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Maxillary Triangular

# Maxillary Second Molar

[Previous tooth Maxillary First Molar FDI 16 · 26](https://endo-guide.app/access-cavities/max-first-molar)[Next tooth Mandibular Central Incisor FDI 31 · 41](https://endo-guide.app/access-cavities/mand-central-incisor)

![Three-canal maxillary molar access — rounded triangular outline with mesiobuccal, distobuccal and palatal orifices](https://endo-guide.app/images/access-cavities/atlas/maxillary-molar-3canal.webp)

Three-canal maxillary molar access — rounded triangular outline with mesiobuccal, distobuccal and palatal orifices

 Average Length 20.0 mm

 Root Development 16 years

 Universal # 2, 15

 FDI # 17, 27

### Access Cavity Design

Shape Triangular

OrientationCompact triangle with vertices at MB, DB, P; more mesially positioned and smaller than first molar

Entry PointCentral pit, mesial two-thirds of occlusal surface

Landmarks

- Central pit as starting reference
- MB-DB-P triangle (more compact than first molar)

Do Not Invade

- Mesial marginal ridge
- Oblique ridge (when present)

### Canal Anatomy

#### Configurations

3 canals (MB, DB, P)55-70%

4 canals (with MB2)18-33%

Fused roots (2 or fewer roots)9-40% (population-dependent)

Single root / single canal~6%

#### Canal Positions

 MB Mesiobuccal

Similar to first molar but closer to other orifices; roots more convergent

 DB Distobuccal

May be very close to MB or even fused in convergent root forms

 P Palatal

Largest canal; may be closer to buccal canals than in first molar

 MB2 Mesiobuccal 218-33%

Significantly lower prevalence than in first molar (18-33% vs 60-93%)

#### Danger Zones

- ⚠Maxillary sinus proximity — root apices avg 0.34 mm from sinus floor; risk of sinus perforation
- ⚠Furcation floor — closer canal orifices increase perforation risk during MB2 search
- ⚠Fused roots — altered canal geometry may confuse orientation during instrumentation

### Clinical Tips

Tip

Access smaller than first molar — canal orifices much closer together; risk of gouging between canals

Tip

Restricted access due to posterior position — longer burs and good mouth opening essential

### Anatomical Variations

#### Fused Roots

9-40% (population-dependent)

Two or more roots fused together, most commonly MB+DB fusion (cone-shaped root). More common than in first molars. Alters canal geometry and orifice positions.

Access Modification: Orifices may appear nearly linear; adapt access shape to follow orifice pattern; CBCT for mapping

#### C-shaped Canal System

~8.3%

Continuous ribbon-shaped canal connecting MB to DB in a C-configuration. More prevalent than in first molars (~2.3%).

Access Modification: Extended access to visualize full C-shape; modified instrumentation (circumferential filing); thermoplasticized obturation preferred

#### Single Root / Single Canal

~6%

Complete root fusion into single conical root with single canal. Considered anatomical anomaly.

Access Modification: Smaller, more centered access; verify with CBCT; treat as single wide canal

### Other teeth in the atlas

Maxillary

[Maxillary Central Incisor](https://endo-guide.app/access-cavities/max-central-incisor)[Maxillary Lateral Incisor](https://endo-guide.app/access-cavities/max-lateral-incisor)[Maxillary Canine](https://endo-guide.app/access-cavities/max-canine)[Maxillary First Premolar](https://endo-guide.app/access-cavities/max-first-premolar)[Maxillary Second Premolar](https://endo-guide.app/access-cavities/max-second-premolar)[Maxillary First Molar](https://endo-guide.app/access-cavities/max-first-molar)

Mandibular

[Mandibular Central Incisor](https://endo-guide.app/access-cavities/mand-central-incisor)[Mandibular Lateral Incisor](https://endo-guide.app/access-cavities/mand-lateral-incisor)[Mandibular Canine](https://endo-guide.app/access-cavities/mand-canine)[Mandibular First Premolar](https://endo-guide.app/access-cavities/mand-first-premolar)[Mandibular Second Premolar](https://endo-guide.app/access-cavities/mand-second-premolar)[Mandibular First Molar](https://endo-guide.app/access-cavities/mand-first-molar)[Mandibular Second Molar](https://endo-guide.app/access-cavities/mand-second-molar)

For Educational Purposes Only

Access cavity designs based on established endodontic principles. Always refer to current literature and clinical guidelines.

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