Miniscrews in orthodontic treatment: Review and analysis of published clinical trials
ABSTRACT A systematic review of effects related to patient, screw, surgery, and loading on the stability of miniscrews was conducted.
Reports of clinical trials published before September 2007 with at least 30 miniscrews were reviewed. Parameters examined were patient sex and age, location and method of screw placement, screw length and diameter, time, and amount of loading.
Fourteen clinical trials included 452 patients and 1519 screws. The mean overall success rate was 83.8% + or - 7.4%. Patient sex showed no significant differences. In terms of age, 1 of 5 studies with patients over 30 years of age showed a significant difference (P <0.05). Screw diameters of 1 to 1.1 mm yielded significantly lower success rates than those of 1.5 to 2.3 mm. One study reported significantly lower success rates for 6-mm vs 8-mm long miniscrews (72% vs 90%). Screw placement with or without a surgical flap showed contradictory results between studies. Three studies showed significantly higher success rates for maxillary than for mandibular screws. Loading and healing period were not significant in the miniscrews' success rates.
All 14 articles described success rates sufficient for orthodontic treatment. Placement protocols varied markedly. Screws under 8 mm in length and 1.2 mm in diameter should be avoided. Immediate or early loading up to 200 cN was adequate and showed no significant influence on screw stability.
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ABSTRACT: In recent years, the skeletal anchorage through miniscrews has expanded the treatment options in orthodontics (Yamaguchi et al., 2012). We hereby present a modified method for tooth extrusion for cases where crown-lengthening surgery is contraindicated for aesthetic reasons. This modified method uses three orthodontic appliances: a mini-implant, an orthodontic wire, and a bracket. The aim of this case report was to increase the length of the clinical crown of a fractured tooth (tooth 23) by means of an orthodontic extrusion with the modified method of Roth and Diedrich.02/2015; 2015:909314. DOI:10.1155/2015/909314
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ABSTRACT: The purpose of this survey was to determine how commonly, and in what clinical situations, German-based orthodontists use skeletal anchorage devices in daily clinical practice. In early 2013, a set of questionnaires on the subject of skeletal anchorage devices was mailed to 2459 members of the German Orthodontic Society (Deutsche Gesellschaft für Kieferorthopädie, DGKFO). The questions dealt separately with miniscrews (MSCs) and osseointegrated palatal implants (OPIs). The addressees were asked whether or not, as well as how frequently and in what clinical situations, they used these MSCs and/or OPIs, what their experience was, and to elaborate on their reasons for using or not using these devices. The rate of returned questionnaires was 48 %. To correctly interpret our data, it should be kept in mind that an unknown number of respondents did not distinguish between OPIs and palatally inserted MSCs. Overall, 62 % indicated that they did use MSCs and/or OPIs, although most of them (> 50 %) infrequently (≤ 2 new patients/3 months). Only ≤ 2 % were frequent users (> 2 new patients/week). While most users (> 70 %) indicated that their experience was mostly good, only ≤ 50 % considered the devices easy and trouble-free to use in daily clinical practice. The median percentage of insertion procedures conducted by the respondents themselves was 2 % for MSCs and 0 % for OPIs. Many of the non-users indicated that their treatment concept did not include suitable clinical indications (≥ 50 %), expressed skepticism about the success rates (56 % of MSC and 21 % of OPI non-users), or thought that the insertion procedures involved were too complex or time-consuming (33 % of MSC and 56 % of OPI non-users). A total of 62 % of German-based orthodontists participating in this survey indicated using skeletal anchorage devices, although most of them infrequently. Major reasons for non-use were lack of clinical indications, skepticism about the success rate of MSCs, and overly complex or time-consuming procedures of surgical OPI insertion.
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ABSTRACT: The aim of this animal study was to develop a model of orthodontic tooth movement using a microimplant as a TSAD in rodents. A finite element model of the TSAD in alveolar bone was built using μCT images of rat maxilla to determine the von Mises stresses and displacement in the alveolar bone surrounding the TSAD. For in vivo validation of the FE model, Sprague-Dawley rats (n = 25) were used and a Stryker 1.2 × 3 mm microimplant was inserted in the right maxilla and used to protract the right first permanent molar using a NiTi closed coil spring. Tooth movement measurements were taken at baseline, 4 and 8 weeks. At 8 weeks, animals were euthanized and tissues were analyzed by histology and EPMA. FE modeling showed maximum von Mises stress of 45 Mpa near the apex of TSAD but the average von Mises stress was under 25 Mpa. Appreciable tooth movement of 0.62 ± 0.04 mm at 4 weeks and 1.99 ± 0.14 mm at 8 weeks was obtained. Histological and EPMA results demonstrated no active bone remodeling around the TSAD at 8 weeks depicting good secondary stability. This study provided evidence that protracted tooth movement is achieved in small animals using TSADs.International Journal of Dentistry 09/2014; 2014:917535. DOI:10.1155/2014/917535