Translate this page into:
Influence of anxiety levels on pain perception during orthodontic Copper–Nickel–Titanium archwire changes at different time intervals: A randomized clinical trial
, Eloísa Peixoto Soares Ueno1, José Rino Neto1, João Batista de Paiva1
*Corresponding author: Tereza Cristina Holtz Schuch, Department of Orthodontics, Faculty of Dentistry of the University of São Paulo, São Paulo, Brazil. crisholtz@gmail.com
-
Received: ,
Accepted: ,
How to cite this article: Schuch TH, Cruz MH, Ueno EP, Neto JR, Paiva JB. Influence of anxiety levels on pain perception during orthodontic Copper–Nickel–Titanium archwire changes at different time intervals: A randomized clinical trial. J Adv Dental Pract Res. 2026;5:30-6. doi: 10.25259/JADPR_41_2025
Abstract
Objectives:
To evaluate the intensity and duration of painful symptoms reported during the Copper–Nickel–Titanium (NiTi) archwire changes and the influence of anxiety levels on pain perception.
Material and Methods:
Forty-five patients treated with fixed appliances and the same sequence of leveling archwires were divided into 3 groups with different time spans for archwire changes stipulated at 28, 56, and 84 days. They received a visual analog scale (VAS) at different times: T0, before the procedure; T1, immediately after the procedure; T2, 8h after the procedure; T3 24 h after the procedure; and every 24 h daily from T4 to T9 for each archwire change. A dental anxiety scale was presented at T0. Data were compared using t-tests.
Results:
The highest values were reported at T3 (3.01 ± 2.58), T2 (2.65 ± 2.40), T2 (3.01 ± 2.69) and T2 (1.77 ± 1.66), in the 4-week Group, T3 (4.61 ± 3.06), T2 (2.55 ± 1.83), T2 (3.46 ± 2.89) and T2 (2.20 ± 2.17) in the 8-week Group, and, T3 (4.74 ± 2.65), T2 (3.04 ± 2.23), T2 (4.01 ± 2.57), and T3 (2.51 ± 2.29) in the 12-week Group. 17 patients were classified as having low anxiety and 25 as moderate anxiety.
Conclusion:
Pain perception initiates shortly after archwire insertion and peaks within 24 h across all protocols, with the 0.014” Copper-NiTi wire eliciting the highest intensity. Furthermore, higher anxiety levels are associated with increased pain perception over prolonged archwire replacement intervals.
Keywords
Dental anxiety
Fixed orthodontic appliances
Pain perception
Pain threshold
Visual analog scale
INTRODUCTION
Orthodontics is in a continuous process of renewal and adaptation to new technological resources and techniques. The objective of these innovations is to make orthodontic therapy faster, more comfortable, and more efficient.
Despite these advantages, painful symptoms during orthodontic treatment remain undesirable yet often inevitable adverse reactions. Identifying factors that influence pain has garnered significant interest within the orthodontic profession, as minimizing patient discomfort is crucial for maintaining cooperation, preventing missed appointments, and avoiding treatment interruptions that could compromise outcomes.[1] Studies indicate that 70–95% of patients undergoing orthodontic treatment experience some degree of pain.[2]
Nickel–titanium (NiTi) alloys have been widely used in orthodontics, especially at the beginning of the treatment. This is largely owing to their mechanical properties, including biocompatibility, ductility, corrosion resistance, low modulus of elasticity, superelasticity, and shape memory effect.[3]
Superelasticity is the ability of the NiTi alloy to deflect upon loading without plastic deformation and return to its preformed shape after unloading. The alloy can be deformed by up to 8% strain, making it useful for treating severely misaligned teeth.[3,4]
There is a growing technological search for accelerated orthodontic movement and, consequently, reduced treatment time. Although not supported by the literature,[5] passive self-ligating brackets have emerged as a proposal to generate increased treatment efficiency using light force and, consequently, provide greater patient comfort.[6] Owing to the great variability in individual responses to orthodontic pain, some researchers[7] have looked for factors that can be associated with this response, such as age, sex, culture, type of appliance, shape, and structure of the wire, and irregularities in tooth position. However, few studies have been conducted on the perception of pain in patients using this system.
