The relation of load deflection of nickel titanium orthodontic wires and the application of different fluoride containing tooth paste : an in vitro study

Abstract EN

Background: This study was designed to find the relation of load deflection of round 0.012 inch nickel titanium orthodontic wires, the application of different fluoride containing tooth paste, and the effect of immersion time in these fluoride containing tooth pastes on the load deflections of nickel titanium orthodontic wires.

Materials and method: The straight portion of preformed (arch form) round 0.012 inch nickel titanium orthodontic arch wire was cut and immersed either in one of the tested fluoride containing tooth pastes or in the controlled medium “artificial saliva”, where incubated at 37oC in special incubator at 2 time intervals (60 and 90 minutes).The load deflections of the wires were measured with a specially designed test apparatus based on the mechanism of 3-point bending test.

Results: The nickel titanium arch wire after immersion in acidulated monoflurophosphate tooth paste reveals lowest load deflection among the immersion test media (tooth paste), while the immersion in neutral sodium fluoride containing tooth paste reveals intermediate load deflection, and the immersion in stannous fluoride containing tooth paste reveals highest load deflection which is closest to that in artificial saliva.

F- test by ANOVA table shows that there is a highly significant difference (P< 0.0001) between all chemical reagents at the mean 2 time intervals for the mean load deflections of nickel titanium arch wires, and there is a significant difference at 60 minutes between all chemical reagents at P< 0.05, and there is a highly significant difference at 90 minutes between all chemical reagents for the mean load deflections of Ni-Ti arch wires at P< 0.0001.

Using fluoride containing tooth paste with nickel titanium arch wire could decrease the load deflection; in addition to the fact that there is an inverse relation between the immersion time and the load deflection of nickel titanium arch wire.

This may contribute to prolong orthodontic treatment.

Conclusions: The stannous fluoride containing tooth paste seems to be the best fluoride containing tooth paste because it shows no detrimental effect on the load deflection of nickel titanium arch wire.

So during the long period orthodontic treatment, both patient and clinical doctor should carefully use the fluoride containing products (teeth pastes, topical prophylactic agents, etc…).

Keyword: Load deflection, nickel titanium wire, Fluoride, Toothpaste.

(J Bagh Coll Dentistry 2007; 19(1): 115-121).