Accuracy of Metal Sleeve-Free Fully Guided Implant Surgery

Background. Computer-guided implant surgery is associated with a known loss of accuracy when compared with virtual implant planning, due to the influence of multiple clinical and technical factors. Deviations between planned and actual implant positions remain a relevant issue in guided implant surgery. Accuracy is commonly assessed by comparing virtually planned implant positions with postoperative implant positions using linear and angular deviation measurements. From a clinical perspective, improving the accuracy of guided implant placement is particularly relevant in complete-arch rehabilitations, where small deviations may affect prosthetic fit and clinical outcomes. Metal sleeves incorporated into surgical guides may contribute to mechanical tolerance between the drilling instrument and the guide, and reducing this tolerance could potentially improve accuracy.

Justification. Despite the widespread use of guided implant surgery, limited in vivo evidence exists regarding the effect of eliminating metal sleeves from surgical guides on implant placement accuracy. Additionally, the influence of reducing the drilling channel diameter on implant deviation relative to virtual planning has not been sufficiently evaluated. This study aims to determine whether the elimination of metal sleeves and the reduction of drilling channel diameter improve the accuracy of guided implant surgery. The findings may help clarify whether the use of metal sleeves is necessary and whether reducing the drilling channel diameter compared with manufacturer standards may decrease implant deviation by minimizing the gap between the drill and the guide.

Study Design. This study is designed as a prospective, single-center, interventional split-mouth clinical trial. An intraindividual comparison will be performed between two guided surgery conditions within the same patient.

Participants. The study population will consist of 15 partially or fully edentulous patients requiring fixed complete-arch rehabilitation with dental implants. Eligible participants will be patients classified as ASA I or II. Patients classified as ASA III or IV will be excluded. All participants will be required to meet the predefined inclusion criteria, none of the exclusion criteria, and will be required to provide written informed consent prior to participation.

Intervention. Virtual implant planning will be performed using guided surgery software by aligning DICOM data from cone-beam computed tomography scans with STL files of the maxillae obtained through intraoral scanning. A virtual diagnostic wax-up of the immediate-loading provisional restoration will be created to guide prosthetically driven implant planning. Following virtual planning, two drilling conditions will be randomly assigned in a split-mouth manner. On one side, drilling channels will be designed with the standard diameter recommended by the manufacturer for use with metal sleeves (4.85 mm). On the contralateral side, drilling channels will be designed with a reduced diameter of 4.83 mm. Surgical guides will be digitally designed, exported as STL files, and fabricated using three-dimensional printing technology with biocompatible surgical guide resin at a resolution of 35 microns. The guides will be sterilized in an autoclave at 134 °C for 5 minutes. Dental implants will be placed using the guided surgical templates.

Outcomes Assessment. After implant placement, postoperative intraoral scans with scan bodies will be obtained, and cone-beam computed tomography scans with scan bodies will be performed following a standardized imaging protocol. The planned and postoperative datasets will be compared to evaluate differences between virtual implant planning and actual implant placement. Measurements will be performed using reverse engineering software to calculate linear and angular deviations between planned and placed implants.

Statistical Analysis. Once data collection is completed, statistical analysis will be performed. Data normality will be assessed, and a chi-square test will be used to evaluate differences between the study conditions.

Inclusion criteria

• Partially or fully edentulous patients requiring fixed complete-arch rehabilitation with dental implants.
• Patients classified as ASA I or ASA II.
• Adult patients aged 18 years or older.
• Ability to understand the study procedures and provide written informed consent.

Exclusion criteria

• Patients classified as ASA III or ASA IV.
• Patients with medical conditions that contraindicate dental implant surgery.
• Inability or unwillingness to provide informed consent.