Assessment of the rate of premolar extraction space closure in the maxillary arch with the AcceleDent Aura appliance vs no appliance in adolescents: A single-blind randomized clinical trial

Introduction

The purpose of this 2-arm parallel trial was to assess the effect of the AcceleDent Aura appliance (OrthoAccel Technologies, Houston, Tex) on the rate of maxillary premolar extraction space closure in adolescent patients.

Methods

Forty Class II adolescents treated with full fixed appliances and maxillary premolar extractions participated in this randomized clinical trial. They were recruited in a private practice and treated by 1 clinician. Randomization was accomplished in blocks of 10 patients assigned to either a no-appliance group or the AcceleDent Aura appliance group with the allocations concealed in opaque, sealed envelopes. Both the operator and the outcome assessor were blinded; however, it was not feasible to blind the patients. Models were taken of the maxillary arch at the start of space closure and just before complete space closure. The space was measured parallel to the occlusal plane from the cusp tips of the teeth mesial and distal to the extraction spaces.

Results

There was no clinically (0.05 mm per month; 95% confidence interval [CI], –0.24, 0.34) or statistically significant difference in the rate of space closure ( P = 0.74). In both the univariable and multivariable analyses, the mean rate of tooth movement was slower by 0.13 mm per month (95% CI, –.26, .005) on the left side compared with the right side, but this was not statistically significant ( P = 0.06).

Conclusions

The AcceleDent Aura appliance had no effect on the rate of maxillary premolar extraction space closure. Only a few participants were considered to be good compliers with the appliance. However, the rate of space closure in the good compliers was similar to the overall group and did not appear to influence the result.

Registration

This trial was not registered.

Protocol

The protocol was not published before trial commencement.

Highlights

  • The AcceleDent Aura appliance did not affect the rate of maxillary extraction space closure.

  • Space closure was slower on the left than on the right, but not statistically significant.

  • Compliance did not appear to influence the rate of movement.

As professionals, orthodontists aim to deliver a quality outcome for their patients; as business people, we would like to deliver that in an expeditious and cost-efficient manner. Not surprisingly, there is a demand by the public for shorter treatment times, with parents wanting treatment completed in 12 to 18 months, although adolescent patients would like it completed in 6 months or less. Traditionally, orthodontic treatment involved 2 or more years in fixed appliances ; more recently, it has been reported to have shortened to less than 2 years. This is longer than many patients would prefer, so to cater to this demand there are several appliances and techniques, both surgical and nonsurgical, currently claiming to accelerate tooth movement and thereby shorten orthodontic treatment. Unfortunately, the paucity of clinical research evaluating their efficacy is of low quality.

It is known that treatment involving extractions in general results in longer treatment times. If it were possible to accelerate the rate of extraction space closure, this would obviously be a desirable outcome, especially if it could be accomplished in a noninvasive manner. Microvibration has been reported in a retrospective, unblinded study to result in a 30% increase in the rates of leveling and alignment with the AcceleDent appliance (30 Hz, 0.2 N or about 20 g). However, authors of 2 prospective randomized clinical trials using the AcceleDent appliance during initial alignment with fixed appliances found no differences in the time for leveling or alignment. Authors of a clinical trial supported by a research grant from OrthoAccel Technologies (Bellaire, Tex) when evaluating the AcceleDent appliance during maxillary canine retraction reported an accelerated rate of canine retraction in the appliance group. However, there are potential concerns with the methodology used in that study because the rate of movement was measured directly in the mouth and from a miniscrew/temporary anchorage device, which is a potentially unstable landmark, and also diagonally and therefore not a true indicator of space closure. See Supplemental Materials for a short video presentation about this study.

Specific objectives or hypotheses

The primary purpose of this study was to assess any possible effect of the AcceleDent Aura appliance (OrthoAccel Technologies, Houston, Tex) when closing maxillary premolar extraction spaces in the treatment of adolescent patients. The null hypothesis is that the AcceleDent Aura appliance does not increase the rate of maxillary premolar extraction space closure.

Material and methods

Trial design and any changes after trial commencement

This was the second part of an ongoing single-center, randomized clinical trial with a 1:1 allocation. No changes occurred during the trial.

Participants, eligibility criteria, and settings

Ethical approval was obtained from the Dental Sciences Research Ethics Committee (project number 1315) of the University of Queensland in Brisbane, Australia, and written informed consent was obtained from all patients and parents. A special research grant was obtained from the Australian Society of Orthodontists Foundation for Research and Education to purchase the AcceleDent Aura appliances. Details of the experimental design, study groups, and treatment methods were published in the earlier article. Adolescent patients up to the age of 16 years who were planned to have maxillary first or second premolars extracted and no mandibular extractions for the treatment of a Class II malocclusion were eligible for inclusion.

