Three-Dimensional Finite-Element Study into the Biomechanical Comparison of Force Distribution in Self-Ligating and Conventional Brackets

Self-ligation: A clinician's point of view

Interest in self-ligating brackets is generally smoother and more comfortable. To compare rate of retraction and rotational control of maxillary canines with self-ligating MBT brackets on one side and conventional MBT brackets on the other side of the maxillary arch. Ten subjects with a mean age range of 18 to 25 years were selected. For each patient in the maxillary arch, bonding was performed with 0.022-inch slot conventional MBT brackets on one side and 0.022-inch slot self-ligating MBT brackets on the other side. Stainless steel 0.009-inch ligatures are used for conventional ligation. Retraction of canines was performed with 0.019 × 0.025-inch stainless steel wires using NiTi closed coil springs with eyelets of 12 mm and 9 mm. The force of retraction was measured using a dynamometer. Dental casts were made at each time interval to record the canine retraction rate (in mm) and rotation (in degrees). The mean difference in the retraction rate was 0.045 mm/month between self-ligating and conventional brackets, respectively (P > 0.05). The mean difference of total rotation of canines with self-ligating and conventional brackets was 1.5°, which gives evidence that there was less rotation of canines with self-ligating brackets. There was no statistically significant difference in canine retraction rates between conventional and self-ligating brackets. Secure ligation with the self-ligating brackets showed better rotational control than the conventional brackets.

The frictional behavior of four conventional and four self-ligating brackets were simulated using a mechanical testing machine. Analyses of the two-bracket types were completed by drawing samples of three standardized archwires through quadrants of typodont models in the dry/wet states. Pretreatment typodonts of an oral cavity featured progressively malocclused quadrants. As nominal dimensions of the archwires were increased, the drawing forces of all brackets increased at different rates. When coupled with a small wire, the self-ligating brackets performed better than the conventional brackets. For the 0.014-inch wires in the upper right quadrant, the maximum drawing forces averaged 125 and 810 cN for self-ligating and conventional brackets, respectively. When coupled with larger wires, various designs interchangeably displayed superior performance. For the 0.019- x 0.025-inch wires in the upper left quadrant, the maximum drawing forces averaged 1635 and 2080 cN for self-ligating and conventional brackets, respectively. As the malocclusion increased, the drawing forces increased. For example, in the least malocclused quadrant and with the smallest wire, maximum drawing forces for self-ligating and conventional brackets averaged 80 and 810 cN, respectively, whereas in the most malocclused quadrant tested with the same wire size, maximum drawing forces for self-ligating and conventional brackets averaged 870 and 1345 cN, respectively. For maximum values between the dry and wet states, significant differences between ambient states existed only for the In-Ovation brackets in the lower left quadrant. These test outcomes illustrated how bracket design, wire size, malocclusion, and ambient state influenced drawing forces.

To investigate the canine retraction rate and anchorage loss during canine retraction using self-ligating (SL) brackets and conventional (CV) brackets. Differences between maxillary and mandibular rates were computed. Twenty-five subjects requiring four first premolar extractions were enrolled in this split-mouth, randomized clinical trial. Each patient had one upper canine and one lower canine bonded randomly with SL brackets and the other canines with CV brackets but never on the same side. NiTi retraction springs were used to retract canines (100 g force). Maxillary and mandibular superimpositions, using cephalometric 45° oblique radiographs at the beginning and at the end of canine retraction, were used to calculate the changes and rates during canine retraction. Paired t-tests were used to compare side and jaw effects. The SL and CV brackets did not show differences related to monthly canine movement in the maxilla (0.71 mm and 0.72 mm, respectively) or in the mandible (0.54 mm and 0.60 mm, respectively). Rates of anchorage loss in the maxilla and in the mandible also did not show differences between the SL and CV brackets. Maxillary canines showed greater amount of tooth movement per month than mandibular canines (0.71 mm and 0.57 mm, respectively). SL brackets did not show faster canine retraction compared with CV brackets nor less anchorage loss. The maxillary canines showed a greater rate of tooth movement than the mandibular canines; however, no difference in anchorage loss between the maxillary and mandibular posterior segments during canine retraction was found.