This study aimed to evaluate the intensity and duration of painful symptoms reported by patients during the archwire exchange sequence in the alignment phase of orthodontic treatment. In addition, the study sought to evaluate the influence of anxiety levels on pain perception.
MATERIAL AND METHODS
Ethics
The study was conducted under the resolution 466/2012 of the National Health Council and was approved by the Research Ethics Committee of the Faculty of Dentistry of the University of São Paulo under opinion N°3.612.566/CAAE:19239719.4.0000.0075.
Trial design
This prospective controlled clinical trial was designed and reported following the CONSORT 2010 Statement guidelines. A parallel-group design with a 1:1:1 allocation ratio was adopted to evaluate the three different time spans for archwire changes. The treatments were administered by postgraduate students specializing in orthodontics, and all patients provided written informed consent. All clinical procedures, interventions, and follow-ups were conducted at the clinics of the Department of Orthodontics of Faculty of Dentistry of the University of São Paulo. Trial registration: REBEC, RBR-6zpvwty. Registered September 03, 2021-Retrospectively registered, https://ensaiosclinicos.gov.br/rg/RBR-6zpvwty
Participants and sample size
A total of 45 patients, comprising young and adult males and females aged 14–25 years with permanent dentition, excluding third molars, were enrolled in this study. The exclusion criteria were defined as follows: History of previous orthodontic treatment; current or regular use of systemic analgesics, anti-inflammatory drugs, or medications that modify pain threshold; active periodontal disease or poor oral hygiene; extensive dental destruction or restorations affecting the clinical crown bonding surface; and any systemic medical condition or chronic pain disorder that could compromise reliable pain perception reporting. These patients were divided into three groups based on the interval between archwire changes: 28 days (4-week Group), 56 days (8-week Group), and 84 days (12-week Group).
Randomization
All participants were selected through public screening processes, without the participation of the operators. Randomization was performed using computer-generated allocation tables from the website https://www.sealedenvelope.com, with blocks of three participants stratified by three types of facial patterns (hypodivergent, neutral, and hyperdivergent) as determined by Ricketts’ cephalometry. Allocation concealment was maintained until the start of the interventions [Figure 1].
Interventions, measurements, and blinding
All patients were treated with the self-ligating Damon® Q–fixed appliance (Ormco Corporation, Glendora, California). Both the upper and lower arches were bonded during the same appointment.
To measure pain levels, we used the visual analog scale (VAS),[8] represented by the figure of a 10 cm horizontal line, where the left end corresponds to the “absence of pain” and the right end represents the “worst pain imaginable,” known as the “pain thermometer.” The VAS was sent to patients via the WhatsApp application (WhatsApp Messenger Inc., Mountain View, California, USA) at the following times: T0, before the procedure; T1, immediately after the procedure; T2, 8 h after the procedure; T3, 24 h after the procedure; and every 24 h daily from T4 to T9. Each procedure was evaluated for 7 days. Monitoring was carried out for each arch replacement used, in a total of 4 evaluations in the following sequence: 0.014”, 0.018”, 0.014” × 0.025”, and 0.018” × 0.025”, all Damon® Copper-NiTi (Ormco Corporation, Glendora, California). Patients were instructed to mark a vertical line on the scale corresponding to their pain level, which was represented by a numerical scale ranging from 1 to 10.
Shortly before installing the device (T0), all patients received a dental anxiety scale (DAS)[9] to classify their degree of anxiety as zero, low, moderate, or exacerbated.
Due to the clinical nature of the interventions, which involved distinctly scheduled clinical appointments for archwire changes (28, 56, or 84 days), blinding of the operating orthodontists and the patients was not feasible. However, to minimize detection and analysis bias, the statistician responsible for running the mixed models and data analysis was completely blinded to the group allocations, receiving a masked dataset with anonymized group codes.
Statistical methods
The calculations were performed using R 3.6.08 software[10], and graphs were created using the ggplot2[11] package.
The sample calculation was performed based on a previous study.[5] We considered 10 measurements for each individual, classified into four groups (representing the types of threads), with a 5% significance level and 80% power for the analysis. Various correlations were examined between repeated measurements within the same individuals, considering small (f = 0.10) and medium (f = 0.25) effect sizes.
