The effect of different environmental factors on force degradation of three common systems of orthodontic space closure

Effect of three common hot beverages on the force decay of orthodontic elastomeric chain within a 28-day period: An in vitro study

Objective

This study aimed to assess the effects of commonly consumed hot drinks on the force decay of orthodontic elastomeric chains.

Methods

This in vitro experimental study evaluated 375 pieces of elastomeric chains with six rings placed on a jig. Four rings were stretched by 23.5 mm corresponding to the approximate distance between the canine and the second premolar. Fifteen pieces served as reference samples at time zero, and 360 pieces were randomized into four groups: control, hot water, hot tea, and hot coffee. Each group was further divided into six subgroups (n = 15) according to the different exposure periods. The specimens in the experimental groups were exposed to the respective solutions at 65.5°C four times per day for 90 seconds at 5-second intervals. The control group was exposed to artificial saliva at 37°C. The force decay of the samples was measured at 1, 2, 7, 14, 21, and 28 days using a universal testing machine. Data were analyzed using repeated-measures analysis of variance.

Results

Maximum force decay occurred on day 1 in all groups. The minimum force was recorded in the control group, followed by the tea, coffee, and hot water groups on day 1. At the other time points, the minimum force was observed in the tea group, followed by the control, coffee, and hot water groups.

Conclusions

Patients can consume hot drinks without concern about any adverse effect on force decay of the orthodontic elastomeric chains.

Influence of pH levels and beverage exposure on force decay and color stability of orthodontic elastomeric chains: An experimental study

Aim of study

To assess the impact of pH level on force decay and color stability of orthodontic elastomeric chains (EOC) after exposure to commonly used beverages.

Materials and methods

A total of 120 chain cuts were prepared from 2 different manufacturers (GC Orthodontics Europe GmbH, Breckerfeld, Germany, and FORESTADENT® - Bernhard Foerster GmbH, Pforzheim, Germany). According to the distance between loops, two types of chains were selected from each manufacturer: short and medium ones. Chains were immersed into 10 commonly used beverages with different pH values. After 7 days, force degradation was evaluated with the universal machine for mechanical testing (Model 4411; Instron, Canton, USA) and color change using a VITA Easyshade® digital spectrophotometer. Kruskal-Wallis with post-hoc Dunn's test for intergroup comparison and Wilcoxon rank test for intragroup comparison.

Results

Initial force varied among EOC brands, with GC short chains having the highest force and Forestadent medium chains the lowest. The most pronounced force decay occurred within 24 h, notably affecting Forestadent short chains the most, followed by Forestadent medium, GC short, and GC medium chains. Despite a higher force drop rate over seven days, short EOCs maintained higher forces than medium EOCs. GC EOCs consistently maintained higher forces after seven days compared to Forestadent EOCs. After the immersion of EOC in different solutions for 24 h, only Evian water, Soy milk, and Coconut water did not change color. After 7 days, the greatest color change was recorded in coffee.

Conclusion

There is no correlation between pH value and force decay of polyurethane chains. Short chains showed more constant force delivery and greater value of remaining force in comparison to medium ones. Color stability was mostly affected by coffee, followed by matcha tea, soy milk, and apple juice.

The Effect of Different Soft Drinks on the Force Degradation of Conventional and Memory Orthodontic Elastic Chains: An In-Vitro Study

