Orthodontic material applications over the past century: Evolution of research methods to address clinical queries

Adverse reactions to orthodontic materials

“…However, the bond strength of fluoride‐releasing orthodontic bonding agents is substantially lower than those of conventional resins. Moreover, the long‐term beneficial effect of fluoride releasing adhesives has not been sufficiently established for some applications, such as glass ionomer cements or fluoride‐releasing resinous adhesives, since most of the fluoride is released within the first few days or weeks. A daily intake of probiotic lozenges was not found to affect the development of WSL during orthodontic treatment with fixed appliances.…”

“…Corrosion of the orthodontic bracket‐arch wire interface has received attention after the corrosion products of the bracket base were shown to diffuse into the bonding adhesive. The property of the materials and the engagement of the wire into the bracket slot using stainless steel or elastic ligatures creates an environment in which various forms of corrosion can develop.…”

“…As an example, a traditional bracket is composed of 2 metallic phases: a low modulus of elasticity stainless steel alloy comprising the base, which presumably facilitates easy debonding after treatment, and a high modulus steel alloy for the tie wings. These minimise deformation caused by the engagement of an arch wire and ensures that stress is transferred from the activated arch wire through the bracket slot to the tooth. The tie wing alloy is more vulnerable to corrosion because of the presence of copper in its composition.…”

“…Orthodontic appliance components are united by brazing alloys of nickel, silver, or gold and are dependent on the manufacturer and so performance differences are expected during intraoral use. The clinician should be familiar with the composition of silver‐based alloy solder and, more particularly, with the quantities of copper and zinc.…”

“…Later, this method was complemented by the introduction of instrument analysis, such as atomic emission or absorption spectroscopy for metals. High‐performance liquid chromatography and gas chromatography–mass spectroscopy were also used for the qualitative and quantitative analysis of immersion media, saliva, blood, or urine to determine the concentrations of polymer by‐products. In vitro quantification of the metallic content of biologic fluids cannot withstand scrutiny regarding the methodological soundness of the approach.…”