A Closer Look at Clear Aligner Therapy

The specialty of orthodontics has greatly evolved from the introduction of metal braces in the mid-1940s.¹ While traditional metal brackets and wires are still used to straighten teeth and correct malocclusions, orthodontics offers a variety of other treatment modalities, including clear aligner therapy (CAT) systems that are effective in the treatment of mild to moderate irregularities.² These removable and less visible systems are attractive to adults seeking corrective alignment. Approved by the United States Food and Drug Administration in 1998, CAT can address minor positioning problems to more complex malocclusions.³ Dental hygienists should be prepared to discuss CAT with patients considering the treatment, including contraindications and possible complications, as well as provide excellent care and education to those patients currently undergoing the treatment. 

While traditional orthodontic treatment is delivered through examination and care provided by an orthodontist, some options are now available directly to consumers through remote supervision of the alignment process. These remotely supervised CAT systems advertise treatment times from 3 months to 12 months at a lower price point than traditional orthodontic treatment.⁴

Implementing Clear Aligner Therapy

CAT begins with impressions of teeth and gingiva to identify the malocclusions. This evaluation typically includes X-rays, photographs, fabrication of diagnostic models, and bite registrations.⁵ Once the impressions are obtained, three-dimensional (3D) imaging is used to project the desired outcome. Using the impressions as a starting point and the projected 3D images as a finishing point, aligners are designed to incrementally move the teeth to the desired location.⁵ Typical treatment lasts slightly more than 1 year, based on the complexity of the necessary tooth movement.⁶ The time frame may need to be extended if the patient does not comply with the treatment regimen. This most commonly manifests as failing to wear the appliance for the specified amount of time each day, or not moving to the next aligner at the appropriate time. Loss of appliances significantly delays treatment time.⁷ 

Jayapal et al⁸ found that adults considering orthodontic treatment chose CAT more often than traditional braces. In the meta-analysis, adults undergoing CAT reported lower levels of pain and diminished impact on quality of life than patients using traditional treatment options.⁷ 

Fabrication of Appliances

According to the American Association of Orthodontists, the process of teeth alignment must be overseen by an orthodontist. Patient visits are scheduled frequently, enabling the orthodontist to address new issues or ongoing problems.⁹

In the traditional care model, dental impressions, photographs, X-rays, and assessment of oral health, including underlying bone structure, are completed. With remotely supervised treatment options, dental impressions, photographs, and self-assessment are completed by the patient. Once diagnostic models are fabricated, whether in the orthodontic facility or by the patient at home, digital scanning is used to develop a 3D image of the teeth. Trained technicians digitally move the teeth to the desired location, which quantifies the stages of movement needed, with each aligner capable of moving the teeth from 25 mm to 33 mm. Typical treatment regimens require between six and 48 aligners.¹⁰

Regardless of the method, the orthodontist overseeing the care should be trained in CAT. When treatment is provided in an orthodontic setting, lab technicians create the devices based on the information provided by the orthodontist. With remotely supervised CAT, an orthodontist is not in charge of the care provided. 

Patient Populations

Orthodontic treatment can improve appearance, oral function, psychosocial well-being, and quality of life.⁸ The American Dental Association reports nearly 25% of adults wear braces, with the majority opting for CAT.¹¹ CAT is also popular among teenagers who are highly concerned about their appearance. Other popular features include comfortable treatment process and accessibility.¹¹ However, CAT is not appropriate for all malocclusion situations. 

Orthodontist-supervised CAT requires frequent in-office visits with a general dentist or orthodontist. This approach also is more expensive, time consuming, and requires patient compliance.^12,13 Remotely supervised CAT does not require in-office visits, and treatment is typically recommended for mild cases due to the use of virtual appointments. While remotely supervised CAT may be more convenient for patients, potential problems can arise. Remotely supervised CAT may lead to limited treatment options, outdated techniques, untailored treatment, and lack of close supervision by a licensed professional. Such lack of supervision could result in unsatisfactory outcomes and other negative oral conditions.^13,14

Contraindications to Treatment

Although originally reserved for simple malocclusion cases, CAT is expanding to more complex cases.¹⁴ Existing research, however, is minimal on the indications and limitations of CAT therapy. Contraindications typically include spacing or crowding issues greater than 5 mm and oral skeletal problems associated with occlusion, severe rotation, extrusion, and missing teeth.¹⁵ Phan and Ling¹⁶ noted that tipped teeth, short crowns, open bites, and arch issues associated with many missing teeth are difficult to treat with CAT. Additional contraindications include the lack of second molar eruption, history of periodontal diseases, presence of dental implants, and poor oral hygiene.¹⁷ 

A thorough medical history should be taken initially and at each subsequent visit. Dental questions should include those related to periodontal health; xerostomia; orthodontic treatment; earaches; neck pain; clicking, popping, and discomfort in the jaw; and serious injuries or surgeries to the head or mouth. A medical history needs to include primary physician information; presence of joint replacements or use of antiresorptive agents; allergies; any conditions affecting the nervous, respiratory, endocrine, digestive, or urinary systems; bone/​​muscle disorders; and heart/​​blood vessel disorders. 

