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

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.

Effectiveness of tubular coaxial nickel-titanium and copper nickel-titanium orthodontic aligning archwires: A randomized clinical trial

BACKGROUND

This study aimed to compare tubular coaxial-NiTi and copper-NiTi orthodontic aligning archwires in terms of teeth alignment, patients' pain perception, and root resorption.

SUBJECTS AND METHODS

Orthodontic patients aged 12 years or older, having Little's irregularity index (LII) of 5-9mm were randomly allocated to either the copper-NiTi group or tubular coaxial-NiTi group with a 1:1 allocation ratio. The archwire sequence was 0.014-inch followed by 0.018-inch for the copper-NiTi group and 0.016-inch followed by 0.018-inch for the tubular coaxial-NiTi group. Each archwire was left in place for eight weeks before progressing to the next size. Good quality impression for the lower arch before treatment (T0) and thereafter every 4 weeks up to 16 weeks was taken to measure LII. Evaluation of pain perception was performed using a visual analog scale (VAS) during the first week following each archwire insertion. Assessment of root resorption was undertaken at T0 and after 16 weeks by taking periapical radiographs for mandibular central incisors using the long cone paralleling technique.

RESULTS

A total of 33 patients were randomized and selected for participation. Of those, 31 patients with a mean age of 15.45±2.22 who completed the trial were included in the analyses (15 patients in the copper-NiTi group and 16 patients in the tubular coaxial-NiTi group). In both groups, the irregularity index significantly decreased after 16 weeks of treatment with an overall reduction of 5.22mm for the copper-NiTi group and 6.03mm for the tubular coaxial-NiTi group. However, the difference between the two groups was not statistically significant. Likewise, pain perception and root resorption were not significantly different between the two study groups.

CONCLUSIONS

Both copper-NiTi and tubular coaxial-NiTi archwires were equally effective in terms of teeth alignment, patients' pain perception, and root resorption. Consideration could be given to the cost and clinician preference when selecting an initial archwire.

REGISTRATION

the trial was registered in ClinicalTrials.gov on 26/05/2022 with a registration ID: NCT05391542, https://clinicaltrials.gov/ct2/show/NCT05391542.

Non-surgical adjunctive interventions for accelerating tooth movement in patients undergoing orthodontic treatment

BACKGROUND

Deviation from a normal bite can be defined as malocclusion. Orthodontic treatment takes 20 months on average to correct malocclusion. Accelerating the rate of tooth movement may help to reduce the duration of orthodontic treatment and associated unwanted effects including orthodontically induced inflammatory root resorption (OIIRR), demineralisation and reduced patient motivation and compliance. Several non-surgical adjuncts have been advocated with the aim of accelerating the rate of orthodontic tooth movement (OTM).         OBJECTIVES: To assess the effect of non-surgical adjunctive interventions on the rate of orthodontic tooth movement and the overall duration of treatment.

SEARCH METHODS

An information specialist searched five bibliographic databases up to 6 September 2022 and used additional search methods to identify published, unpublished and ongoing studies.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) of people receiving orthodontic treatment using fixed or removable appliances along with non-surgical adjunctive interventions to accelerate tooth movement. We excluded split-mouth studies and studies that involved people who were treated with orthognathic surgery, or who had cleft lip or palate, or other craniofacial syndromes or deformities.

