In the soft palate, tongue, pharynx and larynx surrounding the oral region, taste buds are present, allowing the sensation of taste. On the tongue surface, 3 kinds of papillae are present: fungiform, foliate, and circumvallate. Approximately 5,000 taste buds cover the surface of the human tongue, with about 30% fungiform, 30% foliate and 40% circumvallate papillae. Each taste bud comprises 4 kinds of cells, namely high dark (type I), low light (type II), and intermediate (type III) cells in electron density and Merkel-like taste basal cells (type IV) located at a distance from taste pores. Type II cells sense taste stimuli and type III cells transmit taste signals to sensory afferent nerve fibers. However, type I and type IV cells are not considered to possess obvious taste functions. Synaptic interactions that mediate communication in taste cells provide signal outputs to primary afferent fibers. In the study of taste bud cells, molecular functional techniques using single cells have recently been applied. Serotonin (5-HT) plays a role in cell-to-cell transmission of taste signals. ATP fills the criterion of a neurotransmitter that activates receptors of taste nerve fibers. Findings on 5-HT and ATP suggest that various different transmitters and receptors are present in taste buds. However, no firm evidence for taste-evoked release from type III cells has been identified, except for 5-HT and ATP. These results suggest that different transmitters and receptors may not be present in taste buds. Accordingly, an understanding of how transmitters might function remains elusive.

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We performed sagittal splitting osteotomy using fresh, unfixed cadavers. Observation was carried out macroscopically and with light microscopy and 3-dimensionally reconstructed images. The aim of this study was to clarify the relationship between the fracture line and the Haversian canal and Haversian lamellae. Macroscopic observation revealed that the fracture line run through the mandibular angle from the inferior rim of the mandibular ramus towards the posterior rim, passing almost through the center of the ridgeline. Histological observation showed that the fracture line tended to run along the curve of the lamellar structure. The incidence of the fracture line running along the lamellar structure of the Haversian lamellae was approximately 65% (21 cases), and the incidence of the fracture line also cutting across the Haversian canal without passing along the lamellar structure of the Haversian lamellae was approximately 35% (11 cases). Observation of 3-dimensional reconstruction images revealed that the section of Haversian canal near the mandibular angle essentially runs from the mandibular head to the inferior rim of the mandible, and that the fracture plane ran similarly. The direction of an impact-associated bone fracture line is infiuenced by the structures that constitute the lamellar bone such as Haversian canals, Haversian lamellae and interstitial lamellae, with fracture lines tending to run through those parts of the bone that have a low physical bond strength. This suggests that the ideal direction of action of the bone chisel in sagittal splitting surgery is the one in which no resistance to the path of the Haversian canal is encountered.

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The objective of the present study was to investigate frontal morphological asymmetry in the mandibular molar region in terms of tooth axis and skeletal structures using vertical MPR sections in jaw deformity accompanied by facial asymmetry. Subjects consisted of 15 patients with jaw deformity accompanied by facial asymmetry aged 17.4 years to 37.8 years. There were four men and eleven women. Based on X-ray computed tomography (CT) scans, DICOM viewer software was used to prepare multiplanar reconstruction (MPR) sections. The mandible was then positioned on a reference plane based on the menton and left and right gonions, and a vertical MPR section passing through the mesial root of the first mandibular molar was prepared. The following measurements were made on both the shifted and non-shifted sides: maximum buccolingual width of the mandibular body; height of the mandibular body; inclination angle of the mandibular body; degree of buccal protrusion of the mandibular body; and inclination angle of the buccolingual tooth axis of the first molar. Furthermore, degree of median deviation in the menton was measured using frontal cephalograms. Differences in morphological parameters between the shifted and non-shifted sides were assessed. Furthermore, the relationship between median deviation and asymmetry were statistically analyzed. There was no significant asymmetry in the maximum buccolingual width of the mandibular body, the height of the mandibular body or the degree of buccal protrusion of the mandibular body. However, when compared to the shifted side, the inclination angle of the buccolingual tooth axis of the first molar for the non-shifted side was significantly greater. There was a relatively strong correlation between median deviation and inclination angle of the mandibular body. The above findings clarified that, in orthognathic surgery for jaw deformity accompanied by facial asymmetry, actively improving asymmetry in the buccolingual inclination of the tooth axis of the molar region during presurgical orthodontic treatment is important in achieving favorable post-treatment occlusal stability and facial symmetry.

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The effects of X-ray and carbon ion irradiation on DNA and genes in head and neck carcinoma cells were examined. Four head and neck cancer cell lines (squamous cell carcinoma, salivary gland cancer, malignant melanoma, normal keratinocyte) were treated with 1, 4, and 7 GyE of carbon ion, or 1, 4, and 8 Gy of X-ray, respectively. DNA and RNA in the treated cells were extracted and purified. PCR-LOH (polymerase chain reaction-loss of heterozygosity) analysis with 6 microsatellite regions on chromosome 17 was performed to determine DNA structural damage, and then microarray analysis was performed to reveal changes in gene expression. PCR-LOH analysis detected high LOH in cells treated by radiation, indicating that most of the damage by X-ray occurred in the target region on one of the homologous chromosomes. However, carbon ion caused homodeletion, which means deletion of the counterparts in both homologous chromosomes.

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We treated two patients requiring nasolabial flap reconstruction. The first patient was a 75-year-old man with mucoepidermoid carcinoma in the left-side floor of the mouth; requiring resection of the floor of the mouth, partial mandibulectomy, and left supraomohyoid neck dissection. The second patient was a 74-year-old man with recurrent acinic cell carcinoma in the anterior oral floor infiltrating as far as the mandible. This patient required wide excision of the anterior part of the oral cavity, including amputation of the mandible. After tumor resection, both cases had a nasolabial flap reconstruction. The postoperative course of both cases was good; neither postoperative flap necrosis nor infection developed.

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In benign tumors in the mandibular condyle such as osteoma and osteochondroma, symptoms such as pain and limited-mouth-opening are rarely observed. Therefore, these tumors are often detected after the development of changes in occlusion and mandibular midline deviation. We encountered a very rare patient with mandibular condyle osteoma who showed acute pain and markedly limited-mouth-opening.

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In order to find informative salivary biomarkers specific to oral cancer we examined expression of 4 kinds of cytokine in saliva. Levels of interleukins (IL-1β, -6, -8) and osteopontin were measured by ELISA using whole saliva samples collected from 19 patients with oral cancer (9 men, 10 women; mean age, 60.9 years) and 20 healthy persons (15 men, 5 women; mean age, 32 years). Expression of the 4 cytokines was higher in patients with oral cancer than in healthy controls. The difference was significant in IL-6, in particular. The results suggest that saliva offers a potential target for a screening test aimed at detection of precancerous lesions.

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