BIOMET 3i Tapered Implant System
The BIOMET 3i Tapered Implant System: Placement In Dense Bone
By Alan Meltzer, DMD, MScD, Voorhees, NJ, USA
The specifications of the BIOMET 3i Tapered Implant and the corresponding Quad Shaping Drills (QSDs) and Depth and Direction Indicators (NTDIs) are held to rigorous tolerances, which is intended to provide a closely integrated implant-to-osteotomy fit and primary stability. Because of the precise implant-to-osteotomy fit, the Tapered Implant may require reasonably higher levels of insertion torque (cutting torque resistance — the resistance created by the implant threads cutting a path into the osteotomy walls) to seat completely within the osteotomy. Higher torque may be equated with higher primary stability and hand ratcheting the implant to the final position may be required. Therefore, when placing a Tapered Implant, the insertion torque required to fully seat the implant may exceed the maximum torque capable of being delivered by an implant drill unit (typically 50Ncm) and the need to tap the osteotomy may occur, especially in dense bone (Type I). Importantly, tapping (pre-threading) the osteotomy wall reduces cutting torque resistance so that the implant can be placed more passively while still maintaining a precise implant-to-osteotomy fit. The Technical Tips to follow provide guidelines for placement of high torque BIOMET 3i Tapered Implants in dense bone.
Preparation Of An Osteotomy In Dense Bone
The QSDs for placement of BIOMET 3i Tapered Implants are designed to prepare the osteotomy to match the dimension of the minor diameter of the Tapered Implant (i.e. the implant body without the threads). The Tapered Implant NTDI is also precisely matched to the minor diameter of the implant. Therefore, in order to verify the accuracy of the desired placement (bucco-lingually, mesio-distally and apico-occlusally), the NTDI should be placed into the prepared site after irrigating and suctioning bone debris from the osteotomy. The NTDI should fit smoothly and cleanly (without binding or snapping) to the exact depth of the preparation, mimicking the final position of the implant. Should the NTDI not seat to the desired depth of the final seating position of the implant, it is likely because the drill was not advanced to the appropriate depth landmark on the QSD or the site was inadvertently ledged (subcrestal, crestal or supracrestal). If this occurs, additional drilling may be necessary to achieve the desired position using the QSD depth landmark as guidance. When Tapered Implants are placed subcrestally, care should be taken to ensure the residual supracrestal bone does not interfere with complete seating of the implant (Figs. 1a and 1b). Adjustment of the supracrestal bone may be required as illustrated in Figure 2a. After adjustment, the fit of the NTDI should be verified (Fig. 2b). Figures 3a and 3b demonstrate excessive supracrestal bone and the appropriate adjustment performed to permit a smooth and passive fit of the NTDI.
Using Dense Bone Taps
In dense bone (Type I), it is often necessary to tap the osteotomy in order to fully seat the implant and reduce insertion torque. If tapping is not performed, deformation of the internal interface of the implant or placement driver tip may occur. Length and diameter specific Dense Bone Taps should be advanced into the prepared osteotomy with the drilling unit set to 50Ncm and 20rpm. It is not unusual for the handpiece to stop prior to the tap reaching the full depth of the osteotomy. Therefore, a hand ratchet should be used to complete the tapping process (Fig. 4).
Clinical Tip: A thumb or forefinger should be placed on top of the Ratchet Wrench with light downward pressure applied (Fig. 5). This helps ensure continued full engagement of the driver, prevents implant wobble during insertion and assists in keeping the orientation in the proper plane.
Lavage Of The Osteotomy
Bone debris remaining in the osteotomy after site preparation with the drills or taps should be removed by irrigation with sterile saline and suction (Fig. 6), as debris in the site may increase cutting torque resistance during tapping and implant placement or prevent the implant from fully seating.