# Oral Impacts of Aligners versus Fixed Self-Ligating Lingual Orthodontic Appliances
## 4 Discussion  
This prospective study investigated the oral impacts of aligners vs. SLLA, as experienced by the patients, as well as the speech disturbances, evaluated by professionals, during the first 3 months of orthodontic treatment. The present study may assist patients and clinicians in choosing the most appropriate treatment modality in relation to HRQoL and speech parameters. The sample was homogenous, with similar demographic and cephalometric data, as well as orthodontic treatment needs. Thus, the possible tongue restrictions from the lingual appliances due to differences in SNA and SNB angles could be excluded [27]. Most publications evaluating aligners report on mild/moderate cases; however, most patients of the present sample were in moderate/great need of orthodontic treatment (Table 3). Minor differences between sexes were evident in the initial cephalometric measurements, i.e., male patients had higher Z-angle values, as expected due to chin prominence (sexual dimorphism). Non-growing patients were chosen for the study because they represent the majority of patients currently receiving aligner or lingual treatment worldwide [28]. In addition, they may provide better compliance in appliance wear, further reducing possible bias due to incompliance. Six patients reported sleep disorders at T0; however, it is already known that anxious individuals prefer \"invisible\" orthodontic appliances [29]. Pain levels and the consumption of analgesics were similar between the two groups. The use of analgesics was more frequent at the beginning of the treatment (10% of each group took analgesics at day 1). At T3, only one patient took analgesics in each group (in the aligner group, this was the patient with the least adherence to wearing the aligners). A more pronounced decrease in pain perception was evident in the aligner group between T1 and T3, i.e., in the aligner group, the reduction in pain was faster compared to the group with lingual appliances, in which the pain remained at moderate levels, even 3 months later. However, this finding did not reach statistical significance (Figure 3a). [PERSON] et al. did not find any significant differences in pain levels or the intake of analgesics among patients treated with lingual or labial appliances for a period of three months [30]. However, a recent prospective study with a shorter observation period (2 weeks) demonstrated that lingual appliances were associated with more severe pain, greater analgesic consumption, and the most difficult and longest recovery, in comparison with labial appliances or aligners [17]. Furthermore, a recent systematic review concluded that the level of pain was significantly higher, during the first two weeks of treatment, in patients treated with lingual braces compared to patients with buccal brackets [31]. This difference may be explained by the fact that the archive-bracket type combination in this study was 0.014-inch NiTi in Incognito brackets [17], whereas in our study, a 0.012-inch NiTi wire was used in a self-ligating bracket throughout the observation period. Additionally, patients treated  
Figure 7: Speech articulation. with labial self-ligating appliances exhibited lower visual analog scale scores than subjects treated using conventional labial appliances [32; 33]. It should also be considered that pain during orthodontic treatment is associated with several factors such as the patient's age, individual psychological susceptibility, personal expectation of treatment outcome and the duration of orthodontic treatment, with subjects under orthodontic treatment for a longer time being more intolerant and with higher expectations of completing the treatment [17; 34]. Patients well-informed about the discomfort that may occur during orthodontic treatment and patients who have more positive attitudes present lower levels of pain during treatment [24; 35].