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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 (range: 0.0–1.6 mm) in the vertical plane (apico-coronal). All the measurements were within the safety margins of the software. In all the three measures, there were no statistically significant differences between fully digital and conventional impressions. The mean error in angle was 2.56 ± 1.52° (range: 0.3–5.0°) in the fully digital group and 2.18 ± 1.41° (range: 0.3– 5.8°) in the control group (P = 0.519). In the hor- izontal plane (mesiodistal), the mean error was 0.57 ± 0.32 mm (range: 0.1–1.1 mm) in the fully digital group and 0.43 ± 0.26 mm (range: 0.1– 0.9 mm) in the control group (P = 0.249). In the vertical plane (apico-coronal), the mean error was 0.67 ± 0.51 mm (range: 0.0–1.6 mm) in the fully digital group and 0.43 ± 0.32 mm (range: 0.0–1.2 mm) in the control group (P = 0.180). Discussion This randomized controlled trial was conducted with the aim of understanding which procedure is preferable, a conventional impression and a scan model or a digital impression, to rehabilitate par- tially edentulous patients using computer- assisted template-based implant placement. Implants were placed flapless or with a minimally invasive flap and when possible loaded immediately. Both techniques achieved successful results, and no statistically significant differences were observed regarding early implant failure, template-related complications or virtual planning accuracy. To the best of our knowledge, at the time of writing this article, there were no other published randomized clinical trials comparing conventional impressions and scan models to digital impres- sions to plan and rehabilitate partially edentulous patients using computer-assisted template-based implant placement. This made it difficult to evaluate the results of the present study against comparable studies. The scientific evidence available concluded that, regarding implant survival rate, guided sur- gery has no obvious differences compared with the conventional protocols.4 However, according to D’haese et al., the most frequent surgical and mechanical complications are recognized to be specifically associated with computer-guided template-assisted surgery, including misfit of the surgical guide, fracture of the complete acrylic denture and misfit of the suprastructure.14 In the present study, no implant failed early and no templated-related complications were observed in either group. Several independent uncontrolled prospective studies reported substantial deviations in 3-D directions between virtual planning and final implant position, as well as postsurgical compli- cations.15–17 However, excellent clinical results have also been reported using this technique.13, 14, 18–19 Vasak et al. found a mean deviation of 0.43 mm (buccolingual), 0.46 mm (mesiodistal) and 0.53 mm (depth) at the level of the implant shoulder and of 0.70 mm (buccolingual), 0.63 mm (mesiodistal) and 0.52 mm (depth) at the apex level, respectively.20 A maximum deviation of 2.02 mm was found in the apico-coronal direc- tion; nevertheless, significantly lower deviations in the mesiodistal direction were observed for implants in the anterior region and mandibular implants than for implants in the posterior region and maxillary implants. In a historical systematic review and meta-analysis by Jung et al., a mean error in angulation of 4.0°, with a maximum of 20.4°, was found.21 In the present study, a total mean error of 2.34 ± 1.44° (range: 0.3–5.8°) in angle, 0.49 ± 0.29 mm (range: 0.1–1.1 mm) in the horizontal plane (mesiodistal) and 0.53 ± 0.42 mm (range: 0.0–1.6 mm) in the vertical plane (apico- coronal) was found. In all of the cases, the maximum values (5.8° in angle, 1.1 mm in the horizontal plane and 1.6 mm in the vertical plane) did not exceed the safe offset of the software (1.5 mm in the horizontal plane and 2.0 mm in the vertical plane). Although no sta- tistically significant differences were observed between conventional impressions and scan models and digital impressions, a trend of higher discrepancy between virtual and placed implants was observed in the fully digital group (mean error of 2.56 ± 1.52° in angle, 0.57 ± 0.32 mm in the horizontal plane and 0.67 ± 0.51 mm in the vertical plane). Major deviations were found for edentulous areas of three or more teeth (1.1 mm in the horizontal plane in the mandible and 1.6 mm in the vertical plane in the maxilla). No data were reported in the scientific litera- ture about the acceptable angle deviation. In the present study, based on a worse projection using implants of 3.5 and 4.0 mm in width and 15.0 mm in length and with standard offset, the maximum acceptable value ranged from 5.9 to 12.3° (Fig. 10). In the present study, a higher angular deviation was found in partially edentulous patients treated in the control group (5.8°). In contrast, minimum values of 0.1 mm in the horizontal plane and 0.0 mm in the vertical plane were observed in both groups, while a minimum angular deviation of 0.3° was observed in the fully guided group. Journal of Oral Science & Rehabilitation Volume 3 | Issue 3/2017 15