Success and failure rates of orthodontic miniscrews: a systematic review

The purpose of the present study was to systematically review the literature on the success and failure of the miniscrews. Titles and abstracts in Medline Databases (PubMed) were screened by 2 reviewers. First result contains 273 articles, after search filters they have reached to 9 articles. All articles were discussed by 2 reviewers and disagreements were solved. The total success rate were available in all 9 studies and ranged from 70.3% to 96%. The number of treated patients were ranged from 15 to 141and also the number of miniscrews ranged from 44 to 260. The success and failure rates of miniscrews in these 9 studies had no significant correlation with gender. Statistic methods are different among these clinical trials. It seems that weak consensus exist between bulk of data obtained from different clinical trials. Gender has been mentioned as a predisposing factor for success/failure rate and some article reported more success for male, some for female, and some no difference. Immediate loading has more success rate according to some investigations but many investigators suggest a healing period and delayed loading. Diameter and length of miniscrews and their dispersion factor is another source of inconsistency among authors. Diameters start from (in millimeter) 1.2, 1.3, 1.6-1.8 to 2 mm and length starts from (in millimeter) 5, 6,7,8 to 10 mm and different success rate is reported for these parameters. Even success/failure rate is described differently among clinicians and it start from stability during first one week, extends to six month and two year. In addition, some authors believe that because of the pool of subjects (large sample with important elements) in retrospective studies, appropriate statistics are “Kaplan-Meier survival curves” based on rigorous clinical success\failure criteria instead of success\failure rate.