New strategy for osseodensification during osteotomy in low-density bone: an in vitro experimental study.

The goal of this in vitro study was to evaluate and propose a new strategy for osseodensification technique using a drill counterclockwise to densification of bone of low density. Synthetic bone blocks of two different low densities (type III and IV) were used for the tests. The conventional drilling group (CD group) used Turbo-drill in a clockwise direction, and the osseodensification group (OD group) applied Turbo-drill in a counterclockwise direction. The applied tests were: (i) measurement of the temperature variation (DeltaT) and (ii) measurement of the torque during the osteotomies, comparing the new strategy with the conventional drilling. Both groups were tested without (condition c1) and with (condition c2) irrigation, generating four subgroups: CDc1, CDc2, ODc1, and ODc2. Twenty osteotomies were made for each subgroup with a thermocouple positioned intra-bone (1 mm distant from the osteotomy) to measure the temperature produced. Other 20 samples/group were used to measure the torque value during each osteotomy in both synthetic bone density blocks. The mean of the DeltaT during the osteotomies in type III bone was: 6.8 +/- 1.26 degrees C for the CDc1 group, 9.5 +/- 1.84 degrees C for the ODc1, 1.5 +/- 1.35 degrees C for the CDc2, and 4.5 +/- 1.43 degrees C for ODc2. Whereas, in the type IV bone, the DeltaT was: 5.2 +/- 1.30 degrees C for the CDc1 group, 7.0 +/- 1.99 degrees C for the ODc1, 0.9 +/- 1.05 degrees C for the CDc2, and 2.7 +/- 1.30 degrees C for ODc2. The maximum torque during the osteotomies was: 8.8 +/- 0.97 Ncm for CD samples and 11.6 +/- 1.08 Ncm for OD samples in the type III bone; and 5.9 +/- 0.99 Ncm for CD samples and 9.6 +/- 1.29 Ncm for OD samples in the type IV bone. Statistical differences between the groups were detected in tests and conditions analyzed (p < 0.05). Using the drill counterclockwise for osseodensification in low-density bone generated a significantly greater torque of a drill than in CD and temperature variation during osteotomies. However, the temperature range displayed by the OD group was below critical levels that can cause damage to bone tissue.