Effects of 6 different chemical treatments on force kinetics of memory elastic chains versus conventional chains: An in vitro study

Int Orthod. 2020 Jun;18(2):349-358. doi: 10.1016/j.ortho.2020.02.003. Epub 2020 Mar 17.


Introduction: Effects of different oral hygiene controls on force kinetics of memory elastic chains are not assessed adequately or in the case of many oral care products, non-existent. This study assessed these.

Material and methods: This in-vitro study was performed on 647 observations of 132 elastic chains assessed at 5 intervals. In each of the treatments (artificial saliva, fluoride, OralB mouthrinse, whitening OralB mouthrinse, toothpaste, and whitening toothpaste), 11 memory and 11 conventional chains were tested. Chains were stretched for 100%; their initial force was measured (g), and immersed in artificial saliva at 37°C. For treatments other than artificial saliva, the specimens were removed from the saliva twice daily and the main treatment was applied. After washing with distilled water, they were immersed back in artificial saliva. At the days 1st, 7th, 14th, and 28th, their force was re-measured. Data were analysed statistically (α=0.05).

Results: Force degradation of elastic chains was observed in both memory/conventional types (P=0.000) although memory chains showed slightly less declines especially in the beginning days. The interaction of treatment and time was significant (P=0.000) meaning that different treatments caused different rates of force decay, with fluoride having the fastest drop rate followed by whitening toothpaste. However, the difference among 5 intervals of time was not significant (P=0.569). When elastic types were assessed separately, this variable as well became significant (P≤0.002). One-sample t-test showed that all final residual forces (28th day) were either above 150g or at its level.

Conclusion: Chain force degrades over time but stays sufficient for bodily tooth movement after 4 weeks. Memory chains are preferable as they provide greater forces for longer durations. Fluoride mouthwash followed by whitening toothpaste cause the most rapid declines. Both chain types still retained adequate forces after 4 weeks, even after treatment with fluoride or whitening toothpaste.

Keywords: Cetylpyridinium chloride; Conventional elastic chains; Fluoride; Force; Memory elastic chains; Whitening mouthrinse; Whitening toothpaste.

MeSH terms

  • Elasticity / drug effects*
  • Elastomers*
  • Fluorides / pharmacology
  • In Vitro Techniques
  • Mouthwashes / pharmacology
  • Orthodontic Appliances*
  • Saliva, Artificial / pharmacology
  • Tooth Bleaching Agents / pharmacology
  • Tooth Movement Techniques / instrumentation
  • Toothpastes / pharmacology


  • Elastomers
  • Mouthwashes
  • Saliva, Artificial
  • Tooth Bleaching Agents
  • Toothpastes
  • Fluorides