To compare the degree of debris and friction of conventional and self-ligating orthodontic brackets before and after clinical use. Two sets of three conventional and self-ligating brackets were bonded from the first molar to the first premolar in eight individuals, for a total of 16 sets per type of brackets. A passive segment of 0.019 × 0.025-inch stainless steel archwire was inserted into each group of brackets. Frictional force and debris level were evaluated as received and after 8 weeks of intraoral exposure. Two-way analysis of variance and Wilcoxon signed-rank test were applied at P < .05. After the intraoral exposure, there was a significant increase of debris accumulation in both systems of brackets (P < .05). However, the self-ligating brackets showed a higher amount of debris compared with the conventional brackets. The frictional force in conventional brackets was significantly higher when compared with self-ligating brackets before clinical use (P < .001). Clinical exposure for 8 weeks provided a significant increase of friction (P < .001) on both systems. In the self-ligating system, the mean of friction increase was 0.21 N (191%), while 0.52 N (47.2%) was observed for the conventional system. Self-ligating and conventional brackets, when exposed to the intraoral environment, showed a significant increase in frictional force during the sliding mechanics. Debris accumulation was higher for the self-ligating system.

Appliance biocompatibility, orthodontic treatment efficiency and patient convenience are the major issues confronting contemporary orthodontic practice. Very few studies have been published till date regarding the efficiency of self-ligating brackets as against conventional brackets. Hence, the present study was planned to compare the rate of canine retraction between self-ligating and conventional brackets and to determine the amount of anchorage loss during canine retraction. The present clinical study was designed as a prospective, observational study comprising of 25 patients requiring first premolar extraction as a part of orthodontic treatment. Self-ligating and conventional brackets were bonded using a split-mouth study design randomly. Retraction of canines was done with 150 grams of force using Dontrix gauge with E-chains. The study was conducted in relation to upper arch only, while the rate of retraction was evaluated every 4 weeks for 3 months. Average rates of retraction in 3 months were calculated. For anchorage loss, an acrylic guide plug was used in mid-treatment cast (T0) and after 3 months of retraction (T3). The statistical analysis was done using Statistical Package for Social Sciences (SPSS) version 17.0 (SPSS Inc., Chicago, IL, USA). Independent t-test was used to compare the means of the two variables studied, while Pearson's correlation coefficient was used to evaluate the correlation between the variables studied in the groups included. P < .05 was considered statistically significant. The correlation coefficient between the average rate of canine retraction with self-ligating brackets vs. conventional brackets over a period of 3 months came out to be 0.6434, while on comparing the data in terms of anchorage loss over a period of 3 months, the respective correlation coefficient value was found to be 0.6659 with the results being statistically highly significant in either case (P < .001). Self-ligating brackets showed double the amount of displacement compared to conventional brackets in some of the cases. Also, chair side time was significantly reduced with self-ligating brackets as against conventional brackets.

Orthodontists' perception of bracket techniques plays a significant role in planning, allowing critical evaluation of the patient's facial aesthetics. To compare the perception of Peruvian orthodontists regarding treatments with self-ligating and conventional brackets. A questionnaire was applied to 168 orthodontic specialists (53% men, average professional experience 9 years) to evaluate preferences for treatment phases, benefits of patient consultation according to the type of bracket, experience with self-ligating brackets, and demographic and clinical characteristics (sex, years of experience, volume of care and length of experience). The Kruskal-Wallis Test and Chi-square test were used with P < 0.05. The total preference for self-ligating brackets (48.9%) was higher than conventional brackets (18.8%). Self-ligating brackets were preferred in most treatment phases (46.4%-63.7%) but not in completion and finishing, in which conventional brackets were preferred. Most orthodontists preferred self-ligating brackets (40.5%-60.7%) over conventional brackets (4.2%-14.3%) due to patient comfort, oral hygiene, and total treatment and appointment time control, but not the cost. The orthodontists reported SLB having mastered their technique in <10 cases (59.5%), the experience of <2 years (45.2%), applying control times of 4-9 weeks (78.6%), and feeling comfortable with their use (89.3%). Preferences were not associated with sex (P > 0.05) but rather with years of professional experience (P < 0.05). Peruvian orthodontists preferred self-ligating brackets over conventional brackets in most treatment phases associated with user comfort and oral hygiene management and treatment/control time, and professional experience. However, some factors, such as cost-effectiveness, counteracted this preference.

