## 3 Results  
The results from 30 patients of both genders (13 men and 17 women, mean age: 69.2, ranging from 54 to 87 years) were collected and analyzed (Table 1). \begin{table}
\begin{tabular}{c c} \hline \hline
**Characteristics of Included Patients** \\ \hline Number of patients (female, male) & 30 (17, 13) \\ Mean age (range) & 69.2 (54–87) \\ Smokers (five cigarettes per day) & 3 \\ Maxilla & 18 \\ Mandible & 12 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Main characteristics of included patients (mean age in years). A total of 30 complete arches (18 maxilla and 12 mandible) were restored using four NDIs that were loaded immediately to support screw-retained fixed prostheses. In total, 121 NDIs were positioned, and 120 were reviewed at least 1 year after definitive prosthesis positioning (Table 2). In total, 40 implants (33.3%) were positioned flapless, while 80 implants (66.7%) were positioned with flaps, and 68 implants were positioned in healed sites (56.7%), while 52 implants were positioned in postextraction sockets (43.3%). Two types of NDIs were used: 70 \(O\)3.3 mm Narrow Crossfit(r) Bone Level implants (BL NC, Straumann) and 50 \(O\)3.3 Narrow Crossfit Bone Level Tapered implants (BL NC, Straumann). The implants lengths were 14 mm (50.8%), 12 mm (45%), and 10 mm (4.2%) (Table 3). All implants were inserted with insertion torque values of at least 35 Ncm. Twelve arches were treated using prosthetically driven free-hand surgery while the other eighteen arches were treated using fully guided template-driven static computer-guided surgery. In the opposite dentitions, 11 patients presented with natural teeth and fixed restorations, 10 patients had removable dentures, 7 patients had implants supporting complete-arch fixed prostheses, and 2 had natural dentitions. No dropouts occurred during the follow-up period, and no deviations occurred from the original protocol. No prosthetic complications occurred to the interim prosthesis during the healing period. One implant did not achieve osseointegration during the healing period, resulting in an implant survival rate of 99.2%. The failed implant (BLTC 12 mm) was placed in a healed site, removed at the osseointegration check after the healing period, and replaced via a computer-guided surgery procedure after a healing period of 3 months. After the healing period, a total of 30 definitive prostheses with cantilevers were positioned. No prosthetic or implant failures \begin{table}
\begin{tabular}{c c c} \hline \hline
**Baseline Implant Positioning** & **n** & **Follow-Up** \\ \hline
2010 & 8 & 11 \\
2011 & 8 & 10 \\
2012 & 8 & 9 \\
2013 & 12 & 8 \\
2014 & 16 & 7 \\
2015 & 12 & 6 \\
2016 & 16 & 5 \\
2017 & 16 & 4 \\
2018 & 4 & 3 \\
2019 & 4 & 2 \\
2020 & 16 & 1 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Life table analysis at the implant level (n = implants placed per year; follow-up in years). \begin{table}
\begin{tabular}{c c} \hline \hline
**Characteristics of Positioned Implants** & \\ \hline Number of implants & 120 \\ Failed implants & 1 \\ Types of implants & \\ Bone Level Narrow Crossfit & 70 \\ Bone Level Tapered Narrow Crossfit & 50 \\ Maxilla & 72 (60\%) \\ Mandible & 48 (40\%) \\ Postextractive & 52 (43.3\%) \\ Healed sites & 68 (56.7\%) \\ Free-hand surgery & 48 (40\%) \\ Static computer-guided surgery & 72 (60\%) \\ Flapless surgery & 40 (33.3\%) \\ Open-flap surgery & 80 (66.7\%) \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Characteristics of positioned implants. (i.e., framework fracture, abutment fracture, or screw fracture) occurred during the entire observation period. BoP was recorded for three implants (2.5%), and plaque was detected around seven implants (5.8%). No mucositis or peri-implantitis were recorded at the last follow-up visits. Three biological and four prosthetic complications occurred, resulting in a treatment rehabilitation success of 94.1%. Three implants showed mucositis in two patients after 4 and 6 years of use. The patients skipped two professional maintenance sessions.