Abstract: Objective　To measure the dimension of alveolar crest bone left in the anterior and posterior region of the edentulous mandible and sort out their relationship, providing reference for making a clinical implantation plan. Methods The study included 27 adult patients (54 hemi-mandible) with edentulous mandible who were taken CBCT at the Affiliated Stomatological Hospital of Nanjing Medical University from July 2016 to August 2018. The DICOM data of all subjects were imported into the Simplant Pro 11.04 software to measure the alveolar crest bone height and width of the anterior and posterior mandible. The statistical software was used to analyze the data. Pearson correlation coefficient was used to calculate the correlation of bone height and width between anterior area and premolar area or molar area of the edentulous mandible. Results　For the width of the alveolar crest, there was no significant correlation between the anterior and posterior area of the mandible (comparing premolar area with anterior area, p=0.27>0.05, r=0.22; comparing molar area with anterior area p= 0.95>0.05, r=0.01). It showed different degrees of correlation between anterior and posterior area of the edentulous mandible in terms of the width of 3minimeters below the alveolar crest, the width of 5minimeters bel ow the alveolar crest, the height of the mandible, the height of the mandible above the inferior alveolar nerve tube. For the width of 3mm below the alveolar crest, the premolar area was strongly correlated with the anterior area (P<0.001, r=0.74), while the molar area was moderately correlated with the anterior area (P=0.02<0.05, r=0.44). For the width of 5mm below the alveolar crest, the premolar area was strongly correlated with the anterior area (P<0.001, r=0.78), while the molar area was moderately correlated with the anterior area (P=0.003<0.05, r=0.55). For the height of the mandible, the premolar area was strongly correlated with the anterior area (P<0.001, r=0.79), and the molar area was also strongly correlated with the anterior area (P<0.001, r=0.70). For the height of the mandible above the inferior alveolar nerve tube, the premolar area was strongly correlated with the anterior area (P<0.001, r=0.64), while the molar area was moderately correlated with the anterior area (P=0.001<0.05, r=0.58). With the decrease of the width and height of the posterior area of the mandible, the width and height of the anterior area decreased. Conclusion　The progress of bone resorption in anterior and posterior region of edentulous mandible is almost the same. Whether all-on-4 can be applied in the anterior region is still to be considered in the case of serious bone defects in the posterior region of the edentulous mandible.

Key words: mandible, edentulous jaw, bone height, bone width, CBCT