Comparison of force decay pattern in orthodontic elastomeric chains and NiTi closed coil springs, affected by five different mouthwashes: An in vitro Study

Background: The aim of this study was to compare the force decay pattern of elastomeric chains and NiTi coil springs which were exposed to five different commercially available mouthwashes.Methods: In this in vitro study, 60 pieces of elastomeric chain (EC) and 60 NiTi closed coil springs (CS) were divided into 6 groups. The specimens were exposed to one of these mouthwashes twice a day for 60 seconds: Listerine, chlorhexidine, Orthokin, Persica, fluoride and artificial saliva as the control group. The elastomeric chains and NiTi springs were stretched so that they exert the initial force of 250 gr. Their force was measured on the 1, 7, 14 and 28 following days by means of a digital gauge.Results: Elastomeric chains and coil springs had force decrease over time, but EC' force reduction was greater with the highest reduction rate in the first week. However, in the CS group, the force decrease wasn't statistically significant in the first two weeks. After 28 days in the control groups, 49.8% of the initial force was remained in ECs while the value was 93.3% for CSs. In comparison between mouthwashes, in EC groups, in all mouthwashes except Persica, the remained force was statistically less than control group.Conclusion: Force degradation of elastomeric chains could be exacerbated by use of mouthwashes. About coil springs, force decay was also observed. However, it was not statistically significant. Force reduction was detectable after four weeks of coil springs usage, but in EC groups, the greatest reduction was after the first week.

Friction evaluation of an elastic chain positioned under or over the wire in self-ligating brackets

Objectives: This study aimed to evaluate the frictional resistance produced by active and passive self-ligating brackets on stainless steel archwires in the absence or presence of elastomeric chains under or over the wire. Materials and Methods: Four types of self-ligating brackets were used: Two active and two passive. For each commercial brand, five brackets were bonded to an acrylic plate and the frictional resistance was evaluated with 0.018” and 0.019” × 0.025” stainless steel wires in three situations: Without elastomeric chain, with elastomeric chain placed under and over the wire. Results: The bracket type, cross-section of the wire, and type of ligation had significant interactions with each other; the frictional resistance was significantly lower with the use of passive self-ligated brackets, while no difference was found when a 0.018” wire was tested. Moreover, the frictional resistance in the absence of an elastomeric chain, or when the chain was under the wire, was significantly lower in comparison with the values obtained when the chain was placed on the wire. Conclusion: Frictional resistance of passive and active self-ligated brackets is influenced by the ligation methods and the cross-sectioning of archwires.

Force Degradation of Elastomeric Chains after Storage Time and Mechanical Brushing

The purpose of this in vitro study was to evaluate the force decrease of different elastomeric chains after different times: initial, 10 minutes, 1 day, 28 days and after mechanical brushing. Twenty orthodontic elastomeric chains segments were utilized for each commercial brand. Initially, the elastomeric chain of 15mm long were immediate stretched up to 20 mm in an Instron and the force was measured in gf. After all specimens were placed stretched on rectangular acrylic jigs with distance of 20 mm, immersed in deionized water at 37oC for 10 minutes and the force (gf) was measured again. Five test measurements of remaining force were made at the following time intervals: initial, 10 minutes, 1 day, 28 days and mechanical brushing. After 28 days, the acrylic plates with the specimens were adapted in the mechanical brushing machines (MSCT 3) and the elastomeric chains were submitted to mechanical brushing and the force (gf) measure again. The force (gf) was submitted to mixed-model ANOVA and Sidak post-hoc test (α=0.05). A statistically significant reduction in the force was found for all orthodontic elastomeric chain types after 1 day, 28 days and mechanical brushing (p<0.05). Morelli and 3M Unitek elastomeric chains showed significantly higher force than Abzil and GAC (p<0.05) after 1 day, 28 days and mechanical brushing. In conclusion, the force delivered by all elastomeric chains decayed rapidly over time. Morelli and 3M Unitek elastomeric chains consistently had a significantly greater force after mechanic brushing, while GAC the lowest.

UNILATERAL BIJAW PREMOLAR EXTRACTIONS FOR CORRECTION OF CROWDING, BUCCALLY PLACED CANINES AND ASYMMETRIC DENTAL MIDLINE - A CASE REPORT

This case report is of a 22 year old male patient who presented with irregularly placed and crowded teeth in bothmaxillary and mandibular arch on the right side with both upper and lower dental midlines shifted to the patients right. This case was corrected non surgically merely by employing simple mechanics with the help of Fixed Orthodontic Mechanotherapy by extracting a single maxillary and mandibular 1st premolar of right side followed by retraction and closure of spaces with the help of Elastomeric chains. The case ended in a Class I Molar and canine relationship bilaterally. The case report emphasizes on the need for extracting 1st premolars only on 1 side in the upper and lower arch for the purpose of correcting the shifted dental midlines. The extractions also favour correction of crowding and buccally placed upper and lower canines on the right side. Following fixed orthodontic treatment, marked improvement in patients smile was achieved and there was a remarkable increase in the patients confidence and quality of lifeThe profile changes and treatment results were demonstrated with proper case selection and good patient cooperation with Fixed appliance therapy. The patient was extremely satisfied with the results at the end of treatment.

