# 3D Volumetric Analysis and Anatomical Considerations for
## 4 Discussion  
Inadequate bone quantity on posterior maxillary area may be associated with maxillary sinus pneumatization, which may contribute to a further decrease of the available bone for implant placement [23]. Maximillary SBG is a predictable technique to increase available bone for implant surgery [7,24]. In order to avoid unnecessary complications such as arterial bleeding and perforation of SM, it is important to know the clinical anatomy for SBG. For evaluating the location and size of PSAA, CBCT is the most appropriate method for detecting vessel [25]. If unnecessary bleeding occurs during SBG, it is caused by injury of PSAA. This can be prevented by recognizing the position of the PSAA in preoperative CT scan and paying attention to preserving the vessel during operation. In this study, PSAA was 11.94 \(\pm\) 5.08 mm in male and 11.87 \(\pm\) 4.40 mm in female, and residual bone was 2.92 \(\pm\) 1.14 mm in male and 3.05 \(\pm\) 1.00 mm in female on average. In anatomical studies, this distance of PSAA has been shown as 18.9 mm ([PERSON] et al. ), 18 mm ([PERSON] et al.) and 19.6 mm ([PERSON] et al.) [8,26,27]. [PERSON] et al. reported that the distances from inferior margin of PSAA to the middle of interdental alveolar crest were 17.19-17.75 mm on first molar and 17.00-17.17 mm on second molar [28]. [PERSON] et al. found that there was no significant difference between age and gender [27]. In this study, we included the patient who had residual bone less than 5 mm and measured the distance of PSAA from the inferior border of maxillary sinus; thus, the distance was smaller than previous studies. Lateral wall thickness can affect the operation time for making a lateral window and the perforation of the SM [3]. In this study, lateral wall thickness was 1.71 mm on average, maximum 3.93 mm, and minimum 0.74 mm. [PERSON] et al. found that the state of teeth (dentate state or endulous state) did not affect the lateral wall thickness and indicated the lateral wall thickness was 1.98 mm on average [29]. [PERSON] et al. found that the lateral wall thickness was 1.75 \(\pm\) 0.80 mm in dertulous patients [19]. This is very similar to our results. [PERSON] et al. reported that lateral wall thickness of the white skulls was 0.91 \(\pm\) 0.43 mm on average [20]. It was thinner than the results of the current study. The reason for this difference is due to the different point of measuring site. To predict the amount of graft materials for SBG, we measured the sinus volume according to the heights of SBG. [PERSON] et al. reported that the volume of sinus measured at 5 mm height was 0.55 \(\pm\) 0.41 cm\({}^{3}\), and 2.11 \(\pm\) 0.68 cm\({}^{3}\) at 10 mm height [30]. [PERSON] et al. reported that the volume of sinus measured at the height of 5 mm and 10 mm was 0.56 \(\pm\) 0.13 cm\({}^{3}\) and 2.35 \(\pm\) 0.57 cm\({}^{3}\), respectively [31]. These results of volume for SBG were similar to this study, 0.526 \(\pm\) 0.25 cm\({}^{3}\) at 5 mm and 2.184 \(\pm\) 0.74 cm\({}^{3}\) at 10 mm. In this study, the total sinus volume was 12.104 \(\pm\) 6.56 cm\({}^{3}\) on average and there was no difference  
Figure 5: Septum of maxillary sinus. with gender. The average volumes of the maxillary sinus were 14.05 cm\({}^{3}\), 15.7 cm\({}^{3}\), and 20.740 cm\({}^{3}\)[5; 32; 33]. This difference could be due to racial or technical differences. As with other authors, no differences were found with respect to the patient's sinus volume according to gender [4; 34; 35; 36]. [PERSON] et al. reported that the volume of the maxillary sinus increased with age [37; 38]. Septum is one of the reasons for membrane perforation during SBG. The prevalence of the sinus septum was reported as 55.2%, 16.1%, 26.5% [2; 8; 39], and 33.7% in this study. This study has limitations in terms of volume analysis. In order to predict the volume before surgery, it is necessary to investigate the amount of grafted material at the time of the actual surgery.