OBJECTIVETo measure the mesiodistal and buccolingual alveolar bone mass of back teeth in posterior alveolar crest at different height by cone beam computed tomography (CBCT), and analyze the safe area of microscrew implanted at back teeth in posterior alveolar crest.

METHODS30 cases of adult scan image data were selected for the study of jaw bones scan reconstruction. From the distal of first premolar backward, buccolingual (plate) width and the mesiodistal size between each interfurcal region (including tuber maxillae) were measured from alveolar crest at top of 2, 4, 6, 8, 10mm. ANOVA and LSD methods were made by SPSS 16.0 software for comparison.

RESULTS1) The mesiodistal bone mass of back teeth in maxilla at the same height with different position had statistically significant difference (P<0.05). The biggest mesiodistal bone mass was located at the palatal roots between the second premolar and the first molar. The statistically significant difference of buccolingual bone mass also existed at different position and height (P<0.05). The biggest buccolingual bone mass was located at the middle of the first molar and the second molar. 2) The mesiodistal bone mass of back teeth in maxilla at different height and position had statistically significant difference (P<0.05). The statistically significant difference of buccolingual bone mass also existed in the same position with different height (P<0.05). The biggest mesiodistal and buccolingual bone mass was located at the middle of the first molar and the second molar.

CONCLUSIONThe safe area of microscrew implanted at back teeth in posterior alveolar crest is tested by CBCT, which provides valuable reference for the follow-up clinical application.