Alleviation of mandibular anterior crowding with copper-nickel-titanium vs nickel-titanium wires: A double-blind randomized control trial

Comparison of alignment efficiency of different sizes of superelastic nickel-titanium archwires in the initial phase of fixed orthodontic treatment: A single-center, double-blind randomized clinical trial

INTRODUCTION

This 3-arm parallel, double-blind study aimed to evaluate the alignment efficiency of 3 different diameters of superelastic nickel-titanium (NiTi) archwires during the initial phase of orthodontic treatment.

METHODS

Ninety-three patients with nonextraction treatment in the mandibular arch (using 0.022-in Roth prescription brackets) were randomly allocated into 3 groups: 0.012-in NiTi (group 1), 0.014-in NiTi (group 2), and 0.016-in NiTi (group 3). The alignment change was measured using the modified Little's irregularity index before archwire placement and every 4 weeks. The alignment efficiency of the 3 groups was analyzed.

RESULTS

Ninety patients were analyzed (group 1: n = 29, group 2: n = 31, and group 3: n = 30; overall mean age, 16.6 years). The overall Wald test analysis revealed that wire type was not statistically significant (P = 0.91), whereas time exhibited significance as expected (P <0.001). Furthermore, the interaction between wire type and time was not significant (P = 0.93). The time-adjusted estimated difference between 0.014-in and 0.012-in was -0.49 (95% confidence interval, -2.83 to 1.85; P = 0.68). The time-adjusted estimated difference between 0.016-in and 0.012-in was -0.45 (95% confidence interval, -2.95 to 2.05; P = 0.72). No harm was observed.

CONCLUSIONS

The clinical performance of 3 different sizes of NiTi archwires was similar. In addition, 0.014-in and 0.016-in NiTi archwires demonstrated better performances in aligning any irregularities because of a greater number of wire deformations in the 0.012-in group.

REGISTRATION

IR.TBZMED.REC.1395.1039.

PROTOCOL

The protocol was not published before trial commencement.

FUNDING

None.

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.

Alignment efficiency and three-dimensional assessment of root resorption after alignment with conventional and copper-nickel-titanium archwires: A randomized controlled trial

OBJECTIVE

To compare alignment efficiency and root resorption between nickel-titanium (NiTi) and copper-nickel-titanium (CuNiTi) archwires after complete alignment in mandibular anterior region.

METHODS

In this two-arm parallel single-blind randomized controlled trial, forty-four patients with Class I malocclusion with mandibular anterior crowding were recruited form orthodontic clinic of All India Institute of Medical Sciences (Jodhpur, India). Patients were randomly allocated into NiTi and CuNiTi groups, with a 1:1 allocation. Alignment was performed using 0.014-in, 0.016-in, 0.018-in, 0.019x0.025-in archwire sequence in the respective groups, which terminated in 0.019 x 0.025-in stainless-steel working archwire. The primary outcome was alignment efficiency, measured on study models from baseline (T0) to the first, second, third, fourth and fifth-month (T5). Secondary outcome was root resorption, measured from CBCT scans taken at T0 and T5. Mixed-factorial ANOVA was used to compare Little's Irregularity Index (LII). For assessing the proportion of patients with complete alignment at the end of each month, Kaplan-Meier survival curve was built and time to treatment completion was compared between groups using log rank test. Paired t-test was used to assess external apical root resorption (EARR) within groups, whereas independent t-test was used to evaluate LII and EARR between the groups.

RESULTS

Twenty-two patients were recruited in each group. One patient was lost to follow-up in the CuNiTi group. No statistically significant differences were observed in alignment efficiency between the groups (p>0.05). Intergroup comparison revealed that the changes in root measurement in three-dimensions were not statistically significant (p>0.05), except for mandibular right central incisor, which showed increased resorption at root apex in NiTi group (p<0.01).

CONCLUSION

The two alignment archwires showed similar rate of alignment at all time points. Root resorption measurement did not differ between the NiTi and CuNiTi groups, except for the mandibular right central incisor, which showed more resorption in NiTi group.

