Clinical comparison and performance perspective of three aligning arch wires

Initial arch wires used in orthodontic treatment with fixed appliances

BACKGROUND

Initial arch wires are the first arch wires inserted into fixed appliance at the beginning of orthodontic treatment. With a number of different types of orthodontic arch wires available for initial tooth alignment, it is important to understand which are most efficient and which cause the least amount of root resorption and pain during the initial aligning stage of treatment. This is the third update of a Cochrane review first published in 2010.

OBJECTIVES

To assess the effects of initial arch wires for the alignment of teeth with fixed orthodontic braces, in terms of the rate of tooth alignment, amount of root resorption accompanying tooth movement, and intensity of pain experienced by patients during the initial alignment stage of treatment.

SEARCH METHODS

We searched Cochrane Oral Health's Trials Register, CENTRAL, MEDLINE, Embase, and two ongoing trials registries on 4 July 2022.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) of different initial arch wires used to align teeth with fixed orthodontic braces. We included people with full-arch fixed orthodontic appliances on the upper arch, lower arch, or both arches.

DATA COLLECTION AND ANALYSIS

Two independent review authors were responsible for study selection, data extraction, and assessment of risk of bias in included studies. We contacted corresponding authors of included studies to obtain missing information. We resolved disagreements by discussion between the review authors. Our main outcomes were alignment rate (movement of teeth in mm), root resorption, time to alignment, and intensity of pain measured on a 100-mm visual analogue scale (VAS). We pooled data from studies with similar interventions and outcomes using random-effects models. We reported mean differences (MDs) with 95% confidence intervals (CIs) for continuous data, risk ratios (RRs) with 95% CIs for dichotomous data, and alignment rate ratios with 95% CIs for time-to-event data. Two independent review authors assessed the certainty of evidence. We resolved disagreements by discussion between the review authors.

MAIN RESULTS

We included 29 RCTs with 1915 participants (2581 arches) in this review. Studies were generally small (sample sizes ranged from 14 to 200 participants). Duration of follow-up varied between three days and six months. Eleven studies received funding, six received no funding, and 12 provided no information about funding sources. We judged eight studies at high risk of bias, nine at low risk, and 12 at unclear risk. We grouped the studies into six main comparisons. Multistrand stainless steel wires versus wires composed of other materials Six studies with 409 participants (545 arches) evaluated multistrand stainless steel (StSt) wires versus wires composed of other materials. We are very uncertain about the effect of multistrand StSt wires versus other wires on alignment rate (4 studies, 281 participants, 417 arches; very low-certainty evidence). There may be little to no difference between multistrand StSt wires and other wires in terms of intensity of pain (MD -2.68 mm, 95% CI -6.75 to 1.38; 2 studies, 127 participants, 127 arches; low-certainty evidence). Conventional nickel-titanium wires versus superelastic nickel-titanium wires Four studies with 266 participants (274 arches) evaluated conventional nickel-titanium (NiTi) wires versus superelastic NiTi wires. There may be little to no difference between the different wire types in terms of alignment rate (124 participants, 124 arches, 2 studies; low-certainty evidence) and intensity of pain (MD -0.29 mm, 95% CI -1.10 to 0.52; 2 studies, 142 participants, 150 arches; low-certainty evidence). Conventional nickel-titanium wires versus thermoelastic copper-nickel-titanium wires Three studies with 210 participants (210 arches) evaluated conventional Ni-Ti versus thermoelastic copper-nickel-titanium (CuNiTi) wires. We are very uncertain about the effects of the different arch wires on alignment rate (1 study, 66 participants, 66 arches; very low-certainty evidence). There may be little to no difference between conventional NiTi wires and thermoelastic CuNiTi wires in terms of time to alignment (alignment rate ratio 1.30, 95% CI 0.68 to 2.50; 1 study, 60 participants, 60 arches; low-certainty evidence). Superelastic nickel-titanium wires versus thermoelastic nickel-titanium wires Twelve studies with 703 participants (936 arches) evaluated superelastic NiTi versus thermoelastic NiTi wires. There may be little to no difference between superelastic NiTi wires and thermoelastic NiTi wires in alignment rate at four weeks (MD -0.28 mm, 95% CI 0.62 to 0.06; 5 studies, 183 participants, 183 arches; low-certainty evidence). We are very uncertain about the effects of the different wires on root resorption (2 studies, 52 participants, 312 teeth; very low-certainty evidence). Superelastic NiTi wires compared with thermoelastic NiTi wires may result in a slight increase in time to alignment (MD 0.5 months, 95% CI 0.21 to 0.79; 1 study, 32 participants, 32 arches; low-certainty evidence) but are probably associated with a slight increase in intensity of pain (MD 6.96 mm, 95% CI 1.82 to 12.10; 3 studies, 94 participants, 138 arches, moderate-certainty evidence). Single-strand superelastic nickel-titanium wires versus coaxial superelastic nickel-titanium wires Three studies with 104 participants (104 arches) evaluated single-strand superelastic NiTi versus coaxial superelastic NiTi wires. Use of single-strand superelastic NiTi wires compared with coaxial superelastic NiTi wires probably results in a slight reduction in alignment rate at four weeks (MD -2.64 mm, 95% CI -4.61 to -0.67; 2 studies, 64 participants, 64 arches, moderate-certainty evidence). Different sizes of nickel-titanium wires Two studies with 149 participants (232 arches) compared different types of NiTi wires. There may be little to no difference between different sizes of NiTi wires in terms of pain (low-certainty evidence).

AUTHORS' CONCLUSIONS

Superelastic NiTi wires probably produce slightly more pain after one day than thermoelastic NiTi wires, and single-strand superelastic NiTi wires probably have a lower alignment rate over four weeks compared with coaxial superelastic NiTi wires. All other evidence on alignment rate, root resorption, time to alignment, and pain is of low or very low certainty in all comparisons. Therefore, there is insufficient evidence to determine whether any particular arch wire material or size is superior to any other. The findings of this review are imprecise and unreliable; well-designed larger studies are needed to give better estimates of the benefits and harms of different arch wires. Orthodontists should exercise caution when interpreting the findings of this review and be prepared to adapt their treatment plans based on individual patient needs.

EVALUATION AND COMPARISON OF LOAD DEFLECTION RATE OF FOUR INITIAL ORTHODONTIC ARCH WIRES: AN IN VITRO STUDY

Aim: The aim of this study was to evaluate the load-deflection rate of four different types of archwires used in initial stage of orthodontic treatment. Materials and methods: A modified three-point bending test was performed on the sample of 60 wires of superelastic Nickel Titanium(NiTi), everwhite esthetic NiTi, thermal NiTi and multistranded coaxial stainless steel (15 each). The load exerted by each of the wire was measured at the deflections of 2 mm and 4mm, subsequent unloading process at 37°C temperature. Results: Comparison of mean load-deflection values revealed that thermal NiTi wires had lowest value at both 2 and 4mm deflection when compared to other three wires which was statistically significant(p=0.009).  Superelastic and esthetic NiTi showed similar values of load deflection ratios at both the deflections where as co-axial wire showed 1.89N at 2mm and 5.22N at 4mm deflection. Conclusion: The heat-activated NiTi wires are acceptable in severe crowding and periodontally compromised patients. Multistranded co-axial wire is acceptable when we need minimal alignment; whereas esthetic NiTi wires can replace superelastic Niti based on patient’s need.

