(1) Mesial and distal section: The entire pulp chamber is approximately triangular in shape. The top of the pulp chamber, which is the base of the triangle, is the widest, close to the middle 1/3 of the crown. The top of the pulp chamber is slightly concave and the sides are slightly pointed. The pulp chamber narrows slightly toward the cervical edge and gradually tapers from the cervical edge to the root tip. Young people often have three rounded processes on the roof of the pulp chamber, pointing to the incisal ridge. These processes gradually disappear with age.

(2) Labial and lingual cross-section: The pulp cavity is slightly fusiform, thickest at the flat neck edge, and narrows to a pointed shape toward the incisal ridge until the middle 1/3 of the crown. The pulp cavity gradually narrows and becomes thinner from the neck edge to the root apex.

(3) Cross-sectional view:

The pulp cavity shape of the maxillary lateral incisors is similar to that of the maxillary central incisors, but slightly smaller. The top of the pulp chamber in the mesio-distal section is relatively neat, close to the middle of the crown, and is the widest part of the pulp chamber. The width of the pulp cavity gradually decreases from the tooth neck to the middle of the root, and then decreases significantly until the apical 1/3 of the root. In the labial and lingual section, the medullary cavity is thickest near the cervical edge, shrinks until the root tip 1/2 or 1/3, and curves with the root tip. Maxillary lateral incisors usually have a single root canal, but occasionally have 2 root canals.

Characteristics: The mandibular central incisor has the smallest pulp cavity volume, the labial and lingual diameter is larger than the mesio-distal diameter, the root canal is mostly a narrow and flat single canal, and about 4% of the cases are divided into two labial and lingual canals.

The pulp cavity volume of mandibular lateral incisors is larger than that of mandibular central incisors, the mesio-distal diameter of the pulp cavity is smaller, the labial and lingual diameter is larger, and the root canal is longer. Most mandibular lateral incisors have a single root canal, and about 10% have two root canals.

(1) Mesial and distal section: The pulp cavity is narrow, both ends are pointed, the pulp angle is close to the middle 1/3 of the crown, the pulp cavity is wider at the 1/2 of the root neck, and gradually becomes wider at the apical 1/2. narrow.

(2) Labial and lingual profile: The top of the pulp chamber is narrow and pointed, the top of the pulp angle is close to the middle 1/3 of the crown, 2/3 of the pulp cavity is very thick, and it gradually becomes narrower until the apical 1/3, and the apical hole is larger than the incisor. big.

(3) Cross section

(1) Mesial and distal section: The pulp cavity is narrow, the pulp angle is blunt, the top of the pulp angle is close to the middle 1/3 of the crown, the pulp cavity is slightly wider from below the pulp angle to the middle of the root, and gradually tapers toward the root tip.

(2) Labial and lingual section: The labial and lingual diameter of the pulp cavity is relatively large. The largest section is located at the crown neck and root neck 1/3 or 1/2, and gradually becomes thinner towards the root apex. The pulp angle is pointed and the top of the pulp angle is Close to the middle 1/3 of the crown

(3) Cross section:

(1) Mesiodistal section: The shape of the mesiodistal section is slightly similar to that of the canine, but the pulp chamber and root canal are both narrower.

(2) Buccal and lingual section: There is a buccal and lingual pulp angle on the top of the pulp chamber that protrudes toward the buccal and lingual apex respectively. The buccal pulp angle is higher, close to the middle 1/3 of the crown, and the lingual pulp angle is lower, close to the tooth. In the 1/3 of the crown neck (a few are close to the middle 1/3 of the crown), there are two on the bottom of the pulp chamber, and one occasionally has three root canal openings, which are connected with the corresponding root canals.

(3) Cross section

(4) Root canal type of maxillary first premolar:

The shape of the pulp chamber is similar to that of the maxillary first premolar, but the mesio-distal width of the pulp chamber is narrower, the buccal and lingual diameter is larger, the buccal and lingual pulp angles are both low, and it is located in the cervical 1/3 of the crown. There are three main types of root canals

① Transverse section of the tooth neck: The pulp chamber of the mandibular first premolar is mostly oval, and the buccolingual diameter is larger than the mesiodistal diameter. If it has double root canals, both the buccal and lingual canals will be round.

②Transverse section of the middle part of the tooth root: the root canal is small and round

The pulp chamber of the maxillary first molar is like a short rectangle with a very small pulp chamber height, buccolingual diameter > mesial and distal diameter > pulp chamber height. The top of the pulp chamber is concave, and the most concave part is approximately flush with the edge of the neck. The mesiobuccal pulp angle and mesiolingual pulp angle on the top of the pulp chamber are relatively high, both close to the middle 1/3 of the crown; the distobuccal pulp angle and distal lingual pulp angle are low, both close to the top 1/3 of the crown. There are 3 to 4 root canal orifices at the bottom of the pulp chamber, which are arranged in a quadrilateral or triangular shape with a long buccal and lingual diameter and a short mesio-distal diameter. The mesiobuccal root canal orifice is closer to the distobuccal root canal orifice than to the lingual root canal orifice. Farther away, the distobuccal root canal orifice is located distal to the lingual side of the mesiobuccal root canal orifice. The shape of each root canal opening is: the mesiobuccal root canal opening is relatively flat, and the distal buccal root canal opening is slightly rounded. The lingual root canal orifice is larger. Approximately 63% of cases have a double-canal or single-double type in the mesiobuccal root canal, 9% have a distal-buccal root canal that is divided into two canals, and the lingual root canal is mostly a single canal. Maxillary first molars usually have 3 to 4 root canals, 1 to 2 root canals in the mesiobuccal root, and one root canal in the distal buccal root and lingual root.

The mesiobuccal root canal is double-tube type or single-double type, accounting for about 30% of the total. The distal-buccal root canal and lingual root canal are mostly single canal. The maxillary second molar occasionally has two root canals, including a lingual root canal and a larger buccal root canal.

The maxillary third molar is the tooth with the most changes in the shape of the whole mouth. The changes in the pulp cavity also have its own characteristics, which are mainly manifested in the large pulp chamber, thick root canal, low pulp angle, and the position of the pulp chamber bottom is often related to the root shape: three roots In patients with double roots, the pulp chamber floor is usually located in 1/3 of the root diameter or in the middle 1/3 of the root; in patients with double roots, the pulp chamber floor is mostly located in the middle 1/3 of the root; in patients with single root or fused root canals, the pulp chamber is mostly reduced in the apical 1/3 of the root. into tubes.