A "typodont" study of rate of orthodontic space closure: self-ligating systems vs. conventional systems.
OBJECTIVE
The aim of this study was to compare the effectiveness of space closure of two bracket systems, self-ligating and conventional ones, considering two systems with the same design and prescription. The experimental model of this study aims to identify in general if one type of system is more suitable for planning the extractive therapy, without considering the clinical aspect necessary for an adequate orthodontic approach.


METHODS
A resin maxilla without the first premolars was used to test the self-ligating and conventional brackets system. Space closure was achieved on 0.016x0.022" in stainless steel wires with nickel-titanium coil springs 150 grams in strength and 10 mm in length. Two experiment settings have been prepared. The first setting was made bonding conventional bracket on the right side and self-ligating on the left; the last one was made bonding self-ligating bracket on the right side and conventional on the left. All measurements (runs) have been repeated seven times for both settings.


RESULTS
During the closing phase of extraction spaces both systems are equable since there are no significant statistical differences (P=0.70).


CONCLUSIONS
Our typodont model showed no significant difference in the efficiency of space closure between the self-ligating bracket and conventional bracket tied with stainless steel ligatures.
Department of Orthodontics, School of Dentistry, University of Milan, Italy. odontoirene@msn.com
I
I
Saporito
A C
AC
Butti
A
A
Salvato
R
R
Biagi
D001641:Bicuspid; D003722:Dental Alloys; D017276:Friction; D066298:In Vitro Techniques; D008437:Maxilla; D008953:Models, Anatomic; D009532:Nickel; D016382:Orthodontic Appliance Design; D016910:Orthodontic Brackets; D019516:Orthodontic Space Closure / Q000295:instrumentation* / Q000379:methods; D009969:Orthodontic Wires; D013314:Stress, Mechanical; D014025:Titanium
D003722:Dental Alloys; C040654:titanium nickelide; D009532:Nickel; D014025:Titanium