William Brennan, DDS
NPI 1235142746 · Dentist · Downers Grove, IL
Enrolled with Medicare as Order and Referring Only - Oral Surgery · source: CMS PECOS Public Provider Enrollment (2026.04.01)
William Brennan, DDS is a Dentist provider in Downers Grove, IL (NPI 1235142746).
Provider details
- NPI number
- 1235142746
- Entity type
- Individual
- Primary specialty
- DentistDental Providers
- Credential
- DDS
- Sex
- Male
- Sole proprietor
- Yes
- License
- 19A15602 (IL)
Specialties & taxonomies
Dental Providers
Profile Score
A profile completeness & documented-activity index — NOT a quality, outcomes, or patient-satisfaction rating.
- Registry tenure38% of score
19 yrs in NPPES registry
- Profile completeness38% of score
100% of core fields populated
- Practice footprint23% of score
1 documented practice location
Signals a provider has no public data for (e.g. Medicare claims) are left out of the score entirely — never counted as zero — so providers without that data are not penalized. See the full formula and weights in our methodology.
Practice location
Mailing address
Registry dates
- Enumerated
- 2006-08-14
- Last updated
- 2007-07-08
Frequently asked questions
- What is William Brennan's NPI number?
- William Brennan's National Provider Identifier (NPI) is 1235142746, a unique 10-digit ID issued by CMS for use in standard healthcare transactions.
- What is William Brennan's specialty?
- William Brennan is listed in the NPPES registry with a primary specialty of Dentist (Dental Providers).
- Where is William Brennan located?
- William Brennan's practice location on file with NPPES is 5133 Washington St, Downers Grove, IL 60515.
- What is William Brennan's phone number?
- The practice phone number listed in the NPPES registry for William Brennan is (630) 969-4645.
- Does William Brennan accept Medicare?
- William Brennan is approved to bill Medicare according to CMS PECOS enrollment data (2026.04.01). Confirm current participation with the provider before scheduling.
- Is William Brennan's NPI active?
- Yes — William Brennan's NPI (1235142746) is active in the NPPES registry as of the last update on 2007-07-08.
Source: CMS NPPES Data Dissemination (June 2026). NPI Central is not affiliated with CMS. Data is provided as-is from the public registry.