Comparison of two different initial archwires for tooth alignment during fixed orthodontic treatment-A randomized clinical trial

OBJECTIVES:

The aim of the study was to clinically evaluate and compare 0.016-inch superelastic nickel–titanium (NiTi) and 0.016-inch heat-activated nickel–titanium (NiTi) archwires in terms of alignment efficiency, root resorption, and pain intensity.

METHOD:

A total of 20 patients requiring fixed orthodontic treatment, having Little's irregularity index of 5–8, and requiring first premolar extractions were recruited. They were randomly allocated to receive two different archwires (0.016-inch superelastic NiTi or 0.016-inch thermoelastic NiTi). Good-quality impressions were taken of the lower arch before archwire placement (T0) and at every month after that till the alignment was complete. The rate of tooth alignment was measured on casts by determining Little's irregularity index. The pain experienced by the patient was assessed 24 hours and 1 week after the placement of the archwire on a visual analogue scale. Cone beam computed tomographic radiographs of lower anterior teeth were taken before and after alignment to assess root resorption. Data obtained were subjected to statistical analysis using the SPSS software (version 20.0). The level of significance was kept at 5%.

RESULTS:

The repeated measures ANOVA indicated that there was no significant difference in the aligning efficiency of superelastic and heat-activated NiTi wires. (p = 0.45). The Mann Whitney U test showed that superelastic NiTi wires had statistically significant higher VAS scores than heat-activated NiTi at 24 hours and 1-week interval (p < 0.05). Student's t-test indicated greater root resorption with superelastic NiTi but the difference was not statistically significant.

CONCLUSION:

Both the wires showed similar aligning efficiency and resulting root resorption. Superelastic NiTi was observed to produce more pain compared to heat-activated NiTi in the aligning phase.

A clinical comparison of the effectiveness of two types of orthodontic aligning archwire materials: a multicentre randomized clinical trial

OBJECTIVES

To compare the heat-activated nickel titanium (HANT) with superelastic nickel-titanium (SENT) archwires in terms of their effectiveness of aligning teeth, possibility of inducing root resorption, and perception of pain.

SUBJECTS AND METHODS

Orthodontic patients aged 12 years or over with mandibular anterior crowding of 3-6 mm, who required treatment without extractions were randomly allocated (a simple non-stratified randomization) to the HANT and SENT archwires groups with a 1:1 allocation ratio. The archwire sequence in both groups was 0.014-inch and 0.016-inch, respectively. Each archwire was placed for 4 weeks. The outcome measures included the amount of crowding assessed blindly using Little's irregularity index (LII), apical root resorption, and pain perception. The effectiveness of alignment was tested using 2 × 2 mixed factorial analysis of variance (ANOVA) model, while root resorption and pain perception were tested by the Mann-Whitney U-test and Wilcoxon signed-rank test (P < 0.05).

RESULTS

Thirty-four patients were randomized and recruited from four centres, of those 31 were analysed (15 participants for the HANT and 16 for the SENT groups) with an overall mean age of 19.13 ± 5.73 years. The total reduction in the LII was 2.69 mm and 2.74 mm for the HANT and SENT groups, respectively. This did not reach the level of statistical (P = 0.809) or clinical significance. Similarly, root resorption and pain perception showed non-significant difference between groups. However, there was a slight increase in root resorption with the SENT group.

LIMITATIONS

A long-term evaluation of root resorption is required.

CONCLUSIONS

Both HANT and SENT archwires were equally effective in the aligning stage of orthodontic treatment. Root resorption with SENT wires should be monitored throughout treatment.

REGISTRATION

The trial was registered with ClinicalTrials.gov on 18 September 2019, registration number: NCT04090931.

Pain level between clear aligners and fixed appliances: a systematic review

OBJECTIVES

To assess if there is any difference in pain levels between orthodontic treatment with clear aligners or fixed appliances.

MATERIALS AND METHODS

An electronic search was completed in PubMed, The Cochrane Database, Web of Science, Scopus, Lilacs, Google Scholar, Clinical Trials, and OpenGrey databases without any restrictions until February 2019. All comparative study types contrasting pain levels between clear aligners and fixed appliances were included. The risk of bias (RoB) was assessed using the Newcastle-Ottawa Scale, ROBINS-I-Tool, or ROB 2.0 according to the study design. The level of evidence was assessed through the GRADE tool.

RESULTS

After removal of duplicates, exclusion by title and abstract, and reading the full text, only seven articles were included. Five were prospective non-randomized clinical trials (CCT), one was a cross-sectional study, and one was a randomized clinical trial (RCT). Two studies presented a high RoB, three a moderate RoB, and two a low RoB (including the RCT). A meta-analysis was not performed because of clinical, statistical, and methodological heterogeneity. Most of the studies found that pain levels in patients treated with Invisalign were lower than those treated with conventional fixed appliances during the first days of treatment. Differences disappeared thereafter. No evidence was identified for other brands of clear aligners.

CONCLUSIONS

Based on a moderate level of certainty, orthodontic patients treated with Invisalign appear to feel lower levels of pain than those treated with fixed appliances during the first few days of treatment. Thereafter (up to 3 months), differences were not noted. Malocclusion complexity level among included studies was mild. Pain is one of many considerations and predictability and technical outcome are more important, mainly considering that the difference does not seem to occur after the first months of the orthodontic treatment.

Arch Expansion Efficiency of Coaxial Tubular Superelastic Nickel-Titanium in Comparison to Single-Stranded Superelastic Nickel-Titanium While Relieving Mandibular Anterior Crowding: A Randomized Controlled Study

Aim:

The aim of the study is to compare the efficiency of six-stranded coaxial tubular superelastic nickel–titanium (NiTi) archwire and a single-stranded wire in relieving anterior mandibular crowding.

Materials and Methods:

This double-blind randomized study included 40 patients, categorized into two groups: Sentalloy round group and Speed tubular supercable group (20 each). After taking alginate impressions, the allocated archwire was engaged. With a digital caliper, intercanine, interpremolar, and intermolar width were recorded on the study models, immediately and at 4, 8, and 12 weeks stages. The Statistical Package for the Social Sciences (SPSS) version 20 was used for analysis.

Results:

The measured parameters were increased in both the groups, with the difference being insignificant statistically.

Conclusion:

Superelastic coaxial NiTi wires show better efficiency in relieving anterior crowding than single-stranded NiTi wire.

Alignment efficiency of coaxial tubular superelastic nickel-titanium vs single-stranded superelastic nickel-titanium in relieving mandibular anterior crowding in extraction cases: A single-centre randomized controlled clinical trial

OBJECTIVES

To compare the alignment efficiency of coaxial tubular and single-stranded 0.016" superelastic NiTi archwires in relieving mandibular anterior crowding in extraction cases and to evaluate whether alignment efficiency differed as the initial irregularity increased.

SETTING AND SAMPLE POPULATION

Forty female patients aged between twelve and twenty years from the postgraduate orthodontic clinic at the authors' centre.

MATERIALS AND METHODS

All patients in this single-centre, 2-arm parallel trial were randomly allocated in a 1:1 ratio and the mandibular anterior irregularity was measured from the mandibular cast at 0-, 4-, 8- and 12-week intervals using a digital calliper.

