An assessment of the pH changes and metal ions released into artificial saliva by fake orthodontic braces

There is a growing fashion trend of donning fake orthodontic braces in Southeast Asia. Fake is generally defined as not true, not real, not genuine, or artificial [1]. In terms of dentistry, fake braces are ‘orthodontic braces’ that are often sold online or are available from uncertified sellers at much cheaper prices. They are often self-installed or installed by unqualified individuals. Furthermore, proper dental examinations or investigations; such as radiographs or model studies; are not conducted before the fake braces are affixed [2]. The British Dental Association (BDA) is concerned by this service as any type of orthodontic procedure first warrants an oral examination to determine the oral condition of the patient and if the patients has any existing dental disease that should be treated prior to orthodontic procedure followed by a treatment plan [3]. Without careful professional dental supervision, an orthodontic procedure can lead to caries and gingival bleeding [4], thereby, worsening the oral health of the patient. Reports of the severe negative effects of fake braces have emerged. For instance, two Thai teenagers succumbed to infections after wearing fake braces [5]. In fake braces, the archwires (AWs) range from plain ligature wires to twisted multi-ligature wires, figure eights, and nickel titanium (NiTi) wires supported by ring positioning or elastomeric chains (E chains) of different colours and patterns. The brackets (Bs) are made of ceramics or metals and without or with hooks and vary in size.

Fake braces are popular among teenagers as they are a cheap alternative to wearing orthodontic devices. Furthermore, they are removable as they are often loosely affixed by hooks, self-glued, or fixed using self-setting glue. Although 60% of teenagers are aware of do-it-yourself (DIY) braces, almost half of them do not know the difference between actual and fake braces [6]. A recent study of 10 subjects who wore fake braces revealed that fake braces are popular as they are easy to access, convenient, and reasonably priced as they are provided by bogus dentists. Although some did not observe any changes after wearing fake braces, most felt that the condition of their teeth had worsened [7].

The Internet and social media are the main sources of information on fake braces [3, 6]. Patients are also known to show an Internet image or a picture of their friend's fake braces and demand similar Bs, attachments, and plastic chain patterns [8]. Most fake braces suppliers carry a wide range of E chains and modules to satisfy their clients’ colour and pattern demands. These comprise every colour and theme possible; from flowers to power O chain braces and Hello Kitty to Mickey Mouse themed braces [8]. These fake braces are, typically, applied primarily and not completely to the maxillary arch. Active and passive fake braces are the two most common types of fake braces available. Uncertified individuals use etching and bonding techniques to mount fake braces to the teeth. While active fake braces are bonded to the teeth, passive fake braces are not attached to the teeth and are easily worn and removed. Attention-grabbing keywords such as easily worn, removable, does not move the teeth, and accessories are often used to advertise passive fake braces or ‘click braces’ online. These types of braces are equipped with a clasp that temporarily anchors the braces to the molars, with customers expected to wear these braces only for a limited period of time [9]. The composition of these fake braces is unknown as they are never stated online. However, metal ion leaching is a concern as excessive levels of these ions can result in many health issues or toxicity [10].

An extant study assessed the leaching of metal ions from these fake braces into simulated bodily fluid [11]. This present study aimed to explore the metal ion leaching of fake braces as well as the changes that they cause to the pH of artificial saliva (AS). As fake braces are placed in the oral cavity, AS may provide a more accurate representation of the oral condition of patients wearing fake braces. An inductively coupled plasma optical emission spectroscopy (ICP-OES) was conducted to analyse the ions that the fake braces released into the AS.

This present study used AS as the immersion medium as it works the same way as natural saliva to continuously lubricate and moisturise the mouth [14, 15]. As a fake orthodontic appliance will come into contact with the saliva in a mouth, any metal ions that leach will immediately be present in the saliva. As such, AS was used to mimic the natural condition of the human mouth [16]. Although the best test subjects would have been patients fitted with fake braces, it would have been unethical to recruit individuals and fit them with fake braces and it was difficult to locate patients who already wear fake braces as fake braces are illegal.

