## 3 Results  
According to the inclusion and exclusion criteria, 60 patients (32 males, 28 females) with an edentulous posterior maxilla (Applegate-Kennedy Class I, II, or III) or the need for avulsion of residual teeth in the posterior section were enrolled for this study. The mean age was 64 years (range: 52-76). The sample was divided into three groups of 20 according to the surgical procedure they received. Every surgery involved the placement of two implants to support screw-retained prostheses of a minimum of three and a maximum of four dental units according to the antagonist arch (presence or absence of the lower first molar) and presence or absence of adjacent distal teeth. Fixtures were placed at sites 14 and 16, sites 14 and 15, or sites 14, 15, and 16 and in the same sites in the contralateral emi-arch. A total of 144 dental implants (K or TTi or TTx, Winsix, Biosafin, Ancona, Italy) were placed. Group A received 48 implants, Group B received 46 implants, and Group C received 50 implants (Table 2). Immediate loading was performed only in Group C; in both sinus floor elevation techniques, implant loading occurred approximately 4 months after implant placement. 1. _Implant survival rate._ In the lateral sinus floor elevation technique (Group A), no implants were lost in the first six months after surgery; two fixtures were lost in the following period. In the transcrestal approach (Group B), one implant was lost in the first six months after surgery, and only one was lost later. Only one tilted implant (Group C) was lost early; no implants were lost in the following period. Group A, Group B, and Group C demonstrated implant survival rates of 95.83%, 95.65%, and 98%, respectively (Table 3). \begin{table}
\begin{tabular}{c c c c c} \hline \hline  & \multicolumn{2}{c}{**Dependent Variable: Prop\_lost Dental Implants**} \\ \hline
**Source** & **Type III Sum of Squares** & **Df** & **Mean Square** & **F** & **Sig.** \\ \hline
**Corrected Model** & 0.036 1  & 2 & 0.018 & 0.539 & 0.586 \\
**Intercept** & 0.363 & 1 & 0.363 & 10.775 & 0.002 \\
**Group** & 0.036 & 2 & 0.018 & 0.539 & 0.586 \\
**Error** & 1.920 & 57 & 0.034 & & \\
**Total** & 2.319 & 60 & & & \\
**Corrected Total** & 1.956 & 59 & & & \\ \hline \end{tabular}
\end{table} 
Table 4: Differences among groups in terms of the proportion of lost implants. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline  & \multicolumn{5}{c}{**Dental Implant Details**} \\ \hline  & & **Length** & **Length** & **Length** & **Length** \\
**11\_MBL 6** & B & 0.915 & 0.1387 & 20 \\ months (mm) & C & 0.920 & 0.1508 & 20 \\  & Total & 0.935 & 0.1448 & 60 \\ \hline \multirow{3}{*}{\(\Pi\)1\_MBL 12 months (mm)} & A & 1.095 & 0.1356 & 20 \\  & B & 1.085 & 0.1663 & 20 \\ months (mm) & C & 1.040 & 0.1847 & 20 \\  & Total & 1.073 & 0.1625 & 60 \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Average marginal bone loss (millimeters) of mesial implants (II) observed during follow-up. \begin{table}
\begin{tabular}{c c c c c} \hline \hline  & \multicolumn{5}{c}{**Dental Implant Details**} \\ \hline  & & **Length** & **Length** & **Length** & **Length** \\
**(sinus floor augmentation via lateral approach) n = 48** & diameter 3.8 mm & 11 mm & 13 mm & 15 mm \\ \hline
**Group A** & diameter 3.3 mm & 11 mm & 11 mm & 11 mm \\
**(sinus floor augmentation via lateral approach) n = 48** & diameter 3.3 mm & 11 mm & 11 mm & 11 mm \\ \hline
**Group B** & diameter 3.3 mm & 11 mm & 11 mm & 11 mm \\
**(transcrescal sinus floor elevation) n = 46** & diameter 3.3 mm & 11 mm & 11 mm & 11 mm \\ \hline
**Group C** & diameter 3.3 mm & 11 mm & 11 mm & 11 mm \\
**(one tilted and one axial implant) n = 50** & diameter 3.8 mm & 11 mm & 11 mm & 11 mm \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Number, diameter, and length of dental implants classified by group.