The VAS statistical comparisons between the arches according to time and groups were performed using mixed models with a random effect of the individual.[12] To compare the influence of anxiety levels, the average pain reported by the VAS was used, and comparisons between groups were performed using a t-test.
RESULTS
Participants
All patients within their respective groups strictly followed the identical alignment sequence and intervals. Regarding sample attrition, three participants discontinued treatment before study completion (1 from the 4-week group, 1 from the 8-week group, and 1 from the 12-week group), resulting in a final sample of 42 participants available for full statistical analysis.
Baseline data
The mean and standard deviation of the VAS scores for each of the three groups according to the installed arch and replacement interval are presented in Table 1.
| Group | Time | 0.014” | 0.018” | 0.014×0.025” | 0.018×0.025” |
|---|---|---|---|---|---|
| 4 Weeks | T0 | 0.00 (0.00) | 0.48 (1.47) | 0.08 (0.24) | 0.00 (0.00) |
| T1 | 0.64 (0.68) | 1.71 (2.59) | 0.97 (1.55) | 0.79 (1.06) | |
| T2 | 2.31 (2.35) | 2.65 (2.40) | 3.01 (2.69) | 1.77 (1.66) | |
| T3 | 3.01 (2.58) | 1.98 (1.57) | 2.22 (2.41) | 1.53 (1.56) | |
| T4 | 2.71 (2.06) | 1.01 (1.18) | 1.28 (1.19) | 0.76 (0.94) | |
| T5 | 2.21 (2.10) | 0.51 (0.76) | 0.83 (0.95) | 0.40 (0.73) | |
| T6 | 0.88 (1.16) | 0.26 (0.43) | 0.31 (0.45) | 0.21 (0.44) | |
| T7 | 1.07 (2.29) | 0.16 (0.32) | 0.13 (0.27) | 0.08 (0.20) | |
| T8 | 0.39 (0.67) | 0.11 (0.29) | 0.04 (0.15) | 0.03 (0.10) | |
| T9 | 0.06 (0.17) | 0.07 (0.28) | 0.00 (0.00) | 0.03 (0.10) | |
| 8 Weeks | T0 | 0.00 (0.00) | 0.23 (0.45) | 0.14 (0.37) | 0.14 (0.32) |
| T1 | 1.93 (2.56) | 0.86 (1.08) | 1.58 (2.04) | 1.42 (1.98) | |
| T2 | 3.84 (2.72) | 2.55 (1.83) | 3.46 (2.89) | 2.20 (2.17) | |
| T3 | 4.61 (3.06) | 1.50 (1.56) | 3.09 (2.38) | 1.87 (2.49) | |
| T4 | 3.39 (2.32) | 0.87 (1.18) | 1.66 (1.42) | 1.04 (1.80) | |
| T5 | 2.56 (2.33) | 0.50 (1.03) | 0.96 (1.14) | 0.72 (1.58) | |
| T6 | 1.93 (2.37) | 0.38 (0.96) | 0.84 (1.07) | 0.54 (1.40) | |
| T7 | 1.42 (2.09) | 0.31 (0.98) | 0.42 (0.84) | 0.32 (0.95) | |
| T8 | 1.12 (1.71) | 0.25 (0.80) | 0.29 (0.68) | 0.19 (0.64) | |
| T9 | 0.99 (1.49) | 0.14 (0.45) | 0.20 (0.48) | 0.17 (0.64) | |
| 12 Weeks | T0 | 0.00 (0.00) | 0.09 (0.19) | 0.02 (0.08) | 0.16 (0.39) |
| T1 | 1.24 (1.88) | 1.24 (2.15) | 1.30 (2.42) | 1.17 (1.22) | |
| T2 | 3.91 (2.56) | 3.04 (2.23) | 4.01 (2.57) | 2.46 (2.10) | |
| T3 | 4.74 (2.65) | 2.76 (3.01) | 3.88 (2.39) | 2.51 (2.29) | |
| T4 | 3.89 (2.79) | 1.84 (1.90) | 2.70 (2.21) | 1.48 (1.41) | |
| T5 | 2.22 (1.92) | 0.87 (1.13) | 1.84 (1.58) | 1.19 (2.06) | |
| T6 | 1.06 (1.11) | 0.55 (0.84) | 1.01 (1.40) | 0.38 (0.88) | |
| T7 | 0.55 (0.65) | 0.34 (0.58) | 0.63 (1.05) | 0.85 (2.43) | |
| T8 | 0.29 (0.39) | 0.19 (0.41) | 0.45 (0.90) | 0.69 (2.40) | |
| T9 | 0.13 (0.34) | 0.00 (0.00) | 0.04 (0.11) | 0.01 (0.03) |
In the 4-week group, the highest values were reported at T3 (3.01 ± 2.58), T2 (2.65 ± 2.40), T2 (3.01 ± 2.69), and T2 (1.77 ± 1.66), respectively. Similarly, in the 8-week group, the highest scores were also at T3 (4.61 ± 3.06), T2 (2.55 ± 1.83), T2 (3.46 ± 2.89), and T2 (2.20 ± 2.17). Conversely, the 12-week group exhibited the highest values at T3 (4.74 ± 2.65), T2 (3.04 ± 2.23), T2 (4.01 ± 2.57), and T3 (2.51 ± 2.29) during the final arch exchange.
