Assessment of the Alignment Accelera1on of the Lower Incisors Using a Single Aligner Appliance Modified with Nickel-Titanium Coils: A Randomized Controlled Clinical Trial in Adults. Vol 12 No 1 (2024) DOI 10.5195/d3000.2024.532 h#p://den*stry3000.pi#.edu Assessment of the Alignment Acceleration of the Lower Incisors Using a Single Aligner Appliance Modified with Nickel-Titanium Coils: A Randomized Controlled Clinical Trial in Adults. Ziad Mohamad Alhafi1, Nada Rajeh1, Zaher Jumaa2, Zuhir Alasfar3 1Department of Orthodontics, Faculty of Dentistry, Damascus University, Damascus, Syria 2Department of Oral and Maxillofacial Surgery, Faculty of Dentistry, Damascus University, Damascus, Syria 3Department of Periodontology, Faculty of Dentistry, Damascus University, Damascus, Syria Abstract OBJECTIVE: The aim of this study was to inves1gate the effects of a single aligner appliance modified with nickel-1tanium coils in accelera1ng the alignment of crowded lower incisors. MATERIALS AND METHODS: 36 pa1ents with mild crowding of their lower incisors were randomly divided into two groups: one group received a modified aligner appliance with nickel-1tanium coils (Experimental group), while the other group received tradi1onal orthodon1c brackets (Control group). The degree of irregularity in the alignment of the incisors was measured every 2 weeks using LiQle's irregularity index, and this was done at different 1me points throughout the study: before treatment (T0), aTer 2 weeks (T1), aTer 4 weeks (T2), aTer 6 weeks (T3), aTer 8 weeks (T4). RESULTS: A total of 87 pa1ents with anterior mild crowding in the lower dental arch were ini1ally assessed for eligibility. Out of these, 64 pa1ents met the inclusion criteria. Eventually, 36 par1cipants were assigned to receive the treatment. Accordingly, the data from 36 pa1ents were analyzed sta1s1cally. There was no significant difference when comparing the two groups at T0, T1, T3, and T4. However, the difference was significant at T2 (p = 0.037). The differences were sta1s1cally significant at all 1me periods within each group (P < 0.001). CONCLUSION: The use of a modified aligner appliance with nickel-1tanium coils effec1vely treats lower incisors crowding, but it does not accelerate the alignment process compared to the tradi1onal fixed orthodon1c appliance. KEYWORDS: Aligners; Teeth alignment; Dental crowding; Accelera1on Cita9on: Alhafi, ZM et al. (2024) Assessment of the Alignment Accelera9on of the Lower Incisors Using a Single Aligner Appliance Modified with Nickel-Titanium Coils: A Randomized Controlled Clinical Trial in Adults. Den9stry 3000. 1:a001 doi:10.5195/d3000.2024.532 Received: July 13, 2023 Accepted: July 14, 2023 Published: May 9, 2024 Copyright: ©2024 Alhafi, ZM et al. This is an open access ar9cle licensed under a Crea9ve Commons AZribu9on Work 4.0 United States License. Email: ziad.alhafy@gmail.com Introduction The rising focus on appearance in society has resulted in a greater desire among adults to resolve minor dental problems like mild crowding [1-3]. However, instead of choosing conventional braces orthodontic appliances due to the non-aesthetic metallic appearance of wires and brackets, they are increasingly inclined towards reconstructive procedures that may have the potential to harm dental tissues [1, 4- 6]. As a result, there is a growing preference for invisible orthodontic methods, particularly among adults [7]. Consequently, numerous http://dentistry3000.pitt.edu/ Assessment of the Alignment Accelera1on of the Lower Incisors Using a Single Aligner Appliance Modified with Nickel-Titanium Coils: A Randomized Controlled Clinical Trial in Adults. Vol 12 No 1 (2024) DOI 10.5195/d3000.2024.532 h#p://den*stry3000.pi#.edu methods and substances have been created in the field of clinical practice to alleviate these constraints, such as porcelain brackets, orthodontic techniques that are placed on the inner surface of the teeth, and clear aligners [8], but these options tend to be quite costly [9]. The Spring aligner appliance, also known as the spring retainer, was introduced by Barrer in 1974 as a removable device for aligning the incisors. It has