Objectives: The aim of this study was to assess how different soft drinks affect the deterioration of conventional and memory orthodontic elastomeric chains. Materials and Methods: We used 500 five-loop segments of elastomeric chains, which were divided into two equal groups of conventional and memory chains. The samples were kept in artificial saliva during the study period. Each group was further divided into 5 subgroups consisting of artificial saliva (controls), Coca-Cola®, non-alcoholic beer (ISTAK®), and carbonated and non-carbonated yoghurt-based drinks (Alis®). Treatment with the soft drinks consisted of immersion in the test liquids twice a day for 3 minutes each time. Force measurements were taken on days 1, 7, 14, 21, and 28. Data were analyzed using One- and three-way ANOVA tests, and independent t-test, with a significance level of 5%. Results: The mean initial force for the conventional and memory elastomeric chains was 3.34±0.112N and 2.49±0.209N, respectively. Conventional chains showed significantly greater degradation than memory chains (P<0.01). Soft drinks had a significant impact on force degradation for both types of chains at all time points (P<0.01). Coca-Cola® had the highest level of force degradation, while non-carbonated yoghurt-based drinks had the lowest (P<0.01). Conclusion: Based on the findings of this study, it is recommended that orthodontic patients choose non-carbonated yoghurt-based drinks during their treatment. Memory elastomeric chains may be more suitable for patients who consume large amounts of carbonated soft drinks, due to their lower amount of force degradation compared to conventional chains.

Evaluation of force decay rate in orthodontic elastomeric chains in the environment of various mouthwashes: A systematic review

Background

Different studies about the effects of mouthwashes on force reduction by elastomeric chains are reported in the literature. Hence, this review was done for the assessment of force degradation in the elastomeric chains in different mouthwash compositions. This study helps to improve the clinical performance of elastomeric chains used in orthodontics, reducing force degradation, and finally assisting clinicians in choosing better and more efficient methods for their treatments.

Materials and Methods

In this review article, an extensive search was performed in the electronic databases of Cochrane Library, Web of Science, PubMed, and Scopus from the year 1990-2020. No language restriction was considered and manually investigated the reference lists of all articles related to the title. Out of 450 obtained articles, 14 in vitro studies were chosen based on the inclusion criteria, and their quality was assessed using modified CONSORT. This systematic review was limited and written based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses protocol.

Results

Based on the results achieved, mouthwashes containing alcohol caused considerable force degradation in the elastomeric chains compared to the alcohol-free ones and mouthwashes with fluoride caused lesser force degradation compared to other types.

Effect of oral environment on contemporary orthodontic materials and its clinical implications

Contemporary orthodontics entails using advanced materials and devices, simplifying the process of tooth movement. It is well documented that orthodontic materials are subjected to various fluctuations and stresses in the oral environment, such as salivary pH, dietary habits, temperature changes, and masticatory loads. These changes reduce bonding materials' longevity, plasticize resin polymers, and reduce elastic properties. In addition, the corrosion of orthodontic appliances in the oral environment has concerned clinicians for some time. This is focused on two principal issues: whether corrosion products are absorbed into the body and cause either localized or systemic effects, and the results of corrosion on the physical properties and the clinical performance of orthodontic appliances. Recently, another major concern is the potential release of bisphenol-A from materials containing polymers such as thermoplastic aligners and resins, which is known to induce xenoestrogenicity and cytotoxicity when the tissue level exceeds the daily recommended intake. However, most of these findings are based on in vitro studies that suffer from serious drawbacks such as failure to replicate the exact oral environment and process during orthodontic treatment. Therefore, developing clinically relevant methods should be the goal of future research related to the aging of orthodontic materials. The purpose of this review is to outline the impact of the oral environment on contemporary orthodontic materials.

An in vivo and in vitro study on the force degradation and surface morphology of the orthodontic elastic ligatures

INTRODUCTION

The objective of this study was to investigate the characteristics of force degradation and surface morphology of 9 brands of elastic ligatures over 6 weeks, both in vivo and in vitro, to provide some reference for clinical selection of appropriate elastic ligatures and determination of appropriate follow-up visit time.