DATA COLLECTION AND ANALYSIS

Two review authors were responsible for study selection, risk of bias assessment and data extraction; they carried out these tasks independently. Disagreements were resolved by discussion amongst the review team to reach consensus.  MAIN RESULTS: We included 23 studies, none of which were rated as low risk of bias overall. We categorised the included studies as testing light vibrational forces or photobiomodulation, the latter including low level laser therapy and light emitting diode. The studies assessed non-surgical interventions added to fixed or removable orthodontic appliances compared to treatment without the adjunct. A total of 1027 participants (children and adults) were recruited with loss to follow-up ranging from 0% to 27% of the original samples.  Certainty of the evidence For all comparisons and outcomes presented below, the certainty of the evidence is low to very low. Light vibrational forces  Eleven studies assessed how applying light vibrational forces (LVF) affected orthodontic tooth movement (OTM). There was no evidence of a difference between the intervention and control groups for duration of orthodontic treatment (MD -0.61 months, 95% confidence interval (CI) -2.44 to 1.22; 2 studies, 77 participants); total number of orthodontic appliance adjustment visits (MD -0.32 visits, 95% CI -1.69 to 1.05; 2 studies, 77 participants); orthodontic tooth movement during the early alignment stage (reduction of lower incisor irregularity (LII)) at 4-6 weeks (MD 0.12 mm, 95% CI -1.77 to 2.01; 3 studies, 144 participants), or 10-16 weeks (MD -0.18 mm, 95% CI -1.20 to 0.83; 4 studies, 175 participants); rate of canine distalisation (MD -0.01 mm/month, 95% CI -0.20 to 0.18; 2 studies, 40 participants); or rate of OTM during en masse space closure (MD 0.10 mm per month, 95% CI -0.08 to 0.29; 2 studies, 81 participants). No evidence of a difference was found between LVF and control groups in rate of OTM when using removable orthodontic aligners. Nor did the studies show evidence of a difference between groups for our secondary outcomes, including patient perception of pain, patient-reported need for analgesics at different stages of treatment and harms or side effects.  Photobiomodulation Ten studies assessed the effect of applying low level laser therapy (LLLT) on rate of OTM. We found that participants in the LLLT group had a statistically significantly shorter length of time for the teeth to align in the early stages of treatment (MD -50 days, 95% CI -58 to -42; 2 studies, 62 participants) and required fewer appointments (-2.3, 95% CI -2.5 to -2.0; 2 studies, 125 participants). There was no evidence of a difference between the LLLT and control groups in OTM when assessed as percentage reduction in LII in the first month of alignment (1.63%, 95% CI -2.60 to 5.86; 2 studies, 56 participants) or in the second month (percentage reduction MD 3.75%, 95% CI -1.74 to 9.24; 2 studies, 56 participants). However, LLLT resulted in an increase in OTM during the space closure stage in the maxillary arch (MD 0.18 mm/month, 95% CI 0.05 to 0.33; 1 study; 65 participants; very low level of certainty) and the mandibular arch (right side MD 0.16 mm/month, 95% CI 0.12 to 0.19; 1 study; 65 participants). In addition, LLLT resulted in an increased  rate of OTM during maxillary canine retraction (MD 0.01 mm/month, 95% CI 0 to 0.02; 1 study, 37 participants). These  findings were not clinically significant. The studies showed no evidence of a difference between groups for our secondary outcomes, including OIIRR, periodontal health and patient perception of pain at early stages of treatment. Two studies assessed the influence of applying light-emitting diode (LED) on OTM. Participants in the LED group required a significantly shorter time to align the mandibular arch compared to the control group (MD -24.50 days, 95% CI -42.45 to -6.55, 1 study, 34 participants). There is no evidence that LED application increased the rate of OTM during maxillary canine retraction (MD 0.01 mm/month, 95% CI 0 to 0.02; P = 0.28; 1 study, 39 participants ). In terms of secondary outcomes, one study assessed patient perception of pain and found no evidence of a difference between groups.   AUTHORS' CONCLUSIONS: The evidence from randomised controlled trials concerning the effectiveness of non-surgical interventions to accelerate orthodontic treatment is of low to very low certainty. It suggests that there is no additional benefit of light vibrational forces or photobiomodulation for reducing the duration of orthodontic treatment. Although there may be a limited benefit from photobiomodulation application for accelerating discrete treatment phases, these results have to be interpreted with caution due to their questionable clinical significance. Further well-designed, rigorous RCTs with longer follow-up periods spanning from start to completion of orthodontic treatment are required to determine whether non-surgical interventions may reduce the duration of orthodontic treatment by a clinically significant amount, with minimal adverse effects.

