Comparative analysis of anchorage systems for micro implant orthodontics.
OBJECTIVE
The study analysed twelve anchorage systems based on micro implants in terms of their bio-mechanical properties and appraised their actual clinical effectiveness.


METHODS
The analysed micro implants had data provided by the manufacturers or extracted from articles published in specialised journals. The parameters taken into account were: material, surface treatment, head type, length, diameter, neck length, filleted self drilling or self tapping surface, applicable orthodontic forces, possibility of immediate loading, and device removal.


RESULTS
Material Grade 5 titanium, titanium alloy (TiAl6V4), surgical steel; surfaces: smooth, sand-blasted and acid etched; head type: bracket, conic with button, round, hexagonal, button with cross cuts, double melted sphere; lengths: between 8.0 to 14 mm; diameters: between 1.2 to 2.0 mms; neck lengths: inferior to 1.5mm and superior to 2.0mm; filleted portion: self tapping and/or self drilling; applicable orthodontic forces: up to 500 g, possibility of immediate loading, device removal, possibility to use in growing patients.


CONCLUSIONS
The most widely used material was TiAl6V4; most of the surfaces were smooth; the most commonly used head type was the bracket; the most often produced length was the "short" one (8.0-9.9 mm), the most demanded diameter the "smaller" one (1.2-1.4 mms); six systems out of eleven had micro implants with "extra" and "standard" necks; only 3 systems out of eleven produced "non self drilling"devices; all the micro implants analysed were able to withstand orthodontic forces between 150 g and 350 g; all devices were suitable for "immediate loading"; all micro implants had to be removed; all micro implants could be used in growing patients.


CONCLUSIONS
The comparative analysis showed that micro implants could be used as valid anchorage systems, if dental anchorage was insufficient either in qualitative terms (i.e. parodontal problems) or in quantitative terms (i.e. few dental elements remaining), and in all those situations of limited patient compliance.
Department of Orthodontics and Clinical Gnatology, University of Padua, Italy.
Lorenzo
L
Favero
Costantino
C
Giagnorio
Francesco
F
Cocilovo
D000134:Acid Etching, Dental / Q000379:methods; D000497:Alloys; D001672:Biocompatible Materials / Q000737:chemistry; D001696:Biomechanical Phenomena; D003343:Corrosion; D003722:Dental Alloys / Q000737:chemistry; D045662:Dental Etching / Q000379:methods; D003758:Dental Implantation, Endosseous / Q000295:instrumentation; D015921:Dental Implants; D003764:Dental Materials / Q000737:chemistry; D020878:Device Removal; D006801:Humans; D008422:Materials Testing; D052280:Orthodontic Anchorage Procedures / Q000295:instrumentation*; D016382:Orthodontic Appliance Design; D013193:Stainless Steel / Q000737:chemistry; D013314:Stress, Mechanical; D013499:Surface Properties; D013718:Tensile Strength; D014025:Titanium / Q000737:chemistry; D019415:Torque
D000497:Alloys; D001672:Biocompatible Materials; D003722:Dental Alloys; D015921:Dental Implants; D003764:Dental Materials; D013193:Stainless Steel; C031462:titanium alloy (TiAl6V4); D014025:Titanium