## 4 Discussion  
In this retrospective study, a comparison was made to evaluate the efficacy of CS and GBR techniques in bone augmentation of maxilla with insufficient bone thickness needed for dental implant application. Autogenous and inorganic bovine bone graft materials of particle forms were used in both the control and test groups. The grafting procedure was supplemented with a resorbable collagen membrane coverage and flap closure. Following a 7-month healing period, pre- and post-surgical complications were estimated. Additionally, evaluation of volumetric changes at the implantation phase was achieved using CBCT. Moreover, implant insertion torque was measured for comparison between groups. As a result, a lower amount of bone volume loss was assessed to be statistically significant in the CS-augmented group, compared with the GBR-augmented group. However, no significant difference between the two groups was noticed in terms of complication incidence and implant placement torque. Among hard tissue augmentation techniques, immobilization of the applied graft materials is considered one of the most substantial factors affecting the success of the treatment. The graft materials of particulate form applied during an augmentation procedure require physical resistance to prevent any potential collapse. In order to achieve this, efforts are being made to increase the success rate by using block autogenous and allogeneic bone plates combined with various particulate graft materials applied into the spaces created by these block grafts. Use of the shell technique has shown positive results [11]. Autogenous block graft has been used successfully in hard tissue augmentation for many years. Due to its osteogenic, osteoinductive, and osteeconductive effects, it is considered the gold standard graft; thus, it is preferred to any other alternative graft materials, which have unpredictable resorption and can induce donor-site morbidities, such as formation of a second wound area, risk of post-procedure pain, edema, and sensory damage, in addition to their inability to obtain the desired result in some cases [7; 12]. Although autogenous block bone applications are frequently preferred, especially in vertical bone augmentation, resorption rates of 21-25% are reported in the literature [13; 14]. Presently, the utilization of allogeneic block graft in hard tissue augmentation is increasing, which can be stabilized to the existing osseeous defect with the help of tenting screws; resulting in mechanical resistance for the particulate graft, which, in turn, can be condensed to the block-constructed area with the shell technique. In this manner, bone volume can be preserved by minimizing the risk of mobilization or collapse of a bone graft during the healing process. In the present study, it is suggested that the main reason to \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Clinical Assessments/Group** & \(p\) & **CS Group (n = 18)** & **GBR Group (n = 18)** \\ \hline ITV 1 (Ncm) & 0.15 & 29.78 \(\pm\) 3.13 & 30.72 \(\pm\) 2.16 \\ ICW 2 (mm) & 0.41 & 2.83 \(\pm\) 0.35 & 2.78 \(\pm\) 0.36 \\ \hline \hline \end{tabular} 1 Insertion Torque Value, 2 Initial Crestal Width; Note: Data are presented as Mean \(\pm\) Standard Deviation.  
\end{table} 
Table 2: Site-related variables. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Volume\textbackslash{}Group** & \(p\) & **CS Group (n = 18)** & **GBR Group (n = 18)** \\ \hline V1, mm3 & a 0.236 & 5790.80 \(\pm\) 1148.67 & 5741.23 \(\pm\) 1213.15 \\ V2, mm3 & a 0.472 & 5344.49 \(\pm\) 1150.33 & 4872.38 \(\pm\) 1167.49 \\ V1-V2 (\%) & a \textbackslash{} 0.001 * & 8.26 \(\pm\) 1.60 & 14.36 \(\pm\) 3.55 \\ \hline \hline \end{tabular} 1 Independent samples \(t\)-test; * \(p<0.01\). Note 1: Data are presented as Mean \(\pm\) Standard Deviation. Note 2: V1: Immediate postoperative volume measurement; V2: 7-months postoperative volume measurement; V1-V2 (\%): Percentage of bone resorption rate.  
\end{table}