Elastomeric Ligatures Research Articles

Evaluation of Force Degradation Pattern of Elastomeric Ligatures and Elastomeric Separators in Active Tieback State.

Background and aims. The purpose of this study was to evaluate initial force and force decay of commercially available elastomeric ligatures and elastomeric separators in active tieback state in a simulated oral environment.Materials and methods. A total of 288 elastomeric ligatures and elastomeric separators from three manufacturers (Dentaurum, RMO, 3M Unitek) were stretched to 100% and 150% of their original inner diameter. Force levels were measured initially and at 3-minute, 24-hour, and 1-, 2-, 3- and 4-week intervals. Data were analyzed by univariate analysis of variance and a post hoc Tukey test.Results. The means of initial forces of elastomeric ligatures and separators from three above-mentioned companies, when stretched to 100% of their inner diameters, were 199, 305 and 284 g, and 330, 416, 330 g; when they were stretched to 150% of their inner diameters the values were 286, 422 and 375 g, and 433, 540 and 504 g, respectively. In active tieback state, 11-18% of the initial force of the specimens was lost within the first 3 minutes and 29-63% of the force decay occurred in the first 24 hours; then force decay rate decreased. 62-81% of the initial force was lost in 4 weeks. Although force decay pattern was identical in all the products, the initial force and force decay of Dentaurum elastomeric products were less than the similar products of other companies (P<0.05). Under the same conditions, the force of elastomeric separators was greater than elastomeric ligatures of the same company.Conclusion. Regarding the force pattern of elastomeric ligatures and separators and optimal force for tooth movement, many of these products can be selected for applying orthodontic forces in active tieback state.

A comparative study of the physical and elastic properties of new generation elastomeric ligatures with conventional elastomeric ligatures

Context: One of the most common methods of securing arch wires to orthodontic brackets is the application of elastomeric ligatures. New generation elastomeric ligatures were introduced to overcome the disadvantages of force decay and staining in conventional ligatures. Aims: The aim was to compare the physical and elastic properties of new generation elastomeric ligatures with the conventional elastomeric ligatures. Materials and Methods: Four groups of clear elastomeric modules (conventional polyurethane based modules, latex free elastomeric modules, alastik easy to tie modules, silver and silicone impregnated super ligatures) were tested for tensile properties, frictional resistance, and color stability in as received condition and following 1-week, 2 weeks, and 1-month of intra-oral exposure. A universal testing machine was used for testing tensile properties. The color stability was tested by measuring the color change using scanned images of the modules at different time periods. Statistical Analysis: Two-way ANOVA, post-hoc multiple comparisons Bonferroni-Dunn test and the paired t-test were used. Results: The alastik group showed the highest mean tensile strength and super ligatures showed the lowest tensile strength values. There was a statistically significant decrease in the mean tensile strength in all groups following intra-oral exposure (P Conclusions: There are significant differences in physical and elastic properties of different brands of ligatures, which should be considered during the selection of these products.

Evaluation of the effect of different stretching patterns on force decay and tensile properties of elastomeric ligatures.

There have been numerous researches on elastomeric ligatures, but clinical conditions in different stages of treatment are not exactly similar to laboratory conditions. The aim of this in vitro study was to simulate clinical conditions and evaluate the effect of three stretching patterns on the amount of force, tensile strength (TS) and extension to TS of the elastomers during 8 weeks. Forces, TS and extension to TS of two different brands of elastomers were measured at initial, 24 h and 2, 4, and 8-week intervals using a testing machine. During the study period, the elastomers were stored in three different types of jig (uniform stretching, 1 and 3 mm point stretching) designed by the computer-aided design and computer-aided manufacturing technique in order to simulate the different stages of orthodontic treatment. The elastomeric ligatures under study exhibited a similar force decay pattern. The maximum force decay occurred during the first 24 h (49.9% ± 15%) and the amount of force decay was 75.7% ± 8% after 8 weeks. In general, the TS decreased during the study period, and the amount of extension to TS increased. Although the elastic behavior of all ligatures under study was similar, the amount of residual force, TS and extension to TS increased in elastomers under point stretching pattern.

