Journal of Osaka Dental University Vol. 51(2017) No. 1

Cell migration potency is often regulated by extracellular stimuli. We previously reported that the migration potency of the oral squamous cell carcinoma (OSCC) cell lines SAS and HSC3 have high epidermal growth factor receptor (EGFR) inhibitor sensitivity, while the migration of HSC4 is not affected. Hepatocyte growth factor (HGF)/c­Met is known as one of the signaling pathways for cell migration in some cancer cells. In this study, we demonstrated the importance of the c­Met signaling pathway for filopodia and lamellipo­ dia formation in cell migration using HSC4. The cell migration of HSC4 used the HGF/c­ Met pathway. Additionally, the EGF/EGFR pathway is not related to lamellipodia forma­ tion. The HGF/c­Met pathway is important for the formation of filopodia and lamellipodia in HSC4. Furthermore, signaling from c­Met increases the amount of lamellipodin protein,which is necessary for formation of lamellipodia. Our results suggested that signaling from the HGF/c­Met pathway increases the quantity of lamellipodin protein, and induces cell migratory capacity by inducing lamellipodia forming potency in HSC4. (J Osaka Dent Univ 2017 ;51 : 1­8)

The socioeconomic situation in Japan is changing drastically, resulting in the need for a variety of dental interventions. Dental healthcare providers therefore need to offer effi­ cient treatments to prevent dental diseases and take the initiative on providing guidance for oral health. Community dentistry which is the only academic discipline in dentistry to expertly address prevention and health promotion will play a central role in this, and den­ tal hygienists will play an important role. In the present study, we conducted a questionnaire­based survey with intraoral exami­ nations of first­to third­year dental hygiene students enrolled at Osaka Dental University School of Dental Hygienists. The changes in their knowledge and interpretation of dental and oral health after taking a course on oral hygiene were aggregated and analyzed by text mining. After aggregating and analyzing responses to the questionnaire, we found that most students who wanted to become dental hygienists had visited dental clinics 1 to 5 times during their elementary school days, and that most of them answered that they currently had no dental caries. Furthermore, more than 90% of the students reported that they saw themselves working as dental hygienists in 10 years, indicating a strong awareness and attitude that they would continue their profession in the future. In our comparison of stu­ dents before and after taking a course on oral hygiene, most first­year students gave an­ swers closer to the knowledge and interpretation of the general population, while most second­year students gave interpretations based on professional knowledge and think­ ing, such as methods of preventing dental diseases learned from their courses. Third­ year students, however, had a tendency to interpret questions with a focus on dentistry,because their view of prevention and health promotion had been influenced by other clinical courses. Differences in knowledge and interpretation of the field of oral hygiene were dependent on the student's academic year. This suggests that, in order to preserve the concept of oral hygiene required by dental hygienists up into the third academic year, we need to investigate the provision of courses on oral hygiene in a new curriculum that is not bound by the concept of sepa­ rate curricula in each academic year with traditional fixed semesters. This could be achieved by introducing iterative learning of topics addressed in the first year into the second and third years, or by crossover courses of clinical and basic subjects. (J Osaka Dent Univ 2017 ;51 : 9­16)

We retrospectively studied 68 primary cases of keratocystic odontogenic tumor (KCOT) treated in the First Department of Oral and Maxillofacial Surgery, Osaka Dental University between January 1997 and December 2011. KCOT cases were pathologically diagnosed according to the guidelines of the 2005 WHO histological classification of odontogenic tumors. There were 39 (57%) male and 29 (43%) female patients between 11 and 80 years of age with a mean age of 43 years. The KCOT was in the mandible in 56 (82%) of the pa­ tients, and in the maxilla in 12 (18%). The most common site was from the mandibular molar to the mandibular ramus (59%). The modalities used for the initial treatment of KCOTs were enucleation with curettage in 27 patients, marsupialization in 21, enucleation in 19, and marginal resection of the mandible in 1. KCOT cases treated with marsupialization underwent enucleation with cu­ rettage (16), enucleation (4) or marsupialization (1) after the initial treatment. Tumor re­ currence was observed in 9 patients between 1.8 to 11 years after the operation. The sites of recurrence were in close proximity to the adjacent tooth in 5 patients, and near the mandibular canal in 4. (J Osaka Dent Univ 2017 ;51 : 17­22)

Mechanical stress causes cartilage destruction in the temporomandibular joint (TMJ) and dedifferentiation of chondrocytes in TMJ cartilage. Although dedifferentiated chondro­ cytes redifferentiate in vitro under certain culture conditions with growth factors such as BMPs and TGF­βor mechanical loading, the effect of mechanical stress on redifferentia­ tion of chondrocytes is unclear. We attempted to elucidate the effect of cyclic compres­ sive loading on the redifferentiation of dedifferentiated human chondrocytes in three­ dimensional (3D) culture. Our hypothesis was that cyclic compressive loads alter gene expression in an early stage of cartilage redifferentiation. Dedifferentiated human chon­ drocytes in monolayer were seeded onto a collagen scaffold to produce 3D tissue and were cultured with BMP­2 (500 ng/mL) and TGF­β3 (10 ng/mL) for 28 days. The effect of cyclic compressive loading of 20 kPa at 0.5 Hz for 1 hour per day on the 3D tissue was analyzed for Sox9, BMP2, Aggrecan and type II collagen gene expressions on days 1, 4 and 7. Three­dimensional constructs with BMP­2 and TGF­β3 exhibited positive Safranin O staining on day 28. mRNA expression levels of Sox9 and Aggrecan gene were upregu­ latedonday4withBMP­2 and TGF­β3, and type II collagen gene expression was also upregulated on day 7. Cyclic compressive loading on the 3D constructs further upregu­ lated Sox9 and BMP2 gene expression on day 4, and BMP2 gene expression was also upregulated on day 7. We concluded that cyclic compressive loading alters gene expres­ sion during the early stage of cartilage redifferentiation. (J Osaka Dent Univ 2017 ;51 :23­30)

