Generally, metal clasps are used as a part of the assembly for removable partial dentures (RPDs); however, the color of metal clasps is unaesthetic. On the other hand, non-metal clasp dentures (NMCDs) made from thermoplastic resin are being used more often as esthetic prostheses, but the use of such NMCDs without a metal framework may seriously affect the remaining tissues because of their low rigidity. Consequently, we developed a laboratory glass fiber-reinforced thermoplastic (GFRTP) having excellent esthetics and strength for RPD applications, and examined its physical and mechanical properties. In the present study, the GFRTP made from E-glass fibers and polypropylene was fabricated through pultrusion and hot press methods. The fiber volume fraction of the GFRTP was confirmed to be 36.1% using an ashing technique. A dynamic micro-indentation test confirmed that the fibers do not affect the surface properties of the GFRTP. The flexural strength and flexural modulus of the GFRTP obtained from a flexural test were 170.5 ± 7.4 MPa and 16.7 ± 0.7 GPa, respectively. As a result, the flexural properties of the GFRTP were higher than those of commercially available NMCD materials made of thermoplastics, though they were lower than those of metallic clasp wires, such as those made with cobalt–chromium alloy and stainless steel. With mechanical properties better than those of conventional NMCDs, this newly developed GFRTP is potentially useful for esthetic RPDs.
The purpose of this study was to investigate the characteristics of maxillofacial fractures in elderly patients in comparison to young patients. A retrospective study was conducted of 376 patients with maxillofacial fractures who underwent 64 multidetector-row CT (MDCT) procedures. The study patients comprised 81 elderly patients (≥60 years) and 295 young patients (<60 years). Age, sex, cause of injury and fracture location according to MDCT were analyzed using the χ² test with Fisher’s exact test. The proportion of male vs female of elderly patients was 55.6% vs 44.4% and that of young patients was 73.9% vs 26.1% (p = 0.002). The causes of injury in the elderly patients were falls, traffic accidents, assaults, and sports incidents (59.3%, 32.1%, 7.4%, and 1.2%, respectively (p <0.001)). The percentages of cases with mandibular angle fractures, condylar fractures, and median fractures were 3.7% of elderly patients vs 22.4% of young patients (p <0.001), 63.0% of elderly patients vs 44.4% of young patients (p = 0.004), and 16.0% of elderly patients vs 30.8% of young patients (p = 0.008), respectively. In conclusion, mandibular condylar fractures dominate maxillofacial fractures in the elderly compared with mandibular median and angle fractures.
In workshops (WSs) that are part of faculty development, it is first important to set an objective, and then for small numbers of participants to engage in effective and efficient within-group discussions in order to achieve that objective. Generally, tasks in WSs are performed in order to achieve the objective, and WS participants must present feasible products through an on-site learning process in a limited amount of time. They then engage in discussions with other WS participants. Regarding the specific methods and materials for assessing a WS and evaluating its effects on participants, analyses of the WS products and questionnaires, which provide a good general overview, have been carried out and reported. However, studies on the assessment of computer-based testing (CBT) WSs in dental medicine and its effects are extremely limited. Therefore, in the present study, with the objective of achieving further progress and improvement in dental education, we evaluated the effects of CBT WSs on the education and awareness of participants, and report the results herein. An examination regarding the level of understanding achieved according to type of question or educational activity was carried out on participants both pre- and post-WS. In the overall post-WS assessment, the mean scores regarding the value and appropriateness of the content were high, and the WS method was highly evaluated in terms of effectiveness. The mean scores for level of understanding attained through question types were significantly higher post-WS than pre-WS (P < 0.001). The mean scores for level of understanding regarding the Model Core Curriculum for Dental Education and the importance of student-oriented education, as well as self-evaluations of the level of educational awareness were also significantly higher post-WS than pre-WS (P < 0.001). These results suggested the value and appropriateness of the WS content, as well as the effectiveness of the WS as a study method. The results also indicated that WSs contribute to deeper educational understanding and improved awareness, as they were shown to be both useful in helping participants better understand CBT-related questions and effective in helping participants master alternative questions with high applicability.
The use of platelet-rich fibrin (PRF), concentrated growth factor (CGF), or growth factor-rich fibrin (GRF) has been recognized as a new therapeutic concept involving autologous concentration of human platelets by simplified preparation without biochemical processing of blood. Although GRF and these concentrations containing growth factors have been used for bone regeneration and implant treatment, the biological and histological effects in human cases have not yet been understood. Successful bone formation following application of GRF with bone graft materials and atelocollagen in an extraction socket and its histopathological features are reported. A 40-year-old woman came to Hayashi Dental Clinic with the chief complaint of discomfort in an upper left molar. The molar showed severe vertical resorption of the alveolar bone and had to be extracted. The patient requested prosthetic replacement by implant as early as possible after the tooth extraction; therefore, bone augmentation was performed. After extracting the tooth under local anesthesia, the granulation tissue was removed thoroughly, and GRF and bone graft material were inserted into the socket. The socket was covered with condensed atelocollagen, and the adjacent mucosa was coronally placed and sutured. Two months after the extraction, radiopacity could be seen in the socket area. Histopathologically, the socket was filled with minimal inflamed fibrous tissue around the fragments of the anorganic bone graft material, and cancellous bone formation was noted adjacent to the fibrous tissues and fragments. GRF along with bone graft accelerates wound healing and bone formation in the extraction socket, allowing early implant treatment.