Orthodontic Discomfort: Clear Aligners Vs Fixed Appliances

Introduction:

With a society so fixated on social media and the latest trends, aesthetic concerns today are becoming an ever-growing concern for not just young people but adults too. An increasing number of people, when compared to a century ago, are fixated on looks, beauty and fashion. In simpler terms, the population have become infatuated by their self-image and how they are perceived to others. Not only this, but with such hectic lifestyle patients are yearning for convenience, meaning shorter appointment time, shorter treatment length and just generally the least amount of disruption to their daily lives. The orthodontic world is no different in this respect and has had to adapt, evolving from the more traditional fixed orthodontic appliances towards the more popular treatment options available today such as clear aligner therapy. A famous quote is a “business that does not grow, dies”. This applies perfectly to an orthodontic treatment point of view, the treatment choices for patients have had to progress to fit into a continuously changing environment where patients are constantly craving and demanding more and more from their clinician.

This systematic review aims to outline the advances in orthodontics in recent years, focussing on the use of clear aligner therapy. Specifically, if these aligners are in fact more pleasant to patients undergoing treatment when compared to fixed orthodontic appliances. By analysing various studies, it will become clear if patient’s quality of life during treatment is enhanced with their use and if daily life disruptions are minimised. Factors assessed include levels of discomfort, anxiety, confidence, ease of diet consumption and more. Clear aligners are excelling in popularity and becoming a first-choice treatment for patients in today’s world, so it becomes unquestionable that it is necessary to dive into the reasons if and why patient satisfaction levels seem to be increased compared to fixed appliances.

Pain findings are a common finding during any type of orthodontic treatment, there is a direct correlation between the discomfort felt and patient satisfaction. It is one of the main reasons as to why patients discontinue treatment earlier than planned; this could potentially be one of the reasons patients are attracted to clear aligner therapy, a removable appliance so patients feel more in control, as well as being advertised as more comfortable and visually pleasing. Studies have shown that 71% of study participants experience some degree of pain, regardless of the type of orthodontic appliance. Patients also reported pain as one of the main reasons for fear and anxiety before the commencement of orthodontic treatment. Various types of discomforts experienced by the patients were categorised as pressure, strain, stress, and pain. Discomfort has a negative effect on patients’ compliance, oral hygiene, and missed appointments. Its effects on patients’ daily lives are a major reason for discontinuance of orthodontic treatment.

Many adult patients seek for aesthetic appliances such as clear brackets, lingual appliances, and Invisalign. There are several advantages of using Invisalign over other appliances such as superior aesthetics, comfort, and oral hygiene. In addition to these advantages, pain is also suggested to be less compared to conventional brackets. However, there are two past studies that analysed the pain value in Invisalign patients that had contrary results compared with conventional brackets. On the other hand, difficulty in finishing and limitation in treating extraction cases have been known as the disadvantages of Invisalign treatment.

Aesthetics has been shown to be the major concern of patients who elect to undergo clear aligner therapy. Other benefits include the ability to remove the aligners to eat, the enhanced ability to brush and floss, and treatment does not involve metal components that irritate the soft tissue, as seen in fixed orthodontic appliances. The seeking of orthodontic treatment by patients aims to improve their appearance, oral function, psychosocial well-being and quality of life. However, many orthodontic appliances cause an unesthetic appearance, functional limitation, discomfort, and pain during treatment. For this reason, patients can become easily deterred from treatment options and fear the process, which can be detrimental for both their medical and mental health for many reasons.

What exactly are clear aligners and how do they work? They were originally introduced to treat minor irregularities of tooth position only, but as time has progressed so has their capabilities, they have “evolved considerably since its introduction 20 years ago” due to huge advancements in the field. Working like any other orthodontic appliance, pressure is applied that gradually moves the teeth and reshapes the supporting bone. Firstly, impressions or scans are taken, and the clinician will outline how the teeth need to be aligned, then several aligners are printed and “created using a 3-dimensional printer” to produce the clear plastic trays which will navigate the tooth movements sequentially. They are removable and can be ‘snapped’ in and out of the arches, only being taken out for the purposes of eating, drinking, and cleaning. Each aligner applies light pressure to the teeth, shifting them towards the desired position. Traditionally, manufacturing techniques rely on moulding, machining or other methods; the benefit of three-dimensional printing for aligners is that they can be printed layer by layer extremely precisely. Common materials included “acrylontirile-butadiene-styrene plastic, stereolithography materials (epoxy resins), polylactic acid, polyamide (nylon), glass-filled polyamide, photopolymers, and many more.

