Gregory J. Duffner, D.D.S.
General Practice Dentistry · Homewood, IL
Gregory J. Duffner, D.D.S. is a general practice dentistry with a practice address in Homewood, Illinois, and NPI 1225340375, issued on Jul 6, 2010. Check the license (Illinois 019-019782, as entered in NPPES) with the Illinois board that licenses this profession; the Medicare figures below come from public CMS files.
- Name
- Gregory J. Duffner
- Credential
- D.D.S.
- Primary taxonomy
- General Practice Dentistry 1223G0001X
- License number
- 019-019782 IL
Self-reported in NPPES; status is on the state search - Practice location
- 18040 Park Ave, Homewood, IL 60430
- Phone
- (708) 792-2779
- Enumerated
- Jul 6, 2010
- Record last updated
- Oct 23, 2025
- Fax
- (708) 798-6988
- Entity
- Type 1 · individual
8 nearest general practice dentistry records → All 5,276 in Illinois → Look up another NPI →
Also registered at 18040 Park Ave
A shared address usually means a shared clinic or building; it does not show who employs whom.
- Alexander Dolinar, DMDGeneral Practice Dentistry1598506784
- Rebecca Hudson, DMDDentist1427725019
- James Kreuz, D.D.S.General Practice Dentistry1932332269
Verify Gregory J. Duffner in five checks
- 1IdentityNPI record in CMS NPPESNPI lookupConfirmed in NPPES
- 2LicenseActive license and public ordersWhich Illinois board licenses this profession
Search for license 019-019782Check the board - 3Other statesLicenses and actions elsewhereDocInfo (FSMB)Not checked
- 4ExclusionsMedicare and Medicaid bansHHS-OIG exclusion listNot checked
- 5CertificationBoard certificationABMS AOA NCCPA AANPNot checked
72% fewer Medicare Part D claims than the average general practice dentistry in 2024
23 Medicare Part D claims for 15 beneficiaries, against an average of 83 among the 70,290 providers of this specialty who prescribed in Part D.
Most prescribed
- Amoxicillin13 claims
Source: CMS Medicare Part D Prescribers by Provider and Drug, 2024 (data.cms.gov). Part D covers prescriptions for Medicare patients only; drugs with fewer than 11 claims are not published.
Gregory J. Duffner among 5,276 general practice dentistry records in Illinois
Gregory J. Duffner, D.D.S. is one of 5,276 general practice dentistry records with a practice address in Illinois. 64% of them appear in a Medicare file (Part D prescribing, MIPS, Open Payments or Medicare group billing); this one does. Its NPI, issued in 2010, is newer than 66% of them.
- NPI issued2010 · 66% of these records are older, 32% newer
- In a Medicare fileYes · 64% of these records are
- In the CMS Doctors and Clinicians fileNo · under 1% of these records are
- Record last updated2025 · 75% of these records were not updated in five years or more
Source: CMS NPPES, file of Aug 9, 2026, every record with primary taxonomy 1223G0001X and a Illinois practice address; Medicare files: CMS Part D Prescribers 2024, MIPS 2023, Open Payments 2024, Doctors and Clinicians (data.cms.gov).
17 general practice dentistry records list a practice address in Homewood
They are 17 of the 634 NPPES records with a practice address in Homewood, and 5,276 general practice dentistry records in Illinois.
All 5,276 in Illinois → Every provider in Homewood → General Practice Dentistry nationwide →
The 8 general practice dentistry records with the nearest ZIP codes
- David Dunagan, D.D.S.Homewood, IL 604301073730446
- Ronald Eldridge, D.D.S.Homewood, IL 604301902060163
- Thomas Erickson, DDSHomewood, IL 604301609994094
- Walter Flor, DDSHomewood, IL 604301669520813
- James Kreuz, D.D.S.Homewood, IL 604301932332269
- Scott Lang, DDSHomewood, IL 604301871797191
- David Mayer, D.D.S.Homewood, IL 604301235295460
- Ann Mazzotti, D.D.S.Homewood, IL 604301972551737
Common questions
What is Gregory J. Duffner, D.D.S.'s NPI number?
Gregory J. Duffner, D.D.S.'s National Provider Identifier (NPI) is 1225340375, issued on Jul 6, 2010. An NPI identifies a provider in billing; it is not a license.
Where is Gregory J. Duffner, D.D.S. located?
The NPPES record lists a practice address at 18040 Park Ave, Homewood, IL, 60430. Phone: (708) 792-2779. Providers update this record themselves, so call before visiting.
How can I verify Gregory J. Duffner, D.D.S.'s license?
NPPES lists Illinois license number 019-019782, as entered by the provider. Search the Illinois board that licenses this profession; the NPPES record confirms identity only.
How much does Gregory J. Duffner, D.D.S. prescribe under Medicare Part D?
In 2024, Gregory J. Duffner, D.D.S. had 23 Medicare Part D claims for 15 beneficiaries; the average among general practice dentistry prescribers was 83. Part D covers Medicare prescriptions only.
Source: CMS National Plan and Provider Enumeration System (NPPES), file of Aug 9, 2026 (NPPES files on CMS.gov); NUCC Health Care Provider Taxonomy. Medicare files from data.cms.gov. An NPI identifies who bills; it is not a license.
Figures on PlainDoctor are read from the federal files each page names (CMS NPPES, Medicare Part D, MIPS, Open Payments; the HHS-OIG exclusion list only as counts) and from Census population estimates, with the file date shown beside them. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error. Data current as of Aug 9, 2026.