Mini-screws success rates sufficient for orthodontic treatment

Abstract

The term "mini-screw" is one of a number used to describe small screws, surgically placed through alveolar cortical bone to be used as temporary anchorage devices in orthodontic treatment. They have become increasingly prevalent in the past decade as they confer a number of advantages when compared to traditional intra-oral and extra-oral anchorage reinforcement.There is marked heterogeneity in mini-screw design and placement techniques. This review was constructed with the aim of analysing the success rates of mini-screws with a view to defining a set of guidelines for their selection and application. The validity of this review is compromised somewhat by the use of only one database in collating any relevant articles; the paucity of search terms is also discouraging. However, upon comparison with other relevant papers, 1,2 it does appear that the studies included are representative of the available literature. A detailed analysis of each article would also have been desirable; however, information such as the design of each study was unreported. Given one of the main aims was to discern the success rates of mini-screws, a discussion of what is deemed a success would seem to be appropriate. Although not forthcoming, it is pertinent to realise that 'success' differs in the discussed articles. It is most frequently seen as gaining 'anchorage for required treatment time' and so mobile/displaced mini-screws can still be seen as a success provided they can still be used to reinforce anchorage.Accepting these issues, the quoted success rate of over 80% is comparable with that derived in other reviews on the subject. Of worthy mention is one such paper containing more contemporary data on an additional five studies yielding an increase of over 800 mini-screws in its analysis. 3 However, the overall success rate changes little.When comparing the time allowed for the mini-screw to heal before loading, along with the magnitude of the subsequently applied force, there was considerable variation between the studies and within study groups. Along with the poorer performance observed with mini-screws of less than 1.2mm diameter and 8mm in length, these areas generate further avenues for investigation.Given that this area of orthodontic research is still in its infancy, the data shown here can be seen as a starting point for the design of suitable prospective studies to help elucidate the most efficacious method for mini-screw placement. Nicky StanfordGlasgow Dental School and Hospital, University of Glasgow, Glasgow, Scotland, UK

RFA measurements of survival midpalatal orthodontic mini-implants in comparison to initial healing period

“…The survival rate of mini-implants in the anterior palate is reported to be 97.9% in contrast to interradiculary inserted mini-implants with a failure rate of 10-30% [6,7]. Within the so-called T-Zone, the anterior palate offers bone with high quality and is covered with thin mucosa [8][9][10][11].…”

Measurement of mini-implant stability using resonance frequency analysis

“…Two systematic reviews in the literature report mean overall failure rates of 16.4%. 10,11 Different suggestions have been made to increase survival rates. The basic requirement is sufficient primary stability.…”

Mechanical and Histological Effects of Resorbable Blasting Media Surface Treatment on the Initial Stability of Orthodontic Mini-Implants

“…In recent times, mini-implants have been used in orthodontic treatment for absolute anchorage, and these can be used to apply various orthodontic forces to the teeth because of their small size [ 1 – 3 ]. However, orthodontic mini-implants (OMIs) with a small diameter can be easily loosened by a small removal torque [ 4 ]; furthermore, the success rate of mini-implants with a short length has been reported to be low [ 5 ].…”