Maintaining good oral health is critical to healthy aging, as cognitive decline often accelerates the deterioration of oral health. Conversely, poor oral health can exacerbate cognitive decline. The thesis examines if introducing a powered toothbrush could prevent the deterioration of oral health in older individuals with mild cognitive impairment (MCI) and maintain a good quality of life. Another aim was to evaluate the actual use and the possibility of using the powered toothbrush as a carrier for other health sensors. From an interdisciplinary perspective, it examines technology's direct and indirect impact on oral health, which aligns with the  World  Health  Organization's definition of  applied health  technology. Maintaining oral health is critical in a growing aging population and with the increased incidence of MCI. The thesis includes four sub-studies. A pilot study was conducted on healthy adults, where core body temperature was assessed with a sensor attached to the toothbrush. For study I-III, two hundred and thirteen participants who met specific criteria such as age, memory problems, and cognitive levels were initially recruited. Oral health data with medical, cognitive, and quality of life assessments were collected over two years, with visits scheduled every six months. Ethical considerations followed the Declaration of Helsinki, which emphasized informed consent, participant autonomy, and dignity protection, which are particularly important for vulnerable populations such as individuals with MCI. This thesis shows that it is possible to maintain and improve oral health measured by Plaque Index (PI), Bleeding on Probing (BOP), and Periodontal Pocket depth 4mm or deeper (PPD≥4 mm) in a group of older individuals with MCI for at least 24 months. The results underline the potential of smart toothbrushes as tools for improved oral health and as carriers of sensors for health monitoring.