## 2 Materials and Methods
### Histological Processing: Non-Decalcified Bone Samples Embedded in Plastic
Only in four cases was it impossible to elevate all the layers, with the glandular layer left unelevated and a clearer view of the epithelium in the elevated mucous membranes. A thin layer of collagen tissue was observed in the bone, which may be interpreted as the periosteum or parts of it (see Figure 2b-d). The mean maximum pressure obtained during the balloon experiments was 662.62 mmHg. The maximum values did not exceed 726.20 mmHg. The minimum monitored pressure was 598.80 mmHg. The pressure required to overcome the resistance of the balloon material, as determined during the pilot test, was subtracted from the maximum pressure. Therefore, the mean pressure required to elevate the maxillary bone floor mucosa was calculated to be 344.46 mmHg in this ex vivo animal model. No mucosal tearing was observed. Pressure values over time and fill volume showed a strong initial rise in pressure. In 5 of the 15 cases, there was an Underwood septum in the region where the mucosa was elevated. However, the elevation process in regions with Underwood septa (mean pressure = 368.12 mmHg) did not produce significantly different elevation forces (\(p\) = 0.096) compared to sinus mucosal elevations without the presence of septa (mean pressure = 332.63 mmHg) (see Tables 4 and 5, Figure 4a-c) \begin{table}
\begin{tabular}{c c c c} \hline \hline  & **Max** & **Septum** & **Pressure on Membrane** \\ \hline SINUS 1 & 598.8 & NO & 280.7 \\ \hline SINUS 2 & 620.2 & NO & 302.1 \\ \hline SINUS 3 & 680.2 & SI & 362.1 \\ \hline SINUS 4 & 650.7 & NO & 332.6 \\ \hline SINUS 5 & 601.9 & NO & 283.8 \\ \hline SINUS 6 & 630.8 & NO & 312.7 \\ \hline SINUS 7 & 654.9 & SI & 335.8 \\ \hline SINUS 8 & 635.4 & NO & 317.3 \\ \hline SINUS 9 & 726.2 & SI & 408.1 \\ \hline SISUS 10 & 659.7 & NO & 341.6 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Pressure values in mmHg. Figure 3: (a) Distribution of the histological elevation and the membrane perforated in the height groups, (b) Distribution of the histological elevation and the membrane perforated on the global sample. \begin{table}
\begin{tabular}{c c c c} \hline \hline  & **Max** & **Septum** & **Pressure on Membrane** \\ \hline SINUS11 & 704.4 & NO & 386.3 \\ \hline SINUS 12 & 658.2 & SI & 340.1 \\ \hline SINUS 13 & 706.8 & NO & 388.7 \\ \hline SINUS 14 & 698.6 & NO & 380.5 \\ \hline SINUS 15 & 712.6 & SI & 394.5 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: _Cont._  
Figure 4: _Cont._ \begin{table}
\begin{tabular}{c c c c c} \hline \hline  & **Maximum Pressure mmHg** & \multicolumn{2}{c}{**Pressure on Membrane**} \\ \hline
**Mean** & 662.62 & 344.46 \\ \hline SD & 40.86 & 40.88 \\ \hline Median & 658.20 & & 340.10 \\ \hline Minimum value & 598.80 & & 280.70 \\ \hline Maximum value & 726.20 & & 408.10 \\ \hline Groups & Without septum & With septum & Without septum & With septum \\ \hline Media & 650.73 & 686.42 & 332.63 & 368.12 \\ \hline SD & 50.88 & 32.00 & 40.88 & 32.24 \\ \hline Median & 643.050 & 680.20 & 324.95 & 362.10 \\ \hline Minimum value & 598.80 & 654.90 & 280.70 & 335.80 \\ \hline Maximum value & 706.80 & 726.20 & 388.70 & 408.10 \\ \hline \multicolumn{2}{c}{\(p\)-value} & 0.093 & & 0.096 \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Distribution and comparison of maximum pressures and pressures on the membrane in the global sample and in the sinuses with and without a septum.