Clinical application of ultrasonography (US) in dentistry has been limited to the major salivary gland, cervical lymph nodes, facial musculature, and surface soft tissues of the face and the neck. However, in recent years with the development of the high-resolution ultrasound equipments,attempts have been performed in imaging the early tongue carcinomas, periapical lesions and temporomandibular joint disorders (TMD). Recent development of the ultrasonography (US) equipments enables the visualization of fine detail of the surface structure of the face and neck soft tissue.The purpose of this book is to describe the detail about the USG Machine, Its principal and use of ultrasonography in detecting the oral diseases and management of diseases related to dentistry.