Clinical and radiographic assessment of reverse drilling technique on bone dimension and crestal bone level in closed sinus lift surgery

Evaluation of the effect of the reverse drilling technique using two different kits on alveolar ridge geometry and crestal bone stability in closed sinus lift surgery

Triple-blind parallel-group randomized clinical trial

Implant Department, Faculty of Dentistry, Mashhad University of Medical Sciences

Patients eligible for inclusion in the study must be systemically healthy, candidates for implant placement in the posterior maxilla with a bone height of 4 to 5 millimeters in that region, require a closed sinus lift procedure, and have sufficient interarch space. Patients will be excluded if they have uncontrolled systemic diseases such as cardiovascular conditions, diabetes, or immune disorders, or if the Schneiderian membrane is perforated during surgery.

In one group, the reverse drilling technique will be performed using Straumann drills (Straumann, Basel, Switzerland), while in the other group, the bone densification technique will be employed using the Versah drilling system. Specifically, Densah burs (VERSA, California, USA) will be used in reverse mode to simultaneously compact and expand the bone, thereby achieving the required vertical height.

The primary outcomes include: measurement of volumetric changes along with the amount of sinus floor elevation; marginal bone level, assessed by measuring the distance between the first implant thread and the crestal bone on periapical radiographs (in tenths of a millimeter); evaluation of Schneiderian membrane perforation using the Valsalva maneuver; initial survival rate in both groups; and insertion torque in both groups, measured using the torque meter.

In the present study, blocked randomization will be used to ensure that an equal number of participants are allocated to the intervention and control groups in successive but equal time intervals. In this way, for example, one type of treatment will be assigned to the first block, the other type to the second block, then the first type again to the third block, and so on. The advantage of blocked randomization is that it guarantees balance in the number of participants between groups. The difference in the number of individuals in each group will never exceed half the size of each block. Accordingly, envelopes will be prepared equal to the sample size, and each generated random sequence will be recorded on a separate sheet of paper. These sheets will then be placed inside sealed envelopes in the order of the generated sequence. To preserve the randomization sequence, the envelopes will be numbered on the outside accordingly. At the time of surgery, based on the order of eligible participants entering the study, one of the sealed envelopes will be opened in sequence, and the participant’s group allocation will be determined.

In the present study, since two different kits—Straumann and Densah—will be used for reverse drilling, blinding of the surgeon is not feasible. However, the patients and the individual responsible for clinical and radiographic evaluations will be blinded to group allocation.