RESULTS

All forty patients (mean age, 15.08 ± 2.11) completed the study with either coaxial tubular superelastic NiTi (mean age, 15.30 ± 2.36) or single-stranded superelastic NiTi (mean age, 14.85 ± 1.84). The largest mean irregularity index reduction of -4.88 ± 2.74 and -6.17 ± 2.38 in the single-stranded superelastic NiTi and the coaxial tubular superelastic NiTi groups, respectively (P = 0.122) was at 4 weeks. Student's t test and repeated measures ANOVA indicated that none of the mean comparisons were statistically significant at a 5% level. Pearson's correlation value (r) indicated no statistically significant influence of initial crowding on alignment efficiency.

CONCLUSIONS

There was no statistically significant difference between the alignment efficiency of coaxial tubular superelastic NiTi and single-stranded superelastic NiTi in extraction cases, and the degree of initial crowding had no influence on the alignment efficiency.

Initial arch wires used in orthodontic treatment with fixed appliances

BACKGROUND

Initial arch wires are the first arch wires to be inserted into the fixed appliance at the beginning of orthodontic treatment and are used mainly for the alignment of teeth by correcting crowding and rotations. With a number of different types of orthodontic arch wires available for initial tooth alignment, it is important to understand which wire is most efficient, as well as which wires cause least amount of root resorption and pain during the initial aligning stage of treatment. This is an update of the review entitledInitial arch wires for alignment of crooked teeth with fixed orthodontic braces, which was first published in 2010.

OBJECTIVES

To assess the effects of initial arch wires for the alignment of teeth with fixed orthodontic braces, in terms of the rate of tooth alignment, amount of root resorption accompanying tooth movement, and intensity of pain experienced by patients during the initial alignment stage of treatment.

SEARCH METHODS

Cochrane Oral Health's Information Specialist searched the following databases: Cochrane Oral Health's Trials Register (to 5 October 2017), the Cochrane Central Register of Controlled Trials (CENTRAL) (the Cochrane Library, 2017, Issue 9), MEDLINE Ovid (1946 to 5 October 2017), and Embase Ovid (1980 to 5 October 2017. The US National Institutes of Health Trials Registry (ClinicalTrials.gov) and the World Health Organization International Clinical Trials Registry Platform were searched for ongoing trials. No restrictions were placed on the language or date of publication when searching the electronic databases.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) of initial arch wires to align teeth with fixed orthodontic braces. We included only studies involving participants with upper or lower, or both, full arch fixed orthodontic appliances.

DATA COLLECTION AND ANALYSIS

Two review authors were responsible for study selection, 'Risk of bias' assessment and data extraction. We resolved disagreements by discussion between the review authors. We contacted corresponding authors of included studies to obtain missing information. We assessed the quality of the evidence for each comparison and outcome as high, moderate, low or very low, according to GRADE criteria.

MAIN RESULTS

For this update, we found three new RCTs (228 participants), bringing the total to 12 RCTs with 799 participants. We judged three studies to be at high risk of bias, and three to be at low risk of bias; six were unclear. None of the studies reported the adverse outcome of root resorption. The review assessed six comparisons.1. Multistrand stainless steel versus superelastic nickel-titanium (NiTi) arch wires. There were five studies in this group and it was appropriate to undertake a meta-analysis of two of them. There is insufficient evidence from these studies to determine whether there is a difference in rate of alignment between multistrand stainless steel and superelastic NiTi arch wires (mean difference (MD) -7.5 mm per month, 95% confidence interval (CI) -26.27 to 11.27; 1 study, 48 participants; low-quality evidence). The findings for pain at day 1 as measured on a 100 mm visual analogue scale suggested that there was no meaningful difference between the interventions (MD -2.68 mm, 95% CI -6.75 to 1.38; 2 studies, 127 participants; moderate-quality evidence).2. Multistrand stainless steel versus thermoelastic NiTi arch wires. There were two studies in this group, but it was not appropriate to undertake a meta-analysis of the data. There is insufficient evidence from the studies to determine whether there is a difference in rate of alignment between multistrand stainless steel and thermoelastic NiTi arch wires (low-quality evidence). Pain was not measured.3. Conventional NiTi versus superelastic NiTi arch wires. There were three studies in this group, but it was not appropriate to undertake a meta-analysis of the data. There is insufficient evidence from these studies to determine whether there is any difference between conventional and superelastic NiTi arch wires with regard to either alignment or pain (low- to very low-quality evidence).4. Conventional NiTi versus thermoelastic NiTi arch wires. There were two studies in this group, but it was not appropriate to undertake a meta-analysis of the data. There is insufficient evidence from these studies to determine whether there is a difference in alignment between conventional and thermoelastic NiTi arch wires (low-quality evidence). Pain was not measured.5. Single-strand superelastic NiTi versus coaxial superelastic NiTi arch wires. There was only one study (24 participants) in this group. There is moderate-quality evidence that coaxial superelastic NiTi can produce greater tooth movement over 12 weeks (MD -6.76 mm, 95% CI -7.98 to -5.55). Pain was not measured.6. Superelastic NiTi versus thermoelastic NiTi arch wires. There were three studies in this group, but it was not appropriate to undertake a meta-analysis of the data. There is insufficient evidence from these studies to determine whether there is a difference in alignment or pain between superelastic and thermoelastic NiTi arch wires (low-quality evidence).

AUTHORS' CONCLUSIONS

Moderate-quality evidence shows that arch wires of coaxial superelastic nickel-titanium (NiTi) can produce greater tooth movement over 12 weeks than arch wires made of single-strand superelastic NiTi. Moderate-quality evidence also suggests there may be no difference in pain at day 1 between multistrand stainless steel arch wires and superelastic NiTi arch wires. Other than these findings, there is insufficient evidence to determine whether any particular arch wire material is superior to any other in terms of alignment rate, time to alignment, pain and root resorption.

Clinical comparison of two initial arch wires (A-NiTi and Heat Activated NiTi) for amount of tooth alignment and perception of pain: A randomized clinical trial

OBJECTIVES

The aim of this study was to compare two initial arch wires, 0.014″ A-NiTi and 0.016″ Heat Activated NiTi (HANT), for amount of tooth alignment and perception of pain.

MATERIALS AND METHODS

In total, 59 orthodontic patients (21 males and 38 females) from three orthodontic clinics participated in this 2-arm, parallel-group clinical trial and were randomized to 0.014″ A-NiTi (n=30) or 0.016″ HANT groups (n=29). Patient recruitment commenced in April 2016 and ended in December 2016. Age of the patients was between 12 to 25 years with an average of 17.92±3.74 years. Eligibility criteria included permanent dentition, non-extraction treatment plan in lower arch, Irregularity Index>2 in lower arch, no systemic disease influencing pain, no chronic Non Steroid Anti Inflammatory Drug (NSAID) therapy, and no history of dental pain, mucosal ulcers or temporomandibular disorders (TMD). Blinding was applicable to the patients and outcome assessment. The primary outcome was to compare the reduction of the Irregularity Index mean from bonding sessions to 4 weeks later in these groups and the secondary outcome was evaluation of the pain according to the modified McGill Pain Questionnaire (MPQ) with Visual Analogue Scale questionnaire (VAS).

