Application of reverse drilling technique in alveolar ridge expansion

Recently, there is a new model adjustment in the osteotomy preparation named osseodensification. This study focused on the ridge expansion results based on reversed drilling technique regarding osseodensification technique and the modified method.

Twenty-seven samples were fabricated from sawbones, tailored into three different widths: 6.75 mm, 7.25 mm, and 7.75 mm, and drilled by three different protocols: osseodensification bur with 1500 rpm reverse torque, triple-bladed drill with 200 rpm reverse torque, and triple-bladed drill with 1600 rpm standard forward turning; each group contained three samples. After implants were screwed into the sawbones over 5mm or till the bone fractured, the width change of the bone was measured, the insertion depth of the implant was calculated, and the fracture of the bone was also recorded for comparison.

The result showed that in narrow bone width (6.75 mm) the enlargement of bone thickness showed significant difference among the groups (P < 0.05); both reverse torque group expressed a higher expansion result, but in the paired comparison, only osseodensification bur expanded the ridge significantly better than the standard drilling sequence. However, implant insertion depth of osseodensification group was significantly less than those of other two drilling protocols (P < 0.005). Even though the bone fracture happened least in the standard drilling sequence, there is no difference among the groups.

The counter-clockwise rotating method possesses the ability to expand bone ridge but lead to a higher stress in the bone structure, which may affect the insertion depth of the implants.