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.

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.

Tooth alignment and pain experience with A-NiTi versus Cu-NiTi: a randomized clinical trial

Background

Nickel-titanium (NiTi) archwires are routinely used for initial leveling and alignment of teeth in orthodontic treatment. This study aimed to clinically compare the level of pain and tooth alignment in orthodontic treatment with A-NiTi versus Cu-NiTi archwires.

Methods

In this parallel randomized clinical trial, 88 orthodontic patients (12–25 years) with an irregularity index > 2 mm in the anterior site of the lower dental arch who required non-extraction orthodontic treatment of the lower arch were randomized into two age- and sex-matched groups (n = 44) for treatment with A-NiTi and Cu-NiTi initial archwires. Each archwire was used for 6 weeks. After 6 weeks, the irregularity index was measured, and the level of pain was scored using the Modified McGill pain questionnaire (MPQ) and visual analog scale (VAS) according to the time of onset and duration of pain, and analgesic intake. Data were analyzed by paired t test, independent samples t test, and Chi-square test (P < 0.05).

Results

The irregularity index significantly decreased in both groups after 6 weeks of treatment (P < 0.001). However, the difference in this respect was not significant between the two groups (P > 0.05). Pain perception (P = 0.487), duration of pain (P = 0.546), and analgesic intake (P = 0.102) were not significantly different between the two groups either.

Conclusion

Both A-NiTi and Cu-NiTi archwires are equally effective for tooth alignment in the anterior site of the lower dental arch and have no significant difference with regard to the level of pain experienced by patients.

Trial registration number: IRCT20190705044102N1 and Name of the registry: Iranian registry of clinical trials (https://irct.ir/) Date of registration: September, 26, 2019

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.

A comparative assessment of clinical efficiency between premium heat-activated copper nickel-titanium and superelastic nickel-titanium archwires during initial orthodontic alignment in adolescents: a randomized clinical trial

Background

To compare the clinical efficiency of premium heat-activated copper nickel-titanium (Tanzo Cu-NiTi) and NT3 superelastic NiTi during initial orthodontic alignment.

Subject and methods

A total of 50 patients were randomly allocated to 1 of 2 different archwire types (group 1, Tanzo Cu-NiTi; group 2, NT3 superelastic NiTi). Eligibility criteria included Class I or Class II malocclusion, moderate maxillary anterior crowding, and healthy periodontal condition. Impressions of the upper arches were taken before archwire placement (T0) and at every 4 weeks (T1, T2, T3, and T4). For T1 and T2 stages, 0.014-in., and for T3 and T4 stages, 0.018-in. archwires were used. The primary outcome was the alignment efficiency assessed using Little’s irregularity index. The secondary outcomes were arch width and incisor inclination changes. Data were analyzed using independent samples t test, repeated measures ANOVA, and Mann-Whitney U test. Marginal models were established for the estimation of coefficients.

Results

The anterior irregularity index reduction was mostly observed between T0 and T2 periods, which were respectively − 7.40 ± 0.50 mm (p < 0.001; 95% CI, − 8.94, − 5.85) and − 6.80 ± 0.55 mm (p < 0.001; 95% CI, − 8.49, − 5.12) for groups 1 and 2 (p < 0.001). With both wires, Little’s irregularity index decreased over time, and the difference between the groups was not significant (p = 0.581; estimated effect size, 0.011). No statistically significant difference was found between the groups in terms of intercanine and intermolar width and incisor inclination changes.

Conclusion

There were no significant between-group differences in alignment efficiency, arch width, and incisor inclination change. There was an increased alignment with 0.014-in. compared with 0.018-in. diameter archwire.

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.

Comparison of changes in irregularity and transverse width with nickel-titanium and niobium-titanium-tantalum-zirconium archwires during initial orthodontic alignment in adolescents: A double-blind randomized clinical trial

OBJECTIVES

The purpose of this prospective, double-blind, randomized clinical trial was to compare the clinical efficiency of nickel-titanium (NiTi) and niobium-titanium-tantalum-zirconium (TiNbTaZr) archwires during initial orthodontic alignment.