RESULTS

The mean differences of irregularity indices between the two groups are not statistically significant (95% CI: 0.39-1.03; P=0.36) and according to the questionnaire, there was no significant difference between the two groups in trigger, site, description, duration, beginning, medication, and pain reduction over time. However, the VAS scale of HANT group was significantly higher than that of A-NiTi (P=0.04).

CONCLUSION

Results from this investigation suggested that there was no clinical difference in amount of tooth alignment and perception of pain between 0.014″ A-NiTi and 0.016″ HANT wires.

Effectiveness and efficiency in clinical orthodontic practice

Proffitt et al. have described "effectiveness and efficiency" (E&E) as achieving desired results without wasting the orthodontist's and patients' time. In 1972, Archibald Cochrane published a monograph entitled "Effectiveness and Efficiency," which challenged the medical community to use medical protocols that were evidence-based. As a possible starting point for E&E, the orthodontist could consider an "Evidence-based clinical practice" (EBCP) model, which integrates the best research evidence with clinical expertise and patient values. This model considers scientific or evidence-based orthodontics (EBO) together with patient preferences and patient autonomy, clinical or patient circumstances, and clinical experience and judgment. In this paper, therefore, E&E will be discussed from an EBCP perspective which, for our purposes, includes relevant evidence but also our clinical experience and rationale. We will discuss: wire sequence; NiTi Wire types; space closure by sliding; canine retraction versus en masse retraction, 18" slot versus 22" slot, the Bidimensional System; self-ligating brackets (SL); vertical slot; economic aspects.

An evaluation and comparison of myeloperoxidase enzymatic activity during initial orthodontic alignment: an in vivo study

INTRODUCTION

Tooth movement during orthodontic treatment is possible because of mechanical force-induced inflammation and remodelling in the periodontal ligament. Variation in the inflammatory response might be anticipated with initial aligning archwires of different composition. Myloperoxidase (MPO) is an enzyme found in neutrophil granules that represents an important marker of inflammation. The aim of this study was to measure MPO enzyme activity during initial alignment with orthodontic arch wires of different alloy types.

MATERIALS AND METHODS

MPO activity was determined in gingival crevicular fluid (GCF) from a sample of 60 patients divided into three groups during initial orthodontic alignment with three types of arch wire (0.016-inch superelastic (SE) NiTi; 0.016-inch heat-activated (HANT) NiTi and 0.00175-inch multistranded stainless steel). MPO activity was measured at baseline, 2 hours, 7 and 14 days after appliance activation.

RESULTS

MPO activity was significantly increased in GCF at 2 hours (P < 0.01), 7 and 14 days in all groups compared to baseline. Enzymatic activity was highest in the SE NiTi group followed by HANT and multistranded stainless steel groups but with no significant difference between SE NiTi and HANT groups.

CONCLUSION

SE and HANT NiTi arch wires produce an increased inflammatory response based upon MPO activity during initial levelling and alignment compared to multistranded stainless steel.

Which Orthodontic Wire and Working Sequence Should be Preferred for Alignment Phase? A Review

The key to a successful orthodontic therapy depends not only on manual skills and knowledge about treatment steps, but also on knowledge and choice of materials used. One of the major components of fixed orthodontic therapy is the choice of wires. Orthodontic wires are defined as devices consisting of a wire conforming to the alveolar or dental arch, used as an anchorage in correcting irregularities in the position of the teeth. The history of these materials is as old as that of fixed orthodontic treatments and they present different features. With proper general knowledge, doctors can differentiate between wires and use the sufficient wire sequence suitable for each patient. This can increase the quality of treatment. Therefore, the aim of the present review is to focus on the differences in features of wires as well as the sequence of leveling wire selection according to the treatment plan.

Clinical evaluation of dental alignment and leveling with three different types of orthodontic wires

INTRODUCTION

A wide variety of orthodontic wires made of different alloys is available to be used in orthodontic practice and may produce different clinical responses during tooth movement.

OBJECTIVE

This research evaluated the alignment and leveling of lower dental arches after the use of three types of orthodontic wires.

METHODS

A sample of 36 patients was randomly divided into 3 groups: stainless steel, multistranded steel and superelastic nickel-titanium, according to the first leveling arches used. In order to observe differences in tooth position and axial inclination of the lower incisors, all patients had lateral cephalometric radiographs taken before the insertion of the first arches and 2 months later. The irregularity index and the curve of Spee were measured, compared between groups and considered influential on the proclination of incisors during the initial phase of alignment and leveling. The Reflex microscope was used to measure the irregularity index, whereas the ANOVA analysis of variance was used to verify differences between groups with regard to the degree of dental alignment and leveling.

RESULTS

There were significant differences between groups only at T2 for the irregularity index.

CONCLUSIONS

The NiTi and multistranded steel wires showed greater aligning capacity when compared with stainless steel wires.

A randomized clinical trial investigating pain associated with superelastic nickel-titanium and multistranded stainless steel archwires during the initial leveling and aligning phase of orthodontic treatment

Objective:To investigate and compare the effects of superelastic nickel–titanium and multistranded stainless steel archwires on pain during the initial phase of orthodontic treatment.

Design:A double-blind two-arm parallel design stratified randomized clinical trial.

Setting:A single centre in India between December 2010 and June 2012. A total of 96 participants (48 male and 48 females; 14.1±2.1 years old) were randomized (stratified on age, sex and initial crowding) to superelastic nickel–titanium or multistranded stainless steel archwire groups using a computer-generated allocation sequence.

Methods:We compared 0.016-inch superelastic nickel–titanium and 0.0175-inch multistranded stainless steel wires in 0.022-inch slot (Roth prescription) preadjusted edgewise appliances. The follow-up period was 14 days. Outcome was assessed with a visual analogue scale at baseline and 32 pre-specified follow-up points. Data was analyzed using mixed-effects model analysis.

Results:One participant was lost to follow up and 10 were excluded from the analysis due to bond failure or incomplete questionnaire answers. Ultimately, 85 participants (42 males and 43 females; 14.1±2.0 years old) were analysed for the final results. No statistically significant difference was found for overall pain [F value = 2.65, degrees of freedom (df) = 92.6; P = 0.1071]. However, compared to multistranded stainless steel wires, pain in subjects with superelastic nickel–titanium archwires was significantly greater at 12 h (t = 2.34; P = 0.0193), as well as at day 1 in the morning (t = 2.21, P = 0.0273), afternoon (t = 2.11, P = 0.0346) and at bedtime (t = 2.03, P = 0.042).

Conclusion:For overall pain, there was no statistically significant difference between the two wires. However, subjects with superelastic nickel–titanium archwires had a significantly higher pain at peak level.

Mechanical properties of NiTi and CuNiTi shape-memory wires used in orthodontic treatment. Part 1: stress-strain tests

OBJECTIVE

This research aimed to compare, through traction tests, eight types of superelastic and heat-activated NiTi archwires, by six trade companies (GAC, TP, Ormco, Masel, Morelli and Unitek) to those with addition of copper (CuNiTi 27°C and 35°C, Ormco).

METHODS

The tests were performed in an EMIC mechanical testing machine, model DL10000, capacity of 10 tons, at the Military Institute of Engineering (IME).

