Type 1 · Individual ✓ Active NPI ✓ Valid NPI checksum
Dr. John Mark Leib, D.M.D.
Dentist in O Fallon, IL · enumerated 2006.
Data current as of Jul 13, 2026 · sourced from CMS NPPES
National Provider Identifier
1376604678
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Registry record
Entity type Individual (Type 1)
Name Dr. John Mark Leib
Credential D.M.D.
Sex Male
Practice address 741 W State St, Suite 3, O Fallon, IL, 62269
Phone (618) 628-1800
Fax (618) 628-3406
Enumeration date Dec 12, 2006
Last updated in NPPES Sep 11, 2025
Taxonomy & licenses
DMD · Doctor of Medicine in Dentistry: A licensed dentist; DMD and DDS are equivalent dental degrees.
About the DMD 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.
Frequently asked questions
What is the NPI number for John Leib?
The National Provider Identifier (NPI) for John Leib is 1376604678, a Type 1 (individual) record in the CMS NPPES registry.
Where does John Leib practice?
The practice location on file with NPPES is in O Fallon, IL. Providers can have multiple locations; NPPES lists the primary practice address.
Other providers at this practice address
Browse all → Tonya Bowman General Practice Dentistry · O Fallon, IL NPI 1669482345 Ava Hood-Olson Orthodontics and Dentofacial Orthopedics Dentistry · O Fallon, IL NPI 1528166253 Oral Surgeons of Southern Illinois Oral and Maxillofacial Surgery (Dentist) · O Fallon, IL NPI 1477613297 Dale Schutte Dentist · O Fallon, IL NPI 1659431500 Bowman Dental Group General Practice Dentistry · O Fallon, IL NPI 1427102615 Kara Schreder General Practice Dentistry · O Fallon, IL NPI 1285788356 Kirk Satrom Orthodontics and Dentofacial Orthopedics Dentistry · O Fallon, IL NPI 1386788768 Kirk D. Satrom, DDS Ms PC Orthodontics and Dentofacial Orthopedics Dentistry · O Fallon, IL NPI 1669778601
Source: CMS NPPES (public data). Snapshot 2026-07-13. Provider record last updated 2025-09-11.