ortho international No. 1, 2016

Vibration therapy in orthodontics: Realising the benefits Author: Dr Amit Lala, USA

Introduction to vibration therapy– multiple potential benefits Accelerated orthodontics and vibration therapy to fast track orthodontic tooth movement (OTM) have been hotly debated topics in the orthodontic industry in recent years. Periodontally Accelerated Osteogenic Orthodontics (PAOO) techniques such as osteotomy, open flap corticotomy, and piezocision have been shown to decrease treatment time.1 Unfortunately, these classical approaches have had limited patient acceptance because of their invasiveness and side effects.2 In the last several years, micro-osteoperforation, which takes advantage of the same biological regional acceleratory phenomenon as these classical techniques, has been gaining rapid clinical adoption because of the simplicity of its chairside microinvasive nature.3 There is also growing evidence that the application of mechanical energy-based therapies such as vibration can stimulate and accelerate bone formation and possibly bone remodelling.4–7 Orthodontic tooth movement, caused by the application of light continuous forces that induce bone formation and remodelling, could logically be accelerated by the application of vibrational force, with the benefit of reducing the overall treatment time. Since 2008, Accele Dent (OrthoAccel Technologies) has offered a daily use vibration device, offering the promise of accelerated orthodontic treatment based on delivering mechanical stimulation to the dentition. At this point, research on the efficacy of this device in accelerating OTM has been mixed, and clinicians debate its value. The debate on vibration therapy as it applies to accelerated orthodontics in general, and the effectiveness of the AcceleDent device specifically, should consider other factors in evaluating efficacy. First, there is a distinct possibility that frequency optimisation of the devices concerning bone formation/remodelling has not been established. AcceleDent operates in a low frequency range, however, research points towards the benefit of high frequency in bone modulation. Secondly, current research indicates that high frequency low magnitude (HFLM) vibration therapy as applied to orthodontic treatment may have multiple potential benefits, including, but not limited to, accelerated OTM. This article will discuss these additional benefits, including faster more efficient aligner therapy when used as a nightly seating tool, relief of normal orthodontic discomfort from new tight fitting aligners and routine adjustments to fixed appliances, and enhancement of orthodontic retention. Additionally, it will touch upon evidence that HFLM vibration is useful in increasing bone density and trabecular bone thickness suggesting applications in implant dentistry and prosthodontics. Current vibration devices used in orthodontic therapy As mentioned previously, the most common, commercially available, vibration device for orthodontic treatment is AcceleDent manufactured by OrthoAccel Technologies. This device delivers a vibrational frequency of 30 Hz and requires 20 minutes per day user wear time. Several early studies on the AcceleDent device seemed to demonstrate higher rates of OTM than the established norms.8-10 However, there are other more recent studies that have failed to establish the advantages of the same therapy. A study by Woodhouse et al. (2015) analysed the AcceleDent device to demonstrate its effect on OTM in extraction cases. They found that the supplemental vibrational force did not significantly increase rates of orthodontic alignment with a fixed appliance.11 Another comprehensive report on vibration therapy by investigators Yadav et al. (2015) concluded that low frequency mechanical vibration using AcceleDent had no significant effect in accelerating tooth movement.12 The recent studies regarding the apparent ineffectiveness of AcceleDent may be explained by the vibration therapy trends & applications | 25 ortho 1 2016 relatively low vibrational frequency of the device. For purposes of this discussion low and high frequency are defi ned as: Low frequency–less than or equal to 45 Hz; High frequency–greater than or equal to 90 Hz. In a 2010 study by Judex and Rubin, ovariectomised rats were subjected to either low or high frequency vibration. Bone formation rates for subjects treated with high frequency were 159 % greater when compared to controls, whereas bone formation for low frequency rat subjects were not signifi - cantly different than controls. Trabecular bone volume and thickness were also signifi cantly higher for subjects treated with high frequency.13 Similarly Alikhani et al. found a statistically higher rate of alveolar bone formation (+190 %) at higher frequencies, with a 5 min/day application. In short, the most pronounced osteogenic effects of vibration seem to occur well above the AcceleDent’s low vibrational frequency.14, 18 Practically speaking, fi ve minutes of daily wear time may be benefi cial, as it will reduce the dependency on signifi cant patient compliance. In order to realise the maximum benefi ts of vibration therapy, shorter wear times would logically increase compliance, and improve results. Given all other factors being equal, the studies suggest that a higher frequency device would deliver equivalent amounts of HFA Energy to the dentition in a signifi cantly reduced timeframe. The future of vibration therapy: Expanded application, multiple benefi ts The apparent limitations of current commercially available vibration devices should