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Force delivery of NiTi orthodontic arch wire at different magnitude of deflections and temperatures: A finite element study

Razali MF, Mahmud AS, Mokhtar N

J Mech Behav Biomed Mater, 2018 Jan;77:234-241.
PMID: 28954242 DOI: 10.1016/j.jmbbm.2017.09.021

NiTi arch wires are used widely in orthodontic treatment due to its superelastic and biocompatibility properties. In brackets configuration, the force released from the arch wire is influenced by the sliding resistances developed on the arch wire-bracket contact. This study investigated the evolution of the forces released by a rectangular NiTi arch wire towards possible intraoral temperature and deflection changes. A three dimensional finite element model was developed to measure the force-deflection behavior of superelastic arch wire. Finite element analysis was used to distinguish the martensite fraction and phase state of arch wire microstructure in relation to the magnitude of wire deflection. The predicted tensile and bending results from the numerical model showed a good agreement with the experimental results. As contact developed between the wire and bracket, binding influenced the force-deflection curve by changing the martensitic transformation plateau into a slope. The arch wire recovered from greater magnitude of deflection released lower force than one recovered from smaller deflection. In contrast, it was observed that the plateau slope increased from 0.66N/mm to 1.1N/mm when the temperature was increased from 26°C to 46°C.
Effect of Short-Term Ageing Treatment on Bending Force Behavior of Commercial Nickel-Titanium Archwire

Munir A, Razali MF, Hassan MH, Franz G

Materials (Basel), 2023 Jan 21;16(3).
PMID: 36770015 DOI: 10.3390/ma16031008

Superelastic nickel-titanium (NiTi) archwires have become the preferred archwire for orthodontic alignment and the levelling stage due to their ability to exert a light force on teeth throughout a wide range of tooth movement. The magnitude and trend of the force exerted on the malposed tooth is influenced by the orthodontist's consideration of the size and geometry of the NiTi archwire during orthodontic therapy. In this work, a novel approach of a short-term ageing treatment was utilized to modify the magnitude and trend of the bending force of a commercial superelastic NiTi archwire. The bending behavior of the superelastic NiTi archwire was altered by subjecting it to different temperatures in an ageing treatment for 15 min. The bending behavior of the aged NiTi archwire was examined using a three-point and three-bracket setup. The commercial NiTi archwire's bending forces in both the three-point and three-bracket configurations were successfully altered by the 15 min ageing treatment. During unloading in the three-bracket arrangement, the NiTi archwires aged at 490 °C or 520 °C exhibited a lower magnitude and more consistent force compared to the NiTi archwires aged at 400 °C or 430 °C. Ageing the archwire for 15 min at 490 °C produced a suitable size of Ni4Ti3 precipitate, which makes the wire more flexible during bending and reduces the unloading force in the three-bracket bending configuration. The short-term aged NiTi archwire could be used to enhance the force delivery trend to the malposed tooth by lowering the amplitude of the force delivered and sustaining that force throughout the orthodontic treatment duration.
A case of rotenone poisoning from ingesting Derris trifoliata Lour. (Tuba fruit/pod) in Malaysia

Yeoh SL, Choong PS, Zakaria R, Kamaruzaman NA, Md Rashid S, Razali MF, et al.

Toxicon, 2024 Jan;237:107557.
PMID: 38072318 DOI: 10.1016/j.toxicon.2023.107557

Derris trifoliata is mainly found in mangrove area in tropical regions and the plant extract is traditionally used for fishing by poisoning. This is the first case report of rotenone poisoning in a child from ingesting Derris trifoliata seed. The child developed altered consciousness, vomiting, hypotension, metabolic acidosis, and acute kidney injury. Species identification of this case requires the collaborative efforts of various agencies. She survived from the poisoning with no neurological sequelae.
Fulltext Epidemiology and risk factors of pesticide poisoning in Malaysia: a retrospective analysis by the National Poison Centre (NPC) from 2006 to 2015

Kamaruzaman NA, Leong YH, Jaafar MH, Mohamed Khan HR, Abdul Rani NA, Razali MF, et al.

BMJ Open, 2020 06 01;10(6):e036048.
PMID: 32487578 DOI: 10.1136/bmjopen-2019-036048

OBJECTIVE: Pesticide poisoning is a global health problem, and its progressive deterioration is a major cause of concern. The objective of this study is to assess epidemiological characteristics and identify risk factors of pesticide poisoning in Malaysia.
SETTING: Pesticide poisoning database of Malaysia National Poison Centre (NPC) from 2006 to 2015.
PARTICIPANTS: Telephone enquiries regarding pesticide poisoning were made by healthcare professionals. Information received by the NPC was entered into a retrievable database of standardised Poison Case Report Form, as adapted from the World Health Organization (WHO).
OUTCOMES: The outcome of the study is to provide an overview of national epidemiological profile of pesticide poisoning. High-risk groups of people and their circumstances were also identified to ensure that appropriate measures are strategised.
RESULTS: Within the study period, a total of 11 087 pesticide poisoning cases were recorded. Sixty per cent of these cases were intentional in nature and most were found among male individuals (57%) of the Indian race (36.4%) aged between 20 and 29 years (25.5%), which occurred at home (90%) through the route of ingestion (94%). The highest number of poisoning was due to herbicides (44%) followed by agricultural insecticides (34%), rodenticides (9.9%), household insecticides (9.5%) and fungicides (0.5%). In addition, 93.6% of intentional pesticide poisoning cases were caused by suicide attempts. The results of this study show that there was an increasing trend in pesticide poisoning incidents over the 10-year duration. This indicates that pesticide poisoning is a prevalent public health problem in Malaysia, resulting in an average incidence rate of 3.8 per 100 000 population.
CONCLUSIONS: Deliberate pesticide ingestion as a method of suicide has become a disturbing trend among Malaysians. Therefore, regulation of highly hazardous pesticides must be enforced to ensure controlled and limited access to these chemicals by the public.