Tarnish and corrosion with the use of intraoral magnets

Degradation phenomena of magnetic attachments used clinically in the oral environment

“…Accordingly, many studies have been performed to extend the life of magnetic attachments used to retain dental prostheses [10,14,17]. In the present study, we examined Dyna ES magnetic attachments in order to investigate the corrosion-crack mechanism involved in these attachments.…”

“…Magnetic attachments offers many benefits including the following: they simplify the preparation of prostheses; they pose little stress to the abutment teeth when the prosthesis is inserted or removed; they do not transmit too much lateral force, which is harmful to abutment teeth due to a slight absorptive force induced in the horizontal direction; they offer excellent cosmetic appearance; and they can be handled easily by the patient. However, Drago [10] identified problems related with clinically used magnetic retention devices, including corrosion, discoloration, and a consequent decrease in retention force due to demagnetization. He also reported that patient satisfaction with these devices is not high.…”

“…The prevention of corrosion constitutes the most important issue in the use of magnetic retention devices. Despite this, studies related with the corrosion of magnetic materials used in the body are lacking [3,10]. Therefore, the present study was conducted to determine the mechanism involved in the failure of magnets used for denture retention through an examination of failed magnets under SEM following actual clinical use.…”

“…The methods used in the past, including Teflon coating, amalgam filling, *Corresponding author: hcchoe@chosun.ac.kr chrome plating, and synthetic resin covering, suffered from problems such as limited durability and moisture absorption. Accordingly, new methods have been devised in recent years including covering the magnet with stainless steel plating and laser welding the magnet to prevent thermal damage in the magnet assembly and to obtain complete sealing [1,5,10].…”

Corrosion behaviour of FePt-based bulk magnets in artificial saliva solution

“…The cased magnet is housed inside the prosthesis, whereas the keeper is cemented to the root of the abutment tooth or screwed onto the implant. However, for those systems the application is limited so far due to the low corrosion resistance of NdFeB and SmCo magnets in contact with saliva, their low biocompatibility and additional galvanic corrosion effects in contact with the stainless steel or other types of dental alloys [5][6][7][8][9]. FePt alloys are considered as being much more corrosion resistant hard magnetic materials.…”