Figure 2 shows the individual and average profiles for each combination. In general, the VAS peak occurred at times T2, T3, and T4, showing a relative similarity of the three graphs. The 0.014” arch presented the highest reported pain value in the 8-week and 12-week groups, despite the extended working time for arch exhaustion.
Outcomes and estimation
The VAS comparisons between the wires according to instants and periods were performed using mixed models[12] with a random effect for individuals. Table 2 details the threads that exhibited statistically significant differences in VAS scores across each time point and week.
| Time | Comparison | 4 weeks | 8 weeks | 12 weeks |
|---|---|---|---|---|
| T0 | 0.014”–0.018” | |||
| 0.014”–0.014×0.025” | ||||
| 0.014”–0.018×0.025” | ||||
| 0.018”–0.014×0.025” | ||||
| 0.018”–0.018×0.025” | ||||
| 0.014×0.025”–0.018×0.025” | ||||
| T1 | 0.014”–0.018” | |||
| 0.014”–0.014×0.025” | ||||
| 0.014”–0.018×0.025” | ||||
| 0.018”–0.014×0.025” | ||||
| 0.018”–0.018×0.025” | ||||
| 0.014×0.025”–0.018×0.025” | ||||
| T2 | 0.014”–0.018” | |||
| 0.014”–0.014×0.025” | ||||
| 0.014”–0.018”×0.025” | ||||
| 0.018”–0.014×0.025” | ||||
| 0.018”–0.018×0.025” | ||||
| 0.014×0.025”–0.018×0.025” | ||||
| T3 | 0.014”–0.018” | X | ||
| 0.014–0.014×0.025” | ||||
| 0.014”–0.018×0.025” | X | |||
| 0.018”–0.014×0.025” | ||||
| 0.018”–0.018×0.025” | ||||
| 0.014×0.025”–0.018×0.025” | ||||
| T4 | 0.014”–0.018” | X | X | |
| 0.014”–0.014×0.025” | X | X | ||
| 0.014”–0.018×0.025” | X | X | X | |
| 0.018”–0.014×0.025” | ||||
| 0.018”–0.018×0.025” | ||||
| 0.014×0.025”–0.018×0.025” | ||||
| T5 | 0.014”–0.018” | X | X | |
| 0.014”–0.014×0.025” | X | X | ||
| 0.014”–0.018×0.025” | X | X | ||
| 0.018–0.014×0.025” | ||||
| 0.018”–0.018×0.025” | ||||
| 0.014×0.025”–0.018×0.025” | ||||
| T6 | 0.014”–0.018” | X | X | |
| 0.014”–0.014×0.025” | X | |||
| 0.014”–0.018×0.025” | X | X | ||
| 0.018”–0.014×0.025” | ||||
| 0.018”–0.018×0.025” | ||||
| 0.014×0.025”–0.018×0.025” | ||||
| T7 | 0.014”–0.018” | X | ||
| 0.014”–0.014×0.025” | X | |||
| 0.014”–0.018×0.025” | X | |||
| 0.018”–0.014×0.025” | ||||
| 0.018”–0.018×0.025” | ||||
| 0.014×0.025”–0.018×0.025” | ||||
| T8 | 0.014”–0.018” | X | ||
| 0.014”–0.014×0.025” | X | X | ||
| 0.014”–0.018×0.025” | X | X | ||
| 0.018”–0.014×0.025” | ||||
| 0.018”–0.018×0.025” | ||||
| 0.014×0.025”–0.018×0.025” | ||||
| T9 | 0.014”–0.018” | X | ||
| 0.014”–0.014×0.025” | X | |||
| 0.014”–0.018×0.025” | X | |||
| 0.018”–0.014×0.025” | ||||
| 0.018”–0.018×0.025” | ||||
| 0.014×0.025”–0.018×0.025” |
During the application of the DAS questionnaire, 17 patients were classified as having low anxiety and 25 patients were classified as having moderate anxiety. No patient was identified with zero or exacerbated anxiety indices [Table 3]. Figure 3 shows the average pain scale score according to the period and anxiety level categories.