Several medical conditions warrant further exploration prior to initiating CAT. Patients using nonsteroidal anti-inflammatory medications or aspirin may be contraindicated due to CAT’s incitement of inflammatory response. Additionally, individuals taking calcium channel blockers should avoid CAT due to the increased risk of gingival hyperemia, as well as the decrease in orthodontic tooth movement after administration of bisphosphonates. Meticulous oral care is necessary in patients with bleeding disorders, sickle cell anemia, and diabetes.¹⁸ Complications may arise in patients diagnosed with epilepsy or seizure disorders, as well as patients undergoing chemotherapy or radiation therapy. Several medical conditions are noted to increase problems with CAT, such as dry mouth, smoking, allergies, and diabetes.¹⁸ 

Individuals with trigeminal neuralgia should be closely monitored by an orthodontist during CAT as the therapy may exacerbate this condition.^19,20 As the entire periodontium, including osseous and soft tissue components, remodels with orthodontic tooth movement, the association between CAT, facial pain, and the periodontum must be well understood.²¹ 

The Role of the Dental Hygienist

Malocclusion can cause destruction to the teeth, gingiva, bone, jaw structure, and surrounding muscles. Orthodontic treatment may improve the position of the teeth and bite, making a significant difference in the overall health, stability, and longevity of the teeth and gingiva.²² 

When dental hygienists assist in treatment planning, there are two primary questions to ask:¹⁸

1. What is the patient’s main concern? 
2. Are there any medical contraindications or other factors to consider when treatment planning?

Interviewing the patient can provide crucial details about his or her status and goals. After reviewing the medical history, the dental hygienist should perform an intra- and extraoral examination, documenting findings such as occlusion, parafunctional habits, and soft tissue status.²⁰

The American Academy of Periodontology (AAP) states that dental hygienists should include occlusion in the comprehensive periodontal exam. Furthermore, the AAP notes that treatment procedures, when indicated, should include occlusal therapy that may encompass tooth movement.²² If preventive treatment, such as orthodontic appliances, is not provided to patients with malocclusion, more costly and painful dental procedures may be warranted to address symptoms.²² The primary role of the dental hygienist is to educate and advocate for patients. Dental hygienists are often the first oral health professional a patient sees and they often have more time to build a strong relationship with patients. 

If a patient has malocclusion, the dental hygienist should work with the dentist to offer solutions to correct the occlusion. Some of the most obvious indications of malocclusion are the presence of clefting, recession, and ab­fractions. Too often, toothbrush abrasion is diagnosed, although evaluation of the molar and canine relationship should be viewed first. Plaque retention and gingivitis are more common around crowded or misaligned teeth, which can lead to recession and perio­dontitis.²² 

Caring for Patients Undergoing Clear Aligner Therapy

CAT offers some advantages over traditional fixed appliances including fewer clinical emergencies and improved esthetics, comfort, oral hygiene, and periodontal health, in addition to reduced soft tissue irritation.³ Patients wearing aligners can also remove them while eating.⁵ Plaque accumulation is a concern with orthodontic devices because they interfere with oral hygiene, causing inflammation and subsequent decalcification.^5,23,24 Fixed orthodontic appliances can alter oral microbiology, while CAT has minimal effect on the growth of oral bacteria.²⁵ Patients wearing fixed orthodontic appliances may experience a shift in their subgingival bacterial profile from Gram-positive aerobic species to Gram-negative anaerobic species, which is associated with periodontitis.^21,26 An increase in plaque on the distal of the last tooth is also prevalent in those wearing fixed appliances.²⁶ Research has shown periodontal changes induced by orthodontic appliances are transient and do not result in permanent attachment loss, while other studies suggest up to 10% of past orthodontic patients have greater periodontal connective tissue attachment loss than the general population.²¹ Levrini et al²⁵ examined the plaque index, probing depths, and bleeding on probing, comparing microbiological biofilm and the presence of bacteria in those wearing fixed appliances to those undergoing CAT. A significant increase in plaque index and bleeding on probing was noted for those with fixed appliances but probing depths did not significantly change in either group. 

Daily oral hygiene procedures and products greatly impact the periodontal status of orthodontic patients.²⁷ At the initial dental visit, intensive oral hygiene instruction and monitoring and dietary education should be given to prevent and minimize damage to the periodontium. At each subsequent visit, oral hygiene and dietary education should be reinforced. The use of oral hygiene implements—such as power toothbrushes, interproximal brushes, traditional floss, water flossers, and antimicrobial mouthrinses—and routine professional prophylaxes are critical.  

If decalcification is present, remineralization agents can be prescribed for daily use to decrease caries risk, such as 0.05% sodium fluoride mouthrinse and/​or casein phosphopeptide-amorphous calcium phosphate gel. 

In general, clear aligners have less impact on daily life than fixed orthodontics.⁶ They are able to maintain the comfort level of a removable appliance while providing tooth movement as intended.²⁵ With fixed appliances, small gauge wires can slip out of their bracket slots, causing trauma to the soft tissues and possibly undesired tooth movement. The use of CAT removes this discomfort. 

Complications of Clear Aligner Therapy

Complications arising from CAT include loss of the appliance, subsequent slowing of treatment, and thus, extended treatment time.⁸ Wearing the device for the entire prescribed time (typically around 20 hours/ per day) usually prevents this loss. Other complications include altered breathing, sore throat and tongue, oral mucosa irritation, and, rarely, hypersensitivity.²⁸ Altered breathing typically diminishes as the wearer becomes accustomed to wearing the device. Sore throat and oral mucosal irritation can be minimized by adhering to hygienic practices, such as placing the device in the appropriate, clean container when removed. Hypersensitivity should be evaluated if the individual has a history of plastic allergies. 

When not monitored closely by an orthodontist, malocclusion can occur. This may happen more readily when the patient uses a remote treatment option rather than obtaining the device through a local orthodontist with regularly scheduled evaluations.²⁸

Conclusion

While results are promising, more research is needed on CAT. Understanding the history, diagnosis, traditional application, and potential complications of this technique assists dental hygienists in providing excellent patient care. 

References

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From Dimensions of Dental Hygiene. September 2021;19(9):32-35.