Odontogenic tumors originate from tooth­forming tissue cells and are specialized tu­ mors in oral regions. Due to the origin of the tissue cells of these tumors, they are divided into three groups : epithelial, non­epithelial and mixed tumors. In 1746 Pierre Fauchard first pub­ lished a description of the odontogenic tumor. This was followed by descriptions by Broca, and then Bland­Sutton who classified odontogenic tumors based on the structure of the tooth germ. In the 1930's the term ameloblastoma came into use, and then early in the 1950's the term odontoma came into general use. In 1971 WHO published the classification of odontogenic tu­ mors in book form. After that, they published revised editions in 1992, 2005 and 2017. Prior to the 2nd edition in 1992, the classification of odontogenic tumors was published in book form. In the 3rd edition in 2005 and the 4th edition in 2017, the classification was published as one chapter of head and neck tumors. In the 3rd edition in 2005, two lesions, the odontogenic kera­ tocyst (OKC) and the calcifying odontogenic cyst (COC), were classified as odontogenic tumors,which were referred to as the keratocystic odontogenic tumor (KCOT) and the calcifying cystic odontogenic tumor (CCOT) in alternative terminology. However, in the 4th edition in 2017, the terms KCOT and CCOT were restored to OKC and COC because of new information, including developmental molecular data. In addition, the names of three other lesions were deleted from the classification of odontogenic tumors in this edition. They were the odontoameloblastoma, the ameloblastic fibrodentinoma, and the ameloblastic fibro­odontoma, which were considered types of odontoma. Our hospital has had biopsy services from 1994 to the present. For 23 years from January 1994 to December 2016, we saw more than 20,000 cases. The most common was the cystic le­ sion, followed by carcinoma, and then inflammatory and odontogenic tumors, which were less common. Cystic lesions and unicystic ameloblastomas are not always easy to histopathologi­ cally diagnose in small biopsy specimens. However, it is not difficult to make the histopathologic diagnosis with whole sections. The larger the specimen, the easier the diagnosis, even in uni­ cystic ameloblastomas. Shika Igaku (J Osaka Odontol Soc) 2018 ;Mar ;81(1) : 1­10.

We analyzed serial time measurements of occlusal forces with movement from habit­ ual occlusal position to intercuspal position in healthy volunteers (HV) and volunteers with tem­ poromandibular disorders (TMD). The participants were 20 healthy volunteers and 42 volunteers with TMD. We defined the occlusion time (OT) as the duration from 2% to 90% of maximum vol­ untary contraction during intercuspation. The indicator of premature occlusal contacts was estab­ lished as the percentage of the occlusal force of the premature occlusal contacts (DELTA) di­ vided by the occlusal force during maximum intercuspal contraction (DELTA%). The median OT for HV and TMD were 0.36 and 0.61 sec, respectively (p＜0.01). The median DELTA% for HV was 2.7%. It was 3.9% for TMD when OT was less than 0.7 sec, and 8.3% for TMD when OT was greater than 0.7 sec (p＜0.01). Multiple comparisons indicated a significant difference be­ tween HV and TMD when OT was greater than 0.7 sec (p＜0.01). There was also a significant difference between TMD when OT was less than 0.7 sec, and TMD when OT was greater than 0.7 sec (p＜0.05). DELTA is detected when the mandible is displaced in the horizontal plane by interference of premature occlusal contact. The longer OT of TMD when OT was greater than 0.7 sec may have been caused by a complex mandibular displacement of rotation and transla­ tion. Shika Igaku (J Osaka Odontol Soc) 2018 ;Mar ;81(1) : 11­-15.

We investigated whether mucosal and systemic antigen (Ag)­specific immune re­ sponses were induced by nasal administration of synthetic hinokitiol (HNK). Mice in the experi­ mental groups were immunized under anesthesia three times at weekly intervals nasally with 100 μg of chicken ovalbumin (OVA) and 5 μg or 50 μg of HNK simultaneously. As a negative control, mice were given nasally 100 μg of OVA alone, and as a positive control, they were ad­ ministered nasally 100 μg of OVA and 50 μg of DNA plasmid expressing Flt3 ligand (pdF3L) as a mucosal adjuvant. Saliva, nasal washes (NWs), and plasma were collected on days 0, 7, 14 and 21, and we determined the Ag­specific IgA antibodies (Abs) in each sample by Ag­specific ELISA methods. In addition, mononuclear cells from submandibular glands (SMG), nasal pas­ sages (NPs), nasopharyngeal­associated lymphoreticular tissues (NALT), cervical lymph nodes and spleen were supplied to antigen­specific ELISPOT assay in order to examine induction of OVA­specific IgA Ab­forming cells. Consequently, we found little induction of systemic or mu­ cosal IgA immune responses, compared with the positive control. These results suggest that HNK does not bear a mucosal adjuvanticity to provoke Ag­specific IgA immune responses. Shika Igaku (J Osaka Odontol Soc) 2018 ;Mar ;81(1) : 16­-23.

Fabrication of a production of palatal augmentation prosthesis (PAP) was carried out as practice training in an active learning experience. We investigated the educational effect of this active learning style class. We made a jig device to open the incisal edges 4 mm. Fabrica­ tion of the PAP did not elicit a gag reflex in any of the 129 subjects. The maximum tongue pres­ sure between the dorsal lining and the anterior of the palate was measured under three condi­ tions of only the probe (control group), the probe with jig,and the probe with jig and PAP.The purpose of the PAP was explained to the subjects. We investigated the educational effective­ ness of the active learning style class using fabrication of the PAP by questionnaire at the be­ ginning and at the end of the practical training. The maximum tongue pressure of the probe with jig was lower than that of the controls, while the probe with jig and PAP was higher. The practi­ cal training increased self­understanding in all categories of the questionnaire. Shika Igaku (J Osaka Odontol Soc) 2018 ;Mar ;81(1) : 24­-30.

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