We investigated three-dimensional decrease in the volume of the pulp chamber caused by age-related secondary dentin formation using micro-CT and evaluated the applicability of the results to evaluation of age taking into account sex, age and tooth type. Decrease was slightly higher in females than in males, and a higher correlation between decrease and aging was observed in females. A comparison between age-groups revealed that decrease progressed between the fifties and sixties in males, and the forties and fifties in females. A stronger correlation between aging and decrease was observed in the mandibular central incisors than in the mandibular second premolars. This correlation was higher than other correlations between sexes and age-groups.

To clarify the morphological characteristics of the superior pharyngeal constrictor muscle which plays an important role in swallowing, the gross anatomy of the pterygopharyngeal, buccopharyngeal, mylopharyngeal and glossopharyngeal parts of the muscle was examined. Morphology of the origin of the muscle at the buccopharyngeal part could be divided into three types: type A, membranous morphology from superior to inferior areas; type B, membranous only in superior area; and type C, comp lete lack of membrane. In all three types, the muscle at the buccopharyngeal part transitionally originated from the buccinator muscle. Morphology of the origin of the muscle at the mylopharyngeal part could be divided into two types: type A, tip of the origin on the mylohyoid line; and type B, tip of the origin away from the mylohyoid line. The present study indicated that the superior pharyngeal constrictor muscle attached to the buccinator muscle (which plays an important role in mastication) with mucosa, and originated from the mandible and root of the tongue. These findings suggest that the superior pharyngeal constrictor muscle may also play an important role in the expression of smooth coordinated movements associated with ingestion, from mastication to swallowing.

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In an effort to clarify the morphologic characteristics of the palatopharyngeal muscle, we examined the origin, insertion and positional relationship with other muscles. The origin of the palatopharyngeal muscle was both the oral and nasal sides of the soft palate, being also attached to both the palatal aponeurosis and soft palate median. However, in some cases, the muscle originated on the nasal side. When the palatopharyngeal muscle originated from both the oral and nasal sides, it traveled through its insertion via the levator muscle of the palatine velum. This insertion was seen in a wide area and could be divided into three parts; the pharynx anterior, central and posterior walls. In the central pharyngeal wall, insertion into the pharyngeal aponeurosis, inferior constrictor pharyngeal muscle and esophagus were observed. The present results suggest that the palatopharyngeal muscle has a close positional relationship with the levator and tensor muscles of the palatine velum, the pharyngeal constrictor muscles and the esophagus.

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