## 3 Results
### Histological and Histomorphometric Evaluation  
Successful induction of osteoporosis was confirmed by light microscopical examination of the histological sections at low magnification, which indicated that overall the bone trabeculae were decreased and the intertrabecular space increased for the rats receiving saline administration after OVX versus SHAM surgery (Figure 2). Assessment at higher magnification of the histological sections of the rats that received anti-osteoporotic drugs demonstrated that no gross differences in bone formation existed adjacent to the \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline \multirow{3}{*}{**Groups**} & \multicolumn{4}{c}{**Osteoporotic Condition**} & \multicolumn{4}{c}{**Healthy Condition**} \\ \cline{2-9}  & **No. Placed** & **No. Retrieved** & **No. Used Implants** & **No. Placed** & **No. Retrieved** & **No. Used Implants** \\  & **Implants** & **Implants** & **Push-Out** & **Histology** & **Implants** & **Push-Out** & **Histology** \\ \hline
**ALN** & **10** & **8 * & **3** & 5 & 10 & 9 * & 3 & 6 \\ \hline
**5 IM** & 10 & 10 & 3 & 7 & 10 & 9 * & 3 & 6 \\ \hline
**ALN+5 IM** & 10 & 9 * & 3 & 6 & 10 & 10 & 3 & 7 \\ \hline
**Saline** & 10 & 10 & 3 & 7 & 10 & 9 * & 3 & 6 \\ \hline \hline \end{tabular}
* Six implants were lost (four from dead animals; two have no osseointegration).  
\end{table} 
Table 1: Number of implants placed, retrieved, and used for push-out testing, histological evaluation, and histomorphometric measurements. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{3}{*}{**Groups**} & \multicolumn{4}{c}{**Osteoporotic Condition**} & \multicolumn{2}{c}{**Healthy Condition**} \\ \cline{2-7}  & **Push-Out (N)** & \multicolumn{2}{c}{**Histomorphometric**} & \multirow{2}{*}{**Push-Out (N)**} & \multicolumn{2}{c}{**Histomorphometric**} \\ \cline{3-4}  & **BA\%** & **BIC\%** & & & **BA\%** & **BIC\%** \\ \hline
**ALN** & \(12.0\pm 4.2\) & \(21.7\pm 7.1\) & \(57.9\pm 26.3\) & \(18.5\pm 7.2\) & \(18.0\pm 6.3\) & \(44.6\pm 15.7\) \\ \hline
**SIM** & \(9.0\pm 1.1\) & \(14.5\pm 5.0\) & \(29.4\pm 22.3\) & \(7.5\pm 1.4\) & \(19.8\pm 4.5\) & \(55.8\pm 27.6\) \\ \hline
**ALN+SIM** & \(12.7\pm 3.6\) & \(15.5\pm 6.1\) & \(63.2\pm 21.1\) & \(14.0\pm 3.0\) & \(22.6\pm 2.8\) & \(48.4\pm 31.7\) \\ \hline
**Saline** & \(13.5\pm 3.8\) & \(9.2\pm 2.4\) & \(51.1\pm 20.2\) & \(15.2\pm 5.2\) & \(11.1\pm 3.5\) & \(38.0\pm 20.3\) \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Mean values of measured variables in different study groups and drug treatment protocols. Figure 2: Representative histological images stained with methylene blue and basic fuchsin, showing non-decalcified (pMMA embedded) cross-sections of saline group in both osteopororotic and healthy conditions. implants as treated with alendronate and simvastatin, alone or in combination, in both osteoporotic and healthy animals (Figures 3 and 4). On the other hand, bone formation in these rats was considerably increased in the 1 mm peri-implant area compared with the osteoporotic and healthy rats that received saline treatment. At the implant-bone interface, the bone was observed to be in close contact with the implant surface. The bone-implant contact was characterized by intermittent sites, where the bone was deposited without an intervening fibrous tissue layer, while in other areas a small gap was seen between bone and implant. Figure 4: Representative histological images stained with methylene blue and basic fuchsin, showing non-decalcified (pMMA embedded) cross-sections in healthy bone conditions. Figure 3: Representative histological images stained with methylene blue and basic fuchsin, showing non-decalcified (pMMA embedded) cross-sections in osteoporotic bone conditions. This gap was filled with bone marrow-like tissue. In each group a wide variation was found to exist in the amount of tight bone contact between rats. In some specimens, a lot of bone-implant contact was seen, while much less direct bone contact was found in other specimens (Figure 5).