## 3 Results
### Histologic and Histomorphometric Analysis  
Bone specimens obtained from the ridge preservation sites of 18 patients (six patients for each of the three groups) did not show any inflammatory response around Bio-Oss(r) Collagen and DDM. All grafted sites indicated the presence of newly formed bone, remaining parts of tooth, bone graft materials, and connective tissues (Figure 8). The new bone comprised \(\sim\)22% (Group A), 33% (Group B), and 39% (Group C) of the total area, respectively, with no statistically significant differences between the groups, as determined by the Kruskal-Wallis test (\(p\) > 0.05) (Table 4).  
Figure 8: Histomorphometric measurement at 4 months after ridge preservation. Section was stained with Hematoxylin and Eosin (H&E) and [PERSON]’s trichrome with magnification x 100. (**a,d**) Bio-Oss collagen group. (**b,e**) DDM group. (**c,f**) rhBMP-2/DDM group. NB: Newly formed bone, asterisks: residual Bio-Oss particle, arrowheads: residual dentin particle.  
\begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline  & \multicolumn{3}{c}{**Group A**} & \multicolumn{3}{c}{**Group B**} & \multicolumn{3}{c}{**Group C**} \\ \hline \multirow{2}{*}{**(mm)**} & \multirow{2}{*}{**Baseline**} & \multicolumn{2}{c}{**4**} & \multirow{2}{*}{**Baseline**} & \multicolumn{2}{c}{**4**} & \multirow{2}{*}{**Baseline**} & \multicolumn{2}{c}{**4**} & \multirow{2}{*}{**Baseline**} & \multicolumn{2}{c}{**4**} & \multirow{2}{*}{**O**} \\  & & **Months** & & & & **Months** & & & **Months** & \\ \hline \multirow{2}{*}{BBH} & 8.34 \(\pm\) & 7.21 \(\pm\) & 1.14 \(\pm\) & 9.18 \(\pm\) & 8.21 \(\pm\) & 0.97 \(\pm\) & 8.78 \(\pm\) & 7.95 \(\pm\) & 0.82 \(\pm\) \\  & 2.50 & 2.05 & 0.81 & 2.14 & 1.88 \(\pm\) & 0.39 & 1.71 \(\pm\) & 1.73 \(\pm\) & 0.36 \\ \hline \multirow{2}{*}{LBH} & 8.34 \(\pm\) & 7.70 \(\pm\) & 0.65 \(\pm\) & 9.26 \(\pm\) & 8.50\(\pm\) & 0.76 \(\pm\) & 8.61 \(\pm\) & 8.12 \(\pm\) & 0.50 \(\pm\) \\  & 2.54 & 2.52 & 0.37 & 2.09 & 2.06 & 0.29 & 1.65 \(\pm\) & 1.78 \(\pm\) & 0.22 \\ \hline \multirow{2}{*}{RW-1} & 10.68 \(\pm\) & 9.00 \(\pm\) & 1.68 & 12.52 \(\pm\) & 11.74 \(\pm\) & 0.78 \(\pm\) & 12.14 \(\pm\) & 10.60 \(\pm\) & 1.54 \(\pm\) \\  & 2.41 & 2.76 & \(\pm\)1.11 & 1.68 & 1.57 & 0.41 & 1.42 \(\pm\) & 1.90 & 0.74 \\ \hline \multirow{2}{*}{RW-3} & 11.84 \(\pm\) & 10.60 \(\pm\) & 1.24 \(\pm\) & 14.29 \(\pm\) & 13.80 \(\pm\) & 0.49 \(\pm\) & 12.67 \(\pm\) & 11.87 \(\pm\) & 0.79\(\pm\) \\  & 2.28 & 2.61 & 0.65 & 1.84 \(\pm\) & 1.80 & 0.47 \(\pm\) & 1.99 \(\pm\) & 2.03 & 0.54 \\ \hline \multirow{2}{*}{RW-5} & 12.71 \(\pm\) & 12.20 \(\pm\) & 0.50 \(\pm\) & 15.94 \(\pm\) & 15.74 \(\pm\) & 0.20 \(\pm\) & 13.38 \(\pm\) & 13.06 \(\pm\) & 0.32 \(\pm\) \\  & 2.27 & 2.24 & 0.19\({}^{*}\) & 1.88 \({}^{*}\) & 1.89 \({}^{*}\) & 0.15 & 1.80 \({}^{\dagger}\) & 1.73\({}^{\dagger}\) & 0.21 \\ \hline \multicolumn{2}{c}{Values are presented as mean \(\pm\) SD in mm. A vs. B: \({}^{*}\)\(p\) < 0.017, A vs. C: \({}^{\dagger}\)\(p\) < 0.017. Differences in BBH, LBH, and RW-1, 3, and 5 at baseline and at 4 months were analyzed using Kruskal-Wallis tests (between the three groups) and Wilcoxon signed-rank tests (between treatment stages). \({}^{*}\)\({}^{\ddagger}\) Different letters indicate statistical significance under Bonferroni correction. \(\Delta\) is the net change 4 months after extraction and ridge preservation, calculated by Pre – Post. BBH; buccal bone height, LBH; lingual bone height, RW-1; horizontal width at 1 mm, RW-3; horizontal width at 3 mm, RW-5; horizontal width at 5 mm.