key: cord-0831436-czbdprz7
authors: Gou, Yongchao; Ungvijanpunya, Nicha; Chen, Liuting; Zeng, Yushan; Ye, Huayu; Cao, Li
title: Clear aligner VS fixed self-ligating appliances: Orthodontic emergency during 2020 COVID-19 pandemic
date: 2021-12-21
journal: Am J Orthod Dentofacial Orthop
DOI: 10.1016/j.ajodo.2021.12.009
sha: 2f4345bbad6fc134a955dddded3bc157bc2282c2
doc_id: 831436
cord_uid: czbdprz7

Objectives The aim was to investigate the type, incidence, and degree of the orthodontic-related emergency in orthodontic patients during the 2020 COVID-19 pandemic and compare the different effects of clear aligner and fixed self-ligating appliances on the orthodontic emergency. Materials and Methods The questionnaire was based on the emergencies in orthodontics. The responses of 428 patients between the ages of 12 and 38 years (20.4±7.03) who were in orthodontic treatment during 2020 were examined. Results The gender, age, and the type of orthodontic appliance affect the incidence of orthodontic related emergencies. Female or adolescent patients treated by self-ligating appliances showed higher incidence of emergencies. The patients treated by clear aligners exhibited much lower incidence of emergency. The appliance detachment and mucosa injury were very common in respondents, while accidental ingestion and other emergencies were rare. The most common reason leading to appliance detachment was chewing hard food. Interestingly, the fixed self-ligating appliances group were also affected by accidental detachment of appliances to a large extent. The clear aligner group and self-ligating group showed almost equal incidence of accidental ingestion. The most common foreign body was elastics in both group. However, the self-ligating group could accidentally ingest dangerous foreign bodies, such as arch wire, mini-screw and welded attachment. Conclusion Orthodontic-related emergencies were very common in patients. The clear aligner could effectively reduce orthodontic-related emergencies. Dentists should raise patients’ awareness in proper appliance care. Proper and standard protocol should be developed.

It has been reported that emergencies are common in dental practice [1] [2] [3] . Orthodontic emergency although less than other oral specialties, it should not be overlooked since more and more children, adolescents and adults seek orthodontic treatment nowadays [1, 4] . Sometimes dental practice would lead to dental emergency, prolonged courses and complicated treatment methods, not only increase the medical cost , but sometimes also lead to medical accidents and disputes. To strengthen the dental-medical safety, the design and use of effective methods to prevent dental medical mistakes should be paid attention to.

Orthodontic treatment is slightly different from the treatment of other oral diseases. Several appliances have been used in orthodontic treatment [5] [6] [7] . The types of the devices could be one of the most complex appliances among dental therapy. Orthodontic treatment usually lasts for more than 1 year and the appliances, such as appliances, wires, mini-implant, TPA, Nance palate pad and so on, are under patients' control outside the dental clinic. Oral function such as chewing, swallowing, and speech could also have unavoidable effects on the appliances which lead to damage or detachment of the appliances [8] [9] [10] .

It has been reported that a number of patients with a dental emergency increased annually [4] . The most common cause of dental emergency visits was pain due to caries; pulpitis; periapical periodontitis; and dental injury of either soft tissue such as oral mucosa or hard tissue such as primary or permanent teeth. Though it was not common for orthodontic emergency, the broken or detached orthodontic appliances or attachments could lead to severe adverse events outside the dental clinic or hospital [11] .

Orthodontic emergencies include mucosal injury due to displaced arch wire or protruded orthodontic ligation wire, accidental appliances or attachments ingestion and aspiration, discomfort due to detachment of appliances or bands, and so on [12] . Reasonable and effective decision-making was very important for the prevention, early diagnosis and appropriate treatment of foreign body inhalation and ingestion in orthodontic practice to avoid severe consequences [13] .

COVID-19 pandemic altered the visit pattern of the orthodontic patients and it could cause anxiety and tension in patients and lead to more accidents or emergencies [14] [15] [16] [17] . This study aimed to investigate the types and incidence proportion of orthodontic emergencies in orthodontic patients, based on a questionnaire administered by the patients during pandemic prevention and control period in 2020. This study also compared the different effect of clear aligner and fixed self-ligating appliance on the incidence proportion of orthodontic emergency. These results might provide orthodontists appropriate measures to reduce the probability of orthodontic emergency and also patients to avoid potential risks during orthodontic treatment.

This study was approved by the Ethics Committee of Stomatological Hospital of Chongqing Medical University. The screening questionnaire was designed based on the emergencies in orthodontics. Besides age, sex, and the types of appliances used, additional questions intended to reveal types and incidence proportion of orthodontic emergency, including bracket, band or attachment detachment, mucosa injury due to orthodontic appliances, accidental appliances or attachments ingestion or aspiration, and other orthodontic emergencies. Though data were obtained through patient self-reports, the follow-up medical records of the patients were checked to compliment the results. Recall bias was applied to evaluate the consistency of the self-report. 20 patients with fixed appliances and 20 with clear appliances were randomly selected to finish the questionnaire the second time 1 months later.

