Understanding the Effects of Sterilisation Methods on Orthodontic Archwires Properties: A Review Sterilisation is the removal of all microorganisms, vegetative or spore-forming, from an article, surface or medium that can be accomplished through steam autoclaving, dry heat and cold solution following strict guidelines for efficient archwire sterilisation. Orthodontic archwire sterilisation is a concern because patients are often exposed to contaminated dental products. Thus, new and used arch wires will not show significant differences in terms of properties while in usage. This article presents a review of the sterilisation methods effects on the characteristics and properties of several types of orthodontic archwires including stainless steel (SS), nickel-titanium (NiTi), copper NiTi, beta titanium (β-Ti), heat-activated NiTi and titanium molybdenum (TiMb). Available records in “all databases” of Web of Science, PubMed, ScienceDirect, Scopus and Elsevier were searched, and other studies were manually searched using keywords, retrieved and compiled. Studies related to sterilisation of orthodontic archwires such as archwire type, sterilisation method, characterisation techniques and mechanical properties were summarised based on articles published from 1st July 2015 to 29th February 2024, and it is shown that the characteristics of orthodontic archwires may be affected by sterilisation techniques. Heat sterilisation can change the load-deflection properties of some wires, while the chemical composition and surface structures of archwires are unchanged. After sterilisation, the number of nickel ions released from the archwires does not increase significantly. The findings support the idea that archwire sterilisation procedures are an effective infection control treatment and facilitate the mechanical characterisation of orthodontic archwires.

Introduction: Human teeth tend to stain from intrinsic and extrinsic factors with time. The study was aimed to assess colour change of stained enamel after the use of bleaching agents. Methods: 63 extracted human teeth were selected and soaked in the coffee solution for 7 days to stain the teeth. Then they were randomly divided into 3 groups (n = 21). The groups were divided as the control group (distilled water), group using 6% carbamide peroxide (CP6) and group using 9% carbamide peroxide (CP9). The groups of CP6 and CP9 were bleached with 0.2 ml of bleaching agent for 5 minutes daily until 14 days. Colour changes were visually recorded by using VITA Toothguide 3D-MASTER and Ocean Optics Spectrometer instrument. Results: CP6 started to show shade reduction on Day 3 (score 5), followed by a steady reduction until Day 10. Day 12 to 14 showed another steady reduction of CP6. CP9 had a larger shade reduction (scores of 2-5) from Day 1 to Day 4, followed by a steady reduction until Day 14. Spectrometer analysis shows that CP9 samples had lower absorbance unit compared to CP6 samples for both second-day and sixth-day groups. However, most changes can be observed on the CP9 samples from control to the second-day and sixth-day. Conclusion: Bleaching agent with low concentration can approach the efficacy of high concentration of bleaching agent with an extended treatment time.