It is important to know that orthodontic tooth movement is dependent on coordinated tissue resorption and formation in periodontal ligament and adjacent bone. This pressure causes local hypopoxia and fluid flow, which initiates inflammatory response resulting in osteoclastic resorption in compressed areas and osteoblastic deposition in areas on tension. This in turn, prevents the tooth from becoming too loose. The fluid in the periodontal ligaments prevents the teeth from moving initially, but with continued pressure from the aligner can push the tooth. Periodontal ligament is only about 0.25mm thick, so teeth can only move small amounts at a time. After 4-6h of sustained pressure the ligaments respond to the stress by producing enzymes and chemical messengers; after a few days these are what triggers those chemicals produce stimulation of the osteoblasts and osteoclasts. If this aligner pressure stops for too long, the whole process has to restart, hence the critical importance to wear the aligner as per the given instructions, which is usually at least 22 hours per day. Especially crucial in the first few days of new trays, if the bone doesn't reshape then teeth will not remain straight, risking relapse. Once bone finishes shaping, time to progress to the next aligner, which has previously designed for the next stage of treatment. Like this any dental treatment, it is dependent and varies according to teach case, the movement rate depends on the individual. However, there is evidence that “older patients are less responsive to orthodontic force in comparison to younger patients”.

“With the recent increase in adults seeking orthodontic treatment, there has been a corresponding increase in demand for appliances that are both more aesthetic and more comfortable than conventional fixed appliances.” This increase in demand has led to the development of various clear aligner brands, with at least twenty-seven different clear aligner products currently on offer; since the introduction of Invisalign appliances in 1998 aligner therapy has rocketed and become a huge addition to the orthodontic armantarium. As mentioned previously, when putting force on a tooth, it causes pressure one side of root and tension on the other side. This results in bone disappearance on pressure side and deposition on tension side, so the tooth moves through the bone and hence into its new and preferred position. Aligners are scalloped to follow the gum margin, with intimate contact between the plastic and tooth, allowing forces to be delivered to the tooth properly and obtain the desired tooth movement. The operator will design how the teeth plan to be moved through series of steps, which will correlate to a series of differently designed aligners. CAD-CAM and 3D printing is used to construct these precise models of each of these different steps. The plastic on top of these different stages of the teeth models in order to create the aligners for each stage.

Naturally, there are both advantages and limitations to the world of clear aligners. Difficulties began to arise and clear aligners seemed to struggle with movements such as rotation and extrusion. It was hard for rounded teeth such as canines due to the challenge of creating a grip onto the tooth surface to rotate it. Similarly, teeth are slippery therefore plastic can’t get a stable and firm grip. In order to overcome this challenge, with a worry developing that ‘the expense in production, dependency on patient cooperation, and inability to treat certain malocclusions limit the usage of clear aligners”_ However, advancements allowed for the development of different attachments and auxiliaries to perform major tooth movements and treat even complex cases. The attachments are “small composite bulges designed to produce a force system”, they serve in a similar way to traditional brackets. Their tooth-colored aspect means that these aligners offer a “comfortable and aesthetic treatment experience”; not only this but it has been found that less pain is felt by the patients during the treatment when compared to fixed orthodontic appliances. Pain and discomfort in the first week of treatment has been compared to fixed appliances aesthetics, removability and small size of Invisalign aligners resulted in superior functional and psychosocial differences compared with fixed appliances, as well as significantly reduced pain. There are also “fewer clinical emergencies”, lost or damaged aligners can be replaced within two weeks usually while the patient continues wearing their previous aligner in the meantime. The shorter and less frequent visit is beneficial for the orthodontist as it causes them less stress and more patients can be seen in one day, but as well as this it is much less time-consuming and traumatic in terms of chair time for the patient which is always something that is ideal. Patients with good compliance are expected to visit the orthodontist in 10-12 week intervals in aligner therapy, while 4-6 week intervals are unavoidable when treating with fixed appliances, and the chair time in the clear aligner community is greatly reduced, allowing the clinician to see more patients.

In non-extraction patients, “total treatment time was found to be 67% lesser in the Invisalign group” compared to conventional fixed appliances, highlighting the extent to which treatment time can be reduced with more advanced treatment options.

Clear aligner therapy allows for greater oral hygiene to be maintained than traditional fixed appliances, and so they are recommended for treatment planning in cases with risk of periodontitis; “use of clear aligners facilitates oral hygiene, thus improving the periodontal status and causing a decrease in plaque levels, gingival inflammation, bleeding upon probing, and pocket depth.”

Plaque prevention was difficult with fixed appliances, and they had negative effects on periodontal tissues, rendering orthodontic treatment a risk factor for periodontal disease.

Over a 12-month study period, aligner therapy was found to be associated with increased personal status and decreased levels of periodontopathic bacteria when compared with treatment by fixed buccal orthodontic appliances.