MATERIALS AND METHODS

All subjects (ages between 12 and 20 years) underwent nonextraction treatment using 0.022-inch brackets. All patients were randomized into two groups for initial alignment with 0.016-inch NiTi archwires (n = 14), or with 0.016-inch TiNbTaZr archwires (n = 14). Digital scans were taken during the course of treatment and were used to compare the improvement in Little's Irregularity Index and the changes in intercanine and intermolar widths.

RESULTS

There was approximately a 27% reduction in crowding during the first month with the use of 0.016-inch TiNbTaZr (Gummetal) wire, and an additional 25% decrease in crowding was observed during the next month. There was no significant difference between the two treatment groups in the decrease in irregularity over time ( P = .29). There was no significant difference between the two groups in the changes in intercanine and intermolar width ( P = .80).

CONCLUSIONS

It can be concluded that Gummetal wires and conventional NiTi wires possess a similar ability to align teeth, and Gummetal wires have additional advantages over conventional NiTi, such as formability and use in patients with nickel allergy.

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.

Low-level laser therapy effectiveness in accelerating orthodontic tooth movement: A randomized controlled clinical trial

OBJECTIVE

To evaluate the effectiveness of low-level laser therapy (LLLT) in accelerating orthodontic tooth movement of crowded maxillary incisors.

MATERIALS AND METHODS

This two-arm, parallel-group, randomized controlled trial involved 26 patients with severe to extreme maxillary incisors irregularity according to Little's irregularity index, indicating two first premolars extraction. Patients were randomly assigned to either the laser group or the control group (13 each). Following premolars extraction, orthodontic treatment with fixed appliances was initiated for both groups. Immediately after insertion of the first archwire, patients in the laser group received a LLL dose from an 830-nm wavelength Ga-Al-As semiconductor laser device with energy of 2 J/point. The laser was applied to each maxillary incisor's root at four points (two buccal, two palatal). Application was repeated on days 3, 7, 14, and then every 15 days starting from the second month until the end of the leveling and alignment stage. Alignment progress was evaluated on the study casts taken before inserting the first archwire (T0), after 1 month of treatment commencement (T1), after 2 months (T2), and at the end of the leveling and alignment stage (T3). The outcome measures were the overall time needed for leveling and alignment and the leveling and alignment improvement percentage.

RESULTS

A statistically significant difference was found between the two groups in the overall treatment time (P < .001) and the leveling and alignment improvement percentage at T1 (P = .004) and T2; (P = .001).

CONCLUSION

LLLT is an effective method for accelerating orthodontic tooth movement.

Evaluation of Mechanical and Physical Properties of Clinically Used and Recycled Superelastic NiTi Wires

INTRODUCTION

The initial leveling and aligning phase has been simplified with the introduction of superelastic nickel-titanium archwires. The relatively high cost of these wires has prompted some of the clinicians to reuse them after sterilization. The quantitative changes in the surface properties of superelastic 'NiTi' wires after clinical application and recycling by autoclave method have not been established in earlier studies.

AIM

To quantify the changes in mechanical and physical properties of four different commercially available superelastic nitinol (NiTi) archwires after clinical usage and recycling.

MATERIALS AND METHODS

The superelastic 'NiTi archwires obtained from four different manufacturers: Group I-GAC (McMinnville, USA); Group II- 3M Company (California, USA); Group III- G&H Company(Franklin, USA) and Group IV- American Orthodontics (AO) (Sheboygan, USA) were selected for the study. Each of the four groups comprised of 20 samples of wire with 10 of them selected randomly as control and remaining 10 as test specimen in each group. The experimental archwires were placed on selected patients for a period of three months followed by Standard Autoclave sterilization at 121°C and 15 to 20 psi pressure for 20 minutes and were retrieved. The tensile strength was evaluated by Instron-Universal Testing Machine. The quantification of changes in surface roughness was investigated by grid method using Scanning Electron Microscope (SEM). The Control Wires (C) were evaluated at initial time "T1" where as the Experimental sample of wires (T) were subjected to testing at an initial time 'T1' and after clinical usage and sterilization at 'T2'.

