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WILLIAM MICHAEL BRENNAN SR. DDS
NPI 1235142746
Dentist in Downers Grove, IL

Active since August 14, 2006PECOS EnrolledCLIA 14D2245648 · Waiver
5133 WASHINGTON ST, DOWNERS GROVE, IL 60515(630) 969-4645 Get Directions Write a Review

NPPES record last updated: July 8, 2007. Verified against the NPPES registry weekly; last sync: August 16, 2026.

About William Michael Brennan Sr. Dds NPPES

Official registry information on file with the National Plan and Provider Enumeration System.

WILLIAM MICHAEL BRENNAN SR. DDS (NPI 1235142746) is an individual dentist in Downers Grove, Illinois, licensed in Illinois (19A15602) and active in the NPI registry since August 2006. He is enrolled in Medicare PECOS and holds a CLIA Waiver certificate valid through December 14, 2027.

NPPES Registry Identity

NPI1235142746
Entity TypeIndividualMale
Primary Taxonomy122300000X
Provider Legal NameWILLIAM MICHAEL BRENNAN SR.Credential: DDS
Location Address5133 WASHINGTON STDowners Grove, IL 60515
Mailing Address5133 Washington StDowners Grove, IL 60515 · (630) 969-4645
Phone(630) 969-4645
Sole ProprietorYes
Enumeration DateAugust 14, 2006
Last NPPES UpdateJuly 8, 2007
✔ NPI 1235142746 is a valid, active identifier and passes the ISO check-digit test.

Specialties & Licenses

★ Primary SpecialtyDentistDental Providers
Taxonomy Code122300000X
License✔ Licensed in IL · 19A15602
Definition
A dentist is a person qualified by a doctorate in dental surgery (D.D.S.) or dental medicine (D.M.D.), licensed by the state to practice dentistry, and practicing within the scope of that license. There is no difference between the two degrees: dentists who have a DMD or DDS have the same education. Universities have the prerogative to determine what degree is awarded. Both degrees use the same curriculum requirements set by the American Dental Association's Commission on Dental Accreditation. Generally, three or more years of undergraduate education plus four years of dental school is required to graduate and become a general dentist. State licensing boards accept either degree as equivalent, and both degrees allow licensed individuals to practice the same scope of general dentistry. Additional post-graduate training is required to become a dental specialist.
5133 WASHINGTON ST, Downers Grove, IL 60515
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Medicare Participation & PECOS CMS

Medicare enrollment, assignment, and ordering and referring status from the CMS PECOS system.

Medicare Enrollment Status

✔

Enrolled in Medicare (PECOS)

William Michael Brennan Sr. Dds is registered in the CMS Provider Enrollment, Chain and Ownership System (PECOS).

Eligible to Order & Refer✔ Part B Labs & Imaging✔ Durable Medical Equipment✔ Home Health Agency– Power Mobility DevicesPer the CMS Ordering and Referring file. Eligibility means Medicare pays claims that this provider orders or refers for these categories.

CLIA Laboratory Certificates CMS CLIA

Laboratory certificates issued under the Clinical Laboratory Improvement Amendments (CLIA) program, which sets federal quality standards for human laboratory testing in the United States. There is no official CMS crosswalk between CLIA and NPI numbers; these certificates are associated with this NPI by matching facility names, locations and phone numbers in the CMS CLIA registry.

Certificate of Waiver 14D2245648

William M Brennan Jr Dds PC · Downers Grove, IL
Active · expires Dec 14, 2027
CLIA Number14D2245648
Laboratory TypePractitioner Other
Certificate Effective DateDecember 15, 2025
Certificate Expiration DateDecember 14, 2027
Laboratory DirectorWilliam M. Brennan Jr
Laboratory Phone(630) 969-4645
Laboratory LocationWilliam M Brennan Jr Dds PC5133 Washington St - Ste 4, Downers Grove, IL 60515
CLIA data matches this NPI record on: Address Phone
This certificate is issued to a laboratory to perform only waived tests.

Physician Visit Costs CMS claims · ZIP area

Typical Medicare office-visit costs in the 60515 ZIP code area, from fee-for-service claims. These are area statistics, not this provider’s prices; actual charges vary by service and coverage.

New Patient
$93.02 typical visit price
range $59.81 – $181.38
Typical copayment $23.25 (range $14.95 – $45.34)
Most-billed visit code 99203
Established Patient
$74.38 typical visit price
range $19.15 – $147.12
Typical copayment $18.59 (range $4.78 – $36.78)
Most-billed visit code 99213
Amounts reflect what Medicare beneficiaries in this ZIP area are typically charged for office visits. Patients with other coverage should check their individual plans.

Other Providers at the Same Location NPPES 6

Providers registered at the same practice address, or within the immediate area, according to the NPPES registry.

DR. JOHN GERARD MARCHESE D.D.S
Dentist
5133 WASHINGTON ST, SUITE 10
DOWNERS GROVE, IL 60515
Dupage County (630) 964-7852
JOHN G MARCHESE DDS LTD
Dentist (General Practice)
5133 WASHINGTON ST, SUITE # 10
DOWNERS GROVE, IL 60515
Dupage County (630) 964-7852
DR. JOHN E KEENAN DDS
Dentist
5133 WASHINGTON ST, SUITE 2
DOWNERS GROVE, IL 60515
Dupage County (630) 960-1910
DR. WILLIAM MICHAEL BRENNAN JR. D.D.S.
Dentist
5133 WASHINGTON ST, SUITE 4
DOWNERS GROVE, IL 60515
Dupage County (630) 969-4645
MRS. SARAH KAY CLINE L.C.S.W.
Social Worker (Clinical)
5133 WASHINGTON ST
DOWNERS GROVE, IL 60515
Dupage County (630) 205-3211
RACHEL HELEN POWERS MA, LCPC, NCC
Counselor (Professional)
5133 WASHINGTON ST, SUITE 8
DOWNERS GROVE, IL 60515
Dupage County (312) 912-1448

Frequently Asked Questions NPPES & CMS

Common questions about this NPI record, answered from the official NPPES registry and CMS datasets shown on this page.

What is William Brennan's NPI number?

The NPI number for William Brennan is 1235142746. It was assigned to this individual provider in the NPPES registry on August 14, 2006.

Where is William Brennan located?

William Brennan practices at 5133 Washington St, Downers Grove, IL 60515. The listed phone number is (630) 969-4645.

What is William Brennan's specialty?

The primary specialty registered for this NPI is Dentist with taxonomy code 122300000X.

Is William Brennan enrolled in Medicare?

Yes. William Brennan is registered in the Medicare PECOS enrollment system.

Does William Brennan hold a CLIA laboratory certificate?

Yes. A Certificate of Waiver (number 14D2245648) is associated with this NPI, valid through December 14, 2027. CLIA certificates authorize laboratory testing under the federal Clinical Laboratory Improvement Amendments program.

When was this NPI record last updated?

The NPPES record for William Brennan was last updated on July 8, 2007. NPI Profile syncs weekly with the NPPES registry data releases published by CMS. This NPI record was last updated 19 years ago. If this record has changed at CMS more recently, you can request an on-demand re-check against the live CMS registry, directly from this page.