Stainless steel and NiTi torque archwires and apical root resorption

Abstract

Objective The amount of apical root resorption when using the torque-segmented archwire (TSA) was investigated as well as the extent and direction of the therapeutically indicated apical movement and the treatment duration. Materials and methods The degree of apical root resorption in 18 randomly chosen Class II and Class I patients treated with the TSA, as well as in 18 conventionally treated patients were evaluated using pre-and posttreatment panoramic radiographs. The sagittal and vertical apical movements and inclination changes were determined based on pre-and posttreatment lateral cephalograms. Nonparametric tests were applied to test between treatment groups and steps. The Mann-Whitney U test, Kruskal-Wallis, Pearson correlation and Wilcoxon signed-rank test were applied for statistical analysis (p < 0.05). Results The incidence of root resorptions was 89-94.4% in low or moderate level. The relative root-crown ratio (rRCR) was not statistically different between the TSA and control groups except tooth 12. The axis of the incisors in the TSA group was significantly improved. The main direction of movement of the apices of the central incisors was retrusion and extrusion. No interdependence between the amount of resorption and the parameters of treatment duration, extent and direction of apical movement were found. Conclusion The results of the study showed that the amount of apical root resorption with the TSA is slight to moderate and can be compared to conventional orthodontic treatment. The TSA is hence a suitable method for applying targeted torques to the incisors. Keywords Incisors • Orthodontic therapy • Tooth movement • Root-crown ratio • Orthodontic appliances Edelstahl-und NiTi-Torquesegmentbogen und apikale Wurzelresorption Zusammenfassung Ziel Der Umfang der apikalen Wurzelresorption ebenso wie das Ausmaß und die Richtung der therapeutisch angenommenen apikalen Bewegung sowie die Behandlungsdauer wurden bei Anwendung des Torquesegmentbogens (TSB) untersucht. Methoden Das Ausmaß der apikalen Wurzelresorption wurde an 18 willkürlich ausgewählten Klasse-II-und-I-Patienten, die mit dem TSB behandelt wurden, und an 18 konventionell behandelten Patienten anhand von prä-und posttherapeutisch erstellten Panoramaschichtaufnahmen beurteilt. Die sagittalen und vertikalen apikalen Bewegungen sowie die Änderungen der Inklination wurden anhand der FRS(Fernröntgenseitenbilder)-Aufnahmen bestimmt. Unterschiede zwischen Behandlungsgruppen und-schritten wurden mit nichtparametrischen Tests bestimmt. Mann-Whitney-U-, Kruskal-Wallis-, Pearson-Korrelation-und Wilcoxon-Rangsummen-Tests wurden zur statischen Analyse verwendet (p < 0.05).

Force-Controlled Biomechanical Simulation of Orthodontic Tooth Movement with Torque Archwires Using HOSEA (Hexapod for Orthodontic Simulation, Evaluation and Analysis)

“…While force magnitudes can be accurately determined for some components used with fixed appliances, such as elastic chains, nickel–titanium springs, cantilevers, and intermaxillary elastics, the resulting forces of more complex archwire bends are difficult to determine or even estimate in vivo [ 6 ]. However, this knowledge is particularly important for critical orthodontic tooth movements frequently leading to apical root resorption, such as orthodontic torque application [ 7 ]. Clinically, the application of palatal root torque is indicated for orthodontically correct incisor inclination or to maintain it, e.g., during incisor retraction [ 7 ].…”

“…However, this knowledge is particularly important for critical orthodontic tooth movements frequently leading to apical root resorption, such as orthodontic torque application [ 7 ]. Clinically, the application of palatal root torque is indicated for orthodontically correct incisor inclination or to maintain it, e.g., during incisor retraction [ 7 ]. To obtain information about forces, moments, movements or similar, two methods of in vitro investigations are established in orthodontic science: digital, finite element (FE) simulation and biomechanical experiments [ 8 , 9 , 10 ].…”

Thermal Programming of Commercially Available Orthodontic NiTi Archwires

“…Superelastic NiTi archwires are used for initial aligning and tooth irregularity correction and represent a viable addition to conventional steel archwires [ 1 ], which can easily be bent. However, they fatigue quickly due to frequent reactivations and force control is more difficult because of their high elastic modulus, with a latent risk for root resorptions [ 2 ]. This risk can be minimized using superelastic NiTi archwires, since small and constant forces over long displacements are ensured by the horizontal force plateau of the unloading curve of the material [ 2 , 3 ], which is based on reverse martensitic transformation.…”

“…However, they fatigue quickly due to frequent reactivations and force control is more difficult because of their high elastic modulus, with a latent risk for root resorptions [ 2 ]. This risk can be minimized using superelastic NiTi archwires, since small and constant forces over long displacements are ensured by the horizontal force plateau of the unloading curve of the material [ 2 , 3 ], which is based on reverse martensitic transformation. The risk for root resorptions can also be minimized by applying individual forces with regard to tooth root surfaces, i.e., lower forces should be applied on front teeth, while higher forces can be used for tooth movement of premolars and molars.…”

A Comparison of the Ligation Torque Expression of a Ribbonwise Bracket–Archwire Combination and a Conventional Combination: A Primary Study

“…e third-order moment needs to be controlled within a certain range to achieve the desired effect. e moment should not exceed a certain limit to avoid clinical side effects [6,7]. Although there is no scientific consensus regarding the ideal moment, most scholars agree that in clinical practice, the values of effective moments range between 10 and 20 Nmm [8,9], and several have suggested values of 5-20 Nmm [10,11].…”