Interestingly, the pH of the AS of all the samples; the control, the fake Bs, and the AWs; rose from 5.90 to 8.11 when immersed in the AS. Peros et al. [17], similarly, reported an increase; from 7.18 to 7.30; in the pH of three separate stimulated saliva samples of 23 patients collected every six weeks following an AW sequence of 0.012-inch nickel-titanium (NiTi), 0.016-inch NiTi, and 0.016-inch by 0.022-inch NiTi. However, Arab et al. [18] reported a decrease; from 7.18 to 6.81; in the pH of the unstimulated saliva samples of 30 orthodontic patients wearing a fixed orthodontic appliance of 0.022 inch-slot NiTi wire and ‘Ameri-can’ brackets for 18 weeks. The differences in the pH, towards a more acidic or alkaline state, may have been due to the method of collecting the stimulated and unstimulated saliva samples, as unstimulated saliva may contain bacteria that is dominant in the oral ecosystem.

This present study used an in vitro set-up, where the pH and temperature were controlled with no interference from mastication and speech activities. Therefore, the observed changes in pH were entirely due to the orthodontic devices examined. The ions that the fake braces released into the AS may have increased the pH of the AS as it reacted with the heavy metal oxides [19]. An increase in the soluble metal hydroxide content of AS can produce an AS solution that is alkaline. According to Kuhta et al. [20], the oral environment facilitates the corrosion and biodegradation of dental materials as it experiences mechanical, chemical, thermal, enzymatic, and microbiological changes. Therefore, fake braces may increase pH changes in the oral cavity.

The finding of this present study, that fake braces increase the pH of AS, is significant for oral health as a few studies suggest that higher pH facilitates higher dental plaque mineralisation [21, 22]. Patel et al. [22] categorised patients as either gingivitis, periodontally healthy, and chronic periodontitis patients and found that the pH of the saliva samples of chronic periodontitis and gingivitis patients were more alkaline. An alkaline pH is associated with increased proteolytic activity of organisms that favour the deposition of calcium phosphate, which induces plaque mineralisation [22]. Furthermore, a higher oral pH can lead to the accumulation of dental plaque which, if not monitored by dental professionals, could deteriorate the dental enamel.

To date, only one study has assessed the leaching of manganese (Mn), Al, Ni, Cr, and Cu ions from fake Bs into AS at pHs of 4.9 and 7.8 and discovered that fake Bs release more Ni and Cr ions than standard orthodontic Bs [23]. This present study, however, found that the control and fake samples released almost similar concentrations of ions. Interestingly, the control samples released significantly more ions than their fake counterparts. More specifically, Na, Ca, and K ions concentrations of more than 100 mg/L in 28 days. Another study that immersed fake braces in other media; such as simulated bodily fluid; obtained a similar finding [11]. It is noteworthy that Ni ions were not detected in the AS, even in the AS of the control sample which is made of stainless steel, which contains Ni. Multiple factors that affect the quantity of metal ions released from a fixed orthodontic appliance; such as the galvanic corrosion of the metal, the corrosion resistance of the material, the effect of brazing or welding on the metals, and the surface texture of the samples; may explain why the control and fake samples released significantly different quantities of metal ions [23].

The pH of the AS of the AW group differed significantly at Days 0, 1, 7, 14, 21, and 28. However, that of the B group only differed on Days 0 and 7. The finding of this present study indicate that fake braces release 10 different ions into saliva; namely, Na, K, Mg, Ca, Cu, Pb, Al, Li, Ba, and Cr. The concentrations of Na, Ca, and K ions released into the AS exceeded 100 mg/L during the immersion period. The concentrations of Ca and K ions released by the fake braces differed significantly from that of the control samples. However, the quantity of Li, Ba, and Cr ions that the control sample released did not differ significantly. The fake samples released significant more Na, K, Mg, Ca, Cu, Pb, and Al ions than the control samples. The findings of this present study sets the foundation for future studies on the potential risks and toxicity of wearing fake braces.