Objective To investigate Helicobacter pylori combined with N-methyl-N-nitrosourea (MNU) gavage for preparing balb/c mouse gastric cancer model.Methods Eighty balb/c mice were randomly divided into four groups after 1-week adaptive feed,normal group,model group Ⅰ,Ⅱ and Ⅲ,20 cases in each group.The model group Ⅰ,Ⅱ and Ⅲ were given Helicobacter pylori bacteria liquid (CFU=109/mL) gavage,once every other day for 5 times;then,the freshly configured MNU solution 0.15,0.3,0.6 mL gavages were in turn given,MNU and pure water allocation ratio was 5mg:3mL.Once gavage per week for continuous 10 weeks.Results The model group II had 66.67% adenocarcinoma,the model group I were gastritis with mild atypical hyperplasia,and all mice in the model group III died.Conclusion This method can prepare the gastric cancer model.

Occlusal disorder is an abnormal condition in which the static and dynamic relations between the upper and lower teeth are not well aligned . The most common occlusal disorder in clinical practice is the inability to reach the intercuspal position due to early contact of individual points or occlusal interference due to occlusal high points, which can lead to periodontal tissue damage, decreased masticatory function, temporomandibular joint and muscle discomfort; these results can occur through the overactivation of the locus coeruleus-sympathetic-adrenal medullary system and hypothalamic-pituitary-adrenal axis induce elevated serum corticosteroid levels, which leads to chronic stress in the body. This article reviews the effects of chronic stress caused by occlusal disorder on bone tissue, stomatognathic system, emotional health and cognitive function. It has been found that occlusal disorders not only result in the loss of bone in the oral cavity, the reduction of bone mass in the whole body and damage to the local function of the stomatognathic system but also negatively affect the body’s anxiety, sleep, cognitive function and spatial memory ability as a result of the neuroendocrine changes . In recent years, concern about occlusal disorders has been on the rise. Early detection and timely adjustment of uncoordinated occlusion has become an issue that cannot be ignored in the clinic.

Implant dentures have become the main method for the treatment of dentition defects or complete edentulism. However, due to the lack of periodontal ligament and periodontal ligament proprioceptors, implant dentures have very limited cushioning and sensing capabilities and are prone to occlusal overload. As a risk factor for peri-implantitis, occlusal overload seriously threatens the stability and success rate of implant dentures. This paper reviews the occlusal overload of implant dentures, the causal relationship between occlusal overload and plaque biofilms in peri-implantitis, the mechanism by which occlusal overload promotes peri-implantitis, and the effect of reasonable clinical occlusal adjustment on healing. This review shows that occlusal overload is closely related to the occurrence of peri-implantitis. Occlusal overload can promote the process of peri-implantitis by increasing the release of inflammatory factors and mechanical transduction mechanisms. The intervention of the patients’ bad bite habits and occlusal adjustment can promote the healing of peri-implantitis. At present, there is no uniform standard ideal experimental model for occlusal overload. The phenomenon and mechanism of bone resorption around the implant caused by overload force still need further observation and research, which will help determine the intensity, direction and timing of occlusal loading to guide clinical occlusal adjustment.

As the world’s population ages, age-related cognitive decline and dementia are becoming important challenges for geriatric care. Despite the ongoing search for solutions to address cognitive decline, effective interventions have not yet been established. There is increasing evidence from clinical, epidemiological, and animal studies that masticatory dysfunction due to occlusal disharmony is a risk factor for cognitive decline and an increased incidence of dementia. The mechanisms may involve altered nutritional intake, decreased cerebral blood flow, chronic stress, and hippocampal morphological function. These findings suggest that maintaining and adequately restoring the entire masticatory system has a positive impact for the prevention of cognitive decline.