METHODS

Choosing 9 kinds of brands of elastic ligatures (American Orthodontics, Ormco, 3M Grey, TP Orthodontics, Xihu, Yahong, Creative, Protect, 3M dusty blue), which are common in the market. For the in vivo study, 9 volunteers (5 males, 4 females, aged 22-26 years) were chosen to wear elastic ligature fixators, which were made to fix the elastic ligature in the mouth without bonding brackets on the teeth. The residual force and percentage of force degradation of elastic ligatures were estimated after 0, 1 hour, 2 hours, 8 hours, 1 day, 2 days, 1 week, 2 weeks, 4 weeks, and 6 weeks processed in vivo and in vitro (25°C dry air condition, 37°C artificial saliva, pH = 6.7 and oral environment); A 1-way analysis of variance and t test were used to identify statistical significance (P <0.05). The surface morphology of the initial state and after a 6-week process in vivo and in vitro were observed separately.

RESULTS

The characteristics of force degradation and surface morphology of 9 brands of elastic ligatures were different over 6 weeks; With the extension of time, the tensile force declined, and the percentage of force degradation of all groups decreased sharply by about 9.1%-32.3% in the first day, then the rate reduced steadily. In addition, during the first day, the percentage of force degradation declined most sharply in the first hour (4.4%-16.5%). The percentage of force degradation of 9 elastic ligatures was reduced by about 11.3%-37.3% over 6 weeks in all groups. At the same time, the characteristics of force degradation in the same brand are that in vivo > artificial saliva > air (P <0.05). After a 6-week process, the surface morphologic defects were aggravated under a scanning electron microscope, corresponding to the change of mechanical properties in each brand.

CONCLUSIONS

The mechanical properties of elastic ligatures are reduced with time extension and decreased greater in vivo than in vitro; According to the characteristics of force degradation of different brands of elastic ligatures, clinicians can choose the proper elastic ligatures at different stages of treatment, and adjust the follow-up visit time appropriately. For example, in alignment and leveling, the elastic ligatures with slow force degradation, such as Ormco, TP, and so on, maybe more suitable to ensure close contact between the archwire and the bracket. In the space-closing stage, the elastic ligatures with fast force degradation may be more appropriate to reduce the friction between the archwire and the bracket, such as 3M Grey, Yahong, Protect, and so on.

Comparison of in vivo and in vitro force decay of elastomeric chains/modules: a systematic review and meta analysis

BACKGROUND

The study evaluated and compared the force decay of orthodontic elastomeric chains/modules in both in vivo and in vitro settings.

METHODS

A protocol in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines was formulated and registered with the International Prospective Register of Systematic Reviews. A total of 53 articles (44 in vitro and 9 in vivo studies) found via search of the electronic databases of Cochrane and the National Library of Medicine (MEDLINE; PubMed), and manual search of the gray literature from institutional library resources, were selected. Data extraction, quality analysis, risk of bias assessment, and meta-analysis of the level of force decay of elastomeric chains/modules were conducted per standard protocol, and suitable statistical analyses were applied.

RESULTS

The mean force decay in the in vivo setting was 41.9% at 24 hours, 42.6% after 1 week, 46.8% after 2 weeks, and 55.0% after 3 weeks. Similarly, the force decay in the in vitro studies was 38.9% at 24 hours, 42.1% after 1 week, 44.6% after 2 weeks, and 51.1% after 3 weeks. However, at the 95% confidence interval, the force decay rates of in vivo and in vitro studies overlap, with a statistically insignificant difference in force decay observed in the in vivo and in vitro settings.

CONCLUSIONS

This systematic review and meta-analysis observed more force decay in the in vivo studies versus the in vitro studies (although this difference was statistically insignificant), with the maximum force decay occurring during the initial days, with a reduction to approximately 50% within 3 weeks. Hence, change of the elastomeric chains/module, at intervals of 3 weeks, is advised. (PROSPERO registration no. CRD42020209535).

Effect of citric acid on force decay of orthodontic elastomeric chains

BACKGROUND

This study aimed to assess the effect of citric acid, as a weak acid commonly used in food industry, on elastomeric chain force decay.

