## 3 Results  
Seventy-eight patients receiving 209 implants were enrolled in the present clinical investigation. Forty-three patients were male (55.1%) and thirty-five patients were female (44.9%). Patients' mean age at time of surgery was \(55.4\pm 10.7\) years (range 26-84 years). Sixteen patients (20.5%) were smokers and sixty-two (79.5%) were non-smokers as reported in Table 1.  
One-hundred implants were placed in the maxilla (21 in the anterior and 79 in the posterior segment) and 109 in the mandible (25 in the anterior and 84 in the posterior segment), respectively (Table 2). Implants length was 8 (two implants), 9 (32), 11 (105), 13 (65) 15 (5) mm, respectively. All implants features are reported in Table 3.  
Out of 78 treated patients, 11 (14.1%) with 29 (13.9%) dental implants dropped out and were not considered in the statistical analysis (Table 4). One patient dropped out after 1 year of follow up. Six patients were lost after two years. Four patients who received two implants each were lost after 3 years. \begin{table}
\begin{tabular}{c c c} \hline Gender (male/female) & 43/35 \\ Smokers/Non-smokers & 16/62 \\ Age (years) & 55.4 (10.7) \\ \hline \end{tabular}
\end{table} 
Table 1: Patients’ features. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Implant Length (mm)** & **Maxilla** & **Mandible** & **Total** \\ \hline
8 & 2 & 0 & 2 \\
9 & 7 & 25 & 32 \\
11 & 48 & 57 & 105 \\
13 & 43 & 22 & 65 \\
15 & 0 & 5 & 5 \\ Total & 100 & 109 & \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Implant features. No implants were lost during the osseointegration period. One implant affected by peri-implantitis was removed four years post-insertion. No specific anatomical condition was detected as promoting an inflammatory status of peri-implant hard and soft tissues. On the contrary, peri-implantitis was successfully treated in two different patients (one implant each). In all cases, the patients were smokers. The average final pocket probing depth at implant level was \(2.5\pm 1.2\) mm. Probing depths at mesial, distal, buccal, and lingual sites of 3 mm or less were observed at 89.4%, 89.9%, 90.4%, 90.9% of all implants, respectively. An overall success rate of 90.1% was calculated after 5 years of follow-up. Standardized periapical radiographs were used to measure bone loss. The average final bone loss after 5 years of evaluation was \(0.3\pm 0.4\) mm, both at the mesial and distal aspect of the implant. The effects of multiple implants in the same patient were analyzed and were not statistically significant (\(p=0.605\)). The effects of the prosthesis type on marginal bone loss were analyzed, even if no statistical difference was noticed (\(p=0.092\)). Three different sub-groups were considered for the statistical analysis: single tooth (79 prostheses), partial (98) and full (32) prostheses, respectively. Similarly, no statistical difference was calculated for each sub-group (\(p=0.103\), 0.098 and 0.127, respectively). Moreover, sex was not correlated to peri-implant surgical bone loss (\(p=0.125\)). Prosthesis type and distribution are reported in Table 5.  
Furthermore, smoking and its potential effect on implant peri-implant bone stability was analyzed. To this purpose, an average marginal bone loss of \(0.3\pm 0.3\) mm was calculated for implants placed in non-smoker patients while implants placed in smoker patients showed an average marginal bone loss of \(0.5\pm 0.5\) mm. Such difference was statistically significant (\(p=0.021\)). Data on different parameters and the respective effect on marginal bone loss are reported in Table 6.