Percolative, Multifractal, and Symmetry Properties of the Surface at Nanoscale of Cu-Ni Bimetallic Thin Films Deposited by RF-PECVD

We explored the morphological and 3D spatial properties of Cu/Ni thin films obtained by a co-deposition process. The 3D AFM topographic maps analysis indicated that the films displayed different morphologies and rough profiles dictated by their singular directional inhomogeneities. Moreover, Minkowski’s volume showed that the Cu/Ni films deposited after 15 and 20 min had a similar relative distribution of matter as a function of height, which is different from the individual Cu films. The Minkowski boundary and connectivity point out that the percolative properties of the Cu/Ni samples were similar to each other. However, they were distinct from the percolative features of the Cu sample. It was also observed that the surface microtexture of the films showed similar spatial complexity, dominant spatial frequencies, and topographical uniformity. For the Cu/Ni thin films, the Minkowski functionals morphological analysis showed that the type of film dictated the surface percolation. In contrast, clear fingerprints of multifractal behavior in all the samples were also observed, indicating that the multifractality degree increased with the sputtering time, supporting the significant vertical growth of the Cu/Ni thin film deposited after 20 min. Aside from that, the results from a symmetry-based approach indicated that the vertical growth dynamics of individual Cu and Cu/Ni thin films were different in terms of scaling symmetry, where we observed that the sputtering induced the formation of less asymmetric topographies regarding their multiscaling behavior. Finally, our findings suggested that the sputtering process can be employed to tune the percolative properties, multifractality, and scaling symmetry of the films, inducing different vertical growth dynamics, which can be useful in the optimization of the fabrication of bimetallic surfaces for technological purposes.

Orthodontic treatment for crowded teeth in children

BACKGROUND

Crowded teeth develop when there is not enough space in the jaws into which the teeth can erupt. Crowding can affect baby teeth (deciduous dentititon), adult teeth (permanent dentition), or both, and is a common reason for referral to an orthodontist. Crowded teeth can affect a child's self-esteem and quality of life. Early loss of baby teeth as a result of tooth decay or trauma, can lead to crowded permanent teeth. Crowding tends to increase with age, especially in the lower jaw.

OBJECTIVES

To assess the effects of orthodontic intervention for preventing or correcting crowded teeth in children. To test the null hypothesis that there are no differences in outcomes between different orthodontic interventions for preventing or correcting crowded teeth in children.

SEARCH METHODS

Cochrane Oral Health's Information Specialist searched four bibliographic databases up to 11 January 2021 and used additional search methods to identify published, unpublished and ongoing studies.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) that evaluated any active interventions to prevent or correct dental crowding in children and adolescents, such as orthodontic braces or extractions, compared to no or delayed treatment, placebo treatment or another active intervention. The studies had to include at least 80% of participants aged 16 years and under.

DATA COLLECTION AND ANALYSIS

Two review authors, independently and in duplicate, extracted information regarding methods, participants, interventions, outcomes, harms and results. We resolved any disagreements by liaising with a third review author. We used the Cochrane risk of bias tool to assess the risk of bias in the studies. We calculated mean differences (MDs) with 95% confidence intervals (CI) for continuous data and odds ratios (ORs) with 95% CIs for dichotomous data. We undertook meta-analysis when studies of similar comparisons reported comparable outcome measures, using the random-effects model. We used the I2 statistic as a measure of statistical heterogeneity.

