Mandibular second premolar — round occlusal access with a single central orifice
Reference model: “Mandibular Left Second Premolar”, University of Dundee School of Dentistry (Sketchfab), CC BY 4.0. Rendered and adapted by EndoGuide.
Average Length22.3 mm
Root Development14 years
Universal #20, 29
FDI #35, 45
ShapeRound/Oval
OrientationSlight buccolingual orientation; bur directed buccally (same principle as first premolar but less critical)
Entry PointCentral sulcus of occlusal surface
Landmarks- Central developmental groove as guide
- Buccal cusp tip for directional reference
Do Not Invade- Lingual wall (perforation risk, though lower than first premolar)
Configurations
Single canal (Vertucci Type I)92-97.5%
Two canals (Vertucci Type II/V)2.5-8%
Three canals<2%
C-shaped canal system1.5-12.5% (rare in this tooth)
Canal Positions
MCMain Canal
Oval/band-shaped cross-section (~91% oval); requires circumferential debridement
BBuccal Canal
When 2 canals present
LLingual Canal
When 2 canals present; typically harder to locate
Danger Zones
- ⚠Lingual perforation — similar lingual crown tilt to first premolar but less pronounced; still exercise caution
- ⚠Oval canal cross-section — incomplete debridement risk if only rotary instrumentation used
Tip
Most predictable mandibular premolar — single canal in 92-97.5%; simplest anatomy among mandibular premolars
Warning
Always verify canal configuration — rare variants (2-canal, 3-canal, C-shaped) still exist
2.5-8%
Canal bifurcating into buccal and lingual (Type V, 1-2) or two canals merging (Type II, 2-1). Less common than in first premolar.
Access Modification: Extend access buccolingually; explore both walls with small pre-curved files
1.5-12.5%
Continuous ribbon-shaped canal in C-configuration. Less prevalent than in first premolar. Associated with radicular groove.
Access Modification: Oval access; circumferential filing; thermoplasticized obturation
<2%
Exceedingly rare variant with three separate canals. Documented in case reports.
Access Modification: CBCT mandatory; extended access; microscope recommended
