Issue 9.3

Toxicological Aspect of Orthodontic Bonding Materials


Composites are the most commonly used materials in the contemporary orthodontic practice for bonding attachments to the tooth surface. Superior aesthetics, bond strength and adequate working time are the most common advantages cited. The literature however is scarce about the potential adverse effect of these materials. The goal of this article is to provide current information about the potential toxic effects of composite adhesive with primary focus on its estrogenicity. Three topics primarily discussed in this article are, the development of BIS-GMA, the effect of estrogenic hormones and its analogue and the potential toxic effect of BIS-GMA. Finally, some clinical recommendations are provided to minimize the exposure to this chemical from dental composite.

Keywords: Composites, BIS-GMA, bonding material, estrogenicity, toxicity.

Effects of Hot and Cold Sterilization on The Tensile Strength of Orthodontic Wires” (An in-vitro study)


Aims: The purpose of this study was: (1) To determine the effect of different methods of sterilization such as dry heat, autoclave, ethylene oxide and 2.45% glutaraldehyde on tensile strength of Beta-Titanium, Nickel-Titanium and Stainless steel wires. (2) To compare the difference in the tensile strength between different wires and between different methods of sterilization. (3) To evaluate the changes in tensile strength values caused by repeated cycles of sterilization.

Methods and subjects: In this study a total of 135 wires of dimension 0.016” diameter and 7 inches length were used, which  were  divided in 3 groups of 45 wires each in 0.016” Stainless Steel, 0.016” Nickel Titanium and 0.016” Beta Titanium. These groups were further divided into 9 subgroups. The sterilization methods used in this study were: Autoclave, Hot air oven, Ethylene Oxide and 2.45% Glutaraldehyde. An Instron Universal Testing machine was used to record the tensile strength.

Result: On comparison of the results it is concluded that for reuse of orthodontic wires tested none of the sterilization methods used,  significantly altered  the physical properties of the wires.

Conclusion: Sterilization of the wires prevents cross contamination without decreasing the ultimate tensile strength of the wires, making the practice more cost effective.

Keywords: Stainless steel, Nickel Titanium, Beta Titanium, Tensile strength, Sterilization, recycling.


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