Reliability of Digital Camera over Spectrophotometer in measuring the Optical Properties of Orthodontic Elastomeric Ligatures

Reliability of Digital Camera over Spectrophotometer in measuring the Optical Properties of Orthodontic Elastomeric Ligatures

An Investigation of Fluoride Release from Orthodontic Elastomeric Ligatures

Objective: The study aimed to investigate the amount of fluoride release from 3 brands of elastomeric ligatures in vitro, after exposure to daily fluoride mouthrinse. Materials and Methods: The study used 3 brands of elastomeric ligatures (Morelli, Brazil; Unitek, USA; Thai, Thailand). Two elastomeric ligatures from each brand were moistened by de-ionized water and then divided into control and test groups (n=5 per group). In both groups, elastomeric ligatures were placed in individual plastic bottle with 3 ml of de-ionized water. However, In the test group, They were exposed to fluoride mouthrinse (250 ppm fluoride/0.05%NaF) for 1 minute daily. All samples were stored at 37°C for 1, 3, 5, 7 days. After the end of each observation period, the amount of fluoride release in de-ionized water was measured by fluoride ion electrode. The data were analyzed by Kraskal-Wallis and Mann-Whitney U tests (p&lt;0.05). Results: Amount of fluoride release in test group was greater than in the control group in all 3 brands. Within 7 days of daily fluoride exposure, the fluoride released from elastomeric ligatures was continuously increased. Fluoride release from Morelli (0.067±0.013 ppm) and Unitek (0.067±0.012 ppm) were significantly higher than Thai (0.040±0.03 ppm). The fluoride level measured from Morelli and Unitek were not significantly different. Conclusion: The orthodontic elastomeric ligatures can absorb fluoride from mouthwash and release the detectable amount of fluoride within seven days. This fluoride might help prevention of enamel decalcification adjacent to the bracket during orthodontic treatment.

Effect of tooth displacement and vibration on frictional force and stick-slip phenomenon in conventional brackets: a preliminary in vitro mechanical analysis.

To evaluate the effects of tooth displacement and vibration on frictional force and stick-slip phenomenon (SSP) when conventional brackets were used with a levelling/alignment wire. The samples consisted of six groups (n = 10 per group) with combinations of tooth displacement (2mm lingual displacement [LD], 2mm gingival displacement [GD], and no displacement [control]) and vibration conditions (absence and presence at 30 Hz and 0.25 N). A stereolithographically made typodont system was used with conventional brackets and elastomeric ligatures. After application of artificial saliva, static/kinetic frictional forces (SFF/KFF) and frequency/amplitude of SSP were measured while drawing a 0.018-inch copper nickel-titanium (Cu-NiTi) archwire at a speed of 0.5mm/min for 5 minutes at 36.5 degree celsius. Two-way analysis of variance and independent t-test were performed. Tooth displacement increased SFF and KFF (control < LD < GD, all P < 0.001) and reduced SSP frequency (control > [LD, GD], P < 0.01). Vibration reduced SFF, KFF, and SSP amplitude in the control group (P < 0.05, P < 0.05, and P < 0.001, respectively), but not in the LD and GD groups. SSP frequency was increased by vibration in the control, LD, and GD groups (all P < 0.001), and it was lower in the LD and GD groups than in the control group (P < 0.01). When conventional brackets and a 0.018-inch Cu-NiTi archwire were used in the tooth displacement conditions (LD and GD), vibration did not significantly reduce SFF, KFF, or SSP amplitude.

Comparison of frictional resistance between self-ligating and conventional brackets tied with elastomeric and metal ligature in orthodontic archwires

ObjectiveTo compare the frictional resistance between self-ligating and conventional brackets tied to different types of wire.Material and MethodsAbzil Kirium Capelozza (Pattern I) and Easy Clip (Roth prescription) incisor brackets were used. An elastomeric ligature or a ligating wire 0.10-in was used to ligate the wire to the Abzil bracket. Three types of orthodontic archwire alloys were assessed: 0.016-in NiTi wire, 0.016 x 0.021-in NiTi wire and 0.019 x 0.025-in steel wire. Ten observations were carried out for each bracket-archwire angulation combination. Brackets were mounted in a special appliance, positioned at 90 degrees in relation to the wire and tested in two angulations. Frictional test was performed in a Universal Testing Machine at 5 mm/min and 10 mm of displacement. The means (MPa) were submitted to ANOVA and Tukey's test set at 5% of significance. The surfaces of wires and brackets were observed at SEM.ResultsSteel-tied brackets (16.48 ± 8.31) showed higher means of frictional resistance than elastomeric-tied brackets (4.29 ± 2.16 ) and self-ligating brackets (1.66 ± 1.57) (P < 0.05), which also differed from each other (P < 0.05). As for the type of wire, 0.019 x 0.025-in steel wire (5.67 ± 3.97) showed lower means (P < 0.05) than 0.16-in NiTi wire (8.26 ± 10.92) and 0.016 x 0.021-in NiTi wire (8.51 ± 7.95), which did not differ from each other (P > 0.05). No statistical differences (P > 0.05) were found between zero (7.76 ± 8.46) and five-degree (7.19 ± 7.93) angulations.ConclusionsFriction was influenced not only by the type of bracket, but also by the ligating systems. Different morphological aspects were observed for the brackets and wires studied