There are two-three key limitations in association with clear aligner therapy, it is a complex treatment option meaning that a skilled and experienced clinician is required, with detailed planning needed beforehand. The cost of the treatment, therefore, is greater than traditional fixed appliances making them only a treatment choice for certain patients who are willing to pay this extra. A common disadvantage for any removable appliance is that treatment success is highly based on patient compliance, meaning motivated patients who are understanding of the treatment requirements make viable potential patients._ When weighing up the benefits and limitations of clear aligner therapy it seems that most patients experience few limitations in their daily lives, and with the ever-growing research within orthodontics, most drawbacks of clear aligner therapy are becoming overcome, with it being a “viable alternative” and suggesting that “today, practically any malocclusion can be successfully treated”.

Fixed appliances have been around for over a hundred years and over the years they’ve developed massively. The main components of these being bands, bonds, orthodontic adhesives, auxiliaries and archwires. Bands: rings encircling the teeth to which buccal or lingual attachments can be placed; bonds: brackets that are bonded to the teeth, the base has a mesh into which composite can flow and they’re also available in ceramic for heightened aesthetics; orthodontic adhesives: different types of adhesive are available including glass ionomer and composite, they may be light cured or self-curing, recently the need for acid etching has been reduced by the availability of self-etching primers; auxiliaries: there are a variety of these available, rubber modules or metal ligatures to secure the arch wire into the slot, intra oral elastics are available for traction, palatal arches can be used for anchorage reinforcement as well as springs for space opening or closure; arch wires: in the initial stages a very flexible wire with a good resistance to permanent deformation is required for example round nickel-titanium, later into treatment a more rigid wire is required to engage the arch wire slot fully and provide dine control and this would normally be a stainless steel wire, other wires are also available with different characteristics for fine detailing. Due to the fact that the fixed appliance is attached to the tooth via the bracket, the tooth can be moved vertically, tilted, rotated or have its tip and torque altered. Each bracket is a different width corresponding to the specific tooth its attached to, therefore smaller teeth can have narrower brackets, thus increasing the inter bracket distance which allows the archwire to be more flexible.

There are numerous indications for the use of fixed appliances, including correction of mild to moderate skeletal discrepancies, intrusion or extrusion of teeth, correction of rotations, overbite reduction, multiple tooth movements required in one arch, active space closure. Apart from the obvious fact that fixed appliances carry a much less aesthetic attraction for patients, they do carry potential risk in damaging hard and soft tissues. Enamel demineralisation can occur as a result from poor oral hygiene and poor diet, enamel trauma can arise from careless use of a band sealer or when debonding at the end of treatment. Enamel wear is a possibility from tooth-hitting metal or ceramic brackets. Another risk is pulpal reaction, this is usually a transient process. Numerous causes of root resorption have been advocated, the main ones being the use of heavy forces and moving teeth through large distances on rectangular wires. Although most patients experience some gingival reaction during treatment, its vital that oral hygiene is good prior to the start of treatment, in order to avoid more periodontal tissue complications which can easily occur. In rare cases patients have displayed allergies for example to the nickel used. Finally, trauma to the soft tissues from the different components of the appliance is a common finding for patients.

Objectives:

The main objective of this systematic review is to outline the key components as to how clear aligner therapy differs from that of traditional orthodontic fixed appliances, emphasising their features and characteristics; highlighting the reasons they are becoming ever-more popular for patients. The key focus was not their efficacy, but their satisfaction level for the patient during treatment. Therefore, the secondary objective in this research was to evaluate patient’s daily quality of life during these treatment options, with emphasis on comfort level, ease of oral hygiene maintenance and diet alterations needed, treatment time including chair time, and level of social anxiety which is affected by factors such as speech alterations and aesthetics of the appliances.

• Primary objective- to establish if clear aligner therapy is more pleasant for patients than fixed orthodontic appliances, resulting in greater patient satisfaction.
• Secondary objectives- to analyse and compare patient experience of clear aligner therapy versus fixed orthodontic appliances based on features such as:

1. Pain/discomfort intensity
2. Oral hygiene maintenance, e.g. ease of cleaning dentition and appliance
3. Overall treatment time, also including chair time
4. Quality of life and daily interferences, e.g. effects on eating, speaking, sleeping

Materials and Methods:

This bibliographic search was conducted following PRISMA (Preferred Reporting Items for Systemic Reviews and Meta-Analyses guidelines for systemic reviews and meta-analyses. The review also fulfilled the PRISMA 2020 Checklist.

