Application Research Of Cast-Based Implant Surgical Guide Of Biaxial Orientation Technique

Years of experience have shown that dental implants are an effective treatment modality for the restoration of function and esthetics of the stomatognathic system after tooth loss. Single-tooth restorations, bridges and removable partial dentures can be anchored to dental implants successfully and with low complication rates. The greatest key to successful implant therapy is proper placement of implant in the jaw bone, which needs careful preoperative planning. In implant surgery, achieving precise preoperative planning mainly relies on implant surgical guide.Implant surgical guide includes 2 popular designs: cast-based implant surgical guide and computer-aided design and manufacturing(CAD/C AM) based implant surgical guide. The C AD / CAM based implant surgical guide is designed in implant planning software using data from computerized tomography scan(C T) or Cone Beam Computer Tomography(C BCT) and fabricated using stereo lithography. It has s high accuracy and makes more precise placement of implants with less risk. However, special training for familiarity with the entire system and special equipment is necessary. A double scanning procedure is needed. It is time-consuming and expensive and difficulty to widely used in clinical practice.The traditional cast-based guided surgical guide is fabricated by mechanical drilling and vacuum- formed matrix while an approximate implant direction is located on the cast with the help of two-dimensional X-ray imaging, bone sounding and diagnostic wax-up. It's simple for fabrication, cost effective and time-saving but lack of precision. The modified cast-based guided surgical guide uses CT or CBCT data to plan implant location in implant planning software. The 3D position of virtual implant relative to the jaw was transferred to the implant surgical guide using special stereoscopic posit ioning device. However, the accuracy of most modified cast-based guided surgical guides is not high due to the deficiencies and limitations of the special stereoscopic positioning device. C urrently, there has not a simple, cost effective and time-saving technology for fabricating cast-based guided surgical guide of high precision in clinical.This study aimed to establish a new method of fabricating cast-based implant surgical guide based on biaxial orientation technique. An appropriate position of implant in the alveolar bone was based on C BCT data and precisely transferred to diagnostic cast from software by the biaxial orientation device. Then in vitro experiment was carried out to evaluate the accuracy and possibility of clinical application of this technology. Finally, clinical trial was went on to further explore the technology's availability and accuracy. Materials and methodsPart one : A biaxial orientation device was created using dual axis digital angle protractor, crossed line laser and dental sur veyor. Then a new method of cast-based implant surgical guide was established guide based on biaxial orientation technique.Part two: In vitro experiment, according to the method introduced in part one, a radiographic guide was made first and then radiographic data of artificial edentulous maxillary with the radiographic guide was acquired by C BCT imaging. Virtual implant planning was made in SimPlant software according to different buccolingual and mesiodistal angle deviations. Cast-based implant surgical guide was fabricated with the help of biaxial orientation device. 20 implants were placed in 20 artificial edentulous maxillaries assisted by the guides. A postoperative CBCT scanning of artificial edentulous maxillary was taken and the data of pre- and postoperative CBCT scanning was matched in Geomagic Studio, and then discrepancies between the virtual and the actual implant positions were measured in SimPlant. In vitro experiment was aimed to evaluate the accuracy and possibility of clinical application of this technology. Part three: 20 patients of dentition defect(The number of consecutive missing teeth is less than 3) who desired implant restoration were selected. Implant surgical guides were fabricated by the method introduced in part one. 26 implants were placed aided by the guides. The data of pre- and postoperative CBCT scanning was matched in Geomagic Studio, and then discrepancies between the virtual and the actual implant positions were measured in SimPlant. C linical trial was aimed to accuracy and practicability of cast-based implant surgical guide of biaxial orientation technique.Results and conclusions:1. A new method of cast-based implant surgical guide based on biaxial orientation technique was established and a biaxial orientation device was created. The biaxial orientation device consisted of dual axis digital angle protractor, crossed line laser and dental surveyor which were easy to obtain. The fabrication process was that: a radiographic guide was made first and radiographic data was acquired by CBCT imaging. Virtual implant planning was made in planning software, the 3D position of virtual implant relative to the jaw was transferred to the cast using biaxial orientation device. Finally a cast-based implant surgical guide was fabricated. 2. The deviation between the virtual and the actual implant positions measured were 0.97±0.34mm(implant shoulder), 1.50±0.39mm(implant apex) and 4.20±1.67°(implant axis). The results showed that there was a certain bias between the actual and virtual implant in three dimensions, but it was still within a safe distance of 2mm, indicating the implant surgical guide had a good accuracy in vitro and can be applied to the clinical.3. The implant surgical guide had good stability, 26 implants were successfully placed without nerve damage, maxillary sinus perforation and other complications. The accuracy of the implant surgical guide measured after registration was: the shoulder deviation1.09±0.39 mm, the apex deviation 1.62±0.48 mm, the angle deviation 5.07±2.26°. The clinical accuracy was slightly worse than the CAD / CAM implant surgical guide, but the deviation was still within a safe distance of 2mm, the implant surgical guide had a good accuracy and application prospect.In summary, the biaxial orientation device is easy to build, the cast-based implant surgical guide of biaxial orientation technique is simple for fabrication, cost effective and time-saving with a good accuracy. It plays a good role in guiding in precise placing of implant in the three-dimensional position for the cases such as those in vitro and clinical trial.