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ePaper created 2016-04-19, 11:44:05 | version 1.38.0
| trends & applications vibration therapy 26 ortho 1 2016 Accelerated OTM It is well established that bone undergoes forma- tion and resorption in response to external loading such as gravitational forces, as well as to internal loadingsuchasmuscularactivity.16 Recentresearch with both animal and human models have demon- stratedanabolicresponsessuchasbonegrowthand changes in bone mineral density in response to vi- bration.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 in- volving bilateral maxillary canine distraction after first pre-molar extraction on 15 human subjects, Leethanakul et al. (2015) investigated the impact ofvibrationonacceleratedtoothmovement,aswell as on cytokine activity related to osteoblast and osteoclast differentiation (specifically IL-1 levels in GCF). The patients applied vibration to the ex- perimental canine using a commercially available electric toothbrush operating at high frequency (125Hz). This study found significantly increased toothmovement(~+61%)accompaniedbyathree- fold increase in average IL-1 levels.18 It can be hypothesised that vibration, amplifies thefamiliarosteoblast–osteoclastcellularresponse causing bone formation and resorption, when the teeth are under force (i.e. from fixed appliances and aligners). In the absence of force, vibration causes new bone apposition only, which has potential im- plications for the retention phase (see below). Note that the frequency of the device creating the accel- erated tooth movement in the Leethanakul study wasinthathighfrequencyrangeshowntohavesu- perior effects on alveolar bone formation by Judex and Rubin, and Alikani et al.13,14 Enhanced retention Vibration therapy warrants the attention of the scientific community to further explore its effect during the orthodontic retention phase. Scientific literaturedocumentsthattheprimaryreasonforor- thodontic relapse is the inability of collagen fibres (Transseptal fibres 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 im- pacts on both bone formation and reorganisation of the PDL fibres. A study from Rubin et al (referred above) states that vibration therapy by itself has always been an- abolic, which means it led to bone apposition and a decrease in bone resorption. Reports have docu- mentedanincreaseinbonedensity,boneformation, Type-1 collagen and non-collagenous matrix pro- tein expression in response to the therapy.14 Recent studies by Yadav et al. (2015) and Alikhani (2012) (both referred above), have demonstrated thatvibrationtherapyimprovednotonlyboneden- sity, but also restored the integrity and thickness of the collagen fibres. With evidence suggesting that vibration therapy positively impacts both bone morphologyandthePDLfibres,vibrationduringthe retention phase may play a significant role in pre- venting orthodontic relapse. Conclusions 1. The current debate over vibration therapy and its impact on accelerated orthodontic tooth move- ment, should consider other potential benefits of this therapy including applications for aligner seating, relief of normal orthodontic pain, en- hanced retention and applications to implant dentistry and prosthodontics. 2. Itcanbehypothesisedthatavibrationdeviceop- erating in the high frequency range would likely be most effective in creating OTM as well as of- fering shorter wear times impacting compliance. The most commonly available commercial device operates at a frequency that is below thresholds having statistical significance in creating ortho- dontictoothmovementasdocumentedinseveral 0 % 5 % 10 % 15 % 20 % High Freq* Low Freq % Increase in Alveolar Bone Volume Graphic 2: Higher Frequencies are more anabolic Alikani et al found high frequency vibration to be most efficient at accelerating bone growth. * Statistically different from controls and low frequency subjects 12016