Effect of Bracket’s Slot Size on Canine Position and Space Closure Rate (A Typodont Study)

This study aimed to determine the effect of newly introduced 0.020” slot size brackets on di-mensional positions and space closure ratio of mandibular canine. Material and Methods: The study includes six groups according to slot sizes (0.018”, 0.020” and 0.022”) and materials of canine retrac-tion (elastomeric power chain and closed coil spring). A 200 gm of retraction force was used on 0.017” X 0.025” stainless steel wire ligated to brackets by elastomeric ligatures along 13 mm available space. After immersion of the typodont in water bath with (50-55) C for 5 minutes, the rate of space closure were measured in millimeter using vernier (from the distal wings of canine bracket and the mesial wings of the second premolar), In both vertical and horizontal directions, digital images were taken by camera and the angle between canine extension bar )C B) and bite plane extension bar (BPB) was measured by protractor to determine tipping and rotation. Results: The results showed that 0.022” slot bracket groups had highest amount of rate of space clo-sure tipping and rotation, while 0.020” slot brackets groups had higher space closure rate than 0.018” slot brackets groups. Conclusions: bracket slot 0.022” groups showed higher tipping, rotation and space closure rate, while 0.020” slot brackets groups had higher rate of space closure with same or bet-ter rotation and tipping control in comparison with 0.018” slot bracket groups

Physical and chemical properties of orthodontic brackets after 12 and 24 months: in situ study.

ObjectiveThe aim of this article was to assess how intraoral biodegradation influenced the surface characteristics and friction levels of metallic brackets used during 12 and 24 months of orthodontic treatment and also to compare the static friction generated in these brackets with four different methods of the ligation of orthodontic wires.Material and MethodsSeventy premolar brackets as received from the manufacturer and 224 brackets that were used in previous orthodontic treatments were evaluated in this experiment. The surface morphology and the composition of the deposits found in the brackets were evaluated with rugosimetry, scanning electron microscopy, and energy dispersive X-ray spectroscopy. Friction was analyzed by applying tensile tests simulating sliding mechanics with a 0.019x0.025" steel wire. The static friction levels produced by the following ligation methods were evaluated: loosely attached steel ligature around all four bracket wings, steel ligature attached to only two wings, conventional elastomeric ligation around all 4 bracket wings, and non-conventional Slide® elastomeric ligature.ResultsThe results demonstrated the presence of biodegradation effects such as corrosion pits, plastic deformation, cracks, and material deposits. The main chemical elements found on these deposits were Carbon and Oxygen. The maximum friction produced by each ligation method changed according to the time of intraoral use. The steel ligature loosely attached to all four bracket wings produced the lowest friction levels in the new brackets. The conventional elastic ligatures generated the highest friction levels. The metallic brackets underwent significant degradation during orthodontic treatment, showing an increase in surface roughness and the deposit of chemical elements on the surface.ConclusionThe levels of static friction decreased with use. The non-conventional elastic ligatures were the best alternative to reduce friction.

