Smart Bracket for Multi-dimensional Force and Moment Measurement

Abstract

Atraumatic, well-directed, and efficient tooth movement is interrelated with the therapeutic application of adequately dimensioned forces and moments in all three dimensions. The lack of appropriate monitoring tools inspired the development of an orthodontic bracket with an integrated microelectronic chip equipped with multiple piezoresistive stress sensors. Such a 'smart bracket' was constructed (scale of 2.5:1) and calibrated. To evaluate how accurately the integrated sensor system allowed for the quantitative determination of three-dimensional force-moment systems externally applied to the bracket, we exerted 396 different force-moment combinations with dimensions within usual therapeutic ranges (+/- 1.5 N and +/- 15 Nmm). Comparison between the externally applied force-moment components and those reconstructed on the basis of the stress sensor signals revealed very good agreement, with standard deviations in the differences of 0.037 N and 0.985 Nmm, respectively. We conclude that our methodological approach is generally suitable for monitoring the relatively low forces and moments exerted on individual teeth with fixed orthodontic appliances.

The influence of occlusal forces on force delivery properties of aligners during rotation of an upper central incisor

“…As has already been reported, 4 even during a rotation of an upper central incisor with aligners (deflection of 60.34 mm), without occlusal forces the limits given in the literature 10,11 for ideal moments are exceeded by up to three times. The limits for the intrusive forces 12 are mostly exceeded by up to 13 times when no weight is applied, but when an occlusal force was simulated, as is the case during swallowing, the reference values were exceeded by a factor of up to 3 and a half times for Tz and up to 18 times for Fz, respectively.…”

Development and modification of a device for three-dimensional measurement of orthodontic force system: The V-bend system re-visited

“…However, moment sensing is not possible with the three-axis force sensor. The smart bracket system [15][16][17] , incorporating multiple micro-sensor chips, is an excellent innovation that successfully transforms the stress signal to the moment component utilizing the unique "stress-fingerprint" technique, though it is unlikely that this approach will become widely adopted in orthodontic mechanics research due to its high cost. Sixaxis sensors (or force transducer and load cell) allow for moment measurement.…”

“…Multiple measurement devices have been developed for this purpose and can be roughly divided into two categories: those based on actual measurement, and those based on computer simulation. To obtain actual measurements, Friedrich et al attempted to fabricate an apparatus that allowed intra-oral measurement [12][13][14] ; Lapatki et al designed a smart bracket system with encapsulated microelectronic sensor chips [15][16][17] ; Badawi et al developed an orthodontic simulator (OSIM) that incorporates multi-axis force sensors and an artificial dental arch 18) . The OSIM has been used in several previous studies [19][20][21][22] and has been shown to be highly effective for measuring the forces and moments experienced by the whole arch in vitro.…”

Orthodontic material applications over the past century: Evolution of research methods to address clinical queries

“…31 These are capable of providing actual force ranges either in real time (in the case of bulky brackets, which carry a power source) or in a retrospective fashion, which allows the manufacturing of slim forms of appliances.…”