Bioimpedance measurement in dentistry: Detection of inflamed tissues

This work aims at determining if bioimpedance measurements are able to provide information about the inflammatory state of the tissues; if the presence of an inflamed tissue can be located by means of bioimpedance measure, it would be possible to focus a potential treatment in this site. Different numerical 3D models have been realized to simulate the measurement conditions present in the event of inflamed gingiva around a dental implant. A premolar has been represented and different inflammation volumes have been considered; both geometric and electrical properties have been taken from the literature. In addition, some preliminary measurements have been conducted in three patients with dental implants in different conditions: healthy tissues, inflammation and peri-implantitis. The percentage difference of impedance (∆Z) between healthy and inflamed tissues has been considered. In addition, also three numerical models of healthy teeth have been realized (i.e. incisor, canine and premolar roots), in order to evaluate the normal range of teeth bioimpedance values. The results obtained from the numerical simulations show ∆Z values of 6–20% for the dental implant, depending on the inflamed volume. The bioimpedance values experimentally measured are in agreement with the ones obtained from the simulations and ∆Z values are also more marked (34% for inflammation, 55% for peri-implantitis), suggesting that in real inflamed tissues not only electrical properties but also dimensions are different with respect to the normal case. As regards the healthy teeth, the modulus of the measured impedance is higher than that of the implant; this was predictable and is due to the presence of bone instead of the implant. In conclusion, it is possible to state that bioimpedance measurements allow the clinician to detect inflamed tissues, so that the therapy can be focused on the impaired zone, limiting the influence in the surrounding healthy tissues and personalizing the therapy according to the inflammation severity.