Background: Gastric cancer (GC) is the fifth most common cancer and the third cause of cancer deaths globally with late diagnosis, low survival rate and poor prognosis. This case-control study aimed to evaluate the expression of cystatin B (CSTB) and deleted in malignant brain tumor 1 (DMBT1) in the saliva of GC patients with healthy individuals to construct diagnostic algorithms using statistical analysis and machine learning methods.Methods: Demographic data, clinical characteristics and food intake habits of the case and control group were gathered through a standard checklist. Unstimulated whole saliva samples were taken from 31 healthy individuals and 31 GC patients. Through ELISA test and statistical analysis, the expression of salivary CSTB and DMBT1 proteins were evaluated. To construct diagnostic algorithms, we used the machine learning method.Results: The mean salivary expression of CSTB in GC patients was significantly lower (115.55±7.06, p=0.001) and the mean salivary expression of DMBT1 in GC patients was significantly higher (171.88±39.67, p=0.002) than the control. Multiple linear regression analysis demonstrated that GC was significantly correlated with high levels of DMBT1 after controlling the effects of age of participants (R2=0.20, p<0.001). Considering salivary CSTB greater than 119.06 ng/mL as an optimal cut-off value, the sensitivity and specificity of CSTB in the diagnosis of GC was 83.87% and 70.97%, respectively The area under the ROC curve was calculated as 0.728. The optimal cut-off value of DMBT1 for differentiating GC patients from controls was greater than 146.33 ng/mL (sensitivity=80.65% and specificity=64.52%). The area under the ROC curve was up to 0.741. As a result of the machine learning method, the area under the receiver-operating characteristic curve for the diagnostic ability of CSTB, DMBT1, demographic data, clinical characteristics and food intake habits was 0.95. The machine learning model's sensitivity, specificity, and accuracy were 100%, 70.8%, and 80.5%, respectively. Conclusion: Salivary levels of DMBT1 and CSTB may be accurate in diagnosing GCs. Machine learning analyses using salivary biomarkers, demographic, clinical and nutrition habits data simultaneously could provide affordability models with acceptable accuracy for differentiation of GC by a cost-effective and non-invasive method.

Introduction: Headache is a common problem with intense side effects on quality of life. Dental and maxillofacial problems, including dental infections and temporomandibular disorders may trigger the onset of headache or have direct impact on the intensity of headache. The purpose of this paper is assessment of oral health indexes in chronic headache patients and compare it with a healthy control group. Material & Methods: Thirty chronic headache patients based on diagnosis by a neurologist were enrolled in our study and thirty healthy volunteers were recruited into the control group. Dental and periodontal examination were carried out in order to evaluate of the decayed, missing and filled teeth (DMFT) index, the assessment of community periodontal index of treatment needs (CPITN) index and determination of tooth wear status and oral health status. Statistical analysis was done using SPSS statistical package (version 20, IBM). Results: Mean age, educational level, tooth brushing, using dental floss and DMFT index was not statistically different between chronic headache patients and control group. There was no statistically significant difference in CPITN index between cases and control group (p-value=0.538). Conclusion: This study suggest that chronic headache patients have an acceptable oral hygiene which may be attribute to their attempts to omit pain from head and oral region. Considering high prevalence of chronic headache, planning a protocol for oral hygiene instruction is necessary. In this regard, coordination between neurologists and oral medicine specialists can be very effective.