Thermal Behavior Changes of As-Received and Retrieved Bio-Active® (BA) and TriTanium® (TR) Multiforce Nickel–Titanium Orthodontic Archwires

Abstract

Multiforce nickel–titanium (NiTi) orthodontic archwires release progressively increasing forces in a front-to-back direction along their length. The properties of NiTi orthodontic archwires depend on the correlation and characteristics of their microstructural phases (austenite, martensite and the intermediate R-phase). From a clinical and manufacturing point of view, the determination of the austenite finish (Af) temperature is of the greatest importance, as in the austenitic phase, the alloy is most stable and exhibits the final workable form. The main purpose of using multiforce orthodontic archwires is to decrease the intensity of the applied forces to the teeth with a small root surface area, such as the lower central incisors, and also provide forces high enough to move the molars. With the optimally dosed forces of multiforce orthodontic archwires in the frontal, premolar and molar segments, the feeling of pain can be reduced. This will contribute to the greater cooperation of the patient, which is of utmost importance to achieve optimal results. The aim of this research was to determine the Af temperature at each segment of as-received and retrieved Bio-Active® and TriTanium® archwires with dimensions of 0.016 × 0.022 inches, investigated by the differential scanning calorimetry (DSC) method. A classical Kruskal–Wallis one-way ANOVA test and multi-variance comparison based on the ANOVA test statistic using the Bonferroni corrected Mann–Whitney test for multiple comparisons were used. The incisor, premolar and molar segments have different Af temperatures, and they decrease from the anterior to posterior so that the posterior segment has the lowest Af. Bio-Active® and TriTanium® with dimensions of 0.016 × 0.022 inches can be used as first leveling archwires by additional cooling and are not recommended for use on patients with mouth breathing.

Elemental composition and structural characteristics of Bio-active™ orthodontic archwire

“…The DSC curves of each segment (anterior, bicuspid, posterior) of Bio-active™ archwires are shown on figure 6. Three phases were observed on the DSC (visualized by three peaks), namely austenite at heating and both rhombohedral -R-) phase and martensite at cooling [8]. Especially important for the purposes of our study is the finish temperature of Austenite (Af) because it shows full austenite transformation of each segment sample.…”

Multi-Force Bio-Active™ Archwires and Various Contemporary NiTi Multi-Force Archwires: Properties and Characteristics—A Review

“…As their clinical use time increases, an Af temperature difference in all regions of the archwire, especially in the premolar region, can be seen at ~8 • C. Their Af temperature is also set quite below the temperature of the oral cavity. This means that, at room temperature, before engaging the archwires into the bracket slot, they are already in the austenitic phase [40]. A summary of recommendations for the clinical use of the Bio-active™ and TriTanium™ archwires based on the reviewed literature is presented in Table 1.…”

“…The archwire’s biomechanical properties (shape memory, force, and superelasticity) can also be attributed to heat-activated archwires. Its shape memory applies progressive forces from the midline to the posterior sections [ 37 , 38 , 39 , 40 ].…”

“…It is important that independent studies be conducted to verify the information provided by the manufacturer, as manufacturers generally do not openly discuss their proprietary manufacturing techniques. To address this, we carried out studies [ 38 , 39 , 40 , 68 , 69 ], where the mechanical and thermal properties of the Bio-active, along with the TriTanium archwires, were studied and compared. Part of these studies also includes physicochemical characterization [ 38 ], which involves tests such as X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDS), scanning electron microscopy (SEM), and laser-induced breakdown spectroscopy (LIBS).…”

“…Throughout the course of use, no statistically significant variations in the Af are observed in the various segments of the Bio-Active and TriTanium ® archwires. All tested groups (not used and used for up to and over 8 weeks) have the same Af [ 40 ]. We found that the Bio-active™ wires preserve their properties, both mechanical and thermal, over an extended period of clinical use (over 8 weeks), with no statistical differences found between all tested groups (unused and used up to and over 8 weeks) [ 39 , 40 ].…”