Introduction
The purpose of this 2-arm parallel trial was to assess the effects of the AcceleDent Aura (OrthoAccel Technologies, Houston, Tex) appliance on the increase in mandibular anterior arch perimeter, the reduction in mandibular arch irregularity, and the amount of discomfort during initial alignment of the mandibular arch with fixed appliances.
Methods
Forty Class II adolescent patients with full fixed appliances and treated with maxillary premolar extractions and no extractions in the mandibular arch participated in this randomized clinical trial. They were recruited in a private practice and treated by 1 clinician. Randomization to either a no-appliance group or the AcceleDent Aura appliance group was accomplished with permuted blocks of 10 patients with the allocations concealed in opaque, sealed envelopes. Both the operator and the outcome assessor were blinded, but it was not feasible to blind the patients. Discomfort was recorded during the first week of treatment. Mandibular anterior arch perimeter and anterior irregularity were measured from plaster models taken at the start of treatment and after 5, 8, and 10 weeks.
Results
No patients were lost to follow-up, and no data were missing. There was no difference in anterior arch perimeter at the start of treatment ( P = 0.85; median, 0.6 mm; 95% confidence interval [CI], −1.6, +1.8 mm) or at any other time point (5 weeks: P = 0.84; median, −0.2 mm; 95% CI, −1.6, +1.2 mm; 8 weeks: P = 0.56; median, −0.3 mm; 95% CI, −1.6, +0.7 mm; 10 weeks: P = 0.67; median, −0.1 mm; 95% CI, −1.5, +1.1 mm). There was also no difference between groups for incisor irregularity ( P = 0.46; median, −0.5 mm; 95% CI, −2.2, +2.8 mm; P = 0.80; median, 0.0 mm; 95% CI, −1.0, +1.1 mm; P = 0.70; median, 0.1 mm; 95% CI, −0.7, +0.8 mm; P = 0.65; median, 0.2 mm; 95% CI, −0.6, +0.6 mm). No difference was detected at any time during the first week for discomfort (baseline: P = 0.84; median, −1.5 mm; 95% CI, −15.9, +9.8 mm; 6 hours: P = 0.96; median, 0.3 mm; 95% CI, −23.5, +21.8 mm; 1 day: P , 0.75; median, −3.5 mm; 95% CI, −27.1, +26.9 mm; 3 days: P = 0.98; median, −0.6 mm; 95% CI, −20.6, +20.0; 7 days: P = 0.57; median, 0.5 mm; 95% CI, −5.0, +5.3 mm). However, significantly fewer participants in the AcceleDent Aura group used analgesics at day 1 ( P = <0.01).
Conclusions
The AcceleDent Aura appliance had no effect compared with no appliance on increasing anterior arch perimeter, or reducing irregularity or perceived discomfort during initial alignment with fixed appliances, although more subjects used painkillers at 24 hours in the no-appliance group.
Registration
This trial was not registered.
Protocol
The protocol was not published before trial commencement.
Funding
A special research grant was obtained from the Australian Society of Orthodontists Foundation for Research and Education to purchase the AcceleDent Aura appliances and fund the statistical analysis.
Highlights
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The AcceleDent Aura appliance had no effect on the rate of arch perimeter change.
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The appliance had no significant effect on the rate of change in irregularity.
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Discomfort was not affected by use of the AcceleDent Aura appliance.
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Significantly fewer subjects in the AcceleDent Aura group used analgesics at day 1.
With the risks of orthodontic treatment such as root resorption and demineralization, it is not surprising that clinicians are looking for ways to decrease orthodontic treatment times to reduce these risks for their patients. Treatment times can vary widely but often involve 2 or more years in fixed appliances. However, with patients wanting significantly shorter treatments of only 6 to 12 months, this places significant pressure on orthodontic providers and companies to find ways to accelerate treatment.