not diminish the potential importance of vibration therapy. Setting aside applications such as implant dentistry and prosthodontics suggested by the osteogenic properties associated with vibration therapy, there are at least four important clinically benefi cial orthodontic applications that can be anticipated. These potential applications are: 1) as a nightly clear aligner seating device; 2) analgesia; relief from normal discomfort associated with orthodontic treatment; 3) accelerated orthodontic tooth movement; 4) and enhancement of retention to minimise orthodontic relapse. What follows is a brief examination of each of the four applications of HFLM vibration as an orthodontic therapy. Improved aligner seating The importance of properly seated aligners, to ef- fi cient tooth movement in aligner therapy is clearly understood. Improperly seated aligners can slow treatment, forcing patients to back track to previous trays, and create unintended collateral tooth movements, with a consequence being time consuming and costly refi nements. Seating recommendations range from using ‘chewies’, to biting on hard objects. Some clinicians advise seating only when trays are new (immediately post change), while others recommend daily seating. With the current seating modalities, it is unlikely that patients consistently seat aligners fully. A seating protocol, that takes only fi ve minutes nightly, delivering a range of other patient benefi ts, would insure that aligners are fully seated throughout treatment. Consistent proper aligner seating, would likely result in more effi cient, faster aligner treatment, even absent biomechanical acceleration caused by vibration itself. Non-pharmacological analgesia Discomfort or pain is a common side effect of orthodontic treatment. The forces applied to the dentoalveolar complex which are required to move teeth, compress the periodontal ligament (PDL) causing infl ammation. Pain is most notable when seating a new aligner, or immediately after wire changes and adjustments, when pressure on the PDL is at its greatest, and diminishes as the aligner material expands, and/or the dentition comply. In a study accepted in September 2015 by the Angle Orthodontist for future publication, Lobre et al found in a randomised clinical trial that vibration therapy ‘resulted in signifi cantly lower perceived pain and less OTC medication use.’15 One theory is that vibration restores normal circulation to the PDL, which is otherwise restricted by compressive forces. Increased blood fl ow intercepts the ischaemic response and limits infl ammation. 0 % 5 % 10 % 15 % 20 % 25 % High Freq Low Freq Controls Impact on Bone Volume: High vs Low Frequency Vibration Graphic 1: Relative impact of frequency on bone morphology Increases in bone volume for high frequency subjects was 25 % higher than controls; low frequency subjects were not statistically different than controls. | trends & applications vibration therapy 26 ortho 1 2016 Accelerated OTM It is well established that bone undergoes formation and resorption in response to external loading such as gravitational forces, as well as to internal loading such as muscular activity.16 Recent research with both animal and human models have demonstrated anabolic responses such as bone growth and changes in bone mineral density in response to vibration.6, 7, 17 Since OTM is fundamentally based on bone remodelling (formation and resorption) there is little doubt that HFLM vibration has the potential to favourably impact OTM. In a recent split-mouth randomised trial involving bilateral maxillary canine distraction after fi rst pre- molar extraction on 15 human subjects, Leethanakul et al. (2015) investigated the impact of vibration on accelerated tooth movement, as well as on cytokine activity related to osteoblast and osteoclast differentiation (specifi cally IL-1 levels in GCF). The patients applied vibration to the experimental canine using a commercially available electric toothbrush operating at high frequency (125 Hz). This study found signifi cantly increased tooth movement (~+61 %) accompanied by a threefold increase in average IL-1 levels.18 It can be hypothesised that vibration, amplifi es the familiar osteoblast–osteoclast cellular response causing bone formation and resorption, when the teeth are under force (i.e. from fi xed appliances and aligners). In the absence of force, vibration causes new bone apposition only, which has potential implications for the retention phase (see below). Note that the frequency of the device creating the accelerated tooth movement in the Leethanakul study was in that high frequency range shown to have superior effects on alveolar bone formation by Judex and Rubin, and Alikani et al.13, 14 Enhanced retention Vibration therapy warrants the attention of the scientifi c community to further explore its effect during the orthodontic retention phase. Scientifi c literature documents that the primary reason for orthodontic relapse is the inability of collagen fi bres (Transseptal fi bres and PDL) to reorganise quickly after the completion of orthodontic treatment and the delay in new bone apposition.19 Studies suggest that vibration can have potentially favourable impacts on both bone formation and reorganisation of the PDL fi bres. A study from Rubin et al (referred above) states that vibration therapy by itself has always been anabolic, which means it led to bone apposition and a decrease in bone resorption. Reports have documented an increase in bone density, bone formation, Type-1 collagen and non-collagenous matrix protein expression in response to the therapy.14 Recent studies by Yadav et al. (2015) and Alikhani (2012) (both referred above), have demonstrated that vibration therapy improved not only bone density, but also restored the integrity and thickness of the collagen fi bres. With evidence suggesting that vibration therapy positively impacts both bone morphology and the PDL fi bres, vibration during the retention phase may play a signifi cant role in preventing orthodontic relapse. Conclusions 1. The current debate over vibration therapy and its impact on accelerated orthodontic tooth movement, should consider other potential benefi ts of this therapy including applications for aligner seating, relief of normal orthodontic pain, enhanced retention and applications to implant dentistry and prosthodontics. 