RESULTS

The results showed that, generally, heat-activated NiTi archwires presented slighter deactivation loadings in relation to the superelastic ones. Among the archwires that presented deactivation loadings biologically more adequate are the heat-activated by GAC and by Unitek. Among the superelastic NiTi, the CuNiTi 27°C by Ormco were the ones that presented slighter deactivation loadings, being statistically (ANOVA) similar to the ones presented by the heat-activated NiTi archwires from Unitek. When compared the CuNiTi 27°C and 35°C archwires, it was observed that the 27°C presented deactivation forces of, nearly, ⅓ of the presented by the 35°C.

CONCLUSIONS

It was concluded that the CuNiTi 35°C archwires presented deactivation loadings biologically less favorable in relation to the other heat-activated NiTi archwires, associated to lower percentage of deformation, on the constant baselines of deactivation, showing less adequate mechanical behavior under traction, in relation to the other archwires.

A clinical comparison of three aligning archwires in terms of alignment efficiency: A prospective clinical trial

OBJECTIVES

To clinically evaluate the effectiveness of three orthodontic aligning archwires in relation to tooth alignment speed during the initial alignment stage of treatment.

MATERIALS AND METHODS

A consecutive sample of 74 patients requiring lower only or upper and lower fixed orthodontic appliances were randomly allocated into three different archwires (0.014-inch superelastic nickel-titanium [NiTi], 0.014-inch thermoelastic NiTi, or 0.014-inch conventional NiTi). Good quality impressions were taken of the lower arch before archwire placement (T0) and at designated serial stages of alignment (every 2 weeks: T2, T4, T6, …, T16). The change in tooth alignment was measured in millimeters from the resultant casts using Little's irregularity index. Demographic and clinical differences among the three groups were compared with the chi-square or analysis of variance (ANOVA) test. The difference in the change of lower anterior tooth alignment over time among the three groups was explored with a Split Plot ANOVA (SPANOVA, or within- and between-groups ANOVA). The Kruskal-Wallis nonparametric test was used when data were not normally distributed.

RESULTS

The SPANOVA and Wilks Lambda Multivariate test confirmed that the wire type had no influence on the rate of change in alignment (P  =  .98).

CONCLUSION

The three forms of NiTi wires were similar in terms of their alignment efficiency during the initial aligning stage of orthodontic fixed appliance therapy.

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.

A systematic review and meta-analysis of experimental clinical evidence on initial aligning archwires and archwire sequences

The aim of the study was to assess treatment effects and potential side effects of different archwires used on patients receiving orthodontic therapy. Electronic and manual unrestricted searches were conducted in 19 databases including MEDLINE, Cochrane Library, and Google Scholar until April 2012 to identify randomized controlled trials (RCTs) and quasi-RCTs. After duplicate study selection, data extraction, risk of bias assessment with the Cochrane risk of bias tool, and narrative analysis, mean differences (MDs) with confidence intervals (CIs) of similar studies were pooled using a random-effects model and evaluated with GRADE. A total of 16 RCTs were included assessing different archwire characteristics on 1108 patients. Regarding initial archwires, meta-analysis of two trials found slightly greater irregularity correction with an austenitic-active nickel-titanium (NiTi) compared with an martensitic-stabilized NiTi archwire (corresponding to MD: 1.11 mm, 95% CI: -0.38 to 2.61). Regarding archwire sequences, meta-analysis of two trials found it took patient treated with a sequence of martensitic-active copper-nickel-titanium (CuNiTi) slightly longer to reach the working archwire (MD: 0.54 months, 95% CI: -0.87 to 1.95) compared with a martensitic-stabilized NiTi sequence. However, patients treated with a sequence of martensitic-active CuNiTi archwires reported general greater pain intensity on the Likert scale 4 h and 1 day after placement of each archwire, compared with a martensitic-stabilized NiTi sequence. Although confidence in effect estimates ranged from moderate to high, meta-analyses could be performed only for limited comparisons, while inconsistency might pose a threat to some of them. At this point, there is insufficient data to make recommendations about the majority of initial archwires or for a specific archwire sequence.

Initial arch wires for tooth alignment during orthodontic treatment with fixed appliances

BACKGROUND

Initial arch wires are the first arch wires to be inserted into the fixed appliance at the beginning of orthodontic treatment and are used mainly for the alignment of teeth by correcting crowding and rotations. With a number of different types of orthodontic arch wires available for initial tooth alignment, it is important to understand which wire is most efficient, as well as which wires cause the least amount of root resorption and pain during the initial aligning stage of treatment. This is an update of the review 'Initial arch wires for alignment of crooked teeth with fixed orthodontic braces' first published in the Cochrane Database of Systematic Reviews 2010, Issue 4.

OBJECTIVES

To assess the effects of initial arch wires for alignment of teeth with fixed orthodontic braces in relation to alignment speed, root resorption and pain intensity.

SEARCH METHODS

We searched the following electronic databases: the Cochrane Oral Health Group's Trials Register (to 2 August 2012), CENTRAL (The Cochrane Library 2012, Issue 7), MEDLINE via OVID (1950 to 2 August 2012) and EMBASE via OVID (1980 to 2 August 2012). We also searched the reference lists of relevant articles. There was no restriction with regard to publication status or language of publication. We contacted all authors of included studies to identify additional studies.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) of initial arch wires to align teeth with fixed orthodontic braces. Only studies involving participants with upper and/or lower full arch fixed orthodontic appliances were included.

DATA COLLECTION AND ANALYSIS

Two review authors were responsible for study selection, validity assessment and data extraction. All disagreements were resolved by discussion amongst the review team. Corresponding authors of included studies were contacted to obtain missing information.

MAIN RESULTS

Nine RCTs with 571 participants were included in this review. All trials were at high risk of bias and a number of methodological limitations were identified. All trials had at least one potentially confounding factor (such as bracket type, slot size, ligation method, extraction of teeth) which is likely to have influenced the outcome and was not controlled in the trial. None of the trials reported the important adverse outcome of root resorption.Three groups of comparisons were made.(1) Multistrand stainless steel initial arch wires compared to superelastic nickel titanium (NiTi) initial arch wires. There were four trials in this group, with different comparisons and outcomes reported at different times. No meta-analysis was possible. There is insufficient evidence from these trials to determine whether or not there is a difference in either rate of alignment or pain between stainless steel and NiTi initial arch wires.(2) Conventional (stabilised) NiTi initial arch wires compared to superelastic NiTi initial arch wires. There were two trials in this group, one reporting the outcome of alignment over 6 months and the other reporting pain over 1 week. There is insufficient evidence from these trials to determine whether or not there is any difference between conventional (stabilised) and superelastic NiTi initial arch wires with regard to either alignment or pain.(3) Single-strand superelastic NiTi initial arch wires compared to other NiTi (coaxial, copper NiTi (CuNiTi) or thermoelastic) initial arch wires. The three trials in this comparison each compared a different product against single-strand superelastic NiTi. There is very weak unreliable evidence, based on one very small study (n = 24) at high risk of bias, that coaxial superelastic NiTi may produce greater tooth movement over 12 weeks, but no information on associated pain or root resorption. This result should be interpreted with caution until further research evidence is available. There is insufficient evidence to determine whether or not there is a difference between either thermoelastic or CuNiTi and superelastic NiTi initial arch wires.

