Literature Review on Accelerated Orthodontic By Dr. Kevin Ng & Dato' Dr. How Ki Chuan

Orthodontic tooth movements take a long time to complete, the average treatment time is usually about 24-36 months to achieve and this has been one of the main reasons to hinder patients receiving treatment. To avoid long-term suffering and to enhance patient co-operation and compliance, mechanical vibrations have been used to accelerate tooth movement and shorten treatment times. Although different clinician holds different views regarding accelerated orthodontics effects and outcomes, 2 complicated cases were reported here, and they were performed by using a 0.2N 30Hz vibrator for 20 mins daily. It was found that there was 50% treatment time gained for the whole Invisalign treatment course with acceptable results.

Case Report 1

Mr. YKC, aged 24 came in requesting correction of his teeth in order to take his wedding pictures scheduled for in about 1 year’s time. The chief complaint was an anterior crossbite with severe crowdings in both arches. The treatment plan was to remove all 4 first pre-molars and use Invisalign plus the use of a vibrator (0.2N Force 30Hz) to accelerate the treatment time.

The Clincheck was set up followed extractions and the first set of aligners were 68 pairs and the patient was advised to wear 2 aligners per week (previously 1 aligner per week) with a vibrator daily for 20 min. After 34 weeks, all the extractions spaces were closed but presented with posterior open bites, and a second scan was done to order refinement aligners. The second set included 28 aligners and the patient completed the treatment in a total time of 48 weeks. Radiographic findings were normal. The Vivera retainer was ordered and all attachments were removed just before he was able to take the wedding pictures with a perfect smile.

Case Report 2

Mr. JHC, age 50 suffered from supernumerary central, and the tooth was removed due to mobility. The large 5mm diastema has caused concern and he was suggested to close the gap by Invisalign with the use of 0.2N 30 Hz vibration daily for 20 min. The first 40 sets of aligners were finished in 20 weeks to close the space and refinements aligners were ordered to correct the root torque (26 aligners). The case was completed in a total of 33 weeks and the patient is happy with the outcome and is now on Vivera for the retention phase. No Root resorptions were found in X-ray examinations.

Prolong tooth movement under constant pressure could cause root resorption.

(Pandis 2008) During force application, a fluid movement in the periodontal ligament space occurred causing distortion of the matrix and the cells. Biomodulators activities were increased, these chemicals include : Prostaglandin E1, E2, Misoprostol, IgA, and Parathyroid hormones. (Pati A 2018)

Pati et al reported that injections of parathyroid hormone could act directly on osteoblasts and osteoclasts which could promote osteoblastogensis and bone remodelling. Increased of Prostaglandins E2 were shown to increased during tooth movement to faciliate bone resorption. PGE1 were also shown to increased by mechanical stress to induce bone remodeling. (Pati)

In the past, surgical procedures such as corticotomy were used to facilitate tooth movement. The post-oparative complications and discomfort could be severe. Several other non-surgical stimuli were attempted including laser stimulation, electric current stimulation, pulsed electromagnetic fiends and photobiomodulation were used. Among all these methods, vibration stimulation used mainly commercially in recent years and was founded with promising results. They were used in experiments animals (Nishimura 2008) (Patil 2018) and few clinical reports had confirmed the positive effects of accelerated tooth movements by vibrators. (Bowmann 2014)

Recently, most dentists choose this non-invasive approach to accelerate tooth movement and this non-surgical method has gained wide popularity in the market of orthodontics.

Root resorption has caused concerns about prolonged tooth movement. Pavlin et al suggested there was a significant enhancement in retraction velocity and showed that there was no canine root resorption after patients received vibration treatment. (Pavlin)

The popular brands of vibrators include USA-made AcceleDent, VPro, and Koeran brand.

Microvibration

The common brand of Orthodontic vibrator used in the USA with FDA approval is AcceleDent and VPro. The machine is usually applied to the patient by lightly biting forces onto the plastic plate for about 20 min a day. It will deliver a light force of 0.25 N with a vibrating frequency of 30Hz.

Alikhani et al studied the vibrators with a controlled group, they found that the mechanical vibrations could affect tooth movement time due to the induction of anabolic and catabolic effects on the bone around the teeth. (Alikhani)

Liao found that the Periodontal ligament responses were amplified due to the vibrations applied. The responses were recorded by computational stimulation, and the volume-average hydrostatic stress in the periodontal ligament was computationally calculated to be at a higher level with vibration when compared with the control group. (Liao)

Profit studies on the principles of vibrators. They were used in traditional fixed orthodontic appliances and in removable Invisalign aligners. The treatment time was 20 min/day, with a vibration of 30 Hz and a force of 20 g. They could not confirm nor could they fully understand the exact mechanism of alveolar remodeling at that time but he had proposed two hypotheses: the first one related to piezoelectricity which could be generated within the alveolar bone, and the second one related to the pressure‐tension which established within the periodontal ligament. (Proffit)

Grimm stated that: ‘’Piezoelectricity is generated by orthodontic forces bending alveolar bone to produce an electrical charge which, in turn, induces an osteogenic response’’. (Grimm)

This is agreed by Shapiro and he recommended that orthodontic forces should not be continuous as the piezoelectric charges are only created when stress is applied and released. (Shapiro)

Kau concluded that a mechanical vibrational appliance may be suitable for initiating these stress‐induced charges as forces could be applied and released at a rapid rate. A number of cases were reported that support the use of micro-vibration to accelerate tooth movement. (Kau)

Leethanakul reported that there was an increase in movements for patients using one side with a vibrating electric toothbrush head (125Hz) when compared with the control side. Gingival crevicular fluid (GCF) was collected from the mesial and distal sides of each canine at each monthly appointment. Interleukin-1β levels were analyzed using an enzyme-linked immunosorbent assay. The canine movement was measured monthly and was found the movement was accelerated. (Leethanakul)

Despite Pavlin et al. found that AcceleDent could shorten the time of tooth movement when the technique was used during orthodontic treatment and there were increasing reports on the popular uses of the vibrating devices, Woodhouse, Miles et al, did not agreed with Pavlin and pointed out that vibration is not accelerating tooth movement significant with enough scientific data. Woodhouse compared the time for lower arch teeth alignment to the placement of the correction orthodontic wire in the extraction cases. They concluded that there was no evidence that could support the supplemental vibrational force that can significantly increase the rate of lower arch tooth alignment or reduce the treatment time. (Miles)

At present, it is important to note that the non‐surgical methods are associated with very‐low quality evidence. More well‐designed RCTs are encouraged to determine non‐surgical interventions’ safety and clinically‐important reduction in the duration of orthodontic treatment.

Conclusion

Accelerated tooth movement can be achieved with vibration safely including canine retraction. No severe harmful effects such as root resorption and pain were reported by the latest available literature. It is important to point out that there are limitations to such methods and require patients’ full co-operations to use them properly. Detailed comprehensive treatment options should be provided to the patients, so they have the ability to understand the risks and complications involved. The patient should be able to make an informed choice about the most suitable methods for them in order to achieve the most satisfactory outcome of the treatment planned.