Volume 39, Number 5, 2019 675 Submitted September 11, 2018; accepted December 23, 2018. ©2019 by Quintessence Publishing Co Inc. 1 Private Dental Practice, Rome, Italy. 2 Division of Oral Surgery and Implantology, Department of Head and Neck, Institute of Clinical Dentistry and Oral and Maxillofacial Surgery, Fondazione Policlinico Universitario A. Gemelli IRCCS, Rome, Italy; Università Cattolica del Sacro Cuore, Rome, Italy. 3 Division of Oral Surgery and Implantology, Department of Head and Neck, Institute of Clinical Dentistry and Oral and Maxillofacial Surgery, Fondazione Policlinico Universitario A. Gemelli IRCCS, Rome, Italy. 4 Section of Hygiene, Institute of Public Health, Università Cattolica del Sacro Cuore, Rome, Italy. Correspondence to: Dr Paolo De Angelis, Department of Head and Neck, Division of Oral Surgery and Implantology, Institute of Clinical Dentistry, Fondazione Policlinico Universitario A. Gemelli IRCCS—Università Cattolica del Sacro Cuore, Largo Francesco Vito 1, 00168 Rome, Italy. Email: dr.paolodeangelis@gmail.com Comparison of Marginal Bone Loss Around Axial and Tilted Implants: A Retrospective CBCT Analysis of Up to 24 Months This clinical study retrospectively analyzed cone beam computed tomography (CBCT) images to determine the potential infuence of implant inclination on peri- implant marginal bone loss after 18 to 24 months of functional loading. Twenty-fve consecutive patients presenting with an edentulous or partially edentulous maxilla or mandible and an adequate bone volume for receiving oral implants were selected for analysis of the marginal bone loss around tilted and/or axial implants. The study population included patients rehabilitated with Toronto bridges (TBs), fxed partial dentures (FPDs), or single crowns (SCs) on axial and/or tilted implants. The primary outcome was the CBCT analysis of peri-implant marginal bone level change, depending on inclination of implants and type of prostheses. The secondary outcome was analysis of survival and success rates of tilted and axial implants. A signifcant difference was observed for peri-implant buccal bone loss (mean of axials 0.42 ± 0.06; mean of tilted 0.70 ± 0.09) (P = .009). The difference in peri-implant lingual/palatal/mesial/distal bone loss was not signifcant between axial and tilted implants (P > .05). No signifcant difference was observed between the marginal bone level and the type of prostheses for both tilted and axial implants in all the assessed sites (P > .05). The success rate for both tilted and axial implants was 100%, and no complications were observed for all the prosthetic rehabilitations, with a 100% survival rate. Compared to axial implants, tilted implants showed a signifcant statistical difference for peri-implant buccal bone loss, but no other differences were observed for peri-implant bone loss or for implant survival and success rate. Fixed partial or total rehabilitation using tilted or axial implants, or with tilted and axial implants, could be a reliable technique with advantages to patients and operators. Int J Periodontics Restorative Dent 2019;39:675–684. doi: 10.11607/prd.4110 Dental implants, compared to teeth, are less tolerant of traumatic occlusal forces due to the lack of periodontal ligaments. They are more vulner- able to nonaxial forces because of the higher torsional and shear forces exerted on the surrounding bone that damage the bone-to-implant contact surface. 1 As a result, implants should be placed in line with the direction of loading. However, the proximity of anatomical structures, such as the maxillary sinus and the inferior alve- olar nerve, often preclude standard implants from being placed axi- ally. Solutions to inadequate ridge volume include the use of short implants, 2 ridge augmentation procedures, 3,4 or cantilever pros- theses. 5 Although they have a com- parable short-term survival rate, the long-term performance of short im- plants is less understood, especially in the posterior maxilla with lower bone density. 6,7 Vertical augmen- tation procedures increase patient morbidity; the outcome is unpre- dictable and operator-dependent, especially when performed in the posterior mandible. 8 Cantilever prostheses may incur higher rates of prosthetic complications, such as abutment loosening and denture fracture. 9–11 Due to the unpredictable long- term prognosis associated with the abovementioned procedures, Ernesto Bruschi, DDS 1 Paolo Francesco Manicone, DDS 2 Paolo De Angelis, DDS 3 /Laura Papetti, DDS 3 Roberta Pastorino, PhD 4 /Antonio D’Addona, DDS 2 © 2019 BY QUINTESSENCE PUBLISHING CO, INC. PRINTING OF THIS DOCUMENT IS RESTRICTED TO PERSONAL USE ONLY. NO PART MAY BE REPRODUCED OR TRANSMITTED IN ANY FORM WITHOUT WRITTEN PERMISSION FROM THE PUBLISHER.