been used for more than 25 years [10]. However, its activation was limited and it was only used to correct simple issues after orthodontic treatment and for retention [11]. In 2001, Don Inman modified the traditional spring retainer and created the Inman Aligner, a removable appliance that served multiple orthodontic purposes [4]. This new appliance relied on superelastic open coil springs to apply light and constant forces on both the front and back surfaces of the anterior teeth [11]. After reviewing the medical literature, we found that no clinical studies had been conducted that evaluated the acceleration of mandibular incisor alignment using any type of aligner appliance in the treatment of mild crowding in adult patients. Based on this reasoning, the aim of this research was to assess the efficiency of a single aligner appliance modified with nickel-titanium springs, by comparing it with a traditional fixed orthodontic appliance in treating mild crowding of the lower incisors in adults. Material and Methods Study Design The study design was a randomized, single-blinded clinical trial with two groups and an equal allocation ratio. The study received approval from the university institutional review board and the Ethical Review Committee of Damascus University (Approval Number: 3166). The trial was also registered in the ClinicalTrials.gov database with the identifier NCT04988373. Sample Size Estimation Minitab® program (Version 20.1; Minitab, LLC, State College, Pa) was used to determine the sample size for the study. They considered the average movement of teeth per day with traditional fixed orthodontic appliances and aimed for 80% power at a significance level of 5%. Based on previous data, it was determined that a minimum of 17 patients was needed in each group (Figure 1). To account for potential dropouts, the number of patients was increased to 18 per group. Patient selection, recruitment The study included a total of 36 patients, consisting of 29 females and 7 males. These patients were selected from individuals who sought treatment at the Department of Orthodontics, Faculty of Dentistry, Damascus University in Syria between January 2021 and April 2021. Inclusion criteria • Adults’ padents between the ages of 16 - 28 years. • Mild crowding (1-4 mm) in the frontal area of their lower dental arch according to Liele’s irregularity index (LII). • Class I malocclusion. • Should be no extracted or congenitally missing teeth, except for third molars. Exclusion criteria • Previous orthodondc treatment. • Severe skeletal discrepancy. • Severe protrusion of both upper and lower teeth. • Any systemic diseases that could affect tooth movement. • Poor oral hygiene. Randomization and Blinding The participants were divided into both groups using a 1:1 allocation ratio, utilizing the simple computer random method through the Minitab® program (Version 20.1; Minitab, LLC, State College, Pa). Blinding of the examiner and the patient was not possible, but blinding could be implemented during the analysis of the findings to prevent bias in detection. Interventions The patients underwent a clinical examination, and impressions were http://dentistry3000.pitt.edu/ Assessment of the Alignment Accelera1on of the Lower Incisors Using a Single Aligner Appliance Modified with Nickel-Titanium Coils: A Randomized Controlled Clinical Trial in Adults. Vol 12 No 1 (2024) DOI 10.5195/d3000.2024.532 h#p://den*stry3000.pi#.edu made to create study models. Additionally, digital lateral cephalometric and panoramic x-rays were requested. In the single aligner appliance modified with nickel-titanium coils group (Experimental group), 18 patients were treated A setup was created using the orthodontic panel of BlueSkyPlan® software to align the anterior teeth. The setup was then used to create a modified digital model, which was printed using a resin 3D printer. The bands were placed and the single aligner appliance was fabricated on this model. Before placing the aligner appliance, interproximal reduction (IPR) was performed manually using an abrasive strip, which varied depending on the case planning. The amount of IPR was determined