| Group | Low anxiety (n=17) | Moderate anxiety (n=25) | P-value |
|---|---|---|---|
| 4 weeks | 0.89±0.63 | 0.95±0.71 | 0.87 |
| 8 weeks | 0.88±0.50 | 1.55±1.33 | 0.22 |
| 12 weeks | 0.50±0.44 | 1.65±0.71 | 0.02 |
p<0.05 statistically significant.
DISCUSSION
The mechanisms by which pain arises following the application of orthodontic force are not fully understood. However, it is known that the application of orthodontic force compresses the periodontal ligament, initiating an acute inflammatory process, which is essential for tooth movement. The production of inflammatory mediators, such as prostaglandins, substance P, and cytokines, plays an important role in mediating orthodontic pain, as demonstrated in the literature.[13,14]
In this study, 45 orthodontic patients, divided into three groups, were followed for 7 days to monitor painful symptoms during the Copper-NiTi archwire replacement sequence. Accurate measurement of reported pain is crucial for evaluating and adapting methods to control discomfort.[15] The pain experience reported by the patients was measured immediately after insertion of the archwire, regardless of the caliber, reaching its peak pain level in 24 h for the 0.014” archwire. For the 0.018”, 0.014” × 0.025”, and 0.018” × 0.025” (Copper-NiTi) archwires, the pain peak occurred within 8 h, as previously observed by Sandhu and Sandhu,[13] Johal et al. (2018),[16] Erdinç and Dinçer[17] and Jones and Chan.[18]
While there was a decline during the 7-day follow-up period, some patients still reported painful symptoms after 7 days. The observed pain probably reflects the biological response underlying the application of orthodontic force in the periodontal ligament, as described in a study on the interleukin-1beta (IL-1β) protein by Luppanapornlarp et al.[14] IL-1β is the first mediator to regulate bone remodeling in response to orthodontic force and plays a significant role in painful symptoms by inducing the secretion of pain-producing pro-inflammatory mediators. The concentration of IL-1β increases after 1 h of orthodontic force application, peaks within 24 h, and gradually returns to baseline levels over 1 week–1 month.
The highest VAS score, indicating the peak of pain, was recorded with the 0.014” Copper-NiTi archwire. For the 4-week group, this score at 3.01 (±2.58) units, followed by the 8-week group at 4.61 (±3.06), and the 12-week group at 4.74 (±2.65), all at T3 (24 h after the procedure). Although no statistical significance was observed, our study aligns with those reported by Marković et al.[3] and Fernandes et al.,[19] who investigated pain during the initial phase of dental alignment with archwires of the same diameter. One factor to consider regarding the patients’ response was related to the beginning of the treatment; in this study, all brackets were bonded in the first consultation, followed by the installation of the 0.014” Copper-NiTi archwire, and the inconvenience of the new device must be considered.