STATISTICAL ANALYSIS

Paired t-test was used for intra-group comparison and one way ANOVA and Post Hoc Tukey tests were used for inter-group comparison.

RESULTS

There was significant decrease in tensile strength (p = 0.0015 to 0.001) and surface roughness (p< 0.001) between control and experimental arch wires within each group when properties at T1 and T2 were compared.

CONCLUSION

The study suggests discouraging the use of clinically used and sterilized superelastic NiTi archwires.

Intraoral photobiomodulation-induced orthodontic tooth alignment: a preliminary study

BACKGROUND

Numerous strategies have been proposed to decrease orthodontic treatment time. Photobiomodulation (PBM) has previously been demonstrated to assist in this objective. The aim of this study was to test if intraoral PBM increases the rate of tooth alignment and reduces the time required to resolve anterior dental crowding.

METHODS

Nineteen orthodontic subjects with Class I or Class II malocclusion and Little's Irregularity Index (LII) ≥ 3 mm were selected from a pool of applicants, providing 28 total arches. No cases required extraction. The test group (N = 11, 18 arches, 10 upper, 8 lower) received daily PBM treatment with an intraoral LED device (OrthoPulse™, Biolux Research Ltd.) during orthodontic treatment, while the control group (N = 8, 10 arches, 3 upper, 7 lower) received only orthodontic treatment. The PBM device exposed the buccal side of the gums to near-infrared light with a continuous 850-nm wavelength, generating an average daily energy density of 9.5 J/cm(2). LII was measured at the start (T0) of orthodontic treatment until alignment was reached (T1, where LII ≤ 1 mm). The control group was mostly bonded with 0.018-in slot self-ligating SPEED brackets (Hespeler Orthodontics, Cambridge, ON. Canada), while conventionally-ligating Ormco Mini-Diamond twins were used on the PBM group (Ormco, Glendora, Calif. USA). Both groups progressed through alignment with NiTi arch-wires from 0.014-in through to 0.018-in (Ormco), with identical arch-wire changes. The rate of anterior alignment, in LII mm/week, and total treatment time was collected for both groups. Cox proportional hazards models were used to compare groups and while considering age, sex, ethnicity, arch and degree of crowding.

RESULTS

The mean alignment rate for the PBM group was significantly higher than that of the control group, with an LII change rate of 1.27 mm/week (SD 0.53, 95 % CI ± 0.26) versus 0.44 mm/week (SD 0.20, 95 % CI ± 0.12), respectively (p = 0.0002). The treatment time to alignment was significantly smaller for the PBM group, which achieved alignment in 48 days (SD 39, 95 % CI ± 39), while the control group took 104 days (SD 55, 95 % CI ±19, p = 0.0053) on average. These results demonstrated that intraoral PBM increased the average rate of tooth movement by 2.9-fold, resulting in a 54 % average decrease in alignment duration versus control. The average PBM compliance to daily treatments was 93 % during alignment.

CONCLUSIONS

Under the limitations of this study, the findings suggest that intraoral PBM could be used to decrease anterior alignment treatment time, which could consequently decrease full orthodontic treatment time. However, due to its limitations, further research in the form of a large, randomized trial is needed.

TRIAL REGISTRATION

ClinicalTrials.gov NCT02267837 . Registered 10 October 2014.

Non-surgical adjunctive interventions for accelerating tooth movement in patients undergoing fixed orthodontic treatment

BACKGROUND

Accelerating the rate of tooth movement may help to reduce the duration of orthodontic treatment and associated unwanted effects including root resorption and enamel demineralisation. Several methods, including surgical and non-surgical adjuncts, have been advocated to accelerate the rate of tooth movement. Non-surgical techniques include low-intensity laser irradiation, resonance vibration, pulsed electromagnetic fields, electrical currents and pharmacological approaches.

