# New Resorbable Membrane Materials for Guided Bone Regeneration
## 2 Collagen
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Experimental** & \multicolumn{3}{c}{**Experimental Groups**} & **Main Findings** & **Reference** \\ \cline{3-5}
**Model** & **(Membrane with/without New Material)** & & **Main Findings** & **Reference** \\ \hline \multirow{8}{*}{5.25 mm Calvari defect (rat)} & (i) & Sham & \multirow{8}{*}{The percentage of new bone formation in (iii), (iv), and (v) was} \\  & (ii) & Commercial collagen membrane & & \\  & (GenDerm) & & & \\  & (iii) & Mineralized polyanionic collagen membrane & \(\bullet\) & The percentage of new bone formation in (iii), (iv), and (v) was \\  & & membrane (PAC), without impregnation & & higher than (i) and (ii) \\  & with HA and cross-linked & & & higher than (i) and (ii) \\  & with glutaraldehyde & & & No significant difference in bone formation among (iii), (iv), and (v) \\  & (iv) & PAC, impregnated with 25 cycles of HA and cross-linked with glutaraldehydehyde & & \\ \hline \multirow{8}{*}{5 mm Calvari defect (rat)} & (i) & Untreated collagen membrane & \multirow{8}{*}{The thickness of the regenerated bone was significantly higher in (iv)} \\  & (ii) & EGCG cross-linked collagen membranes & & than in (ii) and (iii) \\  & (iii) & Nano-HA modified & \multirow{8}{*}{\(\bullet\)} & (ii) and (iii) exhibited less bone \\  & & EGCG-collagen membranes & & regenerative ability than (i) and (iv) \\ \hline \multirow{8}{*}{5 mm Calvari defect (rat)} & (i) & No membrane & \multirow{8}{*}{The cells on (ii) proliferated to significantly higher degrees than (iii)} \\  & (ii) & Collagen-HA single-layer dense membrane & \multirow{8}{*}{\(\bullet\)} & No significant difference between \\  & (iii) & Collagen-HA double-layer membrane & & (iv) and (ii)/(iii) \\  & (iv) & Collagen membrane (Bio-Gide) & & \\ \hline \multirow{8}{*}{Osteoblast cell line (MC3T3-E1)} & (i) & Collagen/HA membrane & \multirow{8}{*}{The tensile strength and elastic modulus of (ii) increased by -2 and 3 times, compared to (i)} \\  & (ii) & Three-layered membrane & & 3 times, compared to (i) \\ \cline{1-1}  & (iii) & Chitosan membrane & & (i) had better flexibility than (iii) \\ \cline{1-1}  & & & & \(\bullet\) The cells on (ii) proliferated to significantly higher degrees than (iii) \\ \hline \multirow{8}{*}{8 mm Calvari defect (rat)} & (i) & Collagen membrane treated with BMP-2 & \multirow{8}{*}{\(\bullet\)} & Chitosan concentrations up to 2\% \\  & (iii) & Deparimed collagen membrane & & \(\bullet\) and 8\% enhanced the tear \\  & & containing bound BMP-7 & & (iv) were similar \\ \cline{1-1}  & (iv) & Heparimed collagen membrane & & \(\bullet\) After 8 weeks, (iv) had the largest \\ \cline{1-1}  & (iv) & Heparimed collagen membrane & & new bone area, followed by (ii) \\ \cline{1-1}  & & containing bound BMP-7 and treated & & (iii) \\ \hline \multirow{8}{*}{4 mm Mandibular ramus defect (rat)} & (i) & No treatment & \multirow{8}{*}{\(\bullet\)} & (iii) and (iv) significantly enhanced \\ \cline{1-1}  & (ii) & Collagen membrane & & bone regeneration compared to (i) \\ \cline{1-1}  & (iii) & Collagen membrane containing low-dose & & (iv) and (vi) significantly accelerated \\ \cline{1-1}  & (iii) & Collagen membrane containing high-dose 1 & \multirow{8}{*}{\(\bullet\)} & (v) and (vi) significantly accelerated \\ \cline{1-1}  & (iv) & \(\bullet\)g of PDGF & & bone regeneration to an even greater \\ \cline{1-1}  & (v) & Collagen membrane containing low-dose & & extent than (iii) and (iv) \\ \cline{1-1}  & 20 \(\mu\)g of GDF-5 & & & The enhanced bone formation had \\ \cline{1-1}  & (vi) & Collagen membrane containing high-dose & & a dose-dependent response (vi \(>\) v \(>\) iv \(>\) iii) \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Experimental studies evaluating the performance of modified collagen membranes. Collagen/hydroxyapatite (HA) membrane is known to have good biocompatibility, osteoconductivity, and a similar composition and structure to natural bone [25; 27]. However, collagen/HA membrane does not have a substantially positive effect on bone regeneration [13; 25; 26].