In the intergroup descriptive study, the pain peak of each arch showed the same behavior in the three groups, ranked in descending order as follows: Arch 0.014”, 0.014” × 0.025”, 0.018” and finally 0.018” × 0.025” Copper-NiTi, represented in Figure 2. This trend was particularly observed during the transition from round to rectangular archwires. At this treatment stage, inserting a rectangular arch creates pressure within the bracket slot, resulting in torque with root movement owing to the increased arch diameter and shape. This results in greater patient discomfort and orthodontic pain, as reported by Johal et al.[16] and Jian et al.[20] We observed that the first-round and rectangular arches presented with higher levels of pain, regardless of the group. This fact was explained by Lombardo et al.,[4] where they evaluated the level of force between the NiTi arches. The authors observed that a 0.002” increase in the cross-sectional diameter of the wire generated a 50% increase in strength. Furthermore, tooth irregularities in the arch can cause greater deflection and force application, thereby exacerbating orthodontic pain, as reported by Henriques et al.[21]
Previous studies, such as those by Luppanapornlarp et al.[14] and Ogura et al.[22] compared the intensity of pain associated with different magnitudes of force applied to the teeth using a split-mouth model and reported that the greater the force applied, the greater the pain response reported by the patient. According to Pereira et al.[23] anxiety is a subjective state of feeling or reacting to unknown situations. When anxiety occurs before dental treatment, it is termed dental anxiety. They concluded that the prevalence of anxiety was not significantly associated with sex, age, income, education level, frequency of dental visits, or procedures causing greater discomfort. Thus, anxiety was determined to be an individualized fear unique to each patient. Our results are in line with these statements; patients with a moderate anxiety index reported a higher amount of pain than those classified as having low anxiety.
This study successfully identified pain behavior during orthodontic treatment, providing valuable insights for better informing patients about the pain associated with fixed appliances and subsequent appointments. This understanding can significantly aid in managing treatment expectations.
Limitations
One of the limitations of this study is the variability in responses obtained from each patient when subjected to the same orthodontic stimulus. Although this study considered anxiety as a factor influencing this variation, further research is needed to address this aspect of pain perception. In addition, it was also not possible to measure the level of commitment of each patient in completing the pain scales. Some of the participants responded promptly to the study schedule, whereas others took longer to respond.
CONCLUSION
Pain onset
Pain perception initiates shortly after orthodontic archwire insertion, regardless of the wire caliber.
Intensity hierarchy
The 0.014” Copper-NiTi archwire elicits the highest pain intensity, followed in descending order by the 0.014” × 0.025”, 0.018”, and 0.018” × 0.025” archwires.
Pain peaks
While the global peak of pain occurs within 24 h after archwire changes for all groups, an earlier peak occurs at the 8-h mark for the 0.018” and both rectangular (0.014” × 0.025” and 0.018” × 0.025”) CuNiTi wires.
Psychological modulation
Moderate anxiety significantly amplifies pain levels within the 12-week archwire replacement protocol, underscoring the clinical necessity of managing both mechanical and emotional variables.
Authors’ contributions:
TCHS: Concepts, design, literature search, data acquisition, manuscript preparation; MHC: Experimental studies, data analysis, statistical analysis, manuscript editing and review, manuscript preparation; EPSU: Definition of intellectual content, clinical studies, data acquisition JRN: Manuscript preparation, manuscript editing and review, design; JBP: Manuscript preparation, manuscript editing and review, concepts.
Ethical approval:
The research/study was approved by the Institutional Review Board at the Research Ethics Committee of the Faculty of Dentistry of the University of São Paulo, number 3.612.566/CAAE:19239719.4.0000.0075, dated 01st October 2019.
CTR Number:
RBR-6zpvwty
Declaration of patient consent:
The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient has given consent for clinical information to be reported in the journal. The patient understands that the patient’s names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
Conflicts of interest:
There are no conflicts of interest.
Use of artificial intelligence (AI)-assisted technology for manuscript preparation:
The authors confirm that there was no use of artificial intelligence (AI)-assisted technology for assisting in the writing or editing of the manuscript and no images were manipulated using AI.
Financial support and sponsorship: Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) - Finance Code 001.
References
- Attitudes to orthodontic treatment. Br J Orthod. 1985;12:179-88.
- [CrossRef] [PubMed] [Google Scholar]
- Prediction of prolonged pain experiences during orthodontic treatment. Am J Orthod Dentofacial Orthop. 2008;133:339.e1-8.