MAIN RESULTS

Our search identified 24 RCTs that included 1512 participants, 1314 of whom were included in analyses. We assessed 23 studies as being at high risk of bias and one as unclear.  The studies investigated 17 comparisons. Twenty studies evaluated fixed appliances and auxiliaries (lower lingual arch, lower lip bumper, brackets, archwires, lacebacks, headgear and adjunctive vibrational appliances); two studies evaluated removable appliances and auxiliaries (Schwarz appliance, eruption guidance appliance); and two studies evaluated dental extractions (lower deciduous canines or third molars). The evidence should be interpreted cautiously as it is of very low certainty. Most interventions were evaluated by a single study. Fixed appliances and auxiliaries One study found that use of a lip bumper may reduce crowding in the early permanent dentition (MD -4.39 mm, 95% CI -5.07 to -3.71; 34 participants). One study evaluated lower lingual arch but did not measure amount of crowding. One study concluded that coaxial nickel-titanium (NiTi) archwires may cause more tooth movement in the lower arch than single-stranded NiTi archwires (MD 6.77 mm, 95% CI 5.55 to 7.99; 24 participants). Another study, comparing copper NiTi versus NiTi archwires, found NiTi to be more effective for reducing crowding (MD 0.49 mm, 95% CI 0.35 to 0.63, 66 participants). Single studies did not show evidence of one type of archwire being better than another for Titinol versus Nitinol; nickel-titanium versus stainless steel or multistrand stainless steel; and multistranded stainless steel versus stainless steel.  Nor did single studies find evidence of a difference in amount of crowding between self-ligating and conventional brackets, active and passive self-ligating brackets, lacebacks added to fixed appliances versus fixed appliances alone, or cervical pull headgear versus minor interceptive procedures. Meta-analysis of two studies showed no evidence that adding vibrational appliances to fixed appliances reduces crowding at 8 to 10 weeks (MD 0.24 mm, 95% CI -0.81 to 1.30; 119 participants). Removable appliances and auxiliaries One study found use of the Schwarz appliance may be effective at treating dental crowding in the lower arch (MD -2.14 mm, 95% CI -2.79 to -1.49; 28 participants). Another study found an eruption guidance appliance may reduce the number of children with crowded teeth after one year of treatment (OR 0.19, 95% CI 0.05 to 0.68; 46 participants); however, this may have been due to an increase in lower incisor proclination in the treated group. Whether these gains were maintained in the longer term was not assessed. Dental extractions One study found that extracting children's lower deciduous canines had more effect on crowding after one year than no treatment (MD -4.76 mm, 95 CI -6.24 to -3.28; 83 participants), but this was alongside a reduction in arch length. One study found that extracting wisdom teeth did not seem to reduce crowding any more than leaving them in the mouth (MD -0.30 mm, 95% CI -1.30 to 0.70; 77 participants).

AUTHORS' CONCLUSIONS

Most interventions were assessed by single, small studies. We found very low-certainty evidence that lip bumper, used in the mixed dentition, may be effective for preventing crowding in the early permanent dentition, and a Schwarz appliance may reduce crowding in the lower arch. We also found very low-certainty evidence that coaxial NiTi may be better at reducing crowding than single-stranded NiTi, and that NiTi may be better than copper NiTi. As the current evidence is of very low certainty, our findings may change with future research.

Duration of tooth alignment with fixed appliances: A systematic review and meta-analysis

INTRODUCTION

A key goal of orthodontic treatment with fixed appliances is alignment of the dentition, and this remains a commonly selected outcome in clinical studies investigating orthodontic tooth movement. This systematic review has evaluated treatment duration to achieve alignment of the mandibular dentition using fixed appliances.

METHODS

Systematic literature searches without restrictions were undertaken in 9 databases for randomized clinical trials (RCTs) assessing duration and rate of tooth alignment using fixed appliances with or without treatment adjuncts published up to January 2021. After duplicate study selection, data extraction, and risk of bias assessment according to Cochrane, random-effects meta-analyses of aggregate data, and individual patient data were conducted.

RESULTS

Thirty-five trials were included with 2258 participants (39% male; mean age 17.8 years), giving a pooled duration to achieve whole-arch alignment of the mandibular dentition of 263.0 days (4 trials; 95% confidence interval [CI], 186.7-339.4 days) and incisor alignment in the mandibular arch of 100.7 days (9 trials; 95% CI, 84.1-117.4 days). Surgical-assisted orthodontics was associated with reduced duration of incisor alignment: mean difference of 44.3 days less (4 trials; 95% CI, 20.0-68.9 days; P <0.001; high quality of evidence), whereas subgroup and meta-regression analyses indicated significant effects of baseline crowding and premolar extractions. Individual patient data analysis from 3 RCTs indicated that for each additional participant age year, whole-arch alignment of the mandibular dentition took 13.7 days longer (3 trials; 95% CI, 7.7-17.7 days; P <0.001) and for each additional mm of irregularity, 17.5 days more were needed (2 trials; 95% CI, 9.8-25.2 days; P <0.001).