Effect of 2 elastomeric ligatures on microbial flora and periodontal status in orthodontic patients

The aim of this study was to compare the effects of a nonconventional elastomeric ligature (Slide; Leone, Florence, Italy) with those of a conventional elastomeric ligature (Ormco, Orange, Calif) on microbial flora and periodontal status in orthodontic patients. A total of 13 orthodontic patients scheduled for fixed orthodontic treatment were selected for this study. The use of Slide and conventional elastomeric ligatures in fixed orthodontic appliances was tested. Microbial and periodontal records were obtained before bonding and 1 and 5 weeks after bonding. For the statistical analysis and calculations, SPSS software (version 15.0; SPSS, Chicago, Ill) was used. In the statistical decisions, P <0.05 values were accepted as significantly different. No significant differences between Slide and conventional elastomeric ligatures were evident at 1 week or 5 weeks after bonding, with regard to gingival index, plaque index, gingival bleeding index, or pocket depth scores (P >0.05). Similarly, aerobic and anaerobic bacteria counts did not differ significantly on the surface or on the elastics (P >0.05). Although the Slide ligatures cover the total surface of the bracket, they do not cause significantly more plaque accumulation or periodontal problems than do the conventional elastomeric ligatures.

A comparative in-vivo evaluation of the alignment efficiency of 5 ligation methods: A prospective randomized clinical trial.

Objectives:To conduct a prospective randomized study comparing the efficiency of 5 different ligation systems (ELL; elastomeric ligature, SSL; stainless steel ligature, LL; leone slide ligature, PSL; passive self-ligation and ASL; active self-ligation) over the duration of mandibular crowding alleviation.Materials and Methods:Fifty consecutive patients (54.2% male, 45.8% female; mean age: 16.69 years) satisfying the inclusion criteria were randomly allocated to 5 ligation groups with an equal sample size of 10 per group. The 5 groups received treatment with 0.022-inch MBT pre-adjusted edge-wise technique (ELL: Gemini 3M Unitek, SSL: Gemini 3M Unitek, LL: Gemini 3M Unitek, PSL: SmartClip 3M Unitek and ASL: In-Ovation R Euro GAC International). The models and cephalograms were evaluated for anterior arch alignment, extraction space closure, and lower incisal inclinations at pre-treatment T1 and at the end of initial alignment T2. Analysis of variance (ANOVA) and Post-hoc tests were used for data analysis.Results:Forty-eight participants completed the study, and SL systems showed a significant difference over CL groups in time to alignment, passive space closure, and incisal inclination. Multiple regression showed a reduction of 5.28 days in time to alignment by changing the ligation group in the order of ELL to ASL group and 1 mm increase in initial irregularity index increases time to alignment by 11.68 days.Conclusion:Self-ligation brackets were more efficient than conventional ligation brackets during initial leveling and alignment.

Surface Characteristics, Chemical Composition and Ni Release of NiTi Wire in Different pH

Objective: To study the surface characteristics, chemical composition and Ni release from simulated standard fixed orthodontic appliance ligated with two differently priced nickel titanium (NiTi) archwires in artificial saliva at pH 5.14 and 6.69 for 4 weeks at 37oC. Materials and Methods: Two commercial NiTi rectangular wire (Ormco and Smart), 0.016 x 0.022 in size were studied. Their surface characteristics were evaluated: surface morphology by scanning electron microscope, surface roughness by surface roughness tester and grain structure analysis by optical microscope. Their chemical composition was analyzed by an energy dispersive X-ray spectrometer (EDC). For Ni release, twenty-eight simulated standard fixed orthodontic appliance samples sets, each set corresponding to one half-maxillary arch were used. Sample sets were divided in 2 groups (14 sets per group). The first group was ligated with Ormco NiTi archwires (USA) and the second with Smart NiTi archwires (China) with elastomeric ligatures. Half sets of each group were immersed in 50 ml artificial saliva at pH 5.14, and the other half at pH 6.69. Ni release was quantified with the use of flame atomic absorption spectrophotometry. Statistical analysis of variance was determined on days 1, 4, 7, 9, 14, 21 and 28 comparing Ni release between the groups and t-test was determined the difference between pH 5.14 and pH 6.69. Results: The suface morphology showed striations along the longitudinal axes. The Ormco NiTi wire had more surface roughness than Smart NiTi wire and the diameter of grain sizes were 2-8 μm. The chemical composition of the two NiTi wires was Ni, Ti, Cu, Al, and Cr but there was difference in the percentage of elements. Both Ormco NiTi and Smart NiTi wires continuously increased Ni release at time intervals at both pH levels. The Ormco NiTi wire had more Ni release at pH 6.69 than pH 5.14 but Smart NiTi wire had more Ni release at pH 5.14 than 6.69. At 4 weeks, the Ni release of one half-maxillary arch was 1.221 ppm (1221 μg/l) at pH 5.14, 1.267 ppm (1267 μg/l) at pH6.69 for Ormco NiTi wire and 2.175 ppm (2175 μg/l) at pH 5.14, 0.676 ppm (676 μg/l) at pH 6.69 for Smart NiTi wire. No significant difference was found in Ni release from Ormco and Smart NiTi wires at pH 5.14. At pH 6.69, no significant difference was found in Ni release from Ormco NiTi wires while Smart NiTi wire showed significant difference (p &lt;0.05) on days 14, 21 and 28. Conclusion: Ni release depends on surface characteristics and chemical composition of archwires and pH.