using an IPR Gauge (Ortho Technology Inc, West Columbia, USA). The molars were then fitted with bands and cemented using GIC (Ivoclar Vivadent, Enderby, UK). The aligner appliance was subsequently placed. The force applied during the procedure was measured using an intraoral orthodontic force gauge (DTC Medical Apparatus CO, Hangzhou, China) and adjusted to a maximum of 80 grams per side, based on the specific needs of each case (Figure 2). In the conventional orthodontic appliance (control group), 18 patients were treated using a traditional edgewise with the MBT prescription, 0.022-inch slot (Master Series, American Orthodontics, Sheboygan, USA). The archwire sequence used in this group was as follows: 0.012-inch nickel-titanium (NiTi), 0.014-inch NiTi, 0.016-inch NiTi, 0.016 × 0.022-inch NiTi, 0.016 × 0.022-inch stainless steel (SS), and 0.017 × 0.025-inch SS. Interproximal reduction (IPR) was performed in the same manner as described in the experimental group. The visual confirmation of the completion of alignment for both groups was done using Little's Irregularity Index (LII) [12], which Figure 1. Sample size estimation. Figure 2. The applied appliance in the experimental group. http://dentistry3000.pitt.edu/ Assessment of the Alignment Accelera1on of the Lower Incisors Using a Single Aligner Appliance Modified with Nickel-Titanium Coils: A Randomized Controlled Clinical Trial in Adults. Vol 12 No 1 (2024) DOI 10.5195/d3000.2024.532 h#p://den*stry3000.pi#.edu indicated an equality of zero (Figure 3). Outcome Measures Little's Irregularity Index (LII) was the measure used to assess the outcome in this study. The LII was measured on study models at multiple time points: before treatment (T0), after 2 weeks of treatment (T1), after 4 weeks (T2), after 6 weeks (T3), and after 8 weeks (T4). The measurements were conducted using a digital caliper (Insize, Insize Co, China) with a precision of 0.1 mm. The methodology for measuring LII followed Little's guidelines ]12[ . Statistical analysis The statistical analysis of the search results was conducted using SPSS software (version 26.0, IBM Corp, Armonk, NY). The Shapiro- Wilk test was used to assess the normality of the data distribution, and it indicated that the distribution was normal. Therefore, parametric tests were employed. The independent t-Test was utilized to identify significant differences in the mean values of the Little Irregularity Index between the two groups at each time point. Additionally, the paired t-test was used to detect significant differences within each group. The statistical significance level was set at 0.05 with a 95% confidence interval. Results CONSORT guideline shows the flowchart of the patients throughout the trial (Figure 4). A total of 36 patients (7 males, 29 females) were included in the study and divided into two groups of 18 participants. There were no dropouts or withdrawals during any stage of the trial. Figure 3. End of the lower incisor alignment stage. http://dentistry3000.pitt.edu/ Assessment of the Alignment Accelera1on of the Lower Incisors Using a Single Aligner Appliance Modified with Nickel-Titanium Coils: A Randomized Controlled Clinical Trial in Adults. Vol 12 No 1 (2024) DOI 10.5195/d3000.2024.532 h#p://den*stry3000.pi#.edu The enrollment of participants in this study included a total of 36 patients, as shown in Table 1 which presents the basic characteristics of the sample. Table 2 provides the descriptive statistics for the variables that were evaluated in the study. The findings regarding changes in LII at different time points are presented in Table 3. There were no significant differences between the two groups at T0, T1, T3, and T4 (P = 0.994, P=0.095, P=0.060, P=0.191, respectively). However, a significant difference was found at T2 (P=0.037). Table 4 shows that there are statistically significant differences in the mean values of LII between the five studied time periods within each group (P<0.001). Figure 4. CONSORT flow diagram http://dentistry3000.pitt.edu/ Assessment of the Alignment Accelera1on of the Lower Incisors Using a Single Aligner Appliance Modified with Nickel-Titanium Coils: