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

Martha M Sidlowski, DDS

Dentist in Annapolis, MD · enumerated 2008.

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

National Provider Identifier

1659542199

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Registry record

Entity type Individual (Type 1)

Name Martha M Sidlowski

Credential DDS

Sex Female

Practice address Annapolis, MD, 21401

Phone (410) 990-4800

Fax (410) 990-4869

Enumeration date Mar 12, 2008

Last updated in NPPES Mar 12, 2008

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

Taxonomy & licenses

122300000X Dentist Dental Providers · License 13227 (MD) 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

Is NPI 1659542199 active?

Yes, as of the latest NPPES snapshot, NPI 1659542199 is active (record last updated 2008-03-12).

How do I verify Martha Sidlowski's NPI record?

Cross-check NPI 1659542199 against the official CMS registry at npiregistry.cms.hhs.gov. This page mirrors the same public NPPES data with a monthly snapshot.

Source: CMS NPPES (public data). Snapshot 2026-07-13. Provider record last updated 2008-03-12.