Which of the following is not one of the anatomical features of the mandibular central incisor?()
A. It has flat and straight incisal margin.
B. There is almost identical medial incisal angle and distal incisal angle.
C. There is pronounced developmental groove on the labial surface.
D. The incisal ridge is close to the dental long axis.
E. It has flat single root and the elongated depression is deeper on the distal surface than on the medial surface.
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Which of the followings is the predilection site of the caries?()
A. the developmental groove
B. the fissure
C. the accessory groove
D. the fossa
E. all of the above
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.
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.
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