The PICO (population, intervention, comparison, outcome) question was: ‘Are clear aligners more pleasant for the patient than fixed orthodontic appliances during treatment?’ with the following components: population: ????; intervention: ????; comparison: ????; outcome: ???.

An extensive electronic search was conducted using the MEDLINE/PubMed advanced database. Firstly, the search included identifying the main medical subject heading (MeSH) terms which included ‘orthodontics’ and ‘aligners’, along with their synonyms such as ‘dentistry’; ‘Invisalign’; ‘clear aligners’; ‘plastic aligners’. These medical terms were then used alongside various other terms in several searches to access the relevant articles needed. These terms were: ‘pain’; ‘patient satisfaction’; ‘anxiety’; ‘treatment time’; ‘anxiety’; ‘aesthetics’; ‘oral health’. Again, synonyms of the above terms were supplemented to include all relevant articles. The Boolean operators used were (‘AND’ and ‘OR’), the use of (‘NOT’) presented itself as unnecessary hence was not included. The search terms were constructed as follows:

[(‘orthodontics’) OR (‘dentistry’)] AND [(‘aligners’) OR (‘clear aligners’) OR (‘plastic aligners’) OR (‘Invisalign’)] AND [(‘pain’) OR (‘discomfort’)].

[(‘orthodontics’) OR (‘dentistry’)] AND [(‘aligners’) OR (‘clear aligners’) OR (‘plastic aligners’) OR (‘Invisalign’)] AND [(‘patient satisfaction’) OR (‘patient review’) OR (‘patient opinion’)].

[(‘orthodontics’) OR (‘dentistry’)] AND [(‘aligners’) OR (‘clear aligners’) OR (‘plastic aligners’) OR (‘Invisalign’)] AND [(‘social anxiety’) OR (‘anxiety’)].

[(‘orthodontics’) OR (‘dentistry’)] AND [(‘aligners’) OR (‘clear aligners’) OR (‘plastic aligners’) OR (‘Invisalign’)] AND [(‘time’) OR (‘treatment time’) OR (‘chair time’)].

[(‘orthodontics’) OR (‘dentistry’)] AND [(‘aligners’) OR (‘clear aligners’) OR (‘plastic aligners’) OR (‘Invisalign’)] AND [(‘aesthetics’) OR (‘confidence’)].

[(‘orthodontics’) OR (‘dentistry’)] AND [(‘aligners’) OR (‘clear aligners’) OR (‘plastic aligners’) OR (‘Invisalign’)] AND [(‘oral health’) OR (‘hygiene’) OR (‘cleaning’)].

In order to refine the search to the relevant articles even further, filters were applied to achieve inclusion and exclusion criteria. The inclusion criteria: studies including the full texts, articles between 2011-2021 within the last 10 years; English language filter; patients treated with either clear aligners and/or fixed orthodontic appliances; above the age of 13, patients of sound mental and physical capacity; no filter was put on the type of study so a range of information could be sought. Exclusion criteria: abstract-only texts; studies more than 10 years old; duplicates; studies of patients below the age of 13; patients of any form of disability; articles not in English; articles which did not discuss some form of patient experience during the treatment process.

Results

An in-depth analysis of 11 studies were cross-compared and assessed, according to numerous factors in which orthodontic patients base their levels of satisfaction on. This includes aesthetics, pain, treatment time, alterations to daily life such as dietary changes and psychological factors that come alongside these aspects. Six of the examined studies suggest that CAT offers a lower level of pain and discomfort; one article stated that there was not a significant difference of pain levels between FOA and CAT; whilst two articles highlighted that although CAT may not be more pleasant as much, it seems to be better tolerated by patients. The other studies made no reference to discomfort levels. In terms of aesthetics, which impacts confidence and levels of patient anxiety throughout treatment, four of the articles concluded that CAT is far more pleasant than traditional buccal fixed appliances, although it is important to note than CAT matched similarly when compared to lingual brackets, and in some cases lingual brackets seeming more aesthetic to patients and being less noticeable to the eye. However, one article discusses the fact that speech is initially more impaired in CAT which can be important for affecting a patient’s level of satisfaction. When evaluating quality of life and disruption of daily life, four articles demonstrate that FOA have an increased affect, causing modifications in activities such as eating and cleaning. An article also demonstrated how appointment time and treatment time is much greater when fitted with FOA which is of course a concern for patient.

