Invisible orthodontics part 1: invisalign

A recent YouGov Survey estimated that 45% of adults are unhappy with the appearance of their teeth and 20% would consider having some form of orthodontics to improve the alignment and appearance of their teeth.1 The British Lingual Orthodontic Society found in a 2009 survey that 72% of people were unaware of the option of invisible braces.2 When questioned, 90% of adults deem aesthetic appliances (Invisalign, lingual and ceramic) as attractive and acceptable, whilst only 55% viewed stainless steel bracket systems in a similar light.3 Indeed, perceived intellectual ability can be linked to appliance appearance, with those with no visible appliance or a clear aligner rated above those with steel or ceramic appliances.4

Align Technology first introduced Invisalign in 1999. To date over 58,000 dentists and orthodontists worldwide are Invisalign certified, with an estimated one million patients treated so far.5 It involves wearing a series of customized clear plastic aligners (Figure 1) for a minimum of 20 hours per day. They are changed on a two-weekly basis. It is estimated that each aligner moves a tooth or group of teeth by 0.25 to 0.33 mm. CAD-CAM technology is combined with virtual 3D model correction software (ClinCheck) to stage tooth movements and correction of the malocclusion (Figure 2). The ClinCheck can be used for visualization of treatment results and sharing information with patients throughout the duration of treatment. A typical course of treatment takes approximately 25 aligners but varies according to the amount and complexity of required tooth movement.6 Concern has been raised about the potential release of bisphenol A from these plastic aligners but laboratory in vitro ageing studies have ruled out any potential cytotoxicity or oestrogenicity.7