In general, for all the variables, there was a tendency for the FG protocol to yield more accurate implant placement than other protocols (Table 1). In relation to vertical deviation, the PG protocol seemed to be associated with more errors. However, there was no significant difference in vertical deviation among all the protocols. Figure 3 indicates that the PG protocol was associated with deeper implant placement than the planned implant location for anterior (0.53 ± 0.52 mm) and posterior (0.64 ± 0.37 mm) implants. The FH protocol had less vertical deviation than PG protocol for anterior (0.30 ± 0.24 mm) and posterior (0.49 ± 0.22 mm) implants. The FG protocol had a minimal deviation for the anterior (0.21 ± 0.12 mm) and posterior (0.34 ± 0.23 mm) implants, which tended to be slightly above the planned implants. For all the protocols, the anterior and posterior implants exhibited similar vertical deviations.

For the maximum horizontal neck deviation (Fig. 4), the PG protocol was most inferior (1.14 ± 0.47 mm), followed by FH (0.79 ± 0.26 mm) and FG (0.47 ± 0.25 mm) protocols for the anterior implants. For the posterior implants, the FH protocol was most inferior (1.27 ± 0.22 mm), while the FG protocol was most superior (0.52 ± 0.26 mm), followed by the PG protocol (1.01 ± 0.29 mm). The FH and PG protocols were not significantly different in any comparison. The FG and PG protocols seemed less affected by the location of the implant. The FH protocol showed significantly more errors to posterior implants than anterior implants. Figure 5 shows that the FG protocol was associated with implants being centered around 0, indicating the least deviation buccolingually and mesiodistally. The implants of the PG protocol were prominently positioned buccally. The FH protocol appeared to have a wider distribution especially at the buccolingual direction.

For the maximum apex deviation (Fig. 6), the FG protocol (0.71 ± 0.24 mm) was slightly more accurate for anterior implants, followed by PG (1.02 ± 0.54 mm) and FH (1.12 ± 0.71 mm) protocols, respectively. However, the difference among the protocols was insignificant. For the posterior implants, there was a clear tendency for the FG protocol (0.74 ± 0.23 mm) to be more accurate, followed by PG (1.35 ± 0.55 mm) and FH (1.81 ± 0.53 mm) protocols, respectively. As per the neck deviation, the apices of the FG and PG protocol implants were less affected by the location, while the FH protocol showed significantly greater errors with posterior implants than anterior implants. Figure 7 confirms the overall accuracy of the FG protocol for anterior and posterior implants in being closer to the center of the graph. For the PG protocol, the anterior implant apices were skewed to the distobuccal aspect, while the posterior implant apices were placed more lingually. The FH protocol anterior implant apices generally exhibited more variation and were skewed more lingually, while the posterior implant apices were predominantly located lingually.