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Maxillary Triangular

# Maxillary First Molar

[Previous tooth Maxillary Second Premolar FDI 15 · 25](https://endo-guide.app/access-cavities/max-second-premolar)[Next tooth Maxillary Second Molar FDI 17 · 27](https://endo-guide.app/access-cavities/max-second-molar)

![Maxillary first molar — rhomboid occlusal access with four orifices: MB1, MB2, DB and palatal](https://endo-guide.app/images/access-cavities/atlas/maxillary-molar-4canal-mb2.webp)

Maxillary first molar — rhomboid occlusal access with four orifices: MB1, MB2, DB and palatal

 Average Length 21.0 mm

 Root Development 10 years

 Universal # 3, 14

 FDI # 16, 26

### Access Cavity Design

Shape Triangular / Rhomboidal

OrientationVertices at MB, DB, and P; extend mesially for MB2

Entry PointCentral pit, mesial two-thirds of occlusal surface

Landmarks

- Central pit
- MB-DB-P triangle

Do Not Invade

- Mesial marginal ridge
- Oblique ridge

### Canal Anatomy

#### Configurations

4 canals (MB1, MB2, DB, P)~70%

3 canals (MB, DB, P)~30%

#### Canal Positions

 MB1 Mesiobuccal 1

Slightly distal to MB cusp tip

 DB Distobuccal

Distal and slightly palatal to MB1, in line with buccal groove

 P Palatal

Distal to mesiopalatal cusp tip - largest canal

 MB2 Mesiobuccal 273.8% (CBCT), 71-82% (with microscope)

2 mm palatal and 1-2 mm mesial from MB1

### Clinical Tips

Technique

Rule of 2: MB2 is approximately 2 mm palatal to MB1 (range 2-3.5 mm palatally, ~2 mm mesially) — a clinical starting point for exploration

Technique

Champagne/Bubble Test: NaOCl effervesces at orifice with organic tissue

Technique

Use ultrasonic diamond tips (E2D, E6D) for troughing MB-MB2 isthmus

Tip

Dental microscope significantly improves MB2 detection — from ~17% (no magnification) to ~71% (microscope) in comparative studies

### Anatomical Variations

#### MB2 Canal

60-93% (CBCT); ~64-74% in meta-analyses

Second canal in mesiobuccal root, often calcified in older patients. Prevalence varies by study methodology and population.

Access Modification: Convert triangular to rhomboidal shape by extending mesiobuccally

### 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 Second Molar](https://endo-guide.app/access-cavities/max-second-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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