MATERIALS AND METHODS

In this in vitro, experimental study, sixty elastomeric chains from two commercial brands of American Orthodontics and Ortho Technology (n = 30) were cut into five-piece segments. Elastomeric chains of each brand were randomly divided into two groups of control (artificial saliva) and citric acid. All elastomeric chains were incubated in artificial saliva at 37°C. Experimental samples were immersed in 10 mL of citric acid for 90 s daily and were then transferred back to the artificial saliva. The elastomeric chain force was measured at baseline (before the experiment), 1 day, 1 week, 2 weeks, and 3 weeks using an electromechanical universal testing machine. Data were analyzed using t-test, Kruskal-Wallis test, and Mann-Whitney U-test at 0.05 level of significance.

RESULTS

The elastomeric chain force gradually degraded over time. The difference in this respect was not significant at 2 and 3 weeks in any group (P > 0.05). On initiation of the experiment, the force in the citric acid group experienced a greater decay than that in the control group; the difference between the citric acid and control groups in both the brands was significant at all time points until the end of the 3^rd week (P < 0.05). The difference between the American Orthodontics and Ortho Technology brands in the control and citric acid groups was significant at all time points (P < 0.001).

CONCLUSION

Elastomeric chains in both the citric acid and artificial saliva groups experienced force decay over time. Force decay was greater in the citric acid group. Thus, citric acid can effectively decrease the elastomeric chain force. The Ortho Technology chain force was higher than that of American Orthodontics in both the groups at all time points.

Comparative evaluation of force decay pattern in orthodontic active tiebacks exposed to five different mouth rinses: An in vitro Study

Background. This study compared the force decay pattern of two different orthodontic active tiebacks (ATBs) exposed to five different commercially available mouth rinses.

Methods. In this in vitro study, 90 transparent ATBs and 90 gray ATBs were divided into six groups; one was the control group, and the others were exposed to one of these mouth rinses twice a day for 60 seconds: Listerine, chlorhexidine, Orthokin, Persica, and fluoride. The initial force of each ATB was 250 g at a 24-mm extension. The force of ATBs was measured on days 1, 7, 14, and 28 using a digital gauge.

Results. The highest percentage of force loss was observed between days 14 and 28 (P<0.05). At the end of the study, the Persica group exhibited the highest force degradation in both ATB types. In the transparent ATBs, it was followed by Orthokin, Listerine, fluoride, chlorhexidine, and control groups, respectively. In the gray ATBs, Orthokin, chlorhexidine, control, Listerine, and fluoride groups exhibited the highest force decay in descending order. In some groups, the differences between transparent and gray ATBs were significant. In the control group, the force of transparent ATB was significantly higher than gray ones on days 7 and 14 but not significantly after four weeks.

Conclusion. ATBs’ force degradation could be exacerbated by the use of some mouth rinses. There were some differences between force relaxation patterns of transparent and gray ATBs. The data could be beneficial in choosing appropriate O-rings for making ATBs.

Evaluating the effect of clinical usage and autoclave sterilization on the load deflection properties of three different orthodontic wires: Ex-vivo study

OBJECTIVE

The aim of this study was to evaluate the effect of intraoral aging and sterilization on the physical properties of rectangular Nickel-Titanium (NiTi), Beta-Titanium and Cooper NiTi (Cu-NiTi) arch wires.

METHODS

Three types of preformed 0.018×0.025 inch wires: super elastic NiTi wire, Beta-Titanium wire and Cu-NiTi wire (20 of each type) were divided into 4 groups: as-received (T0), autoclave (T1), intra oral aging after sterilization (T2) and intra oral aging (T3). Specimens in T2 and T3 groups were used in oral environment of 30 participants for 8 weeks. In the next step a length of 30mm was cut from both ends of each arch wire, and 120 straight specimens were achieved and tested by Instron for evaluating their load deflection properties. Data were analysed by means of One-way ANOVA and Tukey's (honestly significant difference) HSD tests.