AUTHORS' CONCLUSIONS

There is no reliable evidence from the trials included in this review that any specific initial arch wire material is better or worse than another with regard to speed of alignment or pain. There is no evidence at all about the effect of initial arch wire materials on the important adverse effect of root resorption. Further well-designed and conducted, adequately-powered, RCTs are required to determine whether the performance of initial arch wire materials as demonstrated in the laboratory, makes a clinically important difference to the alignment of teeth in the initial stage of orthodontic treatment in patients.

Alignment efficiency of superelastic coaxial nickel-titanium vs superelastic single-stranded nickel-titanium in relieving mandibular anterior crowding: a randomized controlled prospective study

OBJECTIVE

To clinically evaluate the alignment efficiency of 0.016-inch coaxial superelastic nickel-titanium (NiTi) and 0.016-inch superelastic NiTi in the lower anterior region over a period of 12 weeks.

MATERIALS AND METHODS

A sample of 24 patients requiring lower anterior alignment were included in this single-center, single-operator, double-blind clinical trial and were randomly allocated into two groups of 12 patients. The type of wire selected for each patient was not disclosed to the provider or to the patient. Comparison of pretreatment characteristics of the archwire groups revealed no discrimination between two samples, thus verifying the random allocation of the intervention. An initial alginate impression of the lower arch was followed by impressions at 4-, 8-, and 12-week intervals. Casts were measured using the coordinate measuring machine to denote the degree of alignment. Duplicate readings of the cast series were taken to assess measurement variation.

RESULTS

A statistically significant difference (P < .05) in the mean values of tooth movement demonstrated the superior aligning efficiency of coaxial superelastic NiTi over single-stranded superelastic NiTi in relieving lower anterior crowding. The measurement error recorded was within acceptable limits, with range values within 95% limits of agreement.

CONCLUSION

Coaxial superelastic NiTi wire proved superior to single-stranded NiTi in its efficiency in relieving lower anterior crowding over a 12-week period.

Transversal maxillary dento-alveolar changes in patients treated with active and passive self-ligating brackets: a randomized clinical trial using CBCT-scans and digital models

OBJECTIVE

To assess transversal tooth movements and buccal bone modeling of maxillary lateral segments achieved with active or passive self-ligating bracket systems in a randomized clinical trial.

MATERIALS AND METHODS

Sixty-four patients, with Class I, II, and mild Class III malocclusions, were randomly assigned to treatment with passive (Damon 3 MX) or active (In-Ovation R) SLBs. Impressions and cone-beam CT-scans were taken before (T0) and after treatment (T1). Displacement of maxillary canines, premolars and molars, and buccal alveolar bone modeling were blindly assessed.

RESULTS

Twenty-one patients in the Damon and 20 in the In-Ovation group completed treatment according to the prescribed protocol. Eight Damon and 10 In-Ovation patients were excluded as the treatment approach had to be changed because of deviation from the recommended initial plan, while three Damon and two In-Ovation patients did not complete the treatment. Transversal expansion of the upper arch was achieved by buccal tipping in all but one patient in each group. No statistical significant difference in inter-premolar bucco-lingual inclination was found between the two groups from T0 to T1. The bone area buccal to the 2nd premolar decreased on average of 20% in the Damon and 14% in the In-Ovation group. Only few patients exhibited widening of the alveolar process.

CONCLUSION

The anticipated translation and buccal bone modeling using active or passive SLBs could not be confirmed. Because of the large interindividual variation, a patient-specific analysis seems to be mandatory as individual factors like pre-treatment teeth inclination and occlusion influenced the treatment outcome of the individual patients.

Efficiency, behavior, and clinical properties of superelastic NiTi versus multistranded stainless steel wires: a prospective clinical trial

OBJECTIVE

To investigate efficiency, behavior, and properties of superelastic NiTi vs multistranded stainless steel wires in Begg and preadjusted edgewise appliance (PEA) under moderate to severe crowding conditions.

MATERIAL AND METHODS

Ninety-six participants (48 male, 48 female), aged 12-18 years old (mean age  =  15.2 ± 1.95), with moderate (≤ 6 mm; mean  =  5.3 ± 0.48) to severe (> 6 mm; mean  =  7.9 ± 0.66) initial crowding were distributed into four groups: superelastic NiTi PEA (n  =  24), superelastic NiTi Begg (n  =  24), multistranded (coaxial) stainless steel PEA (n  =  25), and multistranded (coaxial) stainless steel Begg (n = 23). In this study, 0.16-inch superelastic (austenitic active) NiTi and 0.175-inch multistranded (six stranded, coaxial) stainless steel wires were used in a 0.022-inch slot (Roth prescription) PEA and Begg appliance with a follow-up of six weeks.

RESULTS

Analysis of variance revealed no significant difference in reduction of crowding between superelastic NiTi PEA and multistranded (coaxial) stainless steel PEA groups, but reduction in crowding was significantly greater in the superelastic NiTi Begg group compared with the multistranded (coaxial) stainless steel Begg group with F (3, 44)  =  8.896, P < .001, and effect size (ω) 0.57 in moderate crowding and F (3, 44)  =  122.341, P < .001, and effect size (ω) 0.93 in severe crowding. Linear regression demonstrated significant (P < .05) positive correlation between amount of initial crowding and reduction in crowding in all groups except the multistranded (coaxial) stainless steel Begg group, wherein a negative correlation did exist.

CONCLUSION

Superelastic NiTi performed significantly better than multistranded (coaxial) stainless steel wire in the Begg appliance. However, in PEA, there was no significant difference.

Efeitos dos fios de nivelamento de níquel-titânio e de aço inoxidável na posição dos incisivos inferiores

OBJETIVO: estudar os efeitos do nivelamento realizado com fios de NiTi termoativado e de aço inoxidável, avaliando-se as possíveis alterações na posição dos incisivos inferiores, em casos com extrações, correlacionando com o tempo de tratamento. MÉTODOS: a amostra foi composta de 36 indivíduos, de ambos os sexos, leucodermas brasileiros, com idade média inicial de 15 anos e 5 meses, portadores de más oclusões de Classes I e II, distribuídos em dois grupos. No Grupo 1 (n=17), o nivelamento foi realizado com a sequência 1, utilizando-se três fios - 0,016" e 0,019"x0,025" de NiTi termoativado, e 0,019"x0,025" de aço inoxidável. No Grupo 2 (n=19), foi testada a sequência 2, na qual foram utilizados apenas fios de aço inoxidável (0,014"; 0,016"; 0,018"; 0,020" e 0,019"x0,025" com torque passivo nos incisivos inferiores). Os dados foram coletados utilizando-se o método cefalométrico computadorizado e comparados pelo teste t de Student com o nível de significância de 5%. RESULTADOS: no Grupo 1, os incisivos inferiores inclinaram-se para lingual, com movimento significativo apenas da coroa (1,6mm). No Grupo 2, os incisivos inferiores permaneceram estáveis. Não houve alteração vertical em nenhum dos grupos. CONCLUSÕES: a sequência 2 proporcionou um melhor controle dos incisivos inferiores, não alterando suas posições iniciais, enquanto a sequência 1 permitiu a expressão do torque da prescrição utilizada, levando a uma inclinação lingual desses dentes. O tempo de tratamento foi menor utilizando-se a sequência 1. As variações biomecânicas estudadas apresentaram vantagens e desvantagens que devem ser conhecidas e ponderadas pelo ortodontista no planejamento do caso.