Treatment time depends on the rate of tooth movement, which in turn depends on the rate of alveolar remodeling. Therefore, it may be possible to increase the rate of tooth movement by accelerating the biologic response of the periodontal ligament and alveolar bone. Although the exact mechanism of alveolar remodeling is not completely understood, there are 2 main hypotheses: (1) piezoelectricity generated within the alveolar bone, and (2) pressure-tension within the periodontal ligament. With piezoelectricity, orthodontic forces bending alveolar bone generate an electrical charge that in turn induces an osteogenic response. Shapiro et al suggested that these orthodontic forces should not be continuous, since the piezoelectric charges are created only when stress is applied and released. A vibrational appliance may therefore be suitable for initiating these stress-induced charges because forces could be applied and released at a rapid rate.
Early research involving vibrational appliances and orthodontic tooth movement in animal models demonstrated promising results. With Wistar rats, approximately 15% more tooth movement was achieved in 21 days using resonance vibration for 8 minutes per day (on days 0, 7, and 14), when compared with a control group with only static forces. Vibrational force applied to Macaca fuscata monkeys for 1.5 hours per day over 3 weeks was reported to be 1.3 to 1.4 times faster (about 25%-30%) than loading a static force. This could be considered clinically significant if it is found in humans.
In a case report involving a pulsating force with headgear, greater movement of the pulsed tooth was reported when compared with the control tooth. The authors of a later case series stated that they achieved “promising rates of tooth movement” by having patients use a vibrational appliance for 20 minutes per day. Another study reported 2 to 3 mm of movement per month in both arches by measuring the reduction in Little’s irregularity index. However, these studies had low-quality evidence because they lacked control groups and had only small sample sizes. A retrospective study examining the rate of leveling and alignment in the mandibular arch of nonextraction subjects reported a 30% increase in the rate of movement using the AcceleDent (OrthoAccel Technologies, Houston, Tex) appliance (30 Hz; 0.2 N, or about 20 g). However, the lack of blinding and the retrospective nature of the study meant that the results should be interpreted with caution. In contrast, a prospective randomized clinical trial (RCT) using the Tooth Masseuse appliance (111 Hz; 0.06 N, or about 6 g) reported no difference in the rate of mandibular arch initial alignment in nonextraction subjects or in their reported discomfort. More recently, an RCT compared the use of the AcceleDent appliance during initial alignment with fixed appliances in the mandibular arch of patients having mandibular premolar extractions. The authors found no evidence that vibration increased the rate of tooth movement or reduced the time required to achieve final alignment. Therefore, there seems to be some disagreement about any effect of vibration between the previous retrospective trials and the prospective RCTs. See Supplemental Materials for a short video presentation about this study.
Specific objectives or hypotheses
The primary purpose of this study was to assess the amount of tooth movement by measuring the anterior arch perimeter and irregularity index during initial alignment in the mandibular arch when using the AcceleDent Aura appliance (OrthoAccel Technologies) in adolescent orthodontic patients. A secondary outcome was to assess the amount of discomfort and the use of analgesics during the first week of treatment. The null hypothesis was that the AcceleDent Aura appliance does not increase the rate of movement as measured by the irregularity index or the anterior arch perimeter in the mandibular arch or decrease pain during initial alignment.
Material and methods
Trial design and any changes after trial commencement
This was a 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 University of Queensland Dental Sciences Research Ethics Committee (project number 1315), 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 and to fund the statistical analysis. Patients who met the selection criteria were prospectively recruited from the private orthodontic clinic of the first author (P.M.). Eligibility for inclusion consisted of (1) children up to age 16, (2) a fully erupted dentition from first molar forward, (3) erupted or erupting second molars, (4) no missing or previously extracted permanent teeth, (5) undergoing comprehensive orthodontic treatment with full fixed appliances, and (6) a Class II malocclusion requiring extraction of 2 maxillary premolars but no mandibular extractions.
Sample size calculation
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. We decided to enroll 20 subjects per group (n = 40) to allow for approximately 10% dropouts from the study sample.
Randomization (random number generation, allocation concealment, implementation)
Randomization was performed using permuted blocks of 10 randomly generated numbers with the random generation function in Excel (Microsoft, Redmond, Wash); the numbers were sealed in opaque envelopes and shuffled by a staff member. A clinical assistant opened an envelope for the group assignment after a patient’s brackets were bonded and gave routine instructions in a closed consultation room to ensure that the operator (P.M.) was blinded.
