The dental implant placed freehand with a digital planing is vastly increasing. The accuracy between the planned and the placed implants still not well determined. Between a single implant and a full mouth rehabilitation, the precision is very wide. A precision scale must be settled according to each indication in order to offer the clinician a safety and a predictability for his procedures.

In this paper the investigators report an original research evaluating the accuracy of computer-guided implant placement in posterior edentulous mandibular spaces. In this randomized controlled trial, several factors were evaluated such as primary implant stability, possibility of immediate loading, displacement at crestal and apical levels, angle of deviation, surgical guide design, computer-aided design and computer-aided manufacturing accuracy, and variance between different implant macro-geometries and lengths. As exhaustive description of the assessment techniques as well as the statistic results were also presented in this article.

Nowadays, the use of guided surgery is vastly increasing in a daily dental practice. In the "Era of Digital Dentistry", it is of utmost importance to evaluate the accuracy and precision of the computer-guided techniques in order to determine their limits, avoid risks (adjacent anatomical structures, limited crestal volume, immediate loading), and apply them in safe manner. Evidence-based scientific data on this matter is still deficient. In these terms, the investigators consider it very interesting and of high clinical value for all oral surgeons and dental practitioners to evaluate in a clinical research the precision and distortion of computer-guided implant surgery.

Inclusion Criteria:

• Acceptable oral hygiene with no signs of active periodontal disease or local infection
• American Society of Anesthesiologists (ASA) physical status classification 1 and 2
• Non or Light smoking (< 10 cigarettes per day)
• Acceptable intermaxillary space (44 mm minimum)
• Minimal crestal width of 5.5mm
• Minimal residual bone height of 10mm above the alveolar nerve canal

Exclusion Criteria:

• Head and neck irradiation
• Bone grafted sites
• Severe bruxism
• Cone Beam Computed tomography with exaggerated artifacts
• Limited intermaxillary space

Patients presenting at Saint Joseph University of Beirut dental clinics with a distal-shortened mandible or distal intercalary space of two to three missing premolars or molars (class I, II or VI according to Kennedy's classification on edentulous spaces) and requiring implant-supported reconstructions were selected to participate in this study.

For each case two implants were placed with a fully guided procedure. Thirteen patients were included in this study with twenty-five implants eligible for accuracy evaluation.