In the 2022 World Health Statistics published by WHO, Japan was ranked as the world’s top country for longevity, with an average life expectancy of 84.3 years. Thus, Japan, a super-aging developed country, is facing problems the rest of the world has never experienced before. There is a gap of approximately 10 years between average life expectancy and healthy life expectancy, and in order to narrow the gap, daily maintenance of healthy diet, exercise, sleep, and the teeth is essential. In particular, the number of remaining teeth and molar occlusal support have been suggested to correlate with declines in health and cognitive function. A study by Mogi et al. reported that favorable teeth alignment and occlusion were observed in individuals having 20 or more teeth at the age of 80 years. This suggests that correct teeth alignment and occlusion help maintain the number of remaining teeth, thus contributing to health.

On the other hand, jaw deformities are a severe type of malocclusion. Particularly, it is extremely difficult to treat cases involving facial asymmetry. In general, middle-aged and elderly individuals with molar crossbite occlusion often have prostheses or defects in the molar region. Thus, aiming to “elucidate the causes of jaw deformities,” we have conducted “research on the causes of jaw deformities using experimental models” and “biomechanics research on the mandible.” Also, we are conducting “statistical clinical research on osteoarthrosis (OA) of the temporomandibular joint and idiopathic/progressive condylar resorption (ICR/PCR).”

In recent years, prosthodontists and other dentists have been asked to improve malocclusion like unilateral crossbite because of difficulties in treating dentures and implants. In this lecture, we will present middle-aged and elderly cases of patients with jaw deformities and discuss what we, as orthodontists, can do to extend healthy life expectancy.