Pulpal Diseases and Maxillary First Premolar Anatomy

Classification of Pulpal Diseases

Reversible Pulpitis (Acute)

This refers to inflammation of the pulp that is not severe. If the cause is eliminated, the inflammation will resolve and the pulp will return to normal.

Etiology: Mild or short-acting stimuli such as:

• Incipient caries
• Cervical erosion
• Occlusal attrition

Irreversible Pulpitis (Acute)

This is often a sequel to and a progression from reversible pulpitis. It is a severe inflammation that will not resolve even if the cause is removed.

Chronic Ulcerative Pulpitis

The pulp is cariously exposed with an abscess formation at the site. Pain is typically absent because of adequate drainage and the absorption of the exudate.

Chronic Pulpitis (Closed Form)

This may occur from operative procedures, trauma, or periodontal lesions, rather than caries.

Hyperplastic Pulpitis

Also known as a pulp polyp, this is a form of irreversible pulpitis resulting from the growth of chronically inflamed young pulp.

Maxillary First Premolar Anatomy

The canal morphology varies by level:

1. Cervical level: The pulp is enormous in a young tooth, wider in the labiolingual direction (oval).
2. Midroot level: The canal continues to be ovoid.
3. Apical third level: The canal is generally round.

Root and Canal Configuration

One should always expect two roots with two separate canals (57%), one root (38%) (Type III 16%, Type II 12%, and Type I 10%), and occasionally three canals (5%) in two roots, or rarely, three roots.

A. Buccal View of a Recently Calcified First Premolar

• Mesiodistal width of the pulp
• Presence of two pulp canals
• Apparently straight canals
• Distal-axial inclination of the tooth

B. Mesial View of the Same Tooth

• Height of the pulp horns: The buccal horn is larger than the palatal one.
• Broad buccolingual dimension of the pulp.
• Two widespread and separate roots.
• Buccal-axial angulation of the tooth.
• The palatal canal is usually slightly larger than the buccal canal.

C. Cross-Sections

At the cervical level, the pulp is enormous in a young tooth and very wide in the buccolingual direction. Canal orifices are found well to the buccal and lingual. It is kidney-shaped due to its mesial concavity. When three canals are present, the anatomy is further complex.