Accuracy of Computer-assisted Template-based Implant Placement Using CAD/CAM Stereolithographic Surgical Templates With or Without Metallic Sleeves: a Randomized Controlled Trial

This study was designed as a randomized controlled trial of parallel group design conducted at one centre, between May 2016 and March 2017. The study was performed after approval was received from the institutional review board of the Aldent University, Tirana, Albania (2/2017).

The investigation was conducted according to the principles embodied in the Helsinki Declaration of 1975 for biomedical research involving human subjects, as revised in 2013. All patients were informed about the nature of the treatment and their written consent was obtained. Data collection was designed to preserve patient anonymity.

• Inclusion/exclusion criteria:

Any partially edentulous patient, aged 18 years or older, able to sign an informed consent, in need of an implant-supported fixed restoration was considered eligible for this study. Any potential implant location based on individual patient requirements was considered eligible in the present trial. Patients were not admitted to the study if any of the following exclusion criteria was present: general medical contraindication to oral surgery (American Society of Anesthesiologist, ASA, class III or IV); irradiation in the head and neck area less than one year before implantation; psychiatric problems; alcohol or drug abuse; pregnant or nursing; untreated periodontitis; severe bruxism or clenching; uncontrolled diabetes; poor oral hygiene and motivation; and inability to complete the follow-up.

Enrolled patients received preoperative photographs, periapical radiographs or panoramic x-rays for initial screening and evaluation. The prosthetic-driven planning workflow started by taking a cone beam computed tomography (CBCT) scan (Cranex 3Dx, Soredex, Tuusula, Finland) by using a wax bite to separate dental arches. Then, the patients received intraoral digital impression taken using the 3M True Definition Scanner (3M Italia, Pioltello, Milano). The digital data (STL, STereo Lithography interface format) was imported in a 3D design software (exocad DentalCAD, Exocad GmbH, Darmstadt, Germany) to realize a virtual wax-up according to the functional and esthetic requirements. Then, the STL and DICOM (Digital Imaging and COmmunications in Medicine) data were imported in a 3D software planning program (3Diagnosys ver. 5.0, 3DIEMME srl, Cantù, Italy). Then, the reprocessed surface extrapolated from the DICOM data (by using a Hounsfield scale filter) and the surface generated by the master cast scanning process, or by the intraoral scanning process, were merged with the best-fitting repositioning tools of the software (3Diagnosys ver. 5.0, 3DIEMME srl). At this point, prosthetic-driven implants/abutments size and location were planned taking into account the bone quality and quantity, soft tissue thickness, anatomical landmarks, as well as, type, volume and shape of the final restoration. After careful functional and esthetic evaluation and final verification, the prosthetic-driven plan was approved. At this point, patients were randomly assigned to receive conventional stereolithographic surgical template with (control group) or without (test group) metallic sleeves. Stereolithographic surgical templates were designed and fabricated by an independent certified center not previously involved in the study (New Ancorvis srl, Bargellino, Italy). In the test group, conventional templates with close-sleeve-design were produced to place implants between premolars. In case of implants to be place in molar area, template with open sites were produced to solve intermaxillary space limits.