Research On The Controling Of Pilot Drill In Dental Implantation

[Objective]To obtain the optimal drilling depth can avoid complications such as cortical perforation, damage to the maxillary sinus or to the mandibular canal in dental implantation., The measurement of the drilling depth presently relies much on the preoperative radiographic images. However, besides the image distortion of radiological scan, there is no satisfactory method to transfer the preoperative acquired data to the patient. This study aims at the control of the drilling depth in the jaw by the pilot drill, the initial bur for the dental implantation, to ensure the exact implantation depth, and provide an easy, practical and effective way to prevent cortical perforation during the dental implantation. [Materials and Methods]A 3D finite element model was applied by ANSYS11 for the pilot drill, the cancellous and cortical bones, and the simulation of the elastic modulus and poison ratio on the basis of the structure and working principle of the pilot drill. The stress distribution of the drill was analyzed when it reached the cancellous bone and the interface of cancellous and cortical bones through the simulation. Based on the working characteristics and control system of BLDC(Brushless DC Motor), a new instrument was designed to recognize the signals from the hall-sensor which reflected the stress change of the pilot drill on the interface.[Results] The 3D finite element analysis showed that the high stress area was distributed at the cutting tip and guided part when the drill reached the interface of cancellous and cortical bones rather than it was in the cancellous bone. Working as the speed detector, the hall-sensor in the BLDC for the dental implantation became a transducer that varied its output voltage when the drill reached the interface of cancellous and cortical bones. A new instrument can be designed to receive the signals from the hall-sensor to in-time control the action of BLDC to pause and reverse.[Conclusions] There is a stress change when the pilot drill reaches the interface of cancellous and cortical bones. This change can be detected through the variations of output voltage by the hall-sensor. After capturing the signals, the specially designed instrument can control the action of BLDC to pause and reverse when the pilot drill reaches the interface. As a result, the measurement of the drilling depth can be based on the actual objects instead of the radiographic images.