A systemic review carried out by Cardoso et al evaluated the pain level between clear aligners and fixed appliances, with a mean age raging between 23.56 and 28.6 for its control group (group with fixed appliances). Invisalign was the chosen clear aligner, whilst a range of fixed oral appliances were included. Using a visual analogue scale, questionnaire or both pain was assessed at various time intervals. Four of these included articles reported higher pain levels for fixed appliances 24h after beginning treatment. However only one investigation found a statistically significant difference. Two other studies only reported a difference on day 3 and 4; Both studies reported that pain levels were higher in the group treated with fixed appliances. During days 5-7 only one study observed a significantly higher level of pain in the patients with fixed appliances, but the highest level of pain was on the third day. Two studies evaluated pain on day 14 and reported no significant differences between groups. Only one study performed this evaluation 2 months after starting treatment, and significant differences were found only on day 1 and 2, with higher levels of pain in control groups. Another study also agreed that fixed appliances presented higher levels of pain when compared to Invisalign group. One conflicting paper reported higher pain level for aligner group for all evaluation times, however no statistically significant difference was found for any time point. Five studies documented the use of analgesics, of which three studies found statistical differences in time points for 4h, 24h, and day 2, and day 3, and in all these cases patients treated with fixed appliances reported a higher analgesic consumption. One study also assessed quality of life and patient satisfaction during orthodontic treatment, finding a statistical difference only in the evaluation of chewing and eating, where Invisalign group presented a better response than the control group (47% and 24% respectively). Soft tissue irritation was reported to be lower in the Invisalign group in two studies as well as the testing related to eating disorders.

By doing a prospective clinical study of 120 patients to compare pain and its relationship with the oral quality of life of patients with different types of orthodontic appliances, Antonio-zancajo et al tested pain at 4h, 8h, 24h and at 2, 3, 4 ,5, 6, and 7 days after treatment. The appliances used as comparison included conventional and conventional low-friction brackets, lingual brackets, and aligners. Patients ranged between 18-40 years of age and were made sure to not have severe malformations or be taking medication that affects pain perception. Maximum pain was observed at 24-48h after treatment began, with the lingual bracket group presenting the lowest levels of pain at all times analysed which indicates a lower impact on quality of life for this type of appliance. Aligner group showed similar results at lingual, with both being far more tolerated than conventional brackets. Statistically significant differences in the pain level were found 4h after treatment according to visual analogue scale (VAS). The group with the most pain at this time point was the conventional bracket group, with similar results to the Invisalign group, and the lingual group displayed the least pain next to the low friction group.

After 48h, a higher level of pain was observed in low friction patients, without differences in the conventional group, while those with lingual brackets continued to show the lowest level of pain. This trend continued for one week. 24h and 7 days after treatment, differences were found, with low friction bracket group presenting highest level of pain, and lingual least pain. However, after 8h of treatment starting, there was greater pain in conventional group and less in lingual group.

Maximum discomfort was reached 24h after start of treatment in conventional, lingual and Invisalign groups and at 48h in low friction; beyond this point the pain decreased slowly. Greater negative impact on pain levels and physical disability could be observed in the conventional group, with lingual having smallest impact on pain, and Invisalign having lowest effect on physical disability. Psychological discomfort, psychological disability and social disability were seen to be lower in both Invisalign and lingual.

Fujiyama et al evaluates and compares the difference in level of pain using VAS between the fixed edgewise appliance and the clear aligner Invisalign. The main cause of Invisalign pain subject to patients was also found. The VAS scores were taken at stages, Stage 1: 0-7 days, stage 2: 14-21 days, stage 3: 28-35 days and then at the end of treatment. Significantly higher VAS scores were noticed in the edgewise group rather than the Invisalign group in terms of pain intensity level, number of days that pain lasted for and discomfort level. Most causes of problems in Invisalign cases were from deformation of tray.

When comparing pain perception between patients with passive self-ligating fixed appliances to Invisalign, the Almasoud et al prospective study investigated 64 patients, half with Invisalign and half with the fixed appliance. Immediately after fitting, pain perception was evaluated through close-ended and coded self-administrated questionnaire using a VAS. Responses were then recorded at 4h, 24h and at days 3 and 7. A lower percentage of patients treated with Invisalign aligners reported pain, results were statistically significant in this respect. The mean VAS score was significantly lower in Invisalign group during the first week and the Intensity of pain with both peaked around 24h and then dropped to the lowest value on day 7. Fewer participants with Invisalign aligners used analgesics at 4h and 24h; no participant treated with aligners reported taking analgesics on day 7. Compared to 28 (84.85%) participants treated with fixed appliances, only 5 (15.1%) treated with Invisalign took analgesics.