Inclusion criteria consisted of people in the orthodontic treatment without systemic diseases at orthodontic clinic of Stomatological Hospital of Chongqing Medical University during pandemic prevention and control period in 2020. In the survey, the patients and their parents or guardians were informed about the aim of the study, its privacy policy, and their right to refuse to participate. The patients were asked to complete the questionnaire based on the past 12-month situation in 2020 after giving their informed consent. The ages of respondents between were 12 and 38 years (20.4±7.03).

The associations were considered statistically significant if the p value was <0.05. The consistency of subjects' questionnaire was also analyzed. A regression model was done to compare the effect of appliance type while controlling for potential confounders as age and gender. All analyses, including descriptive analysis,  2 test were performed using the Statistical Package for Social Sciences, version 18.0 (SPSS Inc., Chicago, IL, USA).

This survey received feedback from 428 respondents, including 81 patients treated by clear aligner(CA) and 327 patients treated by fixed self-ligating appliances(FS)(as shown in table 1). In order to evaluate the consistency, 40 patients were randomly selected for a second questionnaire survey. The self-reports were consistent. The study consisted of 137 males and 291 females. Male group showed slightly higher incidence proportion of detachment appliance. However, female group showed higher incidence proportion of mucosa injury. While both group showed equally incidence proportion of accidental ingestion. The adolescents exhibited higher incidence proportion of emergency than the adults.

This study investigated the incidence proportion and degree of emergency in orthodontic patients in 2020 (as shown in table 1, linear regression analysis was shown in supplementary table 1). Orthodontic related emergencies included four categories: mucosa injury due to displaced arch wire or prolapsed orthodontic ligation wire, detached orthodontic appliances or attachments, appliances or attachments or other accidental small accessories ingestion and aspiration and other emergencies. The incidence proportion of mucosa injury in the CA group was 14.8%, and in the FS group was 57.3%. The incidence proportion of detached clear attachments in the CA group was 21%, however the incidence proportion of detached orthodontic appliance in FS group was 60.5%. The incidence proportion of accidental ingestion was 7.4% and 7.8% in the CA group and FS group respectively. There was no accidental aspiration in both groups. Other emergencies, such as the arch wire breaking, occurred in low incidence proportion, and only in the FS group. According to the above results, the incidence proportion of mucosa injury and orthodontic appliance detachment was much higher in FS group than which in CA group. Although the two groups had a lower probability of appliances or attachments or accessories accidental ingestion, the FS group was slightly higher than which in CA group.

The degree of orthodontic related emergency was also analyzed (as shown in table 2). Averagely, 0.15 times mucosa injuries occurred in the CA group and 1.45 times mucosa injuries in the FS group within one year. In the CA group, 0.37 attachments fell off, while 1.51 appliances fell off in the selfligating group within one year. The CA and FS group had the similar degree of accidental ingestion, respectively 0.14 and 0.15 foreign body. Other emergencies occurred only in the self-ligating bracket , averagely 0.02 times within one year.

The causes of detachment of attachments or appliances were divided into five categories (as shown in table 3), including chewing hard food, occlusal interference, impact of the external forces, accidental detachment and other reasons. Chewing hard food was the main reason of attachment or appliance detachment with incidence proportion of 14.81% in CA group and 48.7% in FS group. The incidence proportion of appliance detachment due to accidental detachment in FS group was 12.68%, which indicated that accidental detachment was the second important cause of appliance detachment. The incidence proportion of appliance detachment due to other reason was low.

Given to the degree of appliance detachment, chewing hard food was still the main cause of the detachment of attachments or appliances(as shown in table 4). In the CA group, 0.21 attachments fell off per person due to hard food, while 1.19 appliances fell off in the FS group due to hard food.

The position of attachments or appliance detachment was also analyzed (as shown in table 5 ). The CA group showed similar degree of detachment of attachments in the maxillary and mandibular dental arch. While the self-ligating group showed much higher detachment of appliances in the mandibular dental arch.

Linear Regression analysis was done. It was found that female patients were more likely to be uncomfortable due to mucosal injury than male patients (P=0.010*, ＜0.05), and young patients were more likely to encounter appliance detachment than older ones (P=0.000**, ＜ 0.01). (Supplementary Table 1) Since no patients had accidental aspiration, so we only show the data of accidental ingestion in table 6 and table 7 . Combined with the literature, the accidental aspiration caused by orthodontic treatment was rare. The CA group and FS group had the similar amount of accidental ingestion, which was 0.135 and 0.147 foreign body respectively. The main foreign body by mistaking ingestion in both group were elastics, which was relatively safe. The self-ligating group could ingest broken metal arch wire, mini-screw, welding accessories, although the probability was not high, but might cause more serious consequences.