Reliability of Digital Camera over Spectrophotometer in measuring the Optical Properties of Orthodontic Elastomeric Ligatures

Objective: The aim of this study is to evaluate the reliability of digital camera and spectrophotometer in measuring the optical properties of clear elastomeric ligatures under the influence of different solutions. Materials and methods: Four hundred and thirty-two clear elastomeric modules from three manufacturers (3M, ORMCO, OT) were used and were immersed into six different solution of three segments each. Each solution (200 ml) containing a determined substance, as follows: distilled water (control group), coke, turmeric, sauce (20 ml), tea and coffee. All test specimens were immersed in the solutions and kept in an appropriate receptacle for 7, 14, 21 and 30 days. The differences in color changes depen ding on the type of elastomeric modules, immersion solution, and immersion period were analyzed by using the spectro photometer and digital camera. Results: These results were analyzed statistically using the software SPSS version 11.5. 3M showed the least and OT showed the highest staining with all types of immersion solutions. Coffee showed the highest while coke showed the least amount of discoloration. As the immersion time increases, amount of discoloration of elastomeric modules increases.

Comparison of Chemical Properties and Ni Release of Stainless Steel and Nickel Titanium Wires

Objective: This study aimed to determine the composition and corrosion resistance of stainless steel and nickel titanium (NiTi) archwires and to compare Ni released from simulated standard fixed orthodontic appliances ligated with stainless steel and NiTi wires in artificial saliva at pH 5.14 and pH 6.69. in 4 weeks at 37oC. Materials and Method: Two commercial rectangular wires, 0.016 x 0.022 in size were studied, one Ormco stainless steel wire and another Ormco nickel titanium wire. Their composition was analyzed by an energy disporsive X-ray spectrometer (ESC) and their corrosion resistance was evaluated by a potentiodynamic polarization technique. For Ni release, the twenty-eight simulated fixed appliance sample sets were used, each corresponding to one half-maxillary arch. The samples were divided in 2 groups (14 sets per group). The first one was ligated to Ormco stainless steel archwires and the other one to Ormco NiTi archwires with elastomeric ligatures. Half sets of each group were immersed in 50 ml artificial saliva at pH 5.14 and the other half were immersed at pH 6.69. Ni release was quantified using flame atomic absorption spectrophotometry. Statistical analysis of variance (t-test) was determined on days 1, 4, 7, 9, 14, 21 and 28 comparing the amount of Ni released between groups. Results: Stainless steel wire was composed of Ni, Cr, Si, Mn and Fe while the nickel titanium wire was composed of Ti, Ni and Cr. NiTi wire has more percentage of Ni and therefore has less corrosion resistance than stainless steel wire. For Ni release, stainless steel and NiTi continuously increased at the time intervals for both pH levels. For group one, stainless steel wire had more Ni release at pH 5.14 and for the other group, NiTi wire had more Ni-release at pH 6.69. At 4 weeks, the Ni release of one half-maxillary arch was 1.383 ppm (1383 μg/l) at pH 5.14 and 1.079 ppm (1078 μg/l) at pH 6.69 for stainless steel wire while it was 1.221 ppm (1221 μg/l) at pH 5.14 and 1.267 ppm (1267μg/l) at pH 6.69 for NiTi wire. No significant difference was found in the amount of Ni release from stainless steel and NiTi wires at pH 5.14 and pH 6.69 in the different time intervals except on day 1 wherein the stainless steel archwire was significantly different (p&lt;0.05) at pH 5.14 and pH 6.69. Conclusions: The NiTi wire had more Ni contain and less corrosion resistance than stainless steel wire. Stainless steel had more Ni release at pH 5.14 than pH 6.69 but NiTi had greater Ni release at pH 6.69 than pH 5.14.

