Which of the following descriptions about the developmental groove of the maxillary central incisor is correct?()
A. There are two longitudinal developmental grooves at the incisal half.
B. There are two longitudinal developmental grooves at the incisal third.
C. There is one longitudinal developmental groove at the incisal half.
D. There is one longitudinal developmental groove at the incisal third.
E. There is no developmental groove.
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Which of the following is not the characteristics of the deciduous teeth?()
A. short and broad crown
B. small size
C. milky white color
D. narrow occlusal surface and protruded cervical ridge
E. broad crown and broad root of the deciduous anterior teeth
Which of the following descriptions about the lateral canals is incorrect?()
A. They start from the tiny branches of the root canal.
B. They are almost vertical to the root canal.
C. They go through the dentin and the cementum.
D. They are connected with the periodontal membrane space
E. There are more lateral canals at the middle third of the root.
Which of the followings is connected with the periodontium by the apical foramen?()
A. the root canal
B. the intercanal anastomoses
C. the lateral canal
D. the apical ramification
E. the accessory root canal
Which of the following descriptions about the pulp cavity of the mandibular first premolar is incorrect?()
A. The mesiodistal diameter of the pulp chamber is greater than its buccolingual diameter, and the buccolingual diameter is greater than the height of the pulp chamber.
B. The roof of the pulp chamber is concave, and the lowest part is level with the cervical margin.
C. The height of the lingual pulp horn is close to the middle third of the dental crown.
D. The buccal and distal pulp horns are relatively low, which are located at about the cervical third of the crown or near the cervical margin.
E. About 13% of the mesial root canals are double canal type.
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