Dept of Rehabilitation for Orofacial Disorders

 For the improvement of oral function
(What is oral function disorder?)
Speaking, eating, and breathing are important oral functions for human life.

Our clinic performs clinical education and studies disorders of these three
oral functions, including dry mouth (xerostomia) and malnutrition, which can result from oral function disorders.

ProfessorTakayoshi SAKAI
Associate ProfessorKanji NOHARA

■ Research Activities

1) Speech Disorder and Cleft Palate

Oral dysfunction can cause speech disorders. If the tongue or lip does not work in the proper way, an articulation disorder appears. If the soft palate does not work well, expiration air leaks to the nasal cavity during pronunciation, and pronunciation itself becomes indistinct. After our department was established, we performed physiological examinations of velopharyngeal function to treat speech disorders in patients with cleft palate.

Generally, cleft palate can be caused by both environmental and genetic factors.

We are starting basic research using a mouse model to identify the important gene involved in closing the palate in the embryonic stage

2) Dysphagia (Swallowing Disorder)

 Dysphagia is an obstruction disorder of the eating process. If the dysphagia becomes severe, it can cause pneumonia and difficulty with ingestion and can become a problem greatly affecting the QOL (Quality of Life). Our department is using videoendoscopy (VE) to study bolus preparation ability in order to evaluate the swallowing function. It is thought that the bolus preparation ability influences aspiration, and this study is expected to find a connection between the oral function and the missing ring of the aspiration. In addition, we are using video fluorography (VF) to analyze deglutition and the prevention of atrophy from disuse of swallowing-related organs. These studies receive high needs assessment in domestic and foreign societies.

Figure 1
Video endoscopic Evaluation of the Bolus Preparation Function

3) Sleep Apnea Syndrome

Sleep apnea syndrome is a sleep disorder characterized by pauses in breathing during sleep. It shows symptoms such as daytime sleepiness and fatigue associated with significant levels of sleep disturbance. In the dental field, there is a device called an Oral Appliance (OA), which attaches to the oral cavity as a cure for sleep apnea. However, the kind of case OA affects is unknown. In this department, we performed a study to better monitor the effects of the OA using VE to observe the anatomical change of the respiratory tract. We have also begun a collaborative research project to analyze the expiration of gas in order to judge the curative effect of the OA.

4) Dry Mouth

 Dry mouth means not only the decrease of the quantity of saliva but also the feeling that there is not enough saliva in the mouth. It is estimated that there are approximately 8,000,000 to 30,000,000 patients with dry mouth in Japan now. Dry mouth is caused by various factors such as a side effect of medicine, mental stress, aging, diabetes, and Sjogren’s syndrome. We are treating patients using our protocols and collaborating with doctors and dentists. There are some drugs for dry mouth in Sjogren’s syndrome and postradiation therapy. However, there are no perfect methods for all patients yet. New approaches in therapy, such as regenerative medicine, are anticipated by many patients. We are analyzing the mechanism of salivary gland development to understand organ regeneration for the future treatment for dry mouth.

Figure 4
Development and regeneration of salivary gland

5) Malnutrition Resulting From Oral Function Disorder

 A decrease in oral function can cause a decrease in the intake of nourishment. Malnutrition causes weight reduction, immunological dysfunction, muscle weakness, and more. Osaka University Dental Hospital has performed many operations on oral cancer patients in Japan. In this department, we examine clinical data in order to build an accurate index of the nourishment state of oral cancer patients and study unique postoperative cases.