Sample size calculation

As previously described, a power analysis based on the arch perimeter data from an unpublished study from the University of Texas Health Science Center at San Antonio (means, 1.32 mm per week [SD, 1] vs 2.71 mm per week [SD, 1.42]) indicated that a sample size of 17 subjects per group (n = 34) would be required to have 90% power at P = 0.05. It was therefore decided to enroll 20 participants per group (n = 40). A separate power analysis based on the same study and using the data for space closure in adolescents (0.25 mm per week [SD, 0.08]) and aimed at saving a clinically meaningful 2 months of treatment time when closing a 6-mm extraction space indicated that a sample size of only 7 participants per group would be required.

Randomization (random number generation, allocation concealment, implementation)

Randomization was performed with permuted blocks of 10 randomly generated numbers using the random generation function in Excel (Microsoft, Redmond, Wash) that were sealed in opaque envelopes and shuffled by a staff member. Clinical assistants opened the envelopes for group assignments after the brackets were bonded during routine instructions in a closed consultation room to ensure that the operator was blinded.

Blinding

The patients were aware of their treatment group, whereas both the operator (P.M.) and the model assessor (E.F.) were blinded to the treatment groups and the model time points.

Interventions

Each eligible patient was randomly assigned to either a group using the AcceleDent Aura appliance for 20 minutes per day or a group receiving no appliance. All patients were indirectly bonded with conventional 0.018-in slot, MBT prescription brackets (Victory Series; 3M Unitek, Monrovia, Calif) on all mandibular teeth and the maxillary premolars and molars, whereas the maxillary incisors and canines were bonded with MBT equivalent prescription self-ligating In-Ovation C ceramic brackets (GAC International, Bohemia, NY). The maxillary first or second premolars were extracted after the brackets were placed but before placement of the second 0.016 × 0.022-in M5 Heaters thermal nickel-titanium wire (G&H Wire, Franklin, Ind). Approximately 10 weeks later, a 0.016 × 0.022-in stainless steel wire with soldered posts (G&H Wire) was placed and allowed to align for 5 weeks, and an elastomeric chain was placed to consolidate the anterior 6 or 8 teeth depending on which premolar was extracted. At the next visit, photos and alginate impressions of the maxillary arch were taken for the baseline data. In subjects having extractions of first premolars, the second premolar was tied with a stainless steel ligature that was left in place until the extraction space was closed. A 9-mm nickel-titanium medium Sentalloy coil spring (GAC International) was placed across the extraction sites from the bracket hook on the first molar, and the spring was activated between 6 and 9 mm and then ligated with a stainless steel ligature to the archwire hook mesial to the canine as per a previous study to deliver approximately 150 g, confirmed with a Dontrix gauge (E.T.M. Corporation, Monrovia, CA). Based on how much space remained to be closed, patients were recalled at 5- to 8-week intervals to reactivate the coil spring. New alginate impressions were taken when the spaces on 1 side or both sides of the arch were almost but not fully closed; this was considered the end-point for this study.

Outcomes and any changes after trial commencement

The primary outcome of the study was the rate of space closure. The models were measured parallel to the occlusal plane from the cusp tips of the teeth mesial and distal to the extraction spaces. The rate of space closure was calculated by deducting the final measurement from the initial distance and dividing by the time interval. This yielded a rate of space closure for each side in millimeters per month. As in part 1 of this trial, patients assigned to the appliance group were asked to bring their AcceleDent Aura appliance for the staff to download the data from the appliance that recorded their daily usage during the period of space closure. Patients who used the appliance 75% of the time or more were considered to be good compliers.

Interim analyses and stopping guidelines

Not applicable.

Statistical analysis

Descriptive statistics on demographic and clinical parameters were calculated. To account for the correlated nature of the data during the simultaneous analyses of the right and left extraction space closure rates, univariable and multivariable random effects linear regression analyses were implemented. For all analyses, the dependent variable was the rate of tooth movement in millimeters. In the univariable model, the effect on the rate of tooth movement was assessed individually for each of the following predictors: age at treatment start, sex, extraction pattern, side (left or right), and elastic wear pattern. In the multivariable analyses, the same dependent variable (rate of space closure) was regressed on the same predictors individually after adjusting only for treatment group (AcceleDent or control). Ten randomly selected baseline models of participants were measured again after a 2-week interval. The intraclass correlation coefficients were 0.999 for the left side and 0.998 for the right at the first measurement, and 0.991 and 0.997, respectively, at the second measurement, indicating excellent measurement agreement. All analyses were conducted using statistical software (version 14.2; StataCorp, College Station, Tex).

Material and methods

Trial design and any changes after trial commencement

This was the second part of an ongoing single-center, randomized clinical trial with a 1:1 allocation. No changes occurred during the trial.

Participants, eligibility criteria, and settings

Ethical approval was obtained from the Dental Sciences Research Ethics Committee (project number 1315) of the University of Queensland in Brisbane, Australia, and written informed consent was obtained from all patients and parents. A special research grant was obtained from the Australian Society of Orthodontists Foundation for Research and Education to purchase the AcceleDent Aura appliances. Details of the experimental design, study groups, and treatment methods were published in the earlier article. Adolescent patients up to the age of 16 years who were planned to have maxillary first or second premolars extracted and no mandibular extractions for the treatment of a Class II malocclusion were eligible for inclusion.