Comparison of force degradation and color change of esthetic elastomeric chains

Objective: this study compared the force degradation and color change of esthetic elastomeric chains of four commercial brands. Materials and methods: the study analyzed 10 medium-force esthetic elastomeric chains with 6 links of Morelli, Orthometric, Eurodonto and 3M brands from sealed packages within the expiration date. The elastics were stretched twice their length, according to the manufacturer's recommendations, and were immersed in artificial saliva at 37°C. The forces were measured with an orthodontic dynamometer at onset and at intervals of 1, 7, 14, 21 and 30 days after immersion. The force degradation was evaluated calculating the percentage of force lost in relation to the initial force in each time interval, for each group tested separately and also between them. The color change was evaluated by visual analysis scale by observation of photographs of chain elastics before and after study completion by 31 examiners. The ANOVA test of repeated measures was applied considering 2 factors, time and groups, and the Tukey test was used for analysis of multiple comparisons. A significance value of 0.05% was adopted for the analyses. Results: the elastics showed great force degradation. After 7 days the groups presented degradation around 50% of the initial force. In the evaluation between groups, the elastics showed significantly different mean forces. When assessing color change, the scores assigned by examiners evidenced less color changes for elastics of Eurodonto brand. Conclusion: regardless of the commercial brand, transparent elastomeric chains show significant force degradation values ​​after 1 day. The scores assigned to color change evidenced that all commercial brands showed staining, with the best results for Eurodonto elastics.

Effect of sodium fluoride in chlorhexidine mouthwashes on force decay and permanent deformation of orthodontic elastomeric chain

Introduction: Orthodontic elastomeric chain is polyurethane elastomer that is widely used among orthodontists due to its functions. Chlorhexidine (CHX) and sodium fluoride (NaF) are listed in mouthwash composition which could affect the mechanical properties of the elastomeric chain. This study was aimed to analyze the effect of sodium fluoride in chlorhexidine mouthwashes on force decay and permanent deformation of orthodontic elastomeric chains. Methods: This research is an experimental analytic laboratory with pretest-posttest control group design. 150 samples of orthodontic chains were divided into three groups. Group 1: artificial saliva (control group); Group 2: 0,1% chlorhexidine gluconate solution (CHX); Group 3: 0,1% chlorhexidine digluconate with sodium fluoride solution (CHX-NaF). The orthodontic elastomeric chain was stretched and maintained at a standardized distance equivalent to a force of 300 g. The measurement of force decay and permanent deformation were performed with digital force gauge and digital caliper (0.01mm) at intervals of the first, seventh, fourteenth, twenty-first, and twenty-eighth days, respectively. Results: The force decay and permanent deformation of the elastomeric chain compared between three groups (control, CHX mouthwash and CHX+NaF mouthwash) showed did not have any significantly different (p-value>0,05) at the first, seventh, fourteenth, twenty-first, and twenty-eighth days, respectively. Conclusion: Sodium fluoride in chlorhexidine mouthwash showing no significant difference among saliva, CHX mouthwash and CHX+NaF mouthwash on force decay and permanent deformation of elastomeric chain.

Comprehensive comparison of canine retraction using NiTi closed coil springs vs elastomeric chains:

ABSTRACT Objectives To compare canine retraction using NiTi closed coil springs vs elastomeric chains comprehensively in a split-mouth randomized controlled trial. Materials and Methods The canines in 64 quadrants were randomly retracted into the first premolar extraction spaces using NiTi closed coil springs or elastomeric chains, in the maxilla and mandible. The retraction force was 150 g. Cone beam computed tomography scans and study models were obtained before the start of canine retraction and 6 months later. The rate and total amount of canine retraction, canine rotation, tipping, and root resorption were evaluated. A visual analogue scale was used to evaluate patients' pain experience. Results The two methods were statistically similar for dental changes, rate of canine retraction, and root resorption. However, patients reported significantly more days of pain with the elastomeric chain compared to the NiTi closed coil springs. Conclusions Within the constraints of the current study, using either NiTi closed coil springs or elastomeric chains as force delivery systems for canine retraction results in no significant difference in the rate of canine retraction, tipping, rotation, or root resorption. Pain experience during retraction using elastomeric chains is more significant yet needs further investigation.

Generation I and Generation II Elastomeric Chains Characteristics Comparison in Artificial Saliva Immersion

Objective: To determine the force decay and discoloration in Generation I and Generation II elastomeric chain on artificial saliva immersion. Material and methods: Generation I and Generation II elastomeric chains stretched on an acrylic board and immersed in artificial saliva for 1, 7, 14, 21, and 28 days according to the group of days. On each specified day, the force of each sample measured by an orthodontic force gauge and the magnitude of the force obtained is entered to the formula to find out the force decay in percentage, whereas discoloration of each sample analyzed by the color reader with CIE Lab analysis. Results: The force decay between Generation I and Generation II elastomeric chains showed a statistically significant difference in every group of days, in which Generation II is more effective in maintaining stretch force. Similar to force decay, the discoloration in Generation I elastomeric chains on the 14th day showed significant value and Generation II elastomeric chains were more stable in maintaining color compared to Generation I. Conclusions: over the entire research period time, Generation II elastomeric chains are more stable in maintaining stretch forces and color compared to Generation I elastomeric chains. KEYWORDS Discoloration; Elastomeric chain; Force decay; Generation I; Generation II.