This is a Chinese study and the title is misleading (clickbait), the study was done long before the pandemic, from 2011 to 2018.

Social isolation during the pandemic could leave older people with fewer teeth

… Social isolation contributes to a litany of health issues in older adults. From an increased risk of dementia and heart disease to premature death, studies show that spending an extended amount of time alone is detrimental to overall health and well-being. Unfortunately, prior to 2020, the World Health Organization estimated that as many as one in three older adults experience loneliness. Considering how the COVID-19 pandemic has increased isolation across the board over the past two years, those statistics are likely even worse today.

“Socially isolated older adults tend to be less engaged in social and health-promoting behaviors like physical activity, which could have a negative impact on their overall functioning and oral hygiene, as well as increase their risk for systemic inflammation,” Wu notes. “This functional impairment seems to be a major pathway linking social isolation to tooth loss.”