Effects of the Regular Use of Antibacterial Photodynamic Therapy as an Adjunctive Treatment on Oral Hygiene in Elderly Persons Living at Home or at Care Homes

The ageing population is increasing rapidly worldwide. In the year 2000, there were 69 million people over the age of 80 in the world (United Nations, 2003), and it is estimated that by the year 2030, 1 out of 6 persons will be 60 years of age or more worldwide (World Health Organization, 2022). The proportion of the ageing population having their natural teeth left is also increasing. In Finland, the average number of toothless people aged over 65 has decreased from 44% measured in the year 2000 to 21% in 2011. (Suominen et al., 2012, Suominen et al., 2018).

As people get older, their ability to function deteriorates, and the elderly, especially those living in roundthe-clock care, have been found to have shortcomings in maintaining oral hygiene (Hiltunen et al., 2020). 4 Toothlessness is reduced in the elderly population living in care homes, too. According to a Study in Finland, in 2003, 52 % of inhabitants were toothless in enhanced service housing, and in 2017, the proportion of toothless had decreased to 38% (Saarela et al., 2020). In 2017-2018, inhabitants of elderly care homes had an average of 13.8 teeth. Only a small proportion of the population had clean teeth, and the worse the level of oral hygiene, the worse the quality of life (Saarela et al., 2021).

The World Health Organization has proposed a "Decade of Healthy Ageing 2021-2030" action plan to encourage countries to develop and implement policies and programmes to promote healthy ageing and improve the quality of life in the older population (WHO 2020). While there is an interrelation between oral and systemic health, periodontal health has been linked to several chronic systemic conditions such as diabetes and cardiovascular diseases via shared inflammatory pathways. Good oral health enables daily functions like eating and speaking, while tooth loss, hyposalivation and other oral conditions obstruct oral functions and make nutritional intake more difficult. Bad oral condition also affects social interaction and quality of life. As oral functioning declines, it is associated with a decline in general function and weakness in the older population, and it can eventually lead even to disability and loss of independence. Therefore, the World Health Organization together with the FDI World Dental Federation have recognized the importance of oral health maintenance and functioning to enable healthy ageing in older adults (Chan et al., 2023).

The dental condition of elderly persons is often poor. Cavities and dental connective tissue disease are relatively common in persons of 75 and older. Untreated oral infections predispose elderly people to pneumonia, among other complications (Nishizawa et al., 2019). Chronic oral infectious diseases, and sometimes fatal complications, are preventable with good oral hygiene. Regular cleaning of the mouth and teeth from plaque is still the most important thing for keeping the mouth healthy. According to Siukosaari and Nihtilä (2015), one third of the aged population in Finland suffers from dry mouth due to various illnesses or the use of many medications. Lack or reduction of saliva may predispose to inflammatory diseases in the mouth. If multiple medications are in use simultaneously, the dry mouth symptoms may even worsen (Siukosaari et al., 2015).

The use of antibacterial photodynamic therapy (aPDT) and antibacterial blue light, as adjunctive treatments to standard oral home care has been studied and found to reduce the amount of plaque in the mouth (Nikinmaa et al., 2021a). The Lumoral device is a CE class IIa -marked medical device for home use that is effective in reducing the development of plaque and harmful bacteria in the plaque (Pakarinen et al., 2022; Lähteenmäki et al., 2022). The performance of the device is based on the aPDT method, in which the photosensitive substance in the Lumorinse mouthwash attaches to the bacterial coating and is activated as an antibacterial by light, https://lumoralpro.com/pages/how-it-works. The antibacterial effect is applied directly to the plaque, reducing the impact on the normal oral flora. Preliminary studies have found that the method reduces inflammatory factors in periodontitis. (Pakarinen et al., 2022). In addition, the heat produced by the device also enhances saliva production, which also affects maintaining good oral health (Dodds, et al., 2015). Unpublished data from a randomized clinical trial conducted by the University of Helsinki in which Lumoral was used by the residents of elderly 24-hour care also showed that the device was safe to use, and it had a significant impact on oral health measured by the Community Periodontal Index (Saarela et al., 2023).