Autoclaving and clinical recycling: Effects on mechanical properties of orthodontic wires.

Background: About half of the orthodontists recycle and reuse orthodontic wires because of their costs. So when talking about reuse and sterilization of wires, their effects on mechanical properties of wires should be clarified. The purpose of this study was to assess the effects of sterilization and clinical use on mechanical properties of stainless steel wires. Materials and Methods: Thirty stainless steel orthodontic wires were divided into three equal groups of control, autoclave (sterilized by autoclave), and recycle group (wires were used for orthodontic patients up to 4 weeks, cleaned by isopropyl alcohol and sterilized by autoclave). The mechanical properties (tensile test, three-point loading test for load-deflection curve) were determined. Results: Fracture force, yield strength, stiffness and modulus of elasticity in recycle groups were significantly lower than the other groups (P < 0.05). Conclusion: Although recycle wires were softer than those of control group, relatively small differences and also various properties of available wires have obscured the clinical predictability of their application. There is seemingly no problem in terms of mechanical properties to recycle orthodontic wires.

Evaluation of the updated Omani regulations for waste water re-use and discharge

Guidelines for wastewater re-use quality are based on scientific and epidemiological findings. As such, it provides guidance towards making risk management decision that are related to the protection of public health and environmental preservation [Hespanol, 1992]. Over the last thirty years, or so, considerable work has been, done to assess risks emerging from wastewater re-use and develop methods that would aid removal or 'minimization of the risks. For example reports by WHO [WHO, 1973 and 1989] have contributed greatly in reviewing and summarizing research and experience all over the world with the purpose of establishing sensible guidelines for wastewater re-use. Wastewater regulations are established by countries while adopting their national priorities and strategies. Attention is usually paid to technical, economical, social, cultural, hygienic practices, and political characteristics and constraints. The regulations for wastewater re-use and discharge in the Sultanate of Oman were first introduced in 1986. This paper gives a critical review of the updated regulations and makes procedural recommendations