Dear Abu-Hussein-Muhamad! Great explanation of details and dental equipment. This is important for the manipulation skilled in the oral cavity of each patient.
Vladimir
Dear Dr.Muhamad
Have you done retraction on Ni- Ti or do you have an evidence to share? Thanks
Hello Adil,
Upadhyay (1) has pointed out that „an implicit advantage of canine retraction on a continuous arch system lies in limiting the possibility of unpredicted canine movement (e.g., flaring or rotation). Despite the advantages of sliding mechanics, canine retraction does present its own set of problems. When pure forces generated from springs or elastics are induced at the canine, especially when an archwire with a low load-deflection rate is being used or the force levels are too high, the wire tends to deform with undesirable side effects on other teeth . Due to the tipping of the canine a constant stress is created on the wire, resulting in its elastic deflection. This deflection of the wire creates an extrusive force on the incisors and a moment that tends to cause lingual tipping. This tendency for archwire deflection can be reduced by using higher stiffness archwires and/or lighter forces for retraction. Auxiliary archwires, such as an overlay intrusion arch or cantilever springs, can also help to minimize the assumed deflection of the archwire."
Because these adverse effects are exaggerated when using NiTi archwires, they should not be used in sliding mechanics
1) Upadhay M, Yadav S, Nanda R. Biomechanical Basis of Extraction Space Closure. In Nanda R, ed. Esthetics and Biomechanics in Orthodontics, Saunders, St.Louis, 2015
Best wishes
Ulrich Kritzler
Thank you Dr. Kritzer
There is now a black NITI which has the property of Ni -Ti and SS. It has 3 area different in properties. The buccal is for sliding mechanics. I am planning to do a work comparing these wires to SS and NI- TI. extraction and non extraction
Q: Have you experienced or have evidence on retracting the canine on NI-TI archwire?
The 'roller coaster' effect is observed when a wire of low strength such as Niti is used for canine retraction. Niti does not have the strength to remain rigid when a retracting force such as an elastic chain is stretched from the molar to the canine. The molar and premolar crowns tend to tip mesially and extrude distally. The flexible Niti then bends gingivally and as a result tends to tip the canine crown distally. The orientation of the canine bracket when the crown tips distally tend to extrude the incisors and deepen the bite. In short, the entire occlusal plane goes for a toss and when we follow the occlusal plane from the right molar to the left molar it resembles a roller coaster and hence the term is used. To prevent this roller coaster effect, as a rule, try to avoid use of elastic chains with round Niti archwire for canine retraction.
You can read the following article for further clarification:
Kulshrestha RS, Tandon R, Chandra P. Canine retraction: A systematic review of different methods used. J Orthod Sci. 2015 Jan-Mar;4(1):1-8. doi: 10.4103/2278-0203.149608.
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