| Background:The control of anchorage is the core in the process of orthodontic treatment and the key that determines the success or failure of orthodontic treatment.Compared with the traditional anchorage control methods,microimplants have been widely used in clinic as temporary anchorage devices in recent years.They can offer some potential advantages,including:smaller size,flexible implantation site,simple operation,comfortable and high efficiency,and expanding the boundary of tooth movement.However,one of the problems of microimplants is its poor stability,which means microimlants shedding.Although there were many studies on the stability of microimplants at home and abroad,the decisive factors of the studies were different,and there was a lack of comparability among different studies.In order to eliminate these differences and more accurately judge whether different factors affect the stability of microimplants,it is necessary to make a comprehensive and systematic analysis and evaluation.Objective:The purpose of this study was to explore the success rate of microimplants,to find the risk factors related to the failure of microimplants,and to analyze the effects of the factors.Methods:The two researchers searched for randomized controlled trials and then made the systematic review to find risk factors of affecting the stability of microimplants.The databases being searched included Medline database(searched via Pubmed search platform),Cochrane library database,Embase database,Web of Science database,China national knowledge infrastructure(CNKI),Wanfang database,Chinese sci-tech periodical database,China biology medicine database(CBM).The final search time was February 5,2020.Language was limited to Chinese and English.After literature screening,the researchers extracted basic information and related data,while Meta-analysis was used for quantitative data,and descriptive analysis was used for data that could not be statistically analyzed.Bias risk,performed statistical analysis,and tested heterogeneity were assessed by Review Manager 5.3(RevMan 5.3),and evidence quality was assessed by GRADEprofiler 3.6.Results:Finally,14 randomized controlled trials(RCTs)were included,and a total of 942 patients were included in this study,with a total of 1919 microimplants,of which 233 failed and 1686 were successful,the success rate was 81.67%-95.71%,and the average success rate was 88.34%(95%CI:85.99%?90.34%),the result was statistically significant(P<0.01).The results of systematic review showed that the risk factors affecting the stability of microimplants include implant-related factors,clinical operation-related factors and patient-related factors,while implant-related factors including material,surface treatment,size shape,thread shape;clinical operation-related factors including method of implantation,angle and depth of implantation,loading time,loading method,distance from root,purpose of movement,physician experience and secondary implantation;and patient-related factors including gender,age,bone quality and skeletal features,implant site,soft tissue,systemic factors,compliance.According the 14 RCTs,Meta-analysis was performed on material,method of implantation,loading time,gender,age,facial type,and implant site.Only the difference of age was statistically significant(OR=0.40,95%CI:0.20?0.80,P<0.01):the stability of microimplants in adults was higher than that in adolescents.There was no significant difference in the results of other items(P>0.05).Conclusion:In view of the analysis of the available evidence,the following general conclusions can be drawn:1.The success rate of microimplants was high,which could reach more than 80%,basically meeting the clinical requirements.2.The stability of microimplants in adults was higher than that in adolescents,and the difference was statistically significant.It showed that for adult orthodontic patients,using microimplants anchorage is preferred in strong anchorage design,while doctors should pay close attention to the situation of microimplants of adolescent patients and might take other measures to improve the stability when necessary.3.There was no significant correlation from method of implantation,loading time,gender,age,skeletal features,and implant site to the stability of the microimplants.4.Material of microimplants,surface treatment,size shape,thread shape,angle and depth of implantation,loading method,distance from root,purpose of movement,physician experience and secondary implantation,bone quality,soft tissue,systemic factors,compliance possibly impact the stability of microimplants,but the specific influence was not clear,further large sample,multi-center,high-quality researches were needed,which suggested that we should pay more attention to these factors in clinical. |
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