Wireless monitoring of intra-oral pH

Abstract

Introduction and Aim: Intra-oral pH plays a significant role in the pathogenesis of tooth wear as well as white spot lesions in patients with fixed or removable orthodontic appliances. However, there is currently very little information about intra-oral pH variation over time, and in real life settings. The aims of this research were 1) to develop a wireless monitoring intra-oral pH device, which can be used to record real-time pH and temperature data in a natural environment, in which participants carry out their normal daily activities; and 2) to collect preliminary data in a sample of healthy volunteers, in a manner that is as non-invasive as possible, for over 24 hours.

Methods: The wireless device consisted of a miniature pH telemeter, which included a temperature sensor and is capable of transmitting data wirelessly to a smartphone. A monitoring and calibration software application was also developed and was used to aid data input from the participants. In vitro tests were conducted to calibrate and validate the measurements of the device, and the measurements were tested against the glass electrode and the antimony electrode using the Restech system. The wireless device was then embedded into an in-mouth appliance and worn by five participants (mean age 28.6 ± 2.5 years) for over 24 hours, while conducting regular daily activities.

Results: The device was successfully developed and in vitro tests indicated that the measurements of the wireless device were comparable to those of a glass electrode, although the signal had more noise. The device was also successfully used over a period of 24-hours in all participants. The average intra-oral pH in the study sample was 7.4 ± 0.5. The intra-oral pH was on average lower during sleeping hours (7.0 ± 0.5), than in waking hours (7.5 ± 0.5) (P < 0.01). The average intra-oral temperature was higher during sleeping hours (35.4 °C ± 0.7), than in waking hours (34.2 °C ± 1.3). There was a distinct rhythmic pattern of intra-oral pH variation during sleeping hours shown in 4 out of 5 participants. There was also inter-individual variation in the intra-oral pH recovery time following acidic stimuli.

Conclusion: Preliminary results suggest that real-time variations in intra-oral pH and temperature can be successfully collected in participants. This wireless device is therefore capable of providing new insights into the variations of intra-oral pH over time, and its relationship with dental wear, white spot lesions and dental caries.