Table 1.

Summary of included studies.

Author	Year	Type of study	Number of patients/implants	Type of placement				Findings/observational outcomes
				No. of guided implant	No. of failure	No. of non-guided	No. of failure
Arisan et al.	2013	Cohort	54/353	169	4	184	4	Groups; SIM group (mucosa-supported guide), AYT (bone-supported group), freehand method (control). Implants emerging from the interproximal area in the SIM group (5%), AYT (16%), and control groups (19%), with (χ2 = 11.77, P = 0.002). Implants placed via computer-aided methods showed a higher rate of success (98% and 93% for SIM and AYT groups, respectively) in maintaining a sufficient inter-implant distance compared with implants placed via the freehand method (control group, 77%; χ2 = 12.36, P = 0.002). In the SIM group, all implants were parallel (within 20°) within the same segment, 2% of implants in the AYT group and 16% of implants placed in the control group were not parallel to other implants positioned in the same segment, with (χ2 = 23.34, P < 0.0001). Implants placed by computer-aided methods, the offset position (too lingual or buccal from the top of the alveolar crest, 11% and 13% for SIM and AYT groups, respectively) compared with the control group (7%), with (χ2 = 6.243, P = 0.044). Screw access holes in 36% and 48% of the implants in AYT and control groups, respectively, were improperly located, with (χ2 = 8.301, P = 0.015). 55%, 41%, and 16% of the implants were found to be mispositioned in control, AYT, and SIM groups, respectively, with (χ2 = 37.49, P < 0.001).
Behneke et al.	2012	Cohort	52/132	24	0	86	0	Groups; fully guided placement, freehand placement, freehand final drilling. Mean (max) deviation at the implant shoulder for each of freehand final drilling, freehand implant insertion, and full-guided implant insertion groups were 0.52 (0.97), 0.30 (0.78), and 0.21 (0.60) mm, respectively. At the implant apex, they were 0.81 (1.38), 0.47 (1.30), and 0.28 (0.77) mm, respectively. Significant differences seen at all aspects of measurement (implant shoulder level, apex level, and angle), yielding generally higher deviations for the freehand final drilling group. With the exception of the reduced residual dentition, at the implant tip, the transfer accuracy increased with the number of sleeve-guided site preparation steps for all kinds of templates on the freehand methods.
Choi et al.	2017	Retros-pective cohort	251/450	NA	NA	NA	NA	Groups; freehand placement with a preoperative CBCT and postoperative periapical x-ray. Average discrepancy in position and angulation between the ideal and achieved implant was calculated to quantify the accuracy of freehand implant placement. Average mesiodistal angulation discrepancy between ideal and achieved surgical placement was 5.43°, 4.57° SD. Average mesiodistal position discrepancy between ideal and achieved surgical placement was 1.13, 1.48 mm SD. Discrepancies are within the range of those found by previous studies for freehand and guided surgery.
Danza et al.	2009	Cohort	93/300	66	NA	NA	9	Retrospective analysis by comparing a series of implants inserted with and without computer planning and custom model coordination. One hundred and seventy-six (58.6%) implants were placed in post extractive sockets; 72 (249%) were inserted in totally edentulous jaw; the antagonist was a natural tooth in 140 patients and a prosthetic device in the remaining 160 patients. Nine implants were lost, all were free hand inserted. The overall SVR was 97%. Statistically significant difference for immediately loaded implants, but multivariate analysis did not confirm the result, so no studied variable affected SVR. Kaplan–Meier method demonstrates that several variables are potentially associated to the crestal bone resorption. Implants inserted in the healed bone and in the frontal region have a better clinical outcome (i.e., lower bone resorption).
Nickenig et al.	2010	RCT	10/66	23	NA	23	NA	Groups; guided surgery, freehand (maxillofacial surgeon), freehand (prosthodontist). The accuracy of axis was significantly more precise with the 3-D surgical guide (4.2 (range, 0.0–10.0)) compared to the freehand method performed by the maxillofacial surgeon (9.8 (range, 3.7–17; p ¼ 0.000)) or by the prosthodontist (10.9(range, 2.0-20; p ¼ 0.000)). The 3-D surgical guide template produced significantly smaller variation between the planned and actual implant positions at the implant shoulder. With the freehand implantation by maxillofacial surgeon, mean deviation was 2.4 mm (0.0–7.0; p ¼ 0.001) in the posterior/anterior direction and 3.5 mm (4.0–7.0; p ¼ 0.000) in the medial/lateral direction. The comparison between the guided surgery and the freehand surgery performed by prosthodontist demonstrate a significant difference in the base-distance data (p ¼ 0.018 for the posterior/anterior direction; p ¼ 0.004 for the medial/lateral direction). The differences in base distances between freehand implantation performed by prosthodontist and maxillofacial surgeon were not statistically significant. The 3-D surgical guide template produced significantly smaller variation between the planned and the actual implant position at the apex of the implant. With the freehand implantation by the maxillofacial surgeon, these values were 2.0 mm (0.0–6.0; p ¼ 0.004) in the posterior/anterior direction and 2.5 mm (0.0–7.7; p ¼ 0.002) in the medial/lateral direction. The comparison between the guided surgery and the freehand surgery performed by the prosthodontist also demonstrated a significant difference in the base-distance data (p ¼ 0.003 for the posterior/anterior direction and p ¼ 0.002 for the medial–lateral direction). The differences in tip distances between freehand implantation performed by the prosthodontist and the maxillofacial surgeon were not statistically significant.
Pozzi et al.	2014	RCT	51/102	25	0	26	1	Groups; computer-guided implant placement aided with templates (computer-guided group) versus conventional implant placement without templates (conventional group). One provisional prosthesis failed, in the conventional group (P = 1.0). Four patients of the conventionally loaded groups experienced one complication each, versus five patients (six complications) in the computer-guided group (P = 0.726). There were no statistically significant differences between the two groups for any of the tested outcomes with the exception of more postoperative surgical pain (P = 0.002) and swelling (P = 0.024) at conventionally treated patients.
Ravida et al.	2018	Cohort	45/260	149	5	11	22	Groups; test group (computer-guided placement), control group (traditional placement). No significant difference was found between both groups in terms of biologic and technical complications, lower incidence of implant loss was observed in the test group (P < 0.001). A statistically significant difference in favor of the non-guided implant placement group was found for the initial cost (P < 0.05) but not for the prosthetic complications and total cost (P > 0.05).
Tallarico et al.	2018	RCT	20/62	32	0	30	1	Groups; computer-guided group or conventional freehand group. No prostheses failed during the entire follow-up. Two implants failed in the conventional group (6.6%) vs. none in the computer-guided group (P = 0.158). Differences between groups for implant failures and complications were not statistically significant. Five years after loading, the mean marginal bone loss was 0.87 mm ± 0.40 (95% CI: 0.54–1.06 mm) in the computer-guided group and 1.29 mm ± 0.31 (95% CI: 1.09–1.51 mm) in the freehand group. The difference was statistically significant (difference 0.42 mm ± 0.54; 95% CI: 0.05–0.75; P = 0.024). Patient self-reported post-surgical pain (P = 0.037) and swelling (P = 0.007) were found to be statistically significant higher in patients in the freehand group. Number of sessions from patient’s recruitment to delivery of the definitive prosthesis, number of days from the initial CBCT scan to implant placement, consumption of painkillers, averaged surgical, prosthetic, and complication times, were not statistically significant different between the groups.