CONCLUSIONS

Patient and treatment-related characteristics can significantly affect the duration of tooth alignment and should be taken into account both clinically and when designing trial outcomes. Future research studies investigating rates of orthodontic tooth alignment would benefit from adequate sample sizes and a more consistent methodology in outcome assessment. Data in this systematic review provides a basis for appropriate trial design for future RCTs investigating the rate of orthodontic tooth alignment with fixed appliances.

Can we expect similar behavior among CuNiTi 35°C wires?

Objective:

This paper aims to verify the thermodynamic, mechanical and chemical properties of CuNiTi 35ºC commercial wires.

Methods:

Forty pre-contoured copper-nickel-titanium thermodynamic 0.017 x 0.025-in archwires with an Af temperature of 35°C were used. Eight wires from five different manufacturers (American Orthodontics® [G1], Eurodonto® [G2], Morelli® [G3], Ormco® [G4] and Orthometric® [G5]) underwent cross-sectional dimension measurements, tensile tests, SEM-EDS and differential scanning calorimetry (DSC) tests. Parametric tests (One-way ANOVA and Tukey post-test) were used, with a significance level of 5%, and Pearson’s correlation coefficient test was performed between the Af and chemical elements of the wires. All sample tests and statistical analyses were double-blinded.

Results:

All wires presented standard dimensions (0.017 x 0.025-in) and superelastic behavior, with mean plateau forces of: G1 = 36.49N; G2 = 27.34N; G3 = 19.24 N; G4 = 37.54 N; and G5 = 17.87N. The Af means were: G1 = 29.40°C, G2 = 29.13°C and G3 = 31.43°C, with p>0.05 relative to each other. G4 (32.77°C) and G5 (35.17°C) presented statistically significant differences between each other and among the other groups. All samples presented Ni, Ti, Cu and Al in different concentrations.

Conclusions:

The chemical concentration of the elements that compose the alloy significantly influenced the thermodynamic and mechanical properties.

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.

Comparison of the efficacy of tooth alignment among lingual and labial brackets: an in vitro study

Background/objective

The aim of this study was to evaluate the efficacy of tooth alignment with conventional and self-ligating labial and lingual orthodontic bracket systems.

Materials/methods

We tested labial brackets (0.022″ slot size) and lingual brackets (0.018″ slot size). The labial brackets were: (i) regular twin brackets (GAC-Twin [Dentsply]), (ii) passive self-ligating brackets including (Damon-Q® [ORMCO]; Ortho classic H4™ [Orthoclassic]; FLI®SL [RMO]), and (iii) active self-ligating brackets (GAC In-Ovation®C [DENTSPLY] and SPEED™[Strite]). The lingual brackets included (i) twin bracket systems (Incognito [3M] and Joy™ [Adenta]), (ii) passive self-ligating bracket system (GAC In-Ovation®LM™ [Dentsply]), and (iii) active self-ligating bracket system (Evolution SLT [Adenta]). The tested wires were Thermalloy-NiTi 0.013″ and 0.014″ (RMO). The archwires were tied to the regular twin brackets with stainless steel ligatures 0.010″ (RMO). The malocclusion simulated a displaced maxillary central incisor in the x-axis (2 mm gingivally) and in the z-axis (2 mm labially).