A Randomized Controlled Clinical Trial in Adults. Vol 12 No 1 (2024) DOI 10.5195/d3000.2024.532 h#p://den*stry3000.pi#.edu Variable Group Mean SD Min Max Q1 Median Q3 LIIT0 Experimental 3.10 0.68 2 4 2.32 3.38 3.58 Control 3.09 0.68 2 4 2.5 3.08 3.77 LIIT1 Experimental 1.88 0.56 1 2.70 1.27 2 2.24 Control 2.23 0.66 1.23 3.33 1.65 2.15 2.78 LIIT2 Experimental 1.01 0.51 0.22 1.90 0.58 1.06 1.41 Control 1.40 0.54 0.67 1.70 0.91 1.30 1.91 LIIT3 Experimental 0.37 0.33 0 1 0 0.35 0.68 Control 0.63 0.46 0 1.45 0.19 0.60 1 LIIT4 Experimental 0.10 0.17 0 0.56 0 0 0.21 Control 0.18 0.19 0 0.57 0 0.19 0.36 Group Mean Age ±SD Min. Age Max. Age P value* Gender n (%) P value† Experimental 22.56 ± 3.50 18 28 0.130 Male 3 (16.7) 0.674 Female 15 (83.3) Control 20.89 ± 2.90 17 28 Male 4 (22.2) Female 14 (77. 8) Total 21.72 ± 3.28 17 28 Male 7 (19.4) Female 29 (80.6) Table 1: Basic sample characteristics Table 2: Descriptive statistics of Little’s irregularity index values (mm) in the two groups. *: employing independent t-test, Min: minimum, Max: maximum, †: employing chi-square test LIIT0: Little’s irregularity index before treatment; LIIT1: after 2 weeks of treatment; LIIT2: after 4 weeks; LIIT3: after 6 weeks; LIIT4: after 8 weeks; SD: Standard Deviation; Min: minimum; Max: maximum, Q1: first quartile; Q3: third quartile. http://dentistry3000.pitt.edu/ Assessment of the Alignment Accelera1on of the Lower Incisors Using a Single Aligner Appliance Modified with Nickel-Titanium Coils: A Randomized Controlled Clinical Trial in Adults. Vol 12 No 1 (2024) DOI 10.5195/d3000.2024.532 h#p://den*stry3000.pi#.edu Little's Irregularity Index Group Mean (SD) Mean Difference 95% CI of the difference P-value Lower Bound Upper Bound Before treatment Experimental 3.10 (0.68) 0.001 -0.46 0.46 0.994 Control 3.09 (0.68) At 2 weeks Experimental 1.88 (0.56) -0.35 -0.77 0.06 0.095 Control 2.23 (0.66) At 4 weeks Experimental 1.01 (0.51) -0.38 -0.74 -0.02 0.037* Control 1.40 (0.54) At 6 weeks Experimental 0.37 (0.33) -0.26 -0.53 0.01 0.060 Control 0.63 (0.46) At 8 weeks Experimental 0.10 (0.17) -0.08 -0.20 0.04 0.191 Control 0.18 (0.19) Discussion As far as we know, this research is the initial randomized controlled trial to assess the acceleration impact of using a modified single aligner appliance with nickel-titanium springs to align mildly crowded lower incisors. This study is a well-controlled clinical trial with a parallel-group design, and a simple computerized randomization method was used to allocate participants to the two groups to avoid bias in patient selection. It was not possible to blind the researcher and patients during the evaluation period due to the researcher's involvement in the application and periodic monitoring of the orthodontic appliances. However, the researcher was blinded during the plaster cast study phase and measurements were performed by another academic physician who had no connection to the research in Group Time period Mean Difference t P-value Experimental LIIT0- LIIT1 1.21 25.51 <0.001** LIIT1- LIIT2 0.86 17.99 <0.001** LIIT2- LIIT3 0.64 11.37 <0.001** LIIT3- LIIT4 0.27 5.54 <0.001** LIIT0- LIIT4 2.99 21.60 <0.001** Control LIIT0- LIIT1 0.86 24.61 <0.001** LIIT1- LIIT2 0.83 21.84 <0.001** LIIT2- LIIT3 0.76 24.04 <0.001** LIIT3- LIIT4 0.45 6.84 <0.001** LIIT0- LIIT4 2.91 23.25 <0.001** Table 3: The results of the observed LII changes between two groups (in mm)†. †: Independent t-test, *: significant at P<0.05; SD: Standard Deviation. Table 4: The results of the observed LII changes within each group †. †: Paired t-test, *: significant at P<0.05,**: significant at P<0.001; LIIT0: Little’s irregularity index before treatment; LIIT1: after 2 weeks of treatment; LIIT2: after 4 weeks; LIIT3: after 6 weeks; LIIT4: after 8 weeks; SD: Standard Deviation. http://dentistry3000.pitt.edu/ Assessment of the Alignment Accelera1on of the Lower Incisors Using a Single Aligner Appliance Modified with Nickel-Titanium Coils: A Randomized Controlled Clinical Trial in Adults. Vol 12 No 1 (2024) DOI 10.5195/d3000.2024.532 h#p://den*stry3000.pi#.edu order to avoid bias in the investigation. In order to prevent the oversight