RESULTS

In NiTi wire, all conditions led to a significant decrease in deactivation mean load compared with control in most deflections (P=0.000). In Cu-NiTi wire, all conditions led also to a significant decrease in deactivation mean load compared with the control (P=0.000). In Beta-Titanium wire, sterilization had no significant effect on the load deflection properties; but significant increase was observed in T2 (in all deflections) and T3 (in 1.8-1mm) compared with the control.

CONCLUSIONS

After all conditions, NiTi wire in spite of reduction in stiffness presented a mean load which stayed in category of heavy force. The Cu-NiTi wires saw an improvement in light physiologic force. In contrast, the Beta-Titanium stiffness increased after clinical usage, and the force level remained in the range of heavy force.

Effect of Bleaching Mouthwash on Force Decay of Orthodontic Elastomeric Chains

INTRODUCTION

Force decay elastomeric chains are significant, and it is a clinical problem.

AIM

The aim of this study was to evaluate the effects of bleaching agent in the mouthwash on the force decay of orthodontic chains.

MATERIALS AND METHODS

In this experimental study, 160 gray closed elastomeric chains were randomly divided into three groups (one control and two test groups). Four loops of chains were stretched for 25 mm on custom-made jig. Control group specimens were immersed in artificial saliva during the test period. Test group specimens were immersed twice a day for 30 seconds in the whitening (LISTERINE® HEALTHY WHITE™) and daily sodium fluoride (LISTERINE® TOTAL CARE ZERO) mouthwashes. All specimens were immersed in artificial saliva at 37°C. Force was measured at different time points (initial, 1, 7, 14, 21, 28 days). Statistical analysis was performed by two-way analysis of variance (ANOVA) and Bonferroni methods (a = 0.05).

RESULTS

Force of elastomeric chains was decreased dramatically in all groups during the experiment. After 24 hours, force was decreased by 42.18, 48.34, and 53.38% in control group, daily, and bleaching mouthwash groups respectively. The corresponding numbers after 4 weeks were 66.30, 76.73, and 86.48. The difference between three groups at days 1 and 28 was statistically significant (p < 0.05).

CONCLUSION

Within the limitations of the current in vitro study, bleaching and sodium fluoride mouthwashes could cause force decay of orthodontic elastomeric chains. Whitening mouthwash is more weakening for elastomeric chains.

CLINICAL SIGNIFICANCE

Use of whitening mouthwash by orthodontic patients could decrease the force of elastomeric chains, so it could be recommended to use them for a short time.

The effect of toothpastes with bleaching agents on the force decay of elastomeric orthodontic chains

Objective:

The aim of this study was to evaluate the effect of agents available in whitening toothpastes (Crest^® and Sensodyne^®) in vitro on the force decay of elastomeric chains used in orthodontics.

Materials and Methods:

A total of 300 specimens of elastomeric chains were divided into five groups (n = 60) and were evaluated. These groups included (1) the regular Crest® toothpaste and distilled water solution, (2) whitening Crest^® toothpaste and distilled water solution, (3) regular Sensodyne^® toothpaste and distilled water solution, (4) whitening Sensodyne^® toothpaste and distilled water solution, and (5) distilled water as a control group. The samples' force was measured using Instron at intervals of 0, 1, 7, 14, 21, and 28 days. Data were analyzed by SPSS software.

Results:

At the initial time point, the difference in the force values of elastomeric chain between any of the groups was not significant (P > 0.05). On the 1^st day, there was a significant difference (P < 0.05) between all groups except the groups of whitening Crest^®, regular, and whitening Sensodyne^® (P > 0.05). On days 7, 14, and 28, the rate of decline for all groups was statistically significant (P < 0.05).

Conclusions:

According to the results obtained in the present study, it seems that toothpastes without whitening agents have less effect on force decay of elastomeric chain over time.

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

Background:

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.

Materials and Methods:

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.

Results:

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.

Conclusion:

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.