The Oral Biomechanical Functions of Hong Kong Healthy Adults

In 2020, this is not only a year of pandemic but also the year that the number of "super-aged" countries - where more than one in five of the population is 65 or older - reach to 13 including Japan, Germany, Italy, Netherlands, France, Sweden, Portugal, Slovenia and Croatia. By 2030, the number of countries would increase to 34 including Hong Kong, Korea, the US, the UK and New Zealand [1]. These countries are currently generating 80% of global GDP [2]. So, this 10-15% of super-aged global population is expected to create economic burden around 13-20% of GDP depending on the countries and policies [3], that will indeed severely affect global economy in the future if the ageing problem is not properly treated.

Hong Kong and Japan ranks number 1 and 2, respectively, lowest in 0-14 children population in the high income countries/region [2]. Facing to this low birth rate, according to the "Hong Kong Population Forecast 2020-2069", by 2069, the number of elderly people aged 65 or over in Hong Kong will reach 2.6 million, accounting for about 35.9% of the total population. The labor force between the ages of 15 and 64 will shrink to 3.9 million, accounting for 54.6% of the population [4].

In particular to dentistry, maintaining the oral function in elderly is very important, due to:

• food nutrients - when you eat you can obtain the nutrients from food, this provides you the essential energy for daily life. Loss of teeth or misfit of artificial teeth positively correlated with the risk of development in general chronic diseases [5].
• self-esteem - oral appearance and communication are significant factors contributing to elderly's psychological well-being and social life, impacting to the oral health related quality of life (OHRQoL) [6].
• neurological disorder - oral health was shown to related with strokes [7] and Alzheimer's disease [8] due to the invasion of oral bacteria such as Aggregatibacter actinomycetemcomitans, Prevotella intermedia, and Porphyromonas gingivalis. Only these two neurological disorders have accounted 0.08-0.52% loss of GDP in 47 prefectures in Japan in 2012, and the GDP lost is forecasted to be increasing continuously [9]. Tooth lost is a key factor.

Apparently, oral health is important to have healthy aging. The dental personnel play a key role in oral health, in terms of prevention, intervention, and education. In particular, prevention and education are comparatively low-cost strategies while intervention bears the higher cost, as shown in our previous study that countries/regions with better economic status had fewer severe impacts on diet-related aspects of OHRQoL [10]. Besides, our study also showed social and physiological factors "trouble pronouncing words" ranks significantly high similarly as other dietary factors, i.e., "uncomfortable to eat", "diet unsatisfactory" and "interrupt meals" among the developed countries with high economy. Indeed, the loss of teeth, new dental prostheses, and oral muscle dysfunction due to aging are the major contributing factors of pronunciation trouble. This physiological "oral frailty" declines the elder's mental and social health, and should be identified and addressed before the need for long-term care [11].

Utilizing technology to understand this situation deemed possible and "Age-tech" becomes an essential part of health technologies which means applying technology to identify, improve and treat oral frailty situations. The technology can also be useful to monitor and evaluate the efficiency of oral health conditions during this pandemic when the patients have limited mobility around the society.

Inclusion criteria

• Population with aged (50-90 y.o.) neurologically healthy citizens in Hong Kong who have at least 1 occluding paired molars.
• Can read Traditional Chinese and communicate in Cantonese
• Possessed a smartphone with internet access and was able to use it on their own or with the help of at least one family member
• passed the Montreal Cognitive Assessment 5-Minute Protocol (Hong Kong Version)

Exclusion criteria

• Subject who was under 50 or unable to give consent.
• Subject who has Cerebrovascular accident, Head and Neck Cancers, Neurologic Diseases, and other severe systemic diseases.
• Subject who is receiving radiotherapy and chemotherapy.
• Subject who was medically unfit.
• Subject who has no molar.