[Class II interceptive therapy in the mixed dentition: intra-oral distalization appliances]. / Traitements interceptifs de la classe II en denture mixte: thérapeutiques intra-orales de distalisation.

Treatment of Class II malocclusion during the mixed dentition may sometimes require upper molar distalization. To achieve this, many devices have been suggested. The purpose of this article is to classify them and to point out their effects on the dentition and upon skeletal structures.

[Evaluation of orthodontic friction using a tribometer with alternating movement]. / Evaluation du frottement orthodontique par un tribomètre a mouvement alternatif.

It is essential for orthodontists to control the complex phenomenon of friction. The in vitro techniques, usually dynamometers or tensile testing machines, used to measure the frictional resistance between arch wires and brackets are linear and unidirectional and can be criticised because tooth movements, such as tipping and uprighting, as well everyday oral activities, primarily chewing, are not uni-dimensional but more closely resemble the small amplitude oscillatory phenomena known as fretting. We therefore decided to develop a fretting machine not with linear but with alternating movements better suited to evaluate the frictional behaviour of orthodontic bracket-wire combinations. Once we had completed construction of this device, we proceeded to measure the frictional resistance between one stainless steel bracket (MicroArch GAC) and five wires currently used in orthodontics (Two nickel-titanium shape memory alloys: Neo Sentalloy and Neo Sentalloy with Ionguard GAC--Three titanium-molybdenum alloys: TMA and Low Friction TMA Ormco and Resolve GAC). We were able to set up a classification of the wires according to their coefficient of friction, demonstrating the inefficacy of ion implantation and quantifying the increase in the coefficient of friction which occurs when Resolve wires are placed in the oral environment for approximately one year.