Active NPI
Gregory V Sierminski, DDS
- Dentist
- Wonder Lake, IL
National Provider Identifier
1255386801
On this page
Key facts
NPPES NPI Registry- Primary specialty
- Dentist
- License
- 19015910
- Practice address
- 7442 Hancock Dr
Wonder Lake, IL 60097 - Phone
- (815) 728-0100
- Fax
- (815) 728-0114
- NPI assigned
- May 23, 2006
- Sex
- Male
- Sole proprietor
- No
NPPES NPI Registry
Registry information is reported by the provider to CMS and is not verified. About this source
Specialties & licenses 1
| Specialty (taxonomy) | Code | License | State | Primary |
|---|---|---|---|---|
| Dentist | 122300000X | 19015910 | IL | Primary |
Addresses
Primary practice location
7442 Hancock Dr
Wonder Lake, IL 60097
Mailing address
7442 Hancock Dr
Wonder Lake, IL 60097
Phone (815) 728-0100
Medicare participation
Medicare enrollment files- Medicare fee-for-service enrollment
- Not listed in the public Medicare enrollment file
National Provider Directory
National Provider Directory- Medicare enrollment (NPD)
- Enrolled
Practice roles
| Organization | Specialty | Status | New patients |
|---|---|---|---|
| Gregory V. Sierminski, D.D.S., P.C. | Dentist | Past | Accepting new patients |
Organizations & group practices 1
Organizations this provider is connected to: Medicare benefit reassignments (the organization bills Medicare for this provider’s services), Care Compare group memberships and National Provider Directory roles.
-
- Dentist
- Crystal Lake, IL
- NPI 1720259013
NPI Registry JSON
The complete NPPES record for this NPI in the NPI Registry API format.
{
"created_epoch": "1148342400000",
"enumeration_type": "NPI-1",
"last_updated_epoch": "1783900800000",
"number": "1255386801",
"addresses": [
{
"country_code": "US",
"country_name": "United States",
"address_purpose": "MAILING",
"address_type": "DOM",
"address_1": "7442 HANCOCK DR",
"city": "WONDER LAKE",
"state": "IL",
"postal_code": "60097",
"telephone_number": "815-728-0100",
"fax_number": "815-728-0114"
},
{
"country_code": "US",
"country_name": "United States",
"address_purpose": "LOCATION",
"address_type": "DOM",
"address_1": "7442 HANCOCK DR",
"city": "WONDER LAKE",
"state": "IL",
"postal_code": "60097",
"telephone_number": "815-728-0100",
"fax_number": "815-728-0114"
}
],
"practiceLocations": [],
"basic": {
"last_name": "SIERMINSKI",
"first_name": "GREGORY",
"middle_name": "V",
"credential": "DDS",
"sole_proprietor": "NO",
"sex": "M",
"enumeration_date": "2006-05-23",
"last_updated": "2026-07-13",
"status": "A"
},
"taxonomies": [
{
"code": "122300000X",
"taxonomy_group": "",
"desc": "Dentist",
"state": "IL",
"license": "19015910",
"primary": true
}
],
"identifiers": [],
"endpoints": [],
"other_names": []
}Other providers in Wonder Lake, IL
Sources for this page
- NPPES NPI Registry (CMS): identity, addresses, specialties, licenses, identifiers and endpoints. Last updated by the provider on Jul 13, 2026; self-reported and not verified by CMS. Specialty names from the NUCC taxonomy.
- National Provider Directory (CMS): practice roles, locations, licenses, networks and endpoints.