Alignment efficiency and discomfort of three orthodontic archwire sequences: a randomized clinical trial

AIM

To compare the efficiency of orthodontic archwire sequences produced by three manufacturers.

DESIGN

Prospective, randomized clinical trial with three parallel groups.

SETTING

Private orthodontic practice in Caloundra, QLD, Australia.

SUBJECTS AND METHODS

One hundred and thirty-two consecutive patients were randomized to one of three archwire sequence groups: (i) 3M Unitek, 0·014 inch Nitinol, 0·017 inch × 0·017 inch heat activated Ni-Ti; (ii) GAC international, 0·014 inch Sentalloy, 0·016 × 0·022 inch Bioforce; and (iii) Ormco corporation, 0·014 inch Damon Copper Ni-Ti, 0·014 × 0·025 inch Damon Copper Ni-Ti. All patients received 0·018 × 0·025 inch slot Victory Series™ brackets.

OUTCOME MEASURES

Mandibular impressions were taken before the insertion of each archwire. Patients completed discomfort surveys according to a seven-point Likert Scale at 4 h, 24 h, 3 days and 7 days after the insertion of each archwire. Efficiency was measured by time required to reach the working archwire, mandibular anterior alignment and level of discomfort.

RESULTS

No significant differences were found in the reduction of irregularity between the archwire sequences at any time-point (T1: P = 0·12; T2: P = 0·06; T3: P = 0·21) or in the time to reach the working archwire (P = 0·28). No significant differences were found in the overall discomfort scores between the archwire sequences (4 h: P = 0·30; 24 h: P = 0·18; 3 days: P = 0·53; 7 days: P = 0·47). When the time-points were analysed individually, the 3M Unitek archwire sequence induced significantly less discomfort than GAC and Ormco archwires 24 h after the insertion of the third archwire (P = 0·02). This could possibly be attributed to the progression in archwire material and archform.

CONCLUSIONS

The archwire sequences were similar in alignment efficiency and overall discomfort. Progression in archwire dimension and archform may contribute to discomfort levels. This study provides clinical justification for three common archwire sequences in 0·018 × 0·025 inch slot brackets.

Initial arch wires for alignment of crooked teeth with fixed orthodontic braces

BACKGROUND

The initial arch wire is the first arch wire to be inserted into the fixed appliance at the beginning of orthodontic treatment and is used mainly for correcting crowding and rotations of teeth. With a number of orthodontic arch wires available for initial tooth alignment, it is important to understand which wire is most efficient, as well as which wires cause the least amount of root resorption and pain during the initial aligning stage of treatment.

OBJECTIVES

To identify and assess the evidence for the effects of initial arch wires for alignment of teeth with fixed orthodontic braces in relation to alignment speed, root resorption and pain intensity.

SEARCH STRATEGY

We searched the following electronic databases: the Cochrane Oral Health Group's Trials Register (30th November 2009), CENTRAL (The Cochrane Library 2009, Issue 4), MEDLINE (1950 to 30th November 2009) and EMBASE (1980 to 30th November 2009). Reference lists of articles were also searched. There was no restriction with regard to publication status or language of publication. We contacted all authors of included studies to identify additional studies.

SELECTION CRITERIA

Randomised controlled trials (RCTs) of initial arch wires to align crooked teeth with fixed orthodontic braces were selected. Only studies involving patients with upper and/or lower full arch fixed orthodontic appliances were included.

DATA COLLECTION AND ANALYSIS

Two review authors were responsible for study selection, validity assessment and data extraction. All disagreements were resolved by discussion amongst the review team. Corresponding authors of included studies were contacted to obtain missing information.

MAIN RESULTS

Seven RCTs, with 517 participants, provided data for this review. Among them, five trials investigated the speed of initial tooth alignment comparing: 0.016 inch ion-implanted A-NiTi wire versus 0.016 inch A-NiTi versus 0.0175 multistrand stainless steel wire; 0.016x0.022 inch medium force active M-NiTi wire versus 0.016x0.022 inch graded force active M-NiTi wire versus 0.0155 inch multistrand stainless steel wire; 0.016 inch superelastic NiTi wire versus 0.016 inch NiTi wire; 0.014 inch superelastic NiTi wire versus 0.0155 inch multistrand stainless steel wire; 0.016 inch CuNiTi wire versus 0.016 inch NiTi wire. The other two studies investigated pain intensity experienced by patients during the initial stage of treatment comparing: 0.014 inch superelastic NiTi wire versus 0.014 inch NiTi wire; 0.014 inch superelastic NiTi wire versus 0.015 inch multistrand stainless steel wire. Data analyses were often inappropriate within the included studies.

AUTHORS' CONCLUSIONS

There is some evidence to suggest that there is no difference between the speed of tooth alignment or pain experienced by patients when using one initial aligning arch wire over another. However, in view of the general poor quality of the including trials, these results should be viewed with caution. Further RCTs are required.

A systematic review of clinical trials of aligning archwires

OBJECTIVES

This review aimed to identify the evidence for the efficacy of archwires used in the alignment stage of orthodontic treatment by undertaking a systematic review of the literature.

DATA SOURCES

MEDLINE, the Cochrane Central Register of Controlled trials (CENTRAL), EMBASE, and the meta Register of Controlled Trials were searched up to July 2008. Reference lists of identified articles and relevant review articles were checked for further possible studies.

REVIEW METHODS

Controlled clinical trials and randomised clinical trials that compared aligning archwires and reported objective measures of alignment were selected for inclusion. Validity and quality assessment were undertaken to identify studies with a low risk of bias. Details of the study methodology and the reported results were then abstracted.

RESULTS

100 studies were identified by the searches and 7 of these were identified as meeting the selection criteria. Four studies were deemed, after quality assessment, to have a low risk of bias and data was extracted from these. No two studies shared a common methodology or common reporting of outcome. Meta-analysis was therefore not possible.

CONCLUSIONS

There is insufficient data in these studies to make clear recommendations regarding the most effective archwire for alignment. Recommendations on future study design have been made.

Alignment efficiency of Damon3 self-ligating and conventional orthodontic bracket systems: a randomized clinical trial

INTRODUCTION

The aim of this study was to compare the efficiency of mandibular tooth alignment and the clinical effectiveness of a self-ligating and a conventional preadjusted edgewise orthodontic bracket system.

METHODS

A multicenter randomized clinical trial was conducted in 2 orthodontic clinics. Sixty-two subjects (32 male, 30 female; mean age, 16.27 years) with mandibular incisor irregularities of 5 to 12 mm and a prescribed extraction pattern including the mandibular first premolars were randomly allocated to treatment with Damon3 self-ligating (Ormco, Glendora, Calif) or Synthesis (Ormco) conventionally ligated brackets. Fully ligated 0.014-in nickel-titanium archwires were used first in both groups, followed by a sequence of 0.014 x 0.025-in and 0.018 x 0.025-in nickel-titanium, and 0.019 x 0.025-in stainless steel. Study casts were taken at the start of treatment (T1), the first archwire change (T2), and the placement of the final 0.019 x 0.025-in archwire (T3). Cephalometric lateral skull and long-cone periapical radiographs of the mandibular incisors were taken at T1 and T3.

