Analysis of correlation between height of residual ridge and bone density of residual ridge crest at edentulous mandible using computed tomography

Purpose The aim of this study was to investigate the correlation between bone density of the edentulous mandibular ridge crest and residual bone height in edentulous subjects using multidetector computed tomography (MDCT) images. Methods A total of 194 bilateral MDCT images from 97 individuals with an edentulous mandible were selected for analysis. The residual ridge ratio (RRR), the CT values at the residual ridge crest, and the CT values at the lowest point of the mandible measured from MDCT images at molar region. RRR was classified into the three groups (Group 1: >2.0, Group 2: 1.5–2.0, Group 3: <1.5). Bone density at the residual ridge crest was evaluated by calculating the ratio of the CT value at the lowest point of the mandible and the CT value of the residual ridge crest (“ratio of CT values”). The relationship between the height of the residual ridge and the bone density of the residual ridge crest was evaluated by ratio of CT values. Results Median ratio of CT values was 0.62 in Group 1, 0.70 in Group 2, and 0.84 in Group 3, indicating significant differences between all 3 groups (p < 0.05). The correlation coefficient for RRR and residual ridge crest bone density was −0.54 in males and −0.55 in females, implying a moderate correlation for both males and females. Conclusions The present results suggest a negative correlation between residual bone height and the bone density of the edentulous mandibular ridge crest.