title: Success of miniscrews used as anchorage for orthodontic treatment: analysis of different factors.
abstract: OBJECTIVE
  To examine factors involved in clinical success of miniscrew implants used for orthodontic anchorage in the upper jaw.
  
  
  METHODS
  One hundred and forty-four patients (93 females and 51 males) were fitted with a total of 324 miniscrew implants of two different morphologies (cylindrical and conical), and of different lengths and diameters. The clinical factors examined were screw length, side of insertion, miniscrew shape and diameter, bone quality, skeletal type, and relationship between bone quality and skeletal type and patient age.
  
  
  RESULTS
  The mean overall success rate of the implants was 91.4%. The length and shape of the miniscrews significantly influenced the success rate, whereas side of insertion (left or right), screw diameter and skeletal type showed no significant effects. Poor (soft) bone quality and good (hard) bone quality are risk factors for miniscrew failure, with the best results obtained when the screws are inserted into bone of medium quality (10-15Ncm).
  
  
  CONCLUSIONS
  In the posterior areas of the upper jaw, long, conical miniscrews showed a significantly greater success rate. An insertion torque of 10 Ncm to 15 Ncm is also a significant index of higher success rate.
authors.affiliation: Department of Orthodontics, University of Ferrara and Insubria, Italy. vicenza@mainog.com
authors.forename: B
authors.initials: B
authors.lastname: Giuliano Maino
authors.forename: Paolo
authors.initials: P
authors.lastname: Pagin
authors.forename: Alberto
authors.initials: A
authors.lastname: Di Blasio
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D015519:Bone Density; D001863:Bone Screws; D002648:Child; D005260:Female; D006801:Humans; D008297:Male; D008437:Maxilla / Q000601:surgery; D052280:Orthodontic Anchorage Procedures / Q000295:instrumentation*; D016382:Orthodontic Appliance Design; D018709:Statistics, Nonparametric; D019415:Torque; D016896:Treatment Outcome; D055815:Young Adult