Noll et al executed a large-scale twitter sentiment analysis to gather information about patient experience with braces versus Invisalign. Custom data collection programme was created that collected tweets containing the keywords ‘braces’ or ‘Invisalign’ for 5 months. A sentiment analysis classifier was then developed to sort tweets into 5 categories: positive, negative, neutral, advertisement, or not applicable. 419,363 tweets applicable for orthodontics were collected. In general, regardless of appliance type, users posted significantly more positive tweets (61%) than negative (39%). No significant difference between positive and negative sentiment between Invisalign and braces was determined and so no correlation between patient satisfaction and use of Invisalign rather than traditional braces was found. Instead, tweets on gratitude for great new and improved smile, while negative tweets did still frequently focus on pain being the leading issue.

Whilst evaluating differences in the discomfort level between clear aligners and fixed appliances, White et al conducted a randomized prospective trial on 41 adult class I participants; half aligner and half Invisalign. Patients completed daily discomfort diaries following initial treatment appointment, and after 1 and 2 months. They recorded levels of discomfort at rest, while chewing, while biting, as well as analgesic consumption and sleep disturbances. Both treatment modalities demonstrated similar levels of initial discomfort.

The fixed appliance group reported significantly greater discomfort than patients in the aligner group during the first week of active treatment; with significantly more discomfort while chewing was found than at rest. Traditional patients also felt more discomfort than aligner participants after the first and second monthly adjustment appointments. A greater percentage of patients in FOA group reported taking analgesics during the first week for dental pain, but only the difference on day 2 was statistically significant. Immediately following traditional placement, the group reported low levels of discomfort. They then showed significant increases in discomfort (300-500%) that peaked between the first and third day, most discomfort was established when chewing and biting with the anterior teeth. Following the peak there was gradual reduction in discomfort over next 4-5 days, ending at levels similar to or slightly above those reported at baseline. Aligners produce a similar pattern, initially patients report low levels of discomfort, followed by slight increases (50-100%), peaking after first or second day. This then decreases slowly over the rest of first week, by day 7 aligner group experienced minimal discomfort, consistently less than baseline. Between day 1 and 7 the FOA group consistently demonstrated greater discomfort, discomfort was significantly higher statistically after 2-3 days. Approximately 45% of patients in the FOA group took medication during the first 2 days, with numbers decreasing thereafter. The percentage of aligner patients taking medication increased by 11% during the first day and then decreased. While the percentages of patients taking medication was consistently greater in FOA, only the 50% difference on day 2 was statistically significant.

A cross-sectional study by Azaripour et al compared 100 patients, 50 fitted with a FOA and the other 50 fitted with Invisalign for more than 6 months. Clinical examinations were made to evaluate periodontal condition throughout the two groups. Oral hygiene, patient’s satisfaction and dietary habits were documented by a detailed questionnaire. It was discovered that significantly better gingival health conditions can be seen in Invisalign patients with greater patient satisfaction being reported in the Invisalign group. All patients participating in the clinical exam were questioned about their overall well-being, whether they would be willing to undergo the same treatment again, oral hygiene habits, food choices, and the frequency and method of toothbrushing using a specially designed QoL questionnaire. More FOA patients reported to suffer from laughing inhibition because of their aesthetic concerns, which suggests some level of patient anxiety and a lack of confidence whilst undergoing the appliance. 98% of Invisalign patients would be willing to undergo the same treatment again, with a lower 78% of FOA suggesting the same. 70% of FOA group reported that their daily eating habits had to change during orthodontic treatment, compared to 50% in Invisalign group. FOA also stated that they were required to brush their teeth more frequently than before treatment and reported more gingival irritation (56% vs 14%). FOA group participants spent 3.7 - 1.7 minutes on average as tooth brushing time, whereas Invisalign reported to brush teeth on average during 2.2 - 1.2 minutes, thus further heightening the idea that Invisalign offers less disruption to the regular daily lives of patients.

When testing the overall hypothesis that CAT is more pleasant for patients than FOA, Alajmi et al conducted an observational retrospective study of 60 patients, 30 participants per appliance. Patients with aligners reported significantly more difficulty in speech, necessitating change in their speech delivery. However, these same patients reported better chewing abilities, no restrictions on amounts or types of food, and less mucosal ulcerations. Whereas the participants with FOA demonstrated restriction in amount or type of food they were comfortable consuming and more limitation in chewing. Nevertheless, effects on daily routine, use of analgesics, and overall treatment satisfaction were not seen to be significantly different.

CAT was said to not necessarily be more pleasant but was said to be more tolerable as it satisfies patients’ needs over food consumption and absence of mucosal ulcerations. However, CAT alters pronunciation and speech delivery in the short term which was a concerning factor for the group. In terms of oral symptoms assessed, there was no significant difference between other symptoms like halitosis, bleeding, swelling, bruising or difficulty opening mouth.

With the treatment satisfaction, Invisalign reported more satisfaction with appearance of appliance, but both groups would recommend their respective treatments to others. Invisalign produces a pressure-like pain while FOA exhibits sharp or throbbing pain plus ulcerations. FOA group consumed a slightly higher proportion analgesics, however not significant statistically.

