Expression and regulation of genetic genes determine the senescent process. Generally, aging has been regarded as an irreversible process. Along with age increasing, each organ of the body including immune system experiences senescence. Immunosenescence promotes the age-related diseases, such as tumor, cardiovascular diseases, Alzheimer's disease, osteoporosis, and so on. These diseases seriously affect the quality of human life and longevity. How to delay senility, maintain immune function, and keep a good health have become the hot points of social concerns. Inthisreview, by discussing theaging, immunosenescence and its related diseases, aging and tumor treatment as well as anti-aging and disease treatment etc, we explore the mechanisms, prevention and treatment of senescence, senescence-related disease and anti-aging.

Objective:To explore the related mechanisms of biological root resorption in decidual teeth by studying the biological effect of simulated occlusal force on the periodontal ligament stem cells (PDLSC) at different stages of root absorption.Methods:According to the tooth type and root absorption degree, healthy retained deciduous incisors and healthy first premolars that needed to be removed for orthodontic treatment were collected and divided into three groups with six teeth in each group: the deciduous unabsorbed group (UN group), the absorbed group (R group) and the permanent teeth group (P group). PDLSC was isolated from periodontal ligament and cultured. PDLSC of three groups were loaded with dynamic pressure of 0-45, 0-90, 0-135, 0-180, 0-225 and 0-270 kPa, respectively. The proliferation ability was detected by cell counting kit-8 (CCK-8) technique on day 1 to day 7, respectively. The apoptosis levels of PDLSC after loading with dynamic pressure of 0-45, 0-90, 0-135, 0-180 and 0-225 kPa were observed by the flow cytometry. The changes of microfilaments were observed by fibrous actin (F-actin) staining after the cytokeleton was subjected to dynamic pressure of 0-90 kPa.Results:PDLSC of three groups exhibited various proliferation abilities to dynamic pressure. The A values in the UN group and R group were significantly higher than those in the P group and the difference was statistically significant ( P<0.05). However, there was no significant difference between the UN group and the R group ( P>0.05). The A values of PDLSC in UN group and R group under dynamic pressures of 0-45, 0-90, 0-135 and 0-180 kPa had no statistical significance compared with the control group unloading dynamic pressure ( P>0.05). However, under 0-225 and 0-270 kPa dynamic pressures, the A values at the day 3 to day 7 were statistically significant ( P<0.05). The A values of PDLSC in P group under 0-45, 0-90, 0-135, 0-180 and 0-225 kPa dynamic pressures for 1 to 7 days were no statistically significant difference compared with the control group ( P>0.05). The A value in P group under the 0-270 kPa was statistically significant only on day 3 (1.386±0.131) and day 5 to day 7 (1.728±0.226, 2.029±0.168 and 2.263±0.210, respectively)( P<0.05). The result of apoptosis showed that the A values of PDLSC in UN group, R group and P group were significantly increased under 0-90, 0-135, 0-180 kPa and above dynamic pressures, respectively ( P<0.05) compared with the control group unloading dynamic pressure. Under 0-90 kPa dynamic pressure, F-actin fluorescence staining samples in three groups all showed green filaments which were arranged along the long axis of the cells in the R group and the P group, while some fibers in the UN group were closely arranged and promoted stress fiber assembly. Conclusions:The biological characteristics of PDLSC at different root absorption stages were changed when they were stimulated by mechanical stress, and PDLSC of the deciduous teeth at the root unabsorption stage were more sensitive to mechanical stress stimulation.

Objective:To provide references for the clinical popularization of stainless steel crowns by analyzing the clinical application and affecting factors of stainless steel crowns used in primary molars based on a questionnaire survey.Methods:Pediatric dentists from all over the country in June to December 2013 and June to December 2022 were selected to answer the survey questionnaire through the online or offline methods for analyzing the clinical application and influencing factors of stainless steel crowns used in primary molars.Results:A total of 712 and 580 questionnaires were distributed, and 608 and 512 valid questionnaires were recovered respectively in 2013 and 2022. The effective rates of the questionnaires were 85.4% and 88.3%. Among them, the usage rates of stainless steel crowns in 2013 and 2022 were 52.6% (320/608) and 78.1% (400/512) respectively, with a statistically significant difference (χ 2=78.68, P<0.001). The main reasons for not selecting stainless steel crowns in 2013 were high technical sensitivity [52.8% (152/288)], followed by the impact of crown edge on gingiva [50.0% (144/288)] and poor aesthetics [27.8% (80/288)], while in 2022 were the inadequate equipage in hospitals [53.6% (60/112)] and poor aesthetics [21.4% (24/112)]. The main reasons for choosing stainless steel crowns restoration were good protection effect, less tooth fracture [78.1% (250/320) in 2013 and 82.5% (330/400) in 2022], followed by low dropout rate [62.5% (200/320) in 2013 and 68.0% (272/400) in 2022]. The proportions of stainless steel crowns restoration for primary molars after root canal therapy were 51.3% (312/608) and 76.6% (392/512) respectively with statistically significant (χ 2=75.88, P<0.001). The proportions after pulp capping treatment for deep caries were 13.2% (80/608) and 53.1% (272/512) respectively, and the difference was statistically significant (χ 2=206.01, P<0.001). Conclusions:During the 10 years from 2013 to 2022, the technical sensitivity of stainless steel crowns had gradually decreased, and the application in China had gradually increased. However, some hospitals have not yet equipped, which limits the application of stainless steel crowns. Therefore, training efforts should be derived to promote the clinical popularization of stainless steel crowns.

Complicated crown root fracture is a serious combined fracture of the enamel,dentin,and cementum in dental trauma.The treatment method is complicated.During the procedure,the condition of pulp,periodontal,and tooth body should be thoroughly evaluated,and a multidisciplinary approach combined with sequential treatment is recom-mended.This case reported the different treatment and repair processes of one case of two affected teeth after complicat-ed crown root fracture of upper anterior teeth,including regrafting of broken crown after flap surgery at the first visit,di-rect resin repair to remove broken fragments,and pulp treatment and post-crown repair at the second visit.After 18 months of follow-up,the preservation treatment of the affected teeth with complicated crown root fracture was achieved.Therefore,fragment reattachment and post-crown restoration are feasible treatment options for children with complicated crown root fracture.