Blinding
Patients were aware of their treatment group. The operator was blinded to the group assignment, and the model assessor (E.F.) was blinded to the treatment group and the model time point.
Interventions
Each eligible patient was randomly assigned to either a group using the AcceleDent Aura appliance for 20 minutes per day or a group that received 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 archwires were identical in the 2 groups during the 10-week experimental period: a 0.014-in M5 Heaters thermal nickel-titanium wire (G&H Wire, Franklin, Ind).
Alginate impressions of the mandibular anterior teeth were taken at 4 time points: at the start of treatment and at 5, 8, and 10 weeks to allow for comparisons of the amount of movement over the study period. The initial archwire was retied at the 5-week appointment, but no adjustment or retying was undertaken at 8 weeks. Identification numbers were assigned to the models before measurement to ensure blinding of the model assessor.
Outcomes (primary and secondary) and any changes after trial commencement
The main outcome of the study was the change in mandibular anterior arch perimeter over the 10 weeks of the trial. The secondary outcomes were the change in the mandibular arch irregularity index over the 10 weeks and the amounts of discomfort and analgesic use during the first week of the trial. The arch perimeter was measured from the distal contact of the mandibular canines and then to the labiolingual centers of each tooth (canine to canine) according to the unpublished study from the University of Texas Health Science Center at San Antonio. Little’s irregularity index was measured using a digital caliper between each contact from mandibular canine to canine (5 contacts) and summed to give the score for the arch. Patients assigned to the appliance group were asked to bring their AcceleDent Aura appliance for staff to record their daily usage, which the appliance recorded over the 10-week study interval. Since compliance with the appliance can vary and could potentially affect its efficacy, a subset of “good compliers” was assessed separately. The patients who used the appliance 75% of the time or more were considered to comply well with the appliance.
A discomfort score chart was used to evaluate the pain levels experienced by each patient. The patient was instructed to record the level of discomfort at 5 time points (T0, baseline; T1, 6-8 hours later; T2, at 24 hours; T3, at 3 days; and T4, at 7 days) by placing a mark on a 100-mm visual analog scale with the left side (0) being “totally pain free,” and the extreme right (100 mm) being “worst pain ever.” Patients were also asked to avoid analgesics containing ibuprofen because it can slow the rate of tooth movement; if pain medications were required, they could use those containing acetaminophen. The same person (E.F.) blinded to the patient group measured the visual analog scale data using a digital caliper (150 mm, 500-171-20 Absolute Digimatic; Mitutoyo, Kawasaki, Japan) to the nearest 0.1 mm (caliper error, ±0.02 mm). The caliper tips were closed, and the instrument rezeroed for each measurement. There were no changes to the outcome measures after trial commencement.
Interim analyses and stopping guidelines
Not applicable.
Statistical analysis (primary and secondary outcomes, subgroup analyses)
The arch perimeter, irregularity index, and visual analog scale data were assessed using median regression, and the use of analgesics was compared using a chi-square test. To assess the reliability of measuring these data, 10 randomly selected baseline models of subjects were measured again after a 2-week interval. There were mean differences between measurements of 0.07 mm in arch perimeter, 0.10 mm for the irregularity index, and 0.05 mm for the visual analog scale. The intraclass correlation coefficients were 0.98, 1.00, and 1.00, respectively, indicating excellent measurement agreement. All analyses were conducted using Stata software (versions 12.1 and 14; StataCorp, College Station, Tex).
Material and methods
Trial design and any changes after trial commencement
This was a 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 University of Queensland Dental Sciences Research Ethics Committee (project number 1315), 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 and to fund the statistical analysis. Patients who met the selection criteria were prospectively recruited from the private orthodontic clinic of the first author (P.M.). Eligibility for inclusion consisted of (1) children up to age 16, (2) a fully erupted dentition from first molar forward, (3) erupted or erupting second molars, (4) no missing or previously extracted permanent teeth, (5) undergoing comprehensive orthodontic treatment with full fixed appliances, and (6) a Class II malocclusion requiring extraction of 2 maxillary premolars but no mandibular extractions.
