Pressure-inducer and Sensor to Map Dynamic Periodontal Mechanobiological Activity

University Of California, San Francisco, San Francisco CA

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Abstract

ABSTRACT The proposed interdisciplinary approach is to test the functionality of an elastic sensor that will both create and measure pressure on molar teeth in a preclinical rabbit model. Sensitivity of the commercially available sub-millimeter capacitive silicon pressure sensor encapsulated in silicone will be defined as the ability to monitor temporal shifts in pressures/forces on the tooth-crown during short- and long-term phases of tooth movements. Scientific Premise: In orthodontic tooth movement (OTM), the mineral formation and resorption events caused by natural tooth drift in the periodontal complex are often reversed through the time dependent mechanoresponsive nature of the PDL. This is achieved through largely qualitative adjustments of the magnitude and direction of forces and couples on the tooth crowns during clinical manipulations. With a calibrated force on the tooth-crown, preliminary insights have led us to hypothesize that the temporal sensitivity of the proposed biosensor can be mapped by identifying the gradual rate of shift in pressure (?Pg/?t). These shifts will prompt gradual reversal of the naturally occurring mineral resorption and formation at the PDL-entheses resulting in minimum tooth recovery/relapse toward their original position. An abrupt rate of shift in pressure (?Pa/?t) will be indicative of an abrupt reversal of these biological events and significant tooth relapse. The proposed two aims will include; Aim 1. To investigate the sensitivity of an elastic sensor between the 1st and 2nd molars in a rabbit model. Temporal shifts in pressure on the tooth-crown will be correlated with the functional relationship of the root with the alveolar bone, and changes in PDL-space during short- (t=0, 1 day (D)) and long-term (1 week (wk) and 2 weeks (wks)) phases of OTM, as well as tooth recovery/relapse. Aim 2. To investigate the functional effectiveness of an elastic sensor between 1st and 2nd molars of a rabbit. Temporal shifts in the measured in vivo input pressure at different thicknesses of the elastic sensor (relative to PDL-space) will be mapped and correlated with resulting biological responses. Three types of sensor thicknesses (T) will be used: 1) equivalent to PDL-space (T~average PDL-space in a rabbit: 70-100 µm), 15-20% lower (T<PDL-space) and 15-20% higher than average PDL-space (T>PDL-space) with time points similar to Aim 1. This combination of readily available micro-electro-mechanical system (MEMS) and simple fabrication into a pressure sensor will allow early efforts to be focused on proof-of-concept experiments utilizing in vivo models with the future goal of application in orthodontic patients in the clinic. This study will enable precise quantification of force modulation on tooth-crowns (Aim 1) by correlating with biological processes (Aim 2), that will facilitate optimal OTM with minimum tooth recovery/relapse. This data will help translate the proposed technology to clinical applications especially during short- and long-term phases of OTM intervention.