Buschang et al measures the time efficiency of aligner therapy and conventional edgewise braces. 150 FOA and 150 aligner participants with mild to moderate class I malocclusions were used. Prospective portion of study timed the various types of appointments for both treatments using a stopwatch; FOA required significantly more visits, a longer treatment duration of 5.5 months, more emergency visits, a greater emergency chair time of 7 minutes, and a greater total chair time of 93.4 minutes. Although despite this, the aligners drawback is that they showed statistically greater total materials costs and required more total doctor time than the FOA. Invisalign treatment duration was 67% shorter than FOA; aligner patients were treated for only 11.5 months, compared to the FOA group who required 17 months of treatment.

When analysing a study based on aesthetic factors of orthodontic appliances, Fo Moritz et al offered an interesting cross-sectional study which used eye tracking. The investigation evaluated the perception of aesthetic orthodontic appliances by means of eye tracking measurements and survey investigation. En face and images with different appliances showed to 140 participants, eye movement and gaze direction were recorded by an eye tracking system. For different anatomical areas and areas of appliance, the time taken to first fixation and total fixation time recorded. Questions included in a VAS regarding individual sentiency were answered by participants. Risk for fixation on area of interest in close up images was lowest with lingual appliances, followed by aligners and the aligner attachments, and highest with the ceramic brackets. The regression analysis showed these differences to be significant with 94% lower risk of fixation on area of interest in the 7 second timeframe with lingual appliance when compared with aligner, 88% lower when compared with aligner and attachments, and 82% lower when compared with ceramic appliance. In the en face images, the risk for fixation on the mouth was also lowest for lingual appliance, and higher in ceramic and aligner. The risk for fixation on the mouth was 18% lower with lingual appliance than aligner and attachments, however Invisalign risk for fixation was still undoubtedly lower when compared alongside traditional ceramic buccal FOA.

Lin et al assesses impact of wearing fixed orthodontic appliance versus clear aligners on daily performance in adult patients. 152 adults aged 25-35 were evaluated at baseline, 6 months after bonding and 12 months after bonding. Participants randomly assigned to either CA or FOA. Significant changes in OIDP (oral impacts on daily performance) total and subscale scores can be observed while wearing FOA. OIDP total score and subscale scores of eating, cleaning teeth, smiling and social relation were significantly higher than at baseline. However, only OIDP total score was significantly increased at 6 months compared to baseline in CA group. OIDP total score and subscale scores of eating, cleaning teeth, smiling and social relation were significantly higher in patients with FOA.

CA patients have fewer impact on daily life and no significant changes in OIDP subscale scores at 12 months.

Discussion

One of the most notable and immediate response to any type of orthodontic treatment for a patient is the level of discomfort to which they feel promply after a new appliance is fitted and over the duration of the treatment. Daily life and quality of life is hugely based on this; therefore, several studies address and test these pain statuses. Naturally, the depth of pain felt per patient differs since it is a subjective factor; different cases will also, of course, have greater forces applied to the dentition. There are controversial findings regarding pain level between aligners and fixed appliances; under the same trigger conditions patient’s response differently to pain, and it is linked to several features such as age, sex, individual pain threshold and more.

Nevertheless, through various studies and cross-comparison an analysis can be made as to which appliance causes more discomfort in general.

CARDOSO:

The majority of patients are aware that it is a common finding to experience some level of pain and discomfort during the treatment with fixed orthodontic appliances, reaching its peak twenty-four hours after insertion and diminishing almost completely after one week. Although, this is dependent on the type of fixed appliance and can vary slightly. As with removable appliances such as clear aligner therapy, they allow the tissues to reorganise prior to application of compressive forces; hence they produce intermittent forces. Similar findings were found when comparing quality of life between those treated with aligners and fixed appliances, however differences were found during eating and chewing where the aligner patients presented a higher quality of life. ’91-95% of patients experience some level of pain at different stages of treatment’, with studies finding that ‘8% to 30% of patients discontinue orthodontic treatment’ within the early stages. Multiple studies are in agreement with the notion than pain is more intense within the first 3 days and then decreases or even disappears after one week. This pattern is due to initial orthodontic forces that result in discomfort because of compression of the periodontal ligament, leading to ischemia, oedema, and release of inflammatory mediators during the first 24-48h. These mediators, such as prostaglandins and interleukins, sensitise nociceptors of the periodontal ligament which causes greater discomfort; the levels of these mediators within the gingival crevicular fluid peak 24h after the onset of orthodontic force and then return to their original values after approximately 7 days hence this pattern in patient pain can be observed. Pain perception is due to a change in the blood flow once an appliance has been fitted, and analgesic use can reduce the inflammatory process and therefore reduce pain levels for patients; FOA groups generally had a higher intake of medication usage than Invisalign groups in order to mask their greater levels of discomfort. It is crucial to recognise than pain can affect a patient’s quality of life, which can lead to oral hygiene affects and even have a psychosocial impact, affecting patient’s mental health and their rapport with the dental or medical field.