Patients with CA and with FS were investigated in our study. During last year in 2020, due to COVID-19 pandemic, the interval and procedure of revisit for the orthodontic patients were slightly different from before, which might add their anxiety and lead to increased incidence proportion of the emergency [18] [19] [20] [21] [22] .

Orthodontic patients with CA were more and more because of the invisibility. Though no appliances were used in these patients, the attachments including lingual buttons, mini-implants, auxiliary arches and so on, were inevitable sometimes in order to achieve ideal treatment results [15, 23] . The CA group and FS group were found 35.80 ％ and 82.13% respectively encountering orthodontic related emergency in 2020 in our survey. It was reported the most frequent orthodontic urgencies during the COVID-19 were bracket, molar tubes, molar bands and archwire breakage [22] . While it was found besides appliance breakage, mucosa injury and accidental ingestion in orthodontic patients also need to be paid attention to in our survey.

The pain due to mucosal injury is another common dental emergency [2] . In our survey, orthodontic mucosal injury emergency was found mostly due to displaced arch wire, protruded orthodontic ligation wire, and the sharp margin of the clear aligners. In addition, orthodontic miniimplant could also cause mucosal injury related to their angle and position in oral cavity. It was also noticed that female patients were more likely to be uncomfortable due to mucosal injury than male patients. It might be related with women being more sensitive. It relied on the effective methods applied by the orthodontists to decrease mucosa injury, which included wire and clear aligner rechecking, limiting wire slip ability, adding mini-implant protective cap and so on. And female patients should be given more attention during COVID-19 to alleviate their anxiety.

Appliance detachment was more likely to arise in patients with FS than those with CA in our survey. It was the same situation for mucosa injury. It might be in connection with appliances and arch wires mostly used in fixed orthodontic treatment [24] . It was also noticed that young patients were more likely to encounter appliance detachment than older ones. It might be related with young patients' lack of resistance to food temptation, and carelessness. Mehmet AY, et al reported the incidence of bracket bonding failure was significantly higher in men than in women during COVID-19 [25] , while there was no statistically significant in detachment or accidental ingestion between male and female in our investigation. Reasons of appliance detachment were chewing hard food, occlusal interference, impact of the external forces, accidental detachment, and so on. The most common reason was chewing hard food in both CA and FS group, which could be avoided by most patients if they were instructed to change their improper chewing habits, and thus decreasing the orthodontic related emergency incidence proportion.

The incidence proportion of injury was most common in oral and maxillofacial emergency, especially soft tissue injury. Due to obvious pain, most patients with pulpitis, acute periapical periodontitis or other oral inflammation would seek medical treatment in time [3] .

Inhalation and ingestion of foreign bodies might occur in the dental treatment, including orthodontic treatment. Extracted teeth, root canal instruments, prostheses, and parts of orthodontic appliances could be inhaled and ingested by the patient. In the treatment of oral diseases, foreign body inhalation was usually much less than accidental ingestion [26] . In the orthodontic treatment, orthodontists used many small parts, which might lead to the accidental inhalation or ingestion in patient. However, accidental ingestion or inhalation in orthodontic treatment is likely to be ignored by the patients.

Orthodontic patients especially children and adolescents were at increased risk of inhaling and swallowing foreign bodies if they failed to comply with treatment and it might cause problem. For the foreign body inhalation and ingestion, it was reported more common in children than in adults [26] , while in our survey the incidence proportion of accidental ingestion was higher in adults than in Adolescent. Inhaling and swallowing foreign bodies might cause complications, especially when the foreign bodies were sharp, thin or long, such as orthodontic wire, mini-implant, TPA, etc [27] [28] [29] .

Elastics were the most of accidental ingestion in our survey. Though it might be no harm to the patients, they should be instructed to avoid the accidental elastic ingestion. Fracture of TPA, broken short arch wire, min-implant were found be accidental ingested in our survey. Though the patients were all instructed to treat the accidental ingestion in time and no complications were caused, orthodontists should be aware of the potential risk during orthodontic treatment.

It could effectively avoid the occurrence of accidental foreign body inhalation or ingestion in orthodontic treatment, through the training for skilled operation techniques [30, 31] . The use of rubber dam was the most effective prevention method in dental clinic, however, there was no suitable rubber dam available for orthodontic treatment for now. It relied not only on orthodontists but also patients to reduce accidental inhalation or ingestion, and avoid complications.

The clear aligner could effectively reduce orthodontic related emergency. Dentists should raise patients' awareness in proper appliance care. To strengthen the orthodontic medical safety and decrease the orthodontic related emergency, it should be focused on the design and use of effective methods to prevent orthodontic medical related emergency and their potential adverse consequences. Table 7 Type of appliance in accidental ingestion 

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