Sample size calculation

As previously described, a power analysis based on the arch perimeter data from an unpublished study from the University of Texas Health Science Center at San Antonio (means, 1.32 mm per week [SD, 1] vs 2.71 mm per week [SD, 1.42]) indicated that a sample size of 17 subjects per group (n = 34) would be required to have 90% power at P = 0.05. It was therefore decided to enroll 20 participants per group (n = 40). A separate power analysis based on the same study and using the data for space closure in adolescents (0.25 mm per week [SD, 0.08]) and aimed at saving a clinically meaningful 2 months of treatment time when closing a 6-mm extraction space indicated that a sample size of only 7 participants per group would be required.

Randomization (random number generation, allocation concealment, implementation)

Randomization was performed with permuted blocks of 10 randomly generated numbers using the random generation function in Excel (Microsoft, Redmond, Wash) that were sealed in opaque envelopes and shuffled by a staff member. Clinical assistants opened the envelopes for group assignments after the brackets were bonded during routine instructions in a closed consultation room to ensure that the operator was blinded.

Blinding

The patients were aware of their treatment group, whereas both the operator (P.M.) and the model assessor (E.F.) were blinded to the treatment groups and the model time points.

Interventions

Each eligible patient was randomly assigned to either a group using the AcceleDent Aura appliance for 20 minutes per day or a group receiving no appliance. All patients were indirectly bonded with conventional 0.018-in slot, MBT prescription brackets (Victory Series; 3M Unitek, Monrovia, Calif) on all mandibular teeth and the maxillary premolars and molars, whereas the maxillary incisors and canines were bonded with MBT equivalent prescription self-ligating In-Ovation C ceramic brackets (GAC International, Bohemia, NY). The maxillary first or second premolars were extracted after the brackets were placed but before placement of the second 0.016 × 0.022-in M5 Heaters thermal nickel-titanium wire (G&H Wire, Franklin, Ind). Approximately 10 weeks later, a 0.016 × 0.022-in stainless steel wire with soldered posts (G&H Wire) was placed and allowed to align for 5 weeks, and an elastomeric chain was placed to consolidate the anterior 6 or 8 teeth depending on which premolar was extracted. At the next visit, photos and alginate impressions of the maxillary arch were taken for the baseline data. In subjects having extractions of first premolars, the second premolar was tied with a stainless steel ligature that was left in place until the extraction space was closed. A 9-mm nickel-titanium medium Sentalloy coil spring (GAC International) was placed across the extraction sites from the bracket hook on the first molar, and the spring was activated between 6 and 9 mm and then ligated with a stainless steel ligature to the archwire hook mesial to the canine as per a previous study to deliver approximately 150 g, confirmed with a Dontrix gauge (E.T.M. Corporation, Monrovia, CA). Based on how much space remained to be closed, patients were recalled at 5- to 8-week intervals to reactivate the coil spring. New alginate impressions were taken when the spaces on 1 side or both sides of the arch were almost but not fully closed; this was considered the end-point for this study.

Outcomes and any changes after trial commencement

The primary outcome of the study was the rate of space closure. The models were measured parallel to the occlusal plane from the cusp tips of the teeth mesial and distal to the extraction spaces. The rate of space closure was calculated by deducting the final measurement from the initial distance and dividing by the time interval. This yielded a rate of space closure for each side in millimeters per month. As in part 1 of this trial, patients assigned to the appliance group were asked to bring their AcceleDent Aura appliance for the staff to download the data from the appliance that recorded their daily usage during the period of space closure. Patients who used the appliance 75% of the time or more were considered to be good compliers.

Interim analyses and stopping guidelines

Not applicable.

Statistical analysis

Descriptive statistics on demographic and clinical parameters were calculated. To account for the correlated nature of the data during the simultaneous analyses of the right and left extraction space closure rates, univariable and multivariable random effects linear regression analyses were implemented. For all analyses, the dependent variable was the rate of tooth movement in millimeters. In the univariable model, the effect on the rate of tooth movement was assessed individually for each of the following predictors: age at treatment start, sex, extraction pattern, side (left or right), and elastic wear pattern. In the multivariable analyses, the same dependent variable (rate of space closure) was regressed on the same predictors individually after adjusting only for treatment group (AcceleDent or control). Ten randomly selected baseline models of participants were measured again after a 2-week interval. The intraclass correlation coefficients were 0.999 for the left side and 0.998 for the right at the first measurement, and 0.991 and 0.997, respectively, at the second measurement, indicating excellent measurement agreement. All analyses were conducted using statistical software (version 14.2; StataCorp, College Station, Tex).

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Dec 12, 2018 | Posted by in Orthodontics | Comments Off on Assessment of the rate of premolar extraction space closure in the maxillary arch with the AcceleDent Aura appliance vs no appliance in adolescents: A single-blind randomized clinical trial
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