Abstract
A digital process for designing and manufacturing a cobalt-chromium (Co-Cr) surgical template for static computer-aided implant surgery (s-CAIS) is described. The use of Co-Cr provides the advantage of a material with improved mechanical properties to reduce the possibility of surgical template fracture during s-CAIS. The stronger material also allows for a thinner surgical template, which in turn allows better access when the interarch operative space is limited or a longer implant is inserted. Limitations of the technique include the need for computer-aided manufacturing technology and, with the use of Co-Cr, a higher overall cost.
Contemporary static computer-aided implant surgery (s-CAIS) systems allow digital prosthetic and surgical planning by using superimposed data sets from multiple 3D imaging sources. A computer-aided design and computer-aided manufacturing (CAD-CAM) surgical template can be fabricated to transfer the planned implant position to the intraoral environment. Stereolithography (SLA) is commonly used to additively manufacture the surgical template by using photopolymering resin, and the surgical template should have enough material thickness to prevent fracture during the s-CAIS. A recent systematic review reported that although the fracture of a surgical template is a rare intraoperative complication during s-CAIS, it is considered to be a major complication with a high risk for the overall success of the treatment. In the event of the fracture of a surgical template, if the clinician cannot complete the surgery with a conventional surgical approach, the surgery would need to be canceled and the patient reappointed.
Limited mouth opening could contraindicate the use of s-CAIS for a posterior implant or if a longer implant is planned. In these circumstances, the combined length and thickness of the surgical instruments, planned implant, and surgical template often exceed the patient’s maximum mouth opening.
Because of its excellent mechanical properties and biocompatibility, cobalt-chromium (Co-Cr) alloy is gaining popularity in dentistry as a restorative material for fixed and removable dental prostheses. Although the conventional lost-wax casting technique can be used to fabricate Co-Cr dental prostheses, CAM technologies, including computer numerical control (CNC) milling and direct metal printing (DMP), have become popular alternatives because of improved manufacturing efficiency. The purpose of this report was to describe an alternative technique by using a CAD-CAM Co-Cr surgical template for s-CAIS.
Technique
- 1.
Obtain a 3D volumetric data set of the patient’s craniofacial tissue by cone beam computed tomography (CBCT) in the Digital Imaging and Communications in Medicine (DICOM) file format.
- 2.
Obtain diagnostic intraoral scans by using an intraoral scanner (TRIOS 3; 3Shape A/S) and export the scans in the standard tessellation language (STL) file format.
- 3.
Import DICOM files and STL files into a virtual implant planning software program (coDiagnostiX; Dental Wings GmbH) and complete the data registration process to merge all files. Complete virtual diagnostic waxing for the subsequent prosthetically driven surgical plan.
- 4.
Complete the surgical planning based on all diagnostic data ( Fig. 1 ) and design a CAD-CAM surgical template for the s-CAIS. During the design phase, provide 0.1-mm clearance between the intaglio surface of the surgical template and tooth surfaces. Provide 0.7- to 1.0-mm material thickness to provide adequate strength for the surgical template ( Fig. 2 ).