As stated previously, pain is a subjective process and is influenced by various factors such as a patient’s individual personality. It is apparent that patients who have some knowledge regarding orthodontic treatment have a more positive treatment experience and present lower pain levels, therefore it is important for practitioners to fully educate and inform patients on potential discomfort that could occur and advice on how to manage it. FOA activation appointments usually occur once a month, whilst the clear aligners are changed every 15 days more or less, so it can be assumed patients with aligners feel less pain at each activation, however the discomfort is felt for a longer time period throughout the course of the treatment. Throughout the studies the consensus is that FOA are more painful at the beginning of treatment, but both FOA and CA reduce hugely over time especially after the one-week mark.

Undoubtedly, the types of archwires in the FOA are an influencing factor because of their difference in mechanical properties however what bares more relevance is that Invisalign is a removable appliance. This means that less tension, pressure, sensitivity and pain is produced than fixed appliances. FOA are subject to continuous force, whereas Invisalign is an intermittent force; they can be removed for pain relief directly by the patient.

ALMASOUD:

‘Invisalign aligners offer enhanced aesthetics, reduced pain, and improved oral hygiene during orthodontic treatment.’

A lower proportion of patients treated with Invisalign reported pain than passive self-ligating fixed appliances. Using a VAS scale, pain intensity was also higher for the fixed appliance group, with the use of analgesics being greater in the FOA patients. In both groups the discomfort levels declined during the first week of treatment. More patients treated with passive self-ligating fixed appliances consumed analgesics than those treated with aligners by a significant amount, thus confirming the idea that pain intensity is higher in the fixed appliance group. After day 7. Zero patients in the Invisalign group took analgesics on day 7 of treatment which correlates to Cardoso study. 67% of patients treated with fixed appliances took analgesics, compared to 42% in the aligner group.

FUJIYAMA:

The most negative concerns for orthodontic treatment are discomfort and pain, pain adversely affects the quality of life of a patient. The greatest measure of pain during orthodontic treatment occurs 24h after the appliance is fitted, with it decreasing to near-baseline level after 7 days. Pain level is significantly higher in fixed appliances than removable appliances; greater values of intensities of pressure, tension, pain, and sensitivity of the teeth were reported in patients treated with fixed appliances in contrast to those wearing functional appliances. A greater discomfort level may be observed in fixed appliances than with removable appliances in general. Within this study, pain disappeared 5 days after appliance application in the Invisalign group, but not until 6 days after application in the edgewise group. This study is unique because one group of participants experienced both the fixed edgewise appliance as well as the Invisalign appliance afterwards; these participants who experienced both prefer Invisalign treatment from a pain and discomfort angle. However, these patients experienced the edgewise prior to the fitting of Invisalign, and so the pain from Invisalign may have been somewhat masked by the previous edgewise discomfort felt initially. To combat this some patients should receive both Invisalign and edgewise appliances but in the opposite order, receiving edgewise after Invisalign completes the initial misalignment.

WHITE

Pain patterns associated with traditional fixed appliances have been well established, peaking approximately 24 hours after the initiation of treatment, and decreasing thereafter until reaching baseline levels after one week. This correlates to the acute inflammatory response and is seen in various of the studies being investigated. Traditional braces were shown to initially be 25% more painful during the first week when compared to Invisalign. As seen in XXX study, the gradual reduction in pain seen over the first week may be as a result of the decrease of inflammatory mediators in the compressed PDL. An influencing factor to consider in the discomfort of the traditional braces is the type of arch wire used. Participants from the traditional FOA group expressed that their peak discomfort was approximately 33% of their worst imaginable discomfort. This figure was 29% for super elastic NiTi wires and 42% for nitinol arch wires. Nitinol wires produce a greater intensity of discomfort than super elastic NiTi arch wires because they cause a larger amount of initial force, approximately 180g rather than 47g respectively under the same conditions. Discomfort observed been day 2 and 7 was noticeably higher in the traditional group, however aligners may be more comfortable solely due to the fact they are a removable appliance which are usually more tolerated by patients since they produce intermittent forces as appose to continuous. This allows the tissues to reorganise before compressive forces are reapplied. As seen in another study (name study), aligners are also more pleasant.