Evaluation of friction in orthodontics using various brackets and archwire combinations-an in vitro study.

The aim of this study was to compare frictional resistance which was produced between conventional brackets (0.022 slot Otho-Organiser) and self ligating brackets (active Forestadent and passive Damon III) by using various arch wire combinations (0.016 Niti, 0.018 Niti, 0.017 x 0.025 SS and 0.019 x 0.025 SS). An experimental model which consisted of 5 aligned stainless steel 0.022-in brackets was used to assess frictional forces which were produced by SLBs (self ligating brackets) and CELs (conventional elastomeric ligatures) with use of 0.016 nickel titanium, 0.018 nickel titanium, 0.017 X 0.025"stainless steel and 0.019 X 0.025"stainless steel wires. One way ANOVA test was used to study the effect of the bracket type, wire alloy and section on frictional resistance test . Conventional brackets produced highest levels of friction for all bracket/archwire combinations. Both Damon III and Forestadent brackets were found to produce significantly lower levels of friction when they were compared with elastomerically tied conventional brackets. SLBs are valid alternatives for low friction during sliding mechanics.

The effects of different orthodontic appliances upon microbial communities

Orthodontic appliances can promote accumulation of dental plaque, with associated enamel decalcification or gingival inflammation. The aim of this study was to examine longer-term microbiological changes during orthodontic treatment with fixed appliances. Twenty-four orthodontic patients aged 11-14 years undergoing fixed appliance therapy were recruited into the study. Each was randomized for cross-mouth assignment of molar bands and bonded molar tubes to contralateral quadrants of the mouth. All patients received self-ligating brackets, but again using randomization, one upper lateral incisor bracket (left or right) also received an elastomeric ligature. Plaque samples from the molars and upper lateral incisors were obtained at intervals during treatment and up to 1 year after appliance removal. Denaturing gradient gel electrophoresis and 16S rDNA microarray were used to compare plaque microbial fingerprints. Plaque populations changed within 3 months of commencing treatment at all sites. The greatest differences in plaque composition were seen with self-ligating brackets with an elastomeric ligature. Post-treatment plaque associated with both types of molar attachment contained increased levels of periodontal pathogens Porphyromonas gingivalis, Tannerella forsythia, and Eubacterium nodatum, while Campylobacter rectus, Parvimonas micra, and Actinomyces odontolyticus were also elevated with bonds. The results suggest that orthodontic treatment may cause sustained changes in plaque microbiotas and that molar bond-associated plaque may have raised disease potential.

Evaluation of the cytotoxicity of elastomeric ligatures after sterilisation with 0.25% peracetic acid

Abstract Introduction: Sterilisation using peracetic acid (PAA) has been advocated for orthodontic elastic bands. However, cane-loaded elastomeric ligatures can also become contaminated during processing, packaging, and manipulation before placement in the oral cavity and are therefore susceptible, and possible causes, of cross-contamination. Aim: To test the hypothesis that 0.25% peracetic acid (PAA), following the sterilisation of elastomers, influences the cytotoxicity of elastomeric ligatures on L929 cell lines. Materials and methods: Four hundred and eighty silver elastomeric ligatures were divided into 4 groups of 120 ligatures to produce, Group TP (latex natural, bulk pack, TP Orthodontics), Group M1 (Polyurethane, bulk pack, Morelli), Group M2 (Polyurethane, cane-loaded, Morelli) and Group U (Polyurethane, cane-loaded, Uniden). Of the 120 ligatures in each group, 100 were sterilised in 0.25% PAA at time intervals (N = 20) of 1 hour, 2 hours, 3 hours, 4 hours and 5 hours. The 20 remaining elastomeric ligatures in each group were not sterilised and served as controls. Cytotoxicity was assessed using L929 cell lines and a dye-uptake method. Analysis of variance (ANOVA), followed by the Tukey post hoc test (p &lt; 0.05) determined statistical relevance. Results: There was a significant difference between TP, Morelli and Uniden elastomerics (p &lt; 0.05), but no difference between the two types of Morelli elastomerics at the 1 hour time interval. In addition, there was a significant difference between Group CC and the other groups assessed, except between Groups CC and TP at the 1 hour time interval. The non-sterilised elastomeric ligatures showed similar cell viability to that observed after 1 hour of standard sterilisation. Conclusion: PAA did not significantly influence the cytotoxicity of elastomeric ligatures after a sterilisation time of 1 hour and is therefore recommended for clinical use.

