[Effects of first premolar extractions on third molar angulations].
OBJECTIVE
To compare the inclinations of third molars of patients treated orthodontically with and without premolar extractions.


METHODS
Records of 37 first premolar extraction patients and 32 nonextraction patients were examined. The pretreatment and posttreatment panoramic radiographs were analyzed. The angles were measured between the long axis of the third molar and the occlusal plane and between the long axis of the third molar and the long axis of the second molar. Changes in third molar angulations from pretreatment to posttreatment for two groups were compared by Mann-Whitney U-test.


RESULTS
There were statistically significant difference between the extraction and nonextraction groups in the median angle formed by the long axis of third molar angulation relative to the occlusal plane (P<0.05) and the second molar (P<0.05) in mandible but not in maxillary. In the extraction group, at the end of the orthodontic treatment, the mandibular third molars showed more uprighting than did the maxillary third molars.


CONCLUSIONS
Orthodontic treatment involving premolar extractions improves mandibular third molar angulations.
Ke
Hua-Feng
HF
Dept. of Orthodontics, School of Stomatology, Shandong University, Jinan 250012, China.
Wang
Chun-Ling
CL
Liu
Li
L
Wei
Fu-Lan
FL
Guo
Xin-xing
XX
D001641:Bicuspid; D003766:Dental Occlusion; D005260:Female; D006801:Humans; D008297:Male; D008334:Mandible; D008437:Maxilla; D008963:Molar; D008964:Molar, Third; D011862:Radiography, Panoramic; D014081:Tooth Extraction