- [CrossRef] [PubMed] [Google Scholar]
- The correlation between pain perception among patients with six different orthodontic archwires and the degree of dental crowding. Vojnosanit Pregl. 2015;72:262-9.
- [CrossRef] [PubMed] [Google Scholar]
- Load deflection characteristics and force level of nickel titanium initial archwires. Angle Orthod. 2012;82:507-21.
- [CrossRef] [PubMed] [Google Scholar]
- Ask us. Self-ligating bracket claims. Am J Orthod Dentofacial Orthop. 2010;138:128-31.
- [CrossRef] [PubMed] [Google Scholar]
- Maxillary dental and skeletal effects after treatment with self-ligating appliance and miniscrew-assisted rapid maxillary expansion. Am J Orthod Dentofacial Orthop. 2021;159:e93-101.
- [CrossRef] [PubMed] [Google Scholar]
- Orthodontic pain: From causes to management-a review. Eur J Orthod. 2007;29:170-9.
- [CrossRef] [PubMed] [Google Scholar]
- Analysis of the applicability of different pain questionnaires in three hospital settings: Outpatient clinic, ward and emergency unit. Rev Bras Reumatol. 2011;51:299-308.
- [CrossRef] [Google Scholar]
- Development of a dental anxiety scale. J Dent Res. 1969;48:596.
- [CrossRef] [PubMed] [Google Scholar]
- R: A Language and Environment for Statistical Computing. 2019. Vienna, Austria: R Foundation for Statistical Computing; Available from: href="https://www.r-project.org [Last accessed on 2025 Jul 24]
- [Google Scholar]
- (2016) ggplot2: Elegant Graphics for Data Analysis. New York: Springer-Verlag; p. :211.
- [CrossRef] [Google Scholar]
- Linear, Generalized, and Mixed Models In: Wiley Series in Probability and Statistics (2nd Edition). 2008. p. :424.
- [Google Scholar]
- A randomized clinical trial investigating pain associated with superelastic nickel-titanium and multistranded stainless steel archwires during the initial leveling and aligning phase of orthodontic treatment. J Orthod. 2013;40:276-85.
- [CrossRef] [PubMed] [Google Scholar]
- Interleukin-1beta levels, pain intensity, and tooth movement using two different magnitudes of continuous orthodontic force. Eur J Orthod. 2010;32:596-601.
- [CrossRef] [PubMed] [Google Scholar]
- Pain experience during initial alignment with three types of nickel-titanium archwires: A prospective clinical trial. Angle Orthod. 2015;85:1021-6.
- [CrossRef] [PubMed] [Google Scholar]
- Pain experience in adults undergoing treatment: A longitudinal evaluation. Angle Orthod. 2018;88:292-8.
- [CrossRef] [PubMed] [Google Scholar]
- Perception of pain during orthodontic treatment with fixed appliances. Eur J Orthod. 2004;26:79-85.
- [CrossRef] [PubMed] [Google Scholar]
- The pain and discomfort experienced during orthodontic treatment: A randomized controlled clinical trial of two initial aligning arch wires. Am J Orthod Dentofacial Orthop. 1992;102:373-81.
- [CrossRef] [PubMed] [Google Scholar]
- Pain and discomfort experienced after placement of a conventional or a superelastic NiTi aligning archwire. A randomized clinical trial. J Orofac Orthop. 1998;59:331-9.
- [CrossRef] [PubMed] [Google Scholar]
- Initial arch wires for tooth alignment during orthodontic treatment with fixed appliances. Cochrane Database Syst Rev. 2013;4:CD007859.
- [CrossRef] [PubMed] [Google Scholar]
- Evaluation of deflection forces of orthodontic wires with different ligation types. Braz Oral Res. 2017;31:e49.
- [CrossRef] [PubMed] [Google Scholar]
- Pain intensity during the first 7 days following the application of light and heavy continuous forces. Eur J Orthod. 2009;31:314-9.
- [CrossRef] [PubMed] [Google Scholar]
- Assessment of anxiety levels in patients undergoing dental treatment. Rev Bras Cienc Saude. 2013;17:55-64.
- [CrossRef] [Google Scholar]