of important changes, the assessment was performed every two weeks throughout the duration of the treatment to accurately monitor progress. To avoid discrepancies in metabolic rate across various age groups, participants between the ages of 16 and 28 were chosen for the study. The experimental group had an average age of 22.56 ±3.50 years, while the control group had an average age of 20.89 ±2.90 years [13]. The majority of participants in this study were women, aligning with previous studies that women are more likely to seek orthodontic treatment as adults [14, 15]. Digital dental scanning was relied upon to obtain a digital model as it is an accurate and proven effective method [16, 17]. Additionally, the device was manufactured based on a 3D printed resin model, which studies have shown to provide clinically acceptable results [17, 18]. The NiTi springs were activated using a force of 80 g on both sides because each tooth requires a force between 35 and 60 g to create a tipping motion [19]. Specifically, a force of 40 g was applied to each incisor, resulting in a total force of 160 g (80 g on each side). In order to ensure accurate results, a fixed type of appliance was utilized in this research, which eliminates the reliance on patient compliance. It has been established in previous studies that achieving optimal treatment outcomes with removable appliances is contingent upon patient compliance [20, 21]. The researchers used LII as a method to measure the progress in alignment because it is a reliable and widely accepted way to accurately measure the difference in length of the front arch. This method has been proven to be consistent and trustworthy in previous studies [22]. The study results showed that the average values of Little's index were lower in the experimental treatment group compared to the control group. This can be explained by the difference in the application of force between the two appliances, as the point of force application in the traditional fixed orthodontic appliance is towards the buccal side from the center of resistance [23], while it is towards the lingual side in the application of the aligner appliance. This means that it is closer to the center of resistance of the anterior teeth, which may affect the speed of alignment of the lower incisors as in the lingual orthodontic technique [24]. However, this slight difference is not clinically or statistically significant at all evaluation times except at T2 (P=0.037). This can also be attributed to the magnitude of force applied at the beginning of treatment, as the forces applied in the aligner appliance are calibrated and consistent, while these forces were random and unmeasurable in the control group [25]. Therefore, the forces in the aligner appliance gradually dissipate as the treatment progresses and crowding is resolved, which explains the absence of differences in subsequent stages. No study has evaluated the alignment of anterior teeth using any type of spring appliance, and the difference in this current study from other studies limits the possibility of comparison with them [11]. The findings showed a significant difference in the value of the LII between the five time periods studied within both groups (P<0.001). This means that the value of this index decreased significantly as the lower anterior teeth were aligned in both groups. This difference was not due to any problem in the progress of treatment in any of the studied time periods. The application of the single aligner appliance modified with nickel- titanium coils within the lower anterior dental arch was the main limitation of the current study. Conclusion The clinical use of a modified aligner appliance with nickel-titanium coils effectively resolves lower incisors crowding, but it does not accelerate the alignment process compared to the conventional fixed orthodontic appliance. References http://dentistry3000.pitt.edu/ Assessment of the Alignment Accelera1on of the Lower Incisors Using a Single Aligner Appliance Modified with Nickel-Titanium Coils: A Randomized Controlled Clinical Trial in Adults. 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