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A c c u r a c y o f c o m p u t e r - a s s i s t e d i m p l a n t p l a c e m e n t Fig. 4 Fig. 5 Fig. 4 Dental panoramic tomogram taken 1 year after loading. Fig. 5 Frontal photograph taken 1 year after loading. protocol. Implant sites were prepared based on the bone density evaluated by the surgeon at the first drilling. In the case of poor bone density, the implant site was underprepared.12 All of the implants were inserted with a minimum inser- tion torque of 35 Ncm and were immediately loaded at implant or abutment level. Any flaps were then sutured with Vicryl 4-0 sutures (Ethicon J&J International, Sint-Stevens- Woluwe, Belgium). The prefabricated tempo- rary acrylic restorations were trimmed and polished chairside. Single restorations received a nonoccluding occlusal scheme. Multiple-unit implant-supported temporary restorations were splinted together and reinforced using a metal framework. Immediately after implant placement, patients of both groups received a digital impression (CS 3600), taken at implant level using dedicate abutments (Type AQ scan body, New Ancorvis), to check the position of the placed implants. Afterwards, all of the patients received oral and written recommen- dations about medication, oral hygiene main- tenance and diet. Any sutures were removed 10–14 days later, after local cleaning using an antiseptic agent (0.2% chlorhexidine, CURASEPT, Curaden). Patients were followed monthly for up to one year after implant placement (Figs. 4 & 5). O u t c o m e m e a s u r e m e n t s – Early implant failure: An implant was consid- ered to be a failure if it was lost owing to mobil- ity, implant fracture and/or any infection requiring implant removal. The stability of each implant was measured manually with a torque of 25 N cm at delivery of the final resto- ration and later with the prosthesis removed, if needed (infection, extensive periapical bone loss, mucosal inflammation). – Template-related complications: limited access in posterior areas; buccal bony dehis- cence (due to a mismatch of the surgical tem- plate), evaluated by sounding the implant site with a periodontal probe (PCPUNC156, Hu-Friedy Italy, Milan, Italy) before implant placement; insertion of a different implant than planned and fracture of the surgical tem- plate. All of the complications were recorded during follow-up by the same clinician (MT), who performed all of the surgical procedures. – Accuracy: Three deviation parameters (hori- zontal, vertical and angular) were defined and calculated between the planned and placed implant positions (Fig. 6). The postoperative STL file, derived from the intraoral scan (Fig. 7), was geometrically aligned with the files exported from the planning, by auto- mated image registration using maximization of mutual information (Dental SCAN, Version 6, Open Technologies, Brescia, Italy; Figs. 8 & 9). The horizontal (lateral), vertical (depth) and angular deviations between virtual and placed implants was calculated along the long axis of each implant. An expert engineer (FC) perfor- med all of the measurements. R a n d o m i z a t i o n One computer-generated restricted randomiza- tion list was created. Only one of the investiga- tors, not involved in the selection and treatment of the patients, was aware of the randomization sequence and had access to the randomization lists stored in a password-protected portable computer. The random codes were enclosed in sequentially numbered, identical, opaque sealed envelopes. Envelopes were opened sequentially after eligible patients signed the informed con- sent forms; therefore, treatment allocation was concealed from the investigators in charge of enrolling and treating the patients. 12 Volume 3 | Issue 3/2017 Journal of Oral Science & Rehabilitation