IntroductionThis study determined the amount and severity of EARR (external apical root resorption) after orthodontic treatment with self-ligating (SL) and conventional (Non-SL) brackets. Differences regarding rate of extraction cases, appointments and treatment time were evaluated.Material and methods213 patients with a mean age of 12.4 ± 2.2 years were evaluated retrospectively. The treatments were performed with SL brackets (n = 139, Smartclip, 3 M Unitek, USA) or Non-SL brackets (n = 74, Victory Series, 3 M Unitek, USA). Measurements of the crown and root length of the incisors were taken using panoramic radiographs. Three-factor analysis of variance (ANOVA) was performed for an appliance effect.ResultsThere was no difference between patients treated with Non-SL or SL brackets regarding the amount (in percentage) of EARR (Non-SL: 4.5 ± 6.6 vs. SL: 3.0 ± 5.6). Occurrence of severe EARR (sEARR) did also not differ between the two groups (Non-SL 0.5 vs. SL: 0.3). The percentage of patients with need of tooth extraction for treatment (Non SL: 8.1 vs. SL: 6.9) and the number of appointments (Non-SL: 12.4 ± 3.4 vs. SL: 13.9 ± 3.3) did not show any differences. The treatment time was shorter with Non-SL brackets (Non-SL: 18.1 ± 5.3 vs. SL: 20.7 ± 4.9 months).ConclusionsThis is the largest study showing that there is no difference in the amount of EARR, number of appointments and extraction rate between conventional and self-ligating brackets. For the first time we could demonstrate that occurrence of sEARR does not differ between the two types of brackets.

Treatment efficiency of conventional vs self-ligating brackets: Effects of archwire size and material

Orthodontic brackets contribute to the accumulation of bacterial plaque on tooth surfaces because they hinder oral hygiene. In contrast to conventional brackets, self-ligating brackets do not require additional parts to support the arches, thus improving dental hygiene. The aim of this study was to compare the gingival response in orthodontic patients wearing self-ligating or conventional brackets. A sample of 22 patients aged 16 to 30 years was divided into two groups: Group A, treated with selfligating brackets (Damon system) and Group B, treated with conventional brackets (Roth technique). The following were assessed during the treatment: Plaque Index (PI), Gingival Index (GI) and Probing Depth (PD), and sub-gingival samples were taken from teeth 14/24 for microbiological observation. No statistically significant difference was found between Groups A and B; p>0.05 (sign-ranked) or between PI, GI and PD at the different times (Friedman's Analysis of Variance), even though the indices were found to increase at 14 days, particularly for self-ligating brackets. The quantity and quality of microorganisms present were compatible with health on days 0, 28 and 56. As from day 14 there is a predominance of microbiota compatible with gingivitis in both groups. In the samples studied, orthodontic treatment increases bacterial plaque and inflammatory gingival response, but gingival-periodontal health can be maintained with adequate basic therapy. Self-ligating and conventional brackets produced similar gingival response.

Aim:The frictional resistance encountered during sliding mechanics has been well established in the orthodontic literature, and it consists of complex interactions between the bracket, archwire, and method of ligation the claim of reduced friction with self-ligating brackets is often cited as a primary advantage over conventional brackets. This study was done to compare and evaluate the frictional forces generated between fully esthetic brackets and semi-aesthetic self-ligating brackets, which are of passive form and SEM (scanning electron microscope) study of the Brackets after Frictional evaluation.Materials and Methods:Two types of self-ligating esthetic brackets, Damon clear (Ormco) made of fully ceramic and Opal (Ultradent Products, USA) and, Two types of self-ligating semi-esthetic brackets, Clarity SL (3M Unitek) and Damon 3 (Ormco) both of which are made of ceramic with metal slot. Arch wires with different dimensions and quality 17 × 25, 19 × 25 Titanium Molybdenum Alloy (TMA) and 17 × 25, 19 × 25 stainless steel that came from plain strands of wire were used for frictional comparison test. The brackets used in this study had 0.022 × 0.028 inch slot.Results:The statistical tests showed significantly smaller amount of kinetic frictional forces is generated by Damon 3 (semi-esthetic self-ligating brackets). For each wire used, Damon 3 displayed significantly lower frictional forces (P ≤ 0.05) than any of the self-ligating system, followed by Opal (fully esthetic self-ligating brackets) which generated smaller amount of frictional forces but relatively on the higher side when compared with Damon 3. Damon clear (fully esthetic self-ligating brackets) generated the maximum amount of kinetic forces with all types of wire dimensions and properties when compared to the other three types of self-ligating system. Clarity SL (semi-esthetic self-ligating brackets) generated smaller amount of frictional forces when compared with Damon clear and relatively higher amount of frictional forces when compared to Opal and Damon 3