Results

The results showed that lingual brackets are less efficient in aligning teeth when compared with labial brackets in general. The vertical correction achieved by labial bracket systems ranged from 72 to 95 per cent with 13″ Thermalloy wires and from 70 to 87 per cent with 14″ Thermalloy wires. In contrast, the achieved corrections by lingual brackets with 13″ Thermalloy wires ranged between 25-44 per cent and 29-52 per cent for the 14" Thermalloy wires. The anteroposterior correction achieved by labial brackets ranged between 83 and 138 per cent for the 13″ Thermalloy and between 82 and 129 per cent for the 14″ Thermalloy wires. On the other hand, lingual brackets corrections ranged between 12 and 40 per cent for the 13″ Thermalloy wires and between 30 and 45 per cent for the 14″ Thermalloy wires.

Limitation

This is a lab-based study with different labial and lingual bracket slot sizes (however they are the commonly used ones in clinical orthodontics) and study did not consider saliva, periodontal ligament, mastication and other oral functions.

Conclusions

The effectiveness of lingual brackets in correcting vertical and anteroposterior displacement achieved during the initial alignment phase of orthodontic treatment is lower than that of the effectiveness of labial brackets.

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.

Archwire diameter effect on tooth alignment with different bracket-archwire combinations

INTRODUCTION

Our objective was to evaluate the effect of the diameter of the archwire on tooth alignment with different bracket-archwire combinations.

METHODS

The materials included 2 categories of orthodontic brackets (1) conventional ligating brackets (Victory Series [3M Unitek, Monrovia, Calif], Mini-Taurus [Rocky Mountain Orthodontics, Denver, Colo], and Synergy [Rocky Mountain Orthodontics]) and (2) self-ligating brackets (SmartClip [3M Unitek], a passive self-ligating bracket; Time3 [American Orthodontics, Sheboygan, Wis], an active self-ligating bracket; and SPEED [Strite Industries, Cambridge, Ontario, Canada], an active self-ligating bracket). All brackets had a nominal 0.022-in slot size. The brackets were combined with Therma-Ti 0.014-in and Therma-Ti 0.016-in titanium memory archwires (American Orthodontics). The archwires were tied to the conventional brackets with both stainless steel ligatures (0.010 in) and elastomeric rings. Each bracket-archwire combination was tested 20 times with the orthodontic measurement and simulation system built in a temperature-controlled chamber where the temperature was kept at 37°C (±1°C) during testing. The malocclusion simulated in the study represented a maxillary central incisor displaced 2 mm gingivally (x-axis) and 2 mm labially (z-axis).

RESULTS

The incisogingival corrections achieved by the 0.014-in archwire combined with the brackets used ranged from 40% to 95%; the corrections by the 0.016-in wire were 55% to 95%. The labiolingual corrections achieved by the 0.014-in archwire combined with the brackets used ranged from 10% to 100%, and the corrections of the 0.016-in archwires ranged from 15% to 100%.

CONCLUSIONS

Increasing the diameter from 0.014 to 0.016 in increased the correction achieved by up to 15% in certain bracket-archwire combinations, but it decreased the correction by up to 25% in other combinations.

Effect of archwire cross-section changes on force levels during complex tooth alignment with conventional and self-ligating brackets

INTRODUCTION

Our objective was to investigate the effect of archwire cross-section increases on the levels of force applied to teeth during complex malalignment correction with various archwire-bracket combinations using an experimental biomechanical setup.

METHODS

The study comprised 3 types of orthodontic brackets: (1) conventional ligating brackets (Victory Series [3M Unitek, Monrovia, Calif] and Mini-Taurus [Rocky Mountain Orthodontics, Denver, Colo]), (2) self-ligating brackets (SmartClip, a passive self-ligating bracket [3M Unitek]; and Time3 [Rocky Mountain Orthodontics, Denver, Colo] and SPEED [Strite Industries, Cambridge, Ontario, Canada], both active self-ligating brackets), and (3) a conventional low-friction bracket (Synergy [Rocky Mountain Orthodontics]). All brackets had a nominal 0.022-in slot size. The brackets were combined with 0.014-in and 0.016-in titanium memory wires, Therma-Ti archwires (American Orthodontics, Sheboygan, Wis). The archwires were tied to the conventional brackets with both stainless steel ligatures of size 0.010-in and elastomeric rings. A malocclusion of the maxillary central incisor displaced 2 mm gingivally (x-axis) and 2 mm labially (z-axis) was simulated.