2. It can be hypothesised that a vibration device operating in the high frequency range would likely be most effective in creating OTM as well as offering shorter wear times impacting compliance. The most commonly available commercial device operates at a frequency that is below thresholds having statistical signifi cance in creating orthodontic tooth movement as documented in several 0 % 5 % 10 % 15 % 20 % Low Freq High Freq* % Increase in Alveolar Bone Volume Graphic 2: Higher Frequencies are more anabolic Alikani et al found high frequency vibration to be most effi cient at accelerating bone growth. * Statistically different from controls and low frequency subjects vibration therapy trends & applications | 27 ortho 1 2016 recent studies, and requires a relatively long, 20 minutes daily wear time. 3. The strong supporting data concerning the positive effects of vibration therapy on bone formation, bone density and collagen fibre reorganisation leads us to believe that this modality of treatment may revolutionise the concept of orthodontic retention. 4. The effects of high frequency vibration therapy may be useful in modifying the bone density to the clinician’s advantage in implant placement or to maintain the thickness of bone trabeculae in edentulous patients undergoing prosthodontic treatment._ References [1] T.J. Fischer. Orthodontic treatment acceleration with corticotomyassisted exposure of palatally impacted canines. Angle Orthod. 2007;77:417–420. [2] M. Cassetta, S. Di Carlo, M. Giansanti, V. Pompa, G. Pompa, E. Barbato. The impact of osteotomy technique for corticotomyassisted orthodontic treatment (CAOT) on oral health-related quality of life. Eur Rev Med Pharmacol Sci. 2012;16:1735– 1740. 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Swinnen, D. Vanderschueren, S. Boonen. Effect of 6-month whole body vibration training on hip density, muscle strength, and postural control in postmenopausal women: a randomized controlled pilot study. J Bone Miner Res. 2004;19(3):352–359. [8] Kau, Chung H., Jennifer T. Nguyen , and Jeryl D. English. “The clinical evaluation of a novel cyclical force generating device in orthodontics.” Orthodontic Practice. 2010; 1:1. [9] Bowman, S. Jay. “The Effect of Vibration on the Rate of Leveling and Alignment.” Journal of Clinical Orthodontics. 2014;48(11): 678–688. [10] Dubravko Pavlin DMD, MSD, Ph.D., Ravikumar Anthony MSD, Vishnu Raj DDS, MS, Peter T. Gakunga DDS, Ph.D., Cyclic Loading (Vibration) Accelerates Tooth Movement in Orthodontic Patients: A Double-Blind, Randomized Controlled Trial. Semin Orthod. http://dx.doi.org/10.1053/j.sodo.2015.06.005. [11] N R Woodhouse et al. Supplemental Vibrational Force During Orthodontic Treatment: A Randomized Study, Journal of Dental Research. May 2015; 94(5):682–689. [12] Sumit Yadav, Thomas Dobieb, Amir Assefniac, Himank Guptac, Zana Kalajzicd, Ravindra Nandae. Effect of low-frequency mechanical vibration on orthodontic tooth movement. AJODO. September 2015;148:440–449. [13] S. Judex and C.T Rubin. Is Bone formation induced by highfrequency mechanical signals modulated by muscle activity? J Musculosketal Neuronal Interactions. 2010; 10(1):3–11. [14] Alikhani M, Khoo E, Alyami B, Raptis M, Salqueiro JM, et al. Osteogenic effect of high-frequency acceleration on alveolar bone. J Dent Res. 2012; 91:413–419. [15] Wendy D. Lobre, Brent J. Callegari, Gary Gardner, Curtis M. Marsh, Anneke C. Bush, and William J. Dunn. Pain control in orthodontics using a micropulse vibration device: A randomized clinical trial. The Angle Orthodontist In-Press. October 2015. [16] A. Leblanc, V. Schneider, H. Evans, D. Engelbretson, J. Krebs. Bone mineral loss and recovery after 17 weeks of bed rest. J Bone Miner Res. 1990; 5(8):843–850. [17] A Mavropoulosa, S Kiliaridisa, A Bresinb, P Ammann. Effect of different masticatory functional and mechanical demands on the structural adaptation of the mandibular alveolar bone in young growing rats. Bone. July 2004; 35:191–197. [18] Chidchanok Leethanakula, Sumit Suamphanb, Suwanna Jitpukdeebodintrac, Udom Thongudompornd, and Chairat Charoemratrotea. Vibratory stimulation increases interleukin-1 beta secretion during orthodontic tooth movement. The Angle Orthodontist. September 2015; 85(5):899–899. [19] Birgit Thilander. Biological basis of orthodontic relapse. Seminars in orthodontics. 2000; 6:195–205. about Dr Amit Lala, DDS, PhD, earned his Master’s Degree in Oral Biology from the University of California in Los Angeles. He then earned his DDS and PhD in Oral Biology from SUNY Buffalo, NY. He also completed his postgraduate residency in Orthodontics at SUNY, Buffalo, NY. Dr Lala is affiliated with Harvard School of Dental Medicine as a lecturer in the fields of Orthodontics and Oral Biology


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