Comparison of the transformation temperatures of heat-activated Nickel-Titanium orthodontic archwires by two different techniques

Abstract

Objectives: The purpose of this study was to investigate the suitability of the Bend and Free Recovery (BFR) method as a standard test method to determine the transformation temperatures of heat-activated Ni-Ti orthodontic archwires. This was done by determining the transformation temperatures of two brands of heat-activated Ni-Ti orthodontic archwires using the both the BFR method and the standard method of Differential Scanning Calorimetry (DSC). The values obtained from the two methods were compared with each other and to the manufacturer-listed values. Methods: Forty heat-activated Ni-Ti archwires from both Rocky Mountain Orthodontics (RMO) and Opal Orthodontics (Opal) were tested using BFR and DSC. Round (0.016 inches) and rectangular (0.019 × 0.025 inches) archwires from each manufacturer were tested. The austenite start temperatures (As) and austenite finish temperatures (Af) were recorded. Results: For four of the eight test groups, the BFR method resulted in lower standard deviations than the DSC method, and, overall, the average standard deviation for BFR testing was slightly lower than for DSC testing. Statistically significant differences were seen between the transformation temperatures obtained from the BFR and DSC test methods. However, the Af temperatures obtained from the two methods were remarkably similar with the mean differences ranging from 0.0 to 2.1 °C: Af Opal round (BFR 26.7 °C, DSC 27.6 °C) and rectangular (BFR 27.6 °C, DSC 28.6 °C); Af RMO round (BFR 25.5 °C, DSC 25.5 °C) and rectangular (BFR 28.0 °C, DSC 25.9 °C). Significant differences were observed between the manufacturer-listed transformation temperatures and those obtained with BFR and DSC testing for both manufacturers. Significance: The results of this study suggest that the Bend and Free Recovery method is suitable as a standard method to evaluate the transformation temperatures of heat-activated Ni-Ti orthodontic archwires.

Resistance to sliding in orthodontics: misconception or method error? A systematic review and a proposal of a test protocol

“…Despite the use of multiple brackets on a two-dimensional surface 55 56 57 58 59 60 or even in a 3D configuration 9 61 62 63 64 65 may allow the development of more accurate simulations of the clinical situation compared to that from a single bracket, it also creates challenges in understanding causal relationships between experimental variables and RS. Additionally, environmental factors such as temperature 66 and the presence of dry or wet conditions 14 can influence RS. For example, saliva may promote adhesive and lubricious behavior 14 and temperature may influence the mechanical properties of wires.…”

“…For example, saliva may promote adhesive and lubricious behavior 14 and temperature may influence the mechanical properties of wires. 66 Nevertheless, the testing temperature was reported by only a few studies. Furthermore, although the sliding velocity was usually mentioned (89%), previous studies showed variations in RS at different velocities 35 36 67 and it is noteworthy that the values reported, e.g., up to 20 mm/min, 36 68 were far from clinical orthodontic movements by several orders of magnitude.…”

Additively manufactured metallic biomaterials

“…The release of Fe can have detrimental effects on cells Mostly for short-term implants and screws as well as surgical tools. Applications as dental and orthopedic implants as well as surgical instruments are also reported [ [93] , [94] , [95] ] Cobalt-Chrome (Co–Cr) alloys Biocompatible, high hardness, wear, and corrosion resistance Most Co–Cr alloys include Ni that can cause allergic reactions Mostly as short-term implants, dental replacements and implants which are excessively used such as hip and knee substitutes [ 34 , 78 , 100 , 102 , 128 ] Magnesium (Mg) alloys Biocompatible, adjustable biodegradation, biomechanical compatibility with bone, density and elastic modulus compatible with bone, cell ingrowth acceleration and faster bone formation Printing challenges related to high surface energy and electronegativity as well as oxidation when exposed to oxygen, mechanical properties not sufficient for load-bearing applications Mostly used as temporary bone substitutes [ [106] , [107] , [108] , 114 , 129 , 130 ] Smart alloys Biocompatible, recovering original shape upon applying external stimuli, near body transformation temperature, near bone elastic modulus Release of Ni ions due to corrosion may cause safety issues and implants may fail in long-term, precise control over the composition and AM parameters, as well as post-processing conditions, is necessary to assure both shape memory effect and printability Cardiovascular stents, orthodontic wires, and dental braces [ 115 , 116 , [121] , [122] , [123] , [124] , [125] ] …”

Evaluation of the Mechanical Properties and Surface Topography of as-Received, Immersed and as-Retrieved Orthodontic Archwires

“…The effect of the thermal treatments on the mechanical behavior and the microstructure of Ni–Ti archwires of different compositions was also studied [ 12 ]. Obaisi et al [ 13 ] determined the transformation temperatures of two brands of heat-activated Ni-Ti orthodontic archwires using both the Bend and Free Recovery (BFR) method and the standard method of Differential Scanning Calorimetry (DSC). Muguruma et al [ 14 ] analyzed the coatings covering esthetic orthodontic wires and the influence of such coatings on bending and frictional properties.…”