Evaluation of new bone formation after osteotome sinus floor elevation and simultaneous implant placement without grafting by two radiographic methods

Background

After tooth loss, alveolar bone atrophy and pneumatization of the maxillary sinus occur. It is difficult for implant placement to posterior maxilla because of the reduced residual bone height (RBH) available. Osteotome sinus floor elevation (OSFE) is a reliable technique and produced satisfied results. Compared with oral panoramic radiograph (OPG), the application of cone beam computed tomography (CBCT) that provides clinically valuable information is considered to be more accurate assessment.

Aim/Hypothesis

The purpose of this study was to compare radiographically the variances of measurements on OPG and CBCT, and to evaluate the effects of endo-sinus new bone formation after OSFE without grafting in a short time. Simultaneously, to analysis the potential related factors of endo-sinus bone gain (ESBG).

Material and Methods

A prospective study design was adopted. 87 implant placements were inserted in 80 patients. OPG and CBCT were used at preoperative, immediately in postoperative period and before stage II surgery (mean 5-month postoperative). The RBH was measured at preoperative and before stage II surgery, the implant protrusion length (IPL) was assessed at immediately postoperative and before stage II surgery, ESBG was reviewed before stage II surgery. Compare the RBH, IPL, ESBG between two groups from OPG and CBCT. Correlation analysis was conducted to explore the relationship between ESBG with IPL, RBH, age, gender and bone block lifted intraoperatively by osteotomes. Significance was set to 0.05.

Results

The mean RBH was 8.47 ± 1.78 mm on OPG and 8.08 ± 1.47 mm on CBCT preoperatively. After mean 5 months, it was found the averaged RBH was 9.58 ± 1.67 mm on OPG and 10.59 ± 1.51 mm on CBCT. The mean IPL was 2.44 ± 1.16 mm on OPG and 1.98 ± 1.09 mm on CBCT at immediately postoperative. The averaged IPL was 1.27 ± 1.30 mm on OPG and 0.05 ± 1.33 mm on CBCT before the stage II surgery, respectively. ESBG was 1.10 ± 0.76 mm on OPG and 1.90 ± 1.38 mm on CBCT. And there were all significant differences between two groups (P < 0.05). As shown by the numerical value, ESBG with bone block lifted were more than with no bone block lifted, but P value > 0.05 that indicating the difference was again not statistically significant difference between two groups. The relevant factors analysis detected that the final ESBG was positively correlated to IPL at immediately postoperative. Meanwhile, no other variables were detected showed to be associated with the final ESBG, including RBH, age, gender and bone block lifted.

Conclusion and Clinical Implications

In conclusion, compared with the OPG of 2D image, the errors of measurement could be reduced and the results could be assessed more accurately on CBCT. Approximate 2 mm endo-sinus bone augment could be acquired, and the final ESBG was explored to be positively correlated to IPL measured at immediately postoperative. Bone block lifted intraoperatively by osteotomes does not increase the amount of endo-sinus bone formation.