## 4 Discussion
[12] analyzed the mandible CBCT derived images of normal BMD and osteopororotic females and calculated radio morphometric index measurements, concluding those were lower in osteopororotic patients, and so, could be used to refer patients in risk of osteoporosis. [PERSON] et al. [18] used CBCT-derived grayscale values (GS) from jawbones to discriminate normal BMD patients and osteopororotic BMD patients and concluded that CBCT GS values are able to predict the presence of osteoporosis and DXA T-score values. Therefore, based in the results of the aforementioned studies, we can conclude that radio morphometric measurements are a capable tool for the identification of low BMD patients. The samples of the included studies were very distinct. Considering sex and health status, seven studies compared osteopororotic men and women, with healthy men and women with normal BMD, according to DEXA results [10; 11; 12; 16; 17; 18; 19]. Pathophysiologyology, aged-bone loss in women is related with a combination of a negative remodeling balance and an increase of bone remodeling (both in cortical and cancellous bone), and in men, the aged-related bone loss is mostly related with reduction of bone formation, and reduction of bone turnover, however, the World Health Organization and the International Society for Clinical Densitometry stated, recently, that risk of fracture in men and females occurs proximally at the same BMD [22]. Still on the issue of samples of the included studies, one study [20] performed their analysis in a group of diabetic patients (type I and II patients were analyzed). The neuropathy of diabetes mellitus (DM) amplified severally the possibility of developing osteoporosis, and consequently, the likelihood of disease-related fractures, morbidity, and mortality [23]. However, the risk of osteoporosis and the values of BMD in DM patients are not well described, and although most papers stated a lower BMD in DM type I patients, other studies claimed that BMD may be greater, similar or lower in DM type II patients [20]. Another study performed their analysis in acromegaly patients [19], and according to recent data, although BMD in acromegaly patients may be higher, similar or lower and there is no agreement of BMD and the appearance of fractures, a lower hip BMD founded in acromegaly patients has been related to the presence vertebral fractures in those patients [24]. Regarding to the coefficient values, we can state that [PERSON] et al. [17] obtained the highest coefficient values, (r = 0.924). However, this study had a small sample of people included with 14 on the case group and 14 in the control group [17]. The present study has some limitations namely the discrepancy in anatomical structures chosen to perform the DEXA which can introduce a bias due to possible variations in DEXA values in different structures [25]. Also, several studies obtained radiographic density though grey values derived from CBCT images, and those values change with FOV and Voxel size [26]. In addition, BMD in some mandibular areas can be affected by local conditions, which must be taken into account. Other limitations can be scrutinized such as the CBCT equipment used to evaluate BMD which was not the same for all studies and when technical parameters change (like FOV and voxel size), the quality of the image also changes, especially spatial resolution [27]. Five studies [10; 11; 13; 14; 15] used the similar FOV and voxel size, however 3 studies had different FOV and voxel sizes, and two studies [16; 17] did not have any information about FOV and voxel size. In this study local factors such as occlusal forces and masseter muscle tensions were not considered despite their possible influence on the mandibular bony areas, constituting an additional limitation. Further investigation is mandatory to understand if these different technical parameters may change aforementioned results. Also, all included studies had a small and heterogenic sample of individuals analyzed.