Evaluation of Friction of Different Ligation Methods In Accordance With and Without Bracket Types

ABSTRACT Objective: The aim of this in vitro study was to evaluate the frictional values of 3 different ligation methods with different bracket types using a crowded configuration. Materials and Methods: Three aesthetic conventional brackets (monocrystalline ceramic, polycrystalline ceramic, microfilled copolymer) and 1 metal bracket were evaluated in terms of friction. All brackets were tested in a crowded configuration of bracket alignment with 0.014 nickel titanium archwire in place. All brackets were ligated with metal ligatures, elastomeric ligatures, and nonconventional elastomeric ligatures. For accurate and repeatable placement on metal plates, a special jig was designed. The pulling speed was set to 10 mm/min for 30 seconds for each sample. Results: When bracket structure was not considered, nonconventional elastomeric ligature produced the lowest friction. For brackets ligated with elastomeric modules, microfilled copolymer bracket showed the lowest friction and monocrystalline ceramic bracket s...

Comparison of Dimensions and Residual Forces of Various Orthodontic Elastomeric Ligatures

Objective: The study aimed to compare dimensions and residual forces of various commercial type orthodontic elastomeric ligatures available in Thailand. Materials and Methods: The study compared 5 types of elastomeric ligatures: MU-MTEC, UnitekTM, MorelliTM, WelovehealthTM and DentsplyTM. A digital caliper was used to measure dimensions: the inner and outer diameters and cross-sectional thickness. Then the initial extension force and residual force on days 1, 2, 3, 4, 5, 6, 7, 14 and 28 were measured according to ISO 21606: 2007. The data were analyzed with the Kruskal-Wallis test and Spearmans rank correlation. Results: No significant difference was found between the outer diameter of MU-MTEC and WelovehealthTM. However, significant mean differences were found in dimensions among the other ligature types. The lowest mean for inner diameter and cross sectional thickness was found in UnitekTM and the lowest mean for outer diameter was found in MorelliTM. The highest mean inner diameter, outer diameter and cross sectional thickness was found in Dentsply, UnitekTM, and MorelliTM, respectively. In terms of initial extension force, significant differences (p&lt;0.001) were found among all samples. The highest mean was found in DentsplyTM (2.69 N) and the lowest mean was found in WelovehealthTM (1.80 N). All samples had rapid force degradation at about 42.21-56.23% after 24 hours, with a slow degradation rate until Week 1 and a constantly stable rate from Weeks 1-4. The greatest force decay on the first day was found in MorelliTM (56.23%). At 28 days, the residual force for all types of elastomeric ligature was about 31.97-46.84%. Conclusion: All 5 brands of commercial elastomeric ligatures had different dimensions, initial extension forces and residual forces. The correlation between brand and dimension, initial extension force and residual force showed different patterns. All elastomeric ligatures had greater force decay on the first day (residual force 43.77 57.79%), then slightly decreased over 28 days.

English

Fixed or removable orthodontic appliances impede the maintenance of oral hygiene and result in plaque accumulation. Many studies have evaluated the effects of fixed orthodontic appliances on microbial flora and periodontal status, but only a few have evaluated the method of ligation as an additional factor. AIMS AND OBJECTIVES: To determine the amount of microbial colonization with different elastomeric ligation techniques. MATERIALS AND METHODS: Subjects for this study was selected on the basis of good oral hygiene. Amount of microbial colonization was evaluated from both right and the left sides of the maxillary dental arch at day 1 that is (after receiving through oral prophylaxis) and then the arch wire ligated with split mouth technique using Super Slick ties (TP Orthodontics) and Dumbell ligatures (Leone) on right side & Aelastixs- Quick stick ties- Angulated ties (3M Unitek) and Aelastixs- Easy to fit Ties (3M Unitek) on left side. Elastomeric ligatures were removed from the patients' mouth after a period of 7 days and sent for culture of the aerobic and anaerobic bacterial colonies. The amount of microbial colonies was then compared using stereomicroscope. RESULTS: The current study revealed that the teeth ligated with elastomeric rings exhibited greater number of aerobic as well as anaerobic microorganisms and the difference was found to statistically significant.