Some medical professionals have never had color vision tests, preventing them from per­ ceiving their own color vision deficiencies. Color coding is often used for injection nee­ dles, dental root­canal instruments, and other items with different specifications, such as outer diameter, indicating the necessity of special consideration for medical profession­ als with color vision deficiencies. In this study, hue conversion was performed using computers to clarify how the colors of medical materials and devices used in actual set­ tings are seen by individuals with color vision deficiencies. As some injection needles and dental root­canal instruments of adjacent sizes (diameters) were encoded using col­ ors that are indistinguishable to individuals with visual impairment, it may be necessary to indicate the specifications of medical materials and devices, not only using colors, but by also simultaneously providing clear character information, in order to ensure patient safety. (J Osaka Dent Univ 2017 ;51 : 31­38)

We analyzed the gaze points of people viewing photographs of mouths with non­esthetic dental restorations to clarify if they stare at these restorations. Participants included 47 people who had no association with the dental profession. Their gaze was recorded with an eye tracker. The stimuli were 18 photographs of mouths with or without a non­esthetic tooth restoration, each randomly shown for 5 sec. The analysis sites included a tooth with a non­esthetic restoration and the same tooth on the opposite side of the mouth. We measured the number of times their gaze fixated on each analysis site. The number of times for each analysis point did not differ significantly between the left and right in pho­ tographs of mouths without a non­esthetic restoration. The number of times was signifi­ cantly greater in photographs with a non­esthetic restoration, (p＜0.01). We found that the subjects often stare at non­esthetic restorations. (J Osaka Dent Univ 2017 ;51 : 39­ 45)

Human papillomavirus (HPV) is associated with the onset of oral dysplasia and oral squamous cell carcinoma (OSCC). In this study, we examined p53, p16^INK4a, HPV 16/18 E6,and HPV L1 in oral papilloma (OP), oral dysplasia (OD), and OSCC to clarify the relation­ ship between HPV infection and malignant transformation. We used 11 samples of OP, 14 of low grade oral dysplasia, 10 of high grade oral dysplasia, 21 of well to moderately dif­ ferentiated squamous cell carcinomas (W­MSCC), and 8 of poorly differentiated squ­ amous cell carcinomas in oral lesions obtained from Osaka Dental University Hospital. We performed immunohistochemical staining to study the expression of HPV 16/18 E6,HPV L1, p53, and p16^INK4a in each lesion. Marked expression of p16^INK4a was seen in HPV 16/18 E6 positive W­MSCC, and marked expression of p53 was seen in HPV L1 positive OD. These results suggest that HPV may play an important role in the transformation of p53 and p16^INK4a, and that p16^INK4a is a pos­ sible marker of HPV infection. (J Osaka Dent Univ 2017 ;51 : 47­53)

The purpose of this research was to determine factors among various manufacturing conditions that affect the retentive force of the cone crown telescope prosthesis using ceria­stabilized zirconia/alumina nanocomposite (Ce­TZP/A) with a CAD/CAM system. Ce­ TZP/A was used for the primary and secondary crowns. We conferred one of three cone angles for the axial surface of the primary crown and one of three shapes for the tooth cervix border. The conditions for the secondary crown included the milling bur usage fre­ quency, space between the primary and secondary crowns, different lot numbers of the zirconia disks, thickness of the secondary crown, placement location on the sintering tray, and disk milling processing position. The factors, set at the two­ or three­level, were allocated to an L 18 experimental array. We searched for factors that affected retentive force among all the factors. The point estimations for cone angles of 2°,4°and6°were 35.8 N, 15.9 N and 1.4 N, respectively. The conical angle was a significant factor for the retentive force of the cone crown telescope prosthesis using Ce­TZP/A with a CAD/CAM system. (J Osaka Dent Univ 2017 ;51 : 55­62)

Occlusal interference may influence the functional balance of the autonomic nervous system. Salivary amylase levels are related to plasma noradrenaline concentrations and are increasingly being used as a marker for the reaction of the sympathetic nervous sys­ tem to stress. We examined the effect of occlusal interference on salivary amylase activ­ ity (SAA). Saliva samples were obtained from 10 healthy volunteers (9 males and 1 fe­ male, who had an average age of 29 years). They all had normal occlusion and no history or signs of medical disorders. Each subject was instructed to tap his teeth with and with­ out the experimental occlusal inference of metal foil on the occlusal surface of the man­ dibular first molar on the habitual masticatory side. We assayed SAA ten times each for metal foil thicknesses of 12.7, 25.4, 38.1 and 50.8 μm. There was an immediate and sig­ nificant increase in the SAA with all foil thicknesses compared with the control. Further­ more, the SAA returned to the control level after removal of the foil. There results suggest that SAA is a useful indicator of occlusal balance because it sensitively reacts to differences in the thickness of the metal foil. The measurement method of occlusal contact using BiteEye has high reproducibility and reliability. In this study, both occlusal contact area and the number of occlusal contact points were calcu­ lated using the BiteEye, and the occlusal contact area per point on the experimental teeth and both adjacent teeth was calculated. We found that it was possible to objectively eval­ vate the occlusal state by measuring SAA with tapping. (J Osaka Dent Univ 2017 ;51 :63­72)