RESULTS

The forces recorded when using the 0.014-in archwires ranged from 1.7 ± 0.1 to 5.0 ± 0.3 N in the x-axis direction, and from 1.2 ± 0.1 to 5.5 ± 0.3 N in the z-axis direction. When we used the 0.016-in archwires, the forces ranged from 2.6 ± 0.1 to 6.0 ± 0.3 N in the x-axis direction, and from 2.0 ± 0.2 to 6.0 ± 0.4 N in the z-axis direction. Overall, the increases ranged from 16.0% to 120.0% in the x-axis and from 10.4% to 130.0% in the z-axis directions.

CONCLUSIONS

Increasing the cross section of the wire increased the force level invariably with all brackets. Wires of size 0.014 in produced relatively high force levels, and the force level increased with 0.016-in wires.

Clinical Efficiency of Two Sequences of Orthodontic Wires to Correct Crowding of the Lower Anterior Teeth

This study compared time to correction of mandibular anterior crowding using two arch wire sequences, one with conventional nickel-titanium (NiTi) arch wires and the other with conventional and NiTi heat-activated arch wires. Twenty-two boys and girls (mean age: 16.68 ± 2.66) with moderate crowding (3-6 mm) were assigned randomly to one of two groups and followed up for five months (six assessments) when arch wires were changed. Time to crowding correction was analyzed statistically using the Kaplan-Meier method. Data were collected during the five-month follow-up, and time to correction was compared between groups using the log rank test. At the end of follow-up, mandibular crowding was corrected in 100% of the cases in the group treated with the sequence that included NiTi heat-activated arch wires, whereas about 30% of those treated with NiTi arch wires were not completely corrected. There was a significant difference in time to complete treatment between groups (log rank = 5.996; p < 0.05). In the group treated with the sequence that included heat-activated wires, alignment and leveling of mandibular anterior teeth were completed earlier than in the group treated only with conventional NiTi arch wires. Clinical trial registration is found at RBR-7g5zng.

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 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.

Noninvasive induction implant heating: an approach for contactless altering of mechanical properties of shape memory implants

This article shows an approach to change the properties of an orthopaedic shape memory implant within biological tissue, using contactless induction heating. Due to inducing the one way-memory effect, triggered by the rise of temperature within the implant, the geometry and hence the mechanical properties of the implant itself, are altered. The power uptake of the implant, depending on the induction parameters as well as on its position within the induction coil, is shown. Thermographic measurements are carried out in order to determine the surface temperature distribution of the implant. In order to simulate biological tissue, the implant was embedded in agarose gel. Suitable heating parameters, in terms of a short heating process in combination with a reduced heat impact on the surrounding environment, were determined.

Electromagnetic induction heating of an orthopaedic nickel--titanium shape memory device

Shape memory orthopaedic implants made from nickel-titanium (NiTi) might allow the modulation of fracture healing, changing their cross-sectional shape by employing the shape memory effect. We aimed to show the feasibility and safety of contact-free electromagnetic induction heating of NiTi implants in a rat model. A water-cooled generator-oscillator combination was used. Induction characteristics were determined by measuring the temperature increase of a test sample in correlation to generator power and time. In 53 rats, NiTi implants were introduced into the right hind leg. The animals were transferred to the inductor, and the implant was electromagnetically heated to temperatures between 40 and 60°C. Blood samples were drawn before and 4 h after the procedure. IL-1, IL-4, IL-10, TNF-α, and IFN-γ were measured. Animals were euthanized at 3 weeks. Histological specimens from the hind leg and liver were retrieved and examined for inflammatory changes, necrosis, and corrosion pits. Cytokine measurements and histological specimens showed no significant differences among the groups. We concluded that electromagnetic induction heating of orthopedic NiTi implants is feasible and safe in a rat model. This is the first step in the development of new orthopedic implants in which stiffness or rigidity can be modified after implantation to optimize bone-healing.

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.