OBJECTIVES

To assess the effect of non-surgical adjunctive interventions on the rate of orthodontic tooth movement and the overall duration of treatment.

SEARCH METHODS

We searched the following databases on 25 November 2014: the Cochrane Oral Health Group's Trials Register (November 2014), the Cochrane Central Register of Controlled Trials (CENTRAL; The Cochrane Library 2014, Issue 10), MEDLINE via OVID (1946 to November 2014), EMBASE via OVID (1980 to November 2014), LILACS via BIREME (1980 to November 2014), metaRegister of Controlled Trials (November 2014), the US National Institutes of Health Trials Register (ClinicalTrials.gov; November 2014) and the WHO International Clinical Trials Registry Platform (November 2014). We checked the reference lists of all trials identified for further studies. There were no restrictions regarding language or date of publication in the searches of the electronic databases.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) of people receiving orthodontic treatment using fixed appliances along with non-surgical adjunctive interventions to accelerate tooth movement. We excluded non-parallel design studies (for example, split-mouth) as we regarded them as inappropriate for assessment of the effects of this type of intervention.

DATA COLLECTION AND ANALYSIS

Two review authors were responsible for study selection, risk of bias assessment and data extraction; they carried out these tasks independently. Any disagreements were resolved by discussion amongst the review team to reach consensus. The review authors contacted the corresponding authors of trials to obtain missing information and data to allow calculation of mean differences (MD), 95% confidence intervals (CI) or risk ratios (RR) when these were not reported.

MAIN RESULTS

We included two studies in this review, which were both assessed as being at high risk of bias. The two studies, involving a total of 111 participants, compared the use of Tooth Masseuse and OrthoAccel with conventional treatment mechanics during orthodontic alignment and canine retraction phases, respectively. Both studies included objective assessment of the amount or rate of tooth movement, but we were not able to meta-analyse this data as they used different outcome measurements at different stages of the orthodontic treatment process. One study measured subjective evaluation of pain and discomfort and the other evaluated adverse effects. The studies did not directly report either the duration of orthodontic treatment or the number of visits during active treatment.Using the Tooth Masseuse with 111 Hz at 0.06 Newtons (N) for 20 minutes daily resulted in greater reduction in irregularity in the lower incisor region over 10 weeks, assessed using Little's Irregularity Index (LII) with a mean difference (MD) of 0.6 mm (95% confidence interval (CI) -0.94 to 2.34) when compared to the control group. Pain and discomfort increased at six to eight hours after arch wire placement and after seven days, with minimal difference between the intervention and control groups. No statistical tests were provided for either variable and the differences between the two groups were not clinically important.Using OrthoAccel with 30 Hz at 0.25 N for 20 minutes daily produced a higher rate of maxillary canine distalisation in comparison to the control group (MD 0.37 mm/month; 95% CI -0.07 to 0.81; P = 0.05). Whilst this difference suggested 50% faster tooth movement using the vibrational appliance, the absolute differences were marginal and deemed clinically unimportant. Similar levels of non-serious adverse effects were reported in the intervention and control groups with a risk ratio of 0.96 (95% CI 0.32 to 2.85).Overall, the quality of the evidence was very low and therefore we cannot rely on the findings.

AUTHORS' CONCLUSIONS

There is very little clinical research concerning the effectiveness of non-surgical interventions to accelerate orthodontic treatment. The available evidence is of very low quality and so it is not possible to determine if there is a positive effect of non-surgical adjunctive interventions to accelerate tooth movement. Although there have been claims that there may be a positive effect of light vibrational forces, results of the current studies do not reach either statistical or clinical significance. Further well-designed and rigorous RCTs with longer follow-up periods are required to determine whether non-surgical interventions may result in a clinically important reduction in the duration of orthodontic treatment, without any adverse effects.

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.

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.