Sample size calculation
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. We decided to enroll 20 subjects per group (n = 40) to allow for approximately 10% dropouts from the study sample.
Randomization (random number generation, allocation concealment, implementation)
Randomization was performed using permuted blocks of 10 randomly generated numbers with the random generation function in Excel (Microsoft, Redmond, Wash); the numbers were sealed in opaque envelopes and shuffled by a staff member. A clinical assistant opened an envelope for the group assignment after a patient’s brackets were bonded and gave routine instructions in a closed consultation room to ensure that the operator (P.M.) was blinded.
Blinding
Patients were aware of their treatment group. The operator was blinded to the group assignment, and the model assessor (E.F.) was blinded to the treatment group and the model time point.
Interventions
Each eligible patient was randomly assigned to either a group using the AcceleDent Aura appliance for 20 minutes per day or a group that received 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 archwires were identical in the 2 groups during the 10-week experimental period: a 0.014-in M5 Heaters thermal nickel-titanium wire (G&H Wire, Franklin, Ind).
Alginate impressions of the mandibular anterior teeth were taken at 4 time points: at the start of treatment and at 5, 8, and 10 weeks to allow for comparisons of the amount of movement over the study period. The initial archwire was retied at the 5-week appointment, but no adjustment or retying was undertaken at 8 weeks. Identification numbers were assigned to the models before measurement to ensure blinding of the model assessor.
Outcomes (primary and secondary) and any changes after trial commencement
The main outcome of the study was the change in mandibular anterior arch perimeter over the 10 weeks of the trial. The secondary outcomes were the change in the mandibular arch irregularity index over the 10 weeks and the amounts of discomfort and analgesic use during the first week of the trial. The arch perimeter was measured from the distal contact of the mandibular canines and then to the labiolingual centers of each tooth (canine to canine) according to the unpublished study from the University of Texas Health Science Center at San Antonio. Little’s irregularity index was measured using a digital caliper between each contact from mandibular canine to canine (5 contacts) and summed to give the score for the arch. Patients assigned to the appliance group were asked to bring their AcceleDent Aura appliance for staff to record their daily usage, which the appliance recorded over the 10-week study interval. Since compliance with the appliance can vary and could potentially affect its efficacy, a subset of “good compliers” was assessed separately. The patients who used the appliance 75% of the time or more were considered to comply well with the appliance.
A discomfort score chart was used to evaluate the pain levels experienced by each patient. The patient was instructed to record the level of discomfort at 5 time points (T0, baseline; T1, 6-8 hours later; T2, at 24 hours; T3, at 3 days; and T4, at 7 days) by placing a mark on a 100-mm visual analog scale with the left side (0) being “totally pain free,” and the extreme right (100 mm) being “worst pain ever.” Patients were also asked to avoid analgesics containing ibuprofen because it can slow the rate of tooth movement; if pain medications were required, they could use those containing acetaminophen. The same person (E.F.) blinded to the patient group measured the visual analog scale data using a digital caliper (150 mm, 500-171-20 Absolute Digimatic; Mitutoyo, Kawasaki, Japan) to the nearest 0.1 mm (caliper error, ±0.02 mm). The caliper tips were closed, and the instrument rezeroed for each measurement. There were no changes to the outcome measures after trial commencement.
Interim analyses and stopping guidelines
Not applicable.
Statistical analysis (primary and secondary outcomes, subgroup analyses)
The arch perimeter, irregularity index, and visual analog scale data were assessed using median regression, and the use of analgesics was compared using a chi-square test. To assess the reliability of measuring these data, 10 randomly selected baseline models of subjects were measured again after a 2-week interval. There were mean differences between measurements of 0.07 mm in arch perimeter, 0.10 mm for the irregularity index, and 0.05 mm for the visual analog scale. The intraclass correlation coefficients were 0.98, 1.00, and 1.00, respectively, indicating excellent measurement agreement. All analyses were conducted using Stata software (versions 12.1 and 14; StataCorp, College Station, Tex).
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