Background: This paper focuses on the additional time and effort associated with placing a problem based learning (PBL) case within a learning management system (LMS) and reporting on both student LMS utilization and course satisfaction data. Methods: The study involved 13 PBL students who volunteered to participate in one of two 9 week long PBL courses (6 or 7 students in each course). The LMS selected for utilization in this experiment was Moodle version #1.9.5. A questionnaire assessed the students’ attitudes about the hybrid PBL-LMS system. Time-effort data, collected prospectively, were divided into faculty tasks that: occur during a typical PBL case; involved preparing and presenting several lectures as part of an expert resource session(s); and were associated solely with the LMS creating and posting process. Results: The total time in each course was 119.5 hours and the LMS related tasks involved 25.5 hours or 21.3% of the total course time. While opinions will vary on this issue, this extra time is probably outweighed by the advantages a LMS offers. For example, by placing a PBL course inside a LMS tracking and comparing the performance of multiple simultaneous PBL groups and tutors for consistency can be readily accomplished. Conclusions: A majority of the students (72.7%) agreed that the various materials contained on the website (e.g. videos and supplemental materials) were very helpful and 54.5% agreed that all future PBL courses should have a web-based component.

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This study was aimed to observe the fracture surfaces of dentin specimen after the fatigue test to be taken into account for teeth fracture. Radicular dentin from bovine lower central incisors was used. Dentin slabs of 1 mm thickness were trimmed into dumbbell-shaped specimens along the tooth axis, then, fatigue tests were performed. The staircase method was employed to determine fatigue strength and its standard deviation. Thereafter, the fractured surfaces of the specimens were coated using an ion sputtering machine and examined by scanning electron microscopy. Observations of the dentin fatigue specimens using the scanning electron microscopy showed that the fatigue striations were almost aligned perpendicularly to dentinal tubules. Moreover, fatigue striations spaced approximately 3 to 10 μm apart from fracture surfaces of intertubular dentin. Additionally, a porous fibrous reticulate texture can be seen in the intertubular dentin. On the other hand, a thin peritubular collar can be seen lining the tubules in dentin. However, some of the peritubuler cuffs in the dentin appeared debonded from the surrounding intertubular dentin and partially fractured. In addition, it was also confirmed that there was no distinction between the peritubular dentin and the intertubular dentin in fracture surfaces. The peritubular and intertubular dentin differ in fracture and fatigue crack propagations.

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Inexpensive implant treatments reduces a patient’s financial burden. However, substantially lower charges may lead to inappropriate cost savings. Economic analyses were conducted to gather information on appropriate pricing for implant treatments.
The standard implant in the hospital (1 to 4 dental implants), the costs (labor costs, supplies, depreciation, energy bills, guaranteed savings when remanufactured, anti-funded litigation) and the fees charged to the patient (test, diagnosis, implant surgical, superstructure, construction, and management) were compared between two implant systems (N system and I system).
In the N system, the total cost was 480,000 yen and the total price was 410,000 yen for a single missing tooth. In the I system,total cost was 400,000 yen and the total price was 320,000 yen. In both system, one implant was unprofitable, two implants was slightly profitable, and three implants were much profitable.
In the pricing system proportional to the number of structure and surgical implants, small number of implant was unprofitable and conversely, many implants impose too much expense for the patient.

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[in Japanese]

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[in Japanese]

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[in Japanese]

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[in Japanese]

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[in Japanese]

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