Introduction: Fixed orthodontic appliances can lead to enamel demineralization and gingival changes due to increased biofilm. Aim: To detect the presence of Prevotella intermedia, Tannerella forsythia, Streptococcus mutans, Scardovia wiggsiae, Aggregatibacter actinomycetemcomitans, Fusobacterium nucleatum, and Porphyromonas gingivalis in oral biofilm and presence of white spot lesions and gingivitis in users of self-ligating and conventional brackets. Design: This observational controlled study was conducted from January to December 2020. The participants used fixed orthodontic therapy for 6 months and were divided into a conventional and a self-ligating bracket group. The participants underwent clinical examination, and biofilm samples were collected from their lower incisors. Results: No differences were found in the bacteria detection between the groups (p&gt;0.05). However, white spot lesions were more common in users of self-ligating brackets (p=0.019). There was no association between clinical data and the detection of any microorganism (p&gt;0.05). The fluorescence intensity of A. actinomycetemcomitans was higher in self ligating brackets than in conventional brackets (p&lt;0.05). Implications: The microbial diversit did not differ between the types of brackets; however, the presence of white spot lesions and the amount of A. actinomycetemcomitans were higher in patients with self-ligating brackets.

: In sliding mechanics, a considerable amount of applied force is lost to frictional resistance which places undue stress on the anchor unit. Therefore, for a clinical success with maximal efficiency for canine retraction with sliding mechanics, reduction of the resistance due to friction between brackets and arch wires is important. Self-ligating brackets are claimed to reduce the sliding resistance.: Aim of the study was to compare the clinical outcome of canine retraction using Self ligating brackets and Conventional Brackets during canine retraction. Objectives of the study were to compare the amount of canine retraction using Self ligating brackets and Conventional Brackets and to compare the amount of anchorage loss during canine retraction (CR) using Self ligating brackets and Conventional Brackets.: The study comprised a total of 20 patients aged between 13 and 22 years. Bilateral extraction of the first premolars in maxilla and separate canine retraction was done. A split mouth study design was conducted in which maxillary canines randomly bonded with self-ligating and conventional brackets. Study models were used for the measurement of canine retraction, anchorage loss and canine rotation. Statistical analysis was done. Self-ligating and conventional brackets produced similar amount of canine retraction and anchorage loss of the maxillary molars. Self-ligating brackets gave better rotation control of maxillary canines than conventional brackets. Self-ligating and conventional brackets gave similar results for the amount of canine retraction and anchorage loss. Self-ligating brackets give better rotational control.

Evaluation of maxillary arch dimensional and inclination changes with self-ligating and conventional brackets using broad archwires.

Objectives To compare the intrusive forces and labio-palatal moments generated at the maxillary incisors by a 0.017 x 0.025 inch reverse curve NiTi wire using self-ligating and conventional brackets. Methods Ten 0.017 x 0.025 inch reverse curve NiTi archwires were used with each of the following 0.022 inch bracket systems: Titanium Ortho (Ormco/Sybron, CA, USA), In-Ovation R (GAC International, NY, USA) and Damon System 3MX (Ormco/Sybron, CA, USA). The wires were inserted on bracketed maxillary Frasaco models, with segmented maxillary incisors. Simulated intrusion from 0.0-1.0 mm was performed on the Orthodontic Measurement and Simulation System, which recorded the intrusive forces and the labio-palatal moments at 0.05 mm increments. The data were analysed with the ANOVA and Scheffe tests. Results The intrusive forces were significantly different between all bracket types. The highest force was recorded with the conventional Titanium Orthos brackets (8.2 N), followed by the Damon 3MX brackets (6.3 N) and the In-Ovation R brackets (5.5 N). The moments were found to be significantly different between the conventional and the self-ligating brackets, but not between the two types of self-ligating brackets. The highest moments were recorded with the self-ligating brackets (16.6-16.9 N/mm), followed by the conventional brackets (10.8 N/mm). Conclusions The intrusive forces exerted on the maxillary incisors by a 0.017 x 0.025 inch reverse curve NiTi archwire during the final 1 mm of levelling are very high and beyond the necessary intrusive force level for these teeth. Lower intrusive forces, but higher labio-palatal moments, were recorded with the self-ligating brackets.