Understanding Material Science: Orthodontic Clear Aligner Therapy
Daniel Alter, MSc, MDT, CDT
With the advent and increased popularity of manufactured orthodontic appliances, the dental profession is experiencing a significant upswing trend of dental practitioners prescribing orthodontic treatments and maintenance protocols for their patients, both adult and adolescent. The clear oral aligner (COA) treatment provides for the use of esthetic thermoformed aligners to dynamically change the position of the patient’s dentition in order to achieve proper alignment, occlusion, and orthognathic positions. These COAs are fabricated by imprinting thermoplastic sheets on the dental cast model through a heating cycle combined with either vacuum or pressure forming. Several thermoplastics are currently used to prepare these aligners.
Laboratories should realize that these thermoformed aligners attract a significant amount of bacteria. The polymers used to fabricate COAs have poor abrasion resistance, which tends to foster considerable bacterial accumulation. Bacteria often adheres to the surface of medical devices and forms a complex microbial community called a “biofilm.” The health risk factors created by this biofilm mean that there is a need for more frequent appliance replacement. For both dental practitioners and dental laboratories, replacing aligners more often reduces the profitability of these sort of orthodontic treatments due to increased clinical chairtime or the need for more laboratory consumables and labor.
There is, however, a solution in the works. A recent study examined how a coating technique using nano-films impacts the COAs by alleviating bacterial attachment. This method is particularly useful as “it offers site-specific application and can be used to produce COAs with little increase in thickness. Maintaining the minimal thickness of COAs is critical for the function of temporomandibular joints and for the comfort of the patients.” These nano-films attract liquids and reduce biofilm adhesion simply by forming a thin water barrier that interferes with the interaction between the surface of the orthodontic aligner and the biofilm. This liquid layer helps reduce or even prevent the bacteria from attaching to the clear aligner.1
As laboratories offer more types of orthodontic services for their clientele, having this knowledge can help technicians engage in thoughtful consultation with their dentist clients, which will forge a stronger synergy between the practices.
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1. Park S, Kim H, Bin Yank S, Moon J-H, et al. A Polysaccharide-based antibacterial coating with improved durability for clear overlay appliances. ACS Appl. Mater. Interfaces. 2018; 10(21):17714-17721. Published May 4, 2018. https://pubs.acs.org/doi/full/10.1021/acsami.8b04433#. Accessed July 29, 2019.