ste A, Billings, MT, 59102

Phone (702) 869-2800

Fax (702) 869-2803

Enumeration date Jan 31, 2007

Last updated in NPPES Jul 21, 2022

Taxonomy & licenses

1223E0200X Endodontics Dental Providers · License 11499 (MT) Secondary

1223G0001X General Practice Dentistry Dental Providers · License 4702 (NV) Secondary

1223G0001X General Practice Dentistry Dental Providers · License 8806 (CO) Secondary

1223E0200X Endodontics Dental Providers · License 8806 (CO) 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.

Read the full guide → Validate an NPI →

Frequently asked questions

What is the NPI number for Gregory Nielsen?

The National Provider Identifier (NPI) for Gregory Nielsen is 1578600318, a Type 1 (individual) record in the CMS NPPES registry.

Where does Gregory Nielsen practice?

The practice location on file with NPPES is in Billings, MT. Providers can have multiple locations; NPPES lists the primary practice address.

Source: CMS NPPES (public data). Snapshot 2026-07-13. Provider record last updated 2022-07-21.