Question 14 · LDEK · Model analysis
Indicate the true statements concerning Andrew’s keys of normal occlusion:
1) mesial palatal cusp of the first permanent upper molar is situated in the medial fissure of the first permanent lower molar;
2) in the normal occlusion the gingival part of each tooth long axis is mesially inclined in comparison to the part of the crown directed towards the occlusal plane;
3) torque of the crowns of incisors: the incisal edge of upper incisors is situated lingually relative to the cervical part of the crowns of these teeth;
4) molars and premolars rotated around the long axis take up more space in the dental arch;
5) rotated incisors take up less space in the arch in comparison to their normal position.
The correct answer is:
2) in the normal occlusion the gingival part of each tooth long axis is mesially inclined in comparison to the part of the crown directed towards the occlusal plane;
3) torque of the crowns of incisors: the incisal edge of upper incisors is situated lingually relative to the cervical part of the crowns of these teeth;
4) molars and premolars rotated around the long axis take up more space in the dental arch;
5) rotated incisors take up less space in the arch in comparison to their normal position.
The correct answer is:
- A. 1,2,4,5.
- B. 1,4,5.
- C. 1,2,3.
- D. 4,5.
- E. all the above.
Hint
Recall the direction of normal crown angulation and torque in Andrews' keys, and how rotation changes the space a tooth occupies.
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