Analyse der Torquekapazität einer vollständig individuellen lingualen Apparatur (WIN)

Zusammenfassung

Einleitung: In der kieferorthopädischen Lingualtherapie ist eine effektive Torquekontrolle der Schneidezähne aufgrund der biomechanischen Besonderheiten, die mit dem Kraftansatzpunkt und der engen Verknüpfung von Abweichungen der dritten Ordnung mit der vertikalen Zahnposition verbunden sind, von besonderer Bedeutung.

Studienziel: In der vorliegenden In-vitro-Studie sollte daher die Torquekapazität einer vollständig individuellen lingualen Apparatur (WIN) in Verbindung mit verschiedenen Drahtdimensionen, wie sie üblicherweise in der Finishingphase Verwendung finden, untersucht werden.

Methode: An einem Oberkiefertypodonten mit WIN-Apparatur wurden slotfüllende und untermaßige β-Titaniumbögen einligiert und horizontale Kräfte zwischen 0 und 100cN am zentralen Schneidezahn mittels Federwaagen appliziert. Die resultierenden angulären Abweichungen wurden aufgezeichnet und die korrespondierenden Drehmomente berechnet.

Ergebnisse: Bei den slotfüllenden Bögen (0,018×0,018″ und 0,018×0,025″ β-Titanium) musste ein initiales Torquespiel von 0–2° überwunden werden, ehe sich ein effektives Drehmoment entwickelte. Anschließend war eine lineare Korrelation zwischen Torquewinkel und Drehmoment für beide Bogendimensionen mit steilerem Kurvenverlauf für die höhermaßigen Drähte zu verzeichnen. Ein für eine effektive Torquekorrektur notwendiges Drehmoment von 2Nmm wurde nach mindestens 2–3° Verwindung der 0,018×0,018″ β-Titaniumbögen erreicht, verglichen mit 2–4° für das 0,018×0,025″ β-Titanium Untersuchungsgut. Bei der Analyse untermaßiger Bögen (0,0175×0,0175″ β-Titanium) betrug das gemessene Torquespiel 5–7°. Ab einem Torquewinkel von 8–12° wurde die notwendige Schwelle von 2Nmm erreicht. Auch hier ergab sich eine lineare Beziehung zwischen dem Ausmaß der Drahtverwindung und resultierendem Drehmoment mit generell flacherem Kurvenverlauf im Vergleich zu den Berechnungen für die slotfüllenden Bögen.

Schlussfolgerung: Aufgrund der hohen Präzision der Bracketslot-Bogen-Kombination kann mit der WIN-Apparatur klinisch eine effektive Torquekontrolle erreicht werden.

Abstract

Introduction: In lingual orthodontic therapy, effective torque control of the incisors is crucial due to the biomechanical particularities associated with the point of force application and the tight link between third order deviations and vertical tooth position.

Aim: The aim of the present in vitro investigation was to analyze the torque capacity of a completely customized lingual appliance (WIN) in combination with different finishing archwire dimensions.

Methods: Using a typodont of the upper arch carrying the WIN appliance, slot filling and undersized individualized β-titanium archwires were engaged. Horizontal forces ranging from 0 to 100cN were applied at the central incisor by means of spring gauges. The resulting angular deviations were recorded and the corresponding torque moments were calculated.

Results: For full size archwires (0.018×0.018″ β-titanium and 0.018×0.025″ β-titanium), an initial torque play of 0–2° had to be overcome prior to the development of an effective torque moment. Thereafter, a linear correlation between torque angle and torque moment developed for both archwire dimensions with steeper slopes calculated for the specimens with the larger dimension. A torque moment of 2Nmm required for effective torque correction was noted after a minimum of 2–3° of twist for the 0.018×0.018″ β-titanium wires as compared to 2–4° for the 0.018×0.025″ β-titanium study sample. When undersized archwires were analyzed (0.0175×0.0175″ β-titanium), the measured torque play ranged from 5–7°. After 8–12° of torque angle, the threshold of 2Nmm was reached. A linear relationship between twist angle and torque moment in which the steepness of the slopes was generally flatter than the ones calculated for the slot filling archwires was noted.

Conclusions: Given the high precision of the bracket slot-archwire-combination provided with the WIN appliance, an effective torque control can be clinically realized.

Schlüsselwörter

Torquewinkel - Drehmoment - vollständig individuelle linguale Apparatur

Key words

torque angle - torque moment - completely customized lingual appliance

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