RESULTS

No significant difference was noted (P >0.05) in initial rate of alignment for either bracket system. Initial irregularity influenced subsequent rate of movement, but sex, age, and appliance type were statistically insignificant. Alignment was associated with an increase in intercanine width, a reduction in arch length, and proclination of the mandibular incisors for both appliances, but the differences were not significant. Incisor root resorption was not clinically significant and did not differ between systems.

CONCLUSIONS

Damon3 self-ligating brackets are no more efficient than conventional ligated preadjusted brackets during tooth alignment.

The effectiveness of laceback ligatures: a randomized controlled clinical trial

OBJECTIVE

To evaluate the effects of laceback ligatures on the anteroposterior and vertical position of lower incisors and the mesial position of the lower first molars.

DESIGN

Randomized controlled trial.

SETTINGS

Patients under treatment in the Department of Orthodontics, Royal Bournemouth Hospital, Dorset, during a 6 month period from November 1999 to March 2000.

SUBJECTS

Sixty-two adolescents (mean 13.7 years, range 11.2-16.8 years) with similar malocclusions, requiring extraction of all first premolars, were randomly assigned to experimental (laceback: 30; 12 male, 18 female) and control (non-laceback: 32; 14 male, 18 female) groups.

INTERVENTIONS

Treatment using upper and lower fixed appliances following extraction of four premolars. One group had lacebacks placed, whilst the control group had no lacebacks.

MAIN OUTCOME MEASURES

The participants were examined clinically and radiographically, and lateral cephalograms with radio-opaque tooth markers and lower study casts records were taken when lower fixed appliances were placed (T1) and following sufficient leveling with a 0.018 inch stainless steel round wire (T2). Linear measurements were recorded following digitization of the lateral cephalograms and using a vernier caliper on the study casts. A Student t-test was used to examine differences between the two groups following assessment for normality.

RESULTS

In both groups the lower incisors retroclined during T1-T2; (Mean+/-SD: Experimental -0.53+/-1.9 mm, Control -0.44+/-1.29 mm). There was no statistical significance between the two groups (p = 0.84). The lower incisors extruded in both groups; 0.47+/-0.98 mm in the experimental group and 0.44+/-0.87 mm in the control group. There was no statistical difference between the groups (p = 0.9). The lower first molars showed 0.83 mm greater mesial movement in the experimental group, which was statistically significant (p < 0.05). Labial segment crowding decreased in both groups (experimental -3+/-1.6 mm, control -2.67+/-2.28 mm), the difference between the groups being non-significant (p = 0.51). Arch length decreased in both groups (experimental -2.08+/-2.82 mm , control -2.9+/-3.06 mm), but the difference between them was not significant (p = 0.28)

CONCLUSIONS

In first premolar extraction cases, the lower labial segment does not procline during the leveling stage with the pre-adjusted edgewise appliance and the use of laceback ligatures conveys no difference in the anteroposterior or vertical position of the lower labial segment. Furthermore, the use of laceback ligatures creates a statistically and clinically significant increase in the loss of posterior anchorage.

Elastic properties of alternative versus single-stranded leveling archwires

The strength, stiffness, and range of single-stranded stainless steel (SS) and superelastic nickel-titanium (NiTi) archwires were compared with those of alternative leveling products, including nylon-coated and multistranded wires. Wire cross-sections were photographed after being potted in polymer, ground, and polished. Because the rectangular wires had rounded or beveled corners, gravimetric measurements and specific gravity calculations quantified the actual polygonal cross-sectional areas versus the ideal rectangular cross-sectional areas. Beveling reduced the cross-sectional areas by 7% to 8%; this decreased the wire stiffnesses by 15% to 19%. Using a testing machine, we measured the yield strengths, the elastic limits, and the ultimate tensile strengths in tension, and wire stiffnesses in 3-point bending. From cyclic loading tests, the elastic limits of the superelastic NiTi wires were approximately 90% and 45% of their ultimate tensile strengths for the round and rectangular wires, respectively. Using the measurements of the mechanical properties and geometric parameters of each wire, we computed the elastic property ratios (EPRs) versus a 16-mil (0.41 mm) NiTi wire. The single-stranded NiTi wires outperformed the alternative wires, whose EPRs varied from 0.05 to 0.32 for strength, from 0.11 to 1.55 for stiffness, and from 0.10 to 0.80 for range. Based on the current study and a review of the orthodontic literature, few superelastic wires are activated sufficiently in vivo to exhibit superelastic behavior. Therefore, the EPR data reported here for superelastic wires truly represent their performance in most clinical situations.

Load-deflection characteristics of superelastic nickel-titanium orthodontic wires

Previous mechanical testing of orthodontic wires has, in many cases, failed to simulate some key features of the clinical environment. The purpose of this study was to investigate the load-deflection characteristics of 7 different 0.016-in initial alignment archwires (Twistflex, NiTi, and 5 brands of heat-activated superelastic nickel-titanium [HASN]) with modified bending tests simulating a number of conditions encountered clinically. Load-deflection tests were carried out on the wires with 5 different model designs, and data from selected points on the unloading phase of the generated graphs were statistically analyzed. Wire deflection was carried out at 3 temperatures (22.0 degrees C, 35.5 degrees C, and 44.0 degrees C) and to 4 deflection distances (1 mm, 2 mm, 3 mm, and 4 mm). Rankings were derived according to statistically significant differences in each test situation. The effects of model, wire, and temperature variation were all statistically significant. Twistflex and the 5 HASN wires produced a range of broadly comparable results, and NiTi gave the highest unloading values. Model rankings indicated that self-ligating Twin-Lock brackets produced lower friction than regular edgewise brackets. The authors recommend using the rankings from the mechanical test simulations to predict possible clinical performance of archwires.

Force-deflection properties of superelastic nickel-titanium archwires

This in vitro study compared the force-deflection behavior of 8 superelastic nickel-titanium orthodontic wires (0.017 x 0.025 in) under controlled moment and temperature. To simulate leveling a lateral incisor, brackets and first molar tubes without tip and angulation were used. The wires (n = 5) were ligated into stainless steel brackets attached to a plastic jig to simulate a mandibular arch. A testing machine (Instron) applied deflections of 0.2 to 2.0 mm at 35 degrees C in the lateral incisor area. Force-deflection diagrams were determined from the passive position to an activation of 2 mm and then during deactivation. Forces on deactivation at a deflection of 1 mm were compared by analysis of variance. Significant differences (P < .05) in forces were observed among wires. All wires exhibited superelastic behavior, but in stratified loading levels.

Pseudoelasticity and thermoelasticity of nickel-titanium alloys: a clinically oriented review. Part II: Deactivation forces

The purpose of this review was to organize a systematic reference to help orthodontists evaluate commonly used orthodontic nickel-titanium alloys. Part I of the article reviewed the data available in the literature regarding the temperature transitional ranges of the alloys. The thermomechanical behavior of these compounds is, in fact, strictly dependent upon the correlation between the temperature transitional range and the oral temperature range. Part II focuses on the mechanical characteristics of the alloys, such as the magnitude of the forces delivered and correlations with the temperature transitional range and oral temperature.