Three-dimensional radiographic assessment of bone changes around posterior dental implants at native bone site in Gansu Province, Northwest of China: A retrospective cohort study.

Purpose: The aim of this study was to assess bone density and thickness changed following dental implant placement in the maxillary and mandibular jaws. Also, observe the form of bone loss around the implant and the relationship between preoperative bone density and bone thickness with bone loss around dental implants.
Methods: 65 patients, including 102 dental implants, were assessed in this study. CBCT was utilized to determine the bone condition (bone thickness and density at three levels (sub-crestal bone at 3 mm (CB3), 6 mm (CB6), and 9 mm (CB9)) before implant placement, and 2 to 3 years after placement, also determine the bone loss pattern.
Results: The difference in bone thickness was 0.32 ± 0.50 mm at CB3, 0.18 ± 0.40 mm at CB6, and 0.14 ± 0.07 mm at CB9. The change buccal bone density at CB3, CB6, and CB9 were 344.5 ± 278.9, 260.5 ± 276, and 138.9 ± 313.9 HU, respectively, and the change in lingual bone density was 252.7 ± 247, 179.9 ± 244.1, and 281 ± 4063 HU, respectively. Only the CB3 level showed a significant decrease in bone thickness (p < 0.001), and a change in bone density was observed at the three levels (p < 0.001). The means of vertical and horizontal bone loss were 0.19 ± 0.23 mm and 0.18 ± 0.22 mm, respectively. Splinted or adjacent dental implants have more horizontal bone loss, with statistically significant (p < 0.001). Age, gender, and implant position were not statistically related to the outcome variables. There was a negative correlation between the preoperative status of the bone condition and pattern bone loss, as indicated by Pearson's correlation coefficient.
Conclusion: CBCT detected a significant bone thickness decrease was found only at the crestal third. A significant bone density increase was found at three levels around dental implants. Implant areas with higher bone thickness and density had less bone loss.
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