This article reports on the lessons learned while teaching an 8-week-long online course about the principles of clinical research design in Japan. Student activity data and how it relates to performance in the course are presented. As prolog, this article focuses on the barriers and solutions to creating and delivering a web-based course and it lists and discusses the most common concerns that educators often have about this process, namely, cost of the system and time requirement of the faculty. Options that must be considered when selecting the support software and hardware needed to conduct live streaming lecture, online video-based conference course are presented. The ancillary role of e-mail based distribution lists as an essential instruction tool within an interactive, instructor-supervised online course is discussed. This article then discusses the inclusion of active learning elements within an online course as well as the pros and cons regarding open-book versus closed book, proctored testing. Lastly, copyright issues the online instructor should know about are discussed. The student tracking data show that as the course progresses, students will reduce the number for page viewings. We speculate that this reduction is due to a combination of conflicting priorities plus increasing efficiency of the students at extracting the critical information. The article also concludes that software and hardware costs to deliver an online course are relatively minor but the faculty's time requirement is initially substantially higher than teaching in a conventional face-to-face course.

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The restoration of endodontically treated teeth is a topic that is extensively studied and yet remains controversial. This article emphasizes the characteristics of endodontically treated teeth and some principles to be observed when restorations of these teeth are planned. It was concluded that the amount of remaining coronal tooth structure and functional requirements determine the best way to restore these teeth, indicating the material to be used, direct or indirect restorations, associated or not to posts.

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Purpose: Although daytime clenching is believed to be one of the oral parafunctions leading to dental problems, a treatment strategy has not yet been devised. Electromyogram (EMG) biofeedback training was performed to ascertain its effect on the regulation of daytime clenching behavior.
Materials and methods: Twenty subjects (mean age, 30.9 ± 5.6 years) who had mild to moderate masticatory muscle pain with daytime clenching behavior were randomly divided into either a biofeedback group (BF) or control group (CO). Subjects were fitted with a hearing-aid-shaped EMG recording and biofeedback apparatus which was used to record EMG data under natural conditions from the temporal muscle, continuously for five hours on four consecutive days. EMG data on Days 1 and 4 were recorded without biofeedback as pre-test and post-test, respectively, and on Days 2 and 3, subjects in the BF group noticed their clenching behaviors via an alert sound from the EMG biofeedback apparatus. No alert sound was given for the CO group throughout the recording sessions.
Results: There was no significant difference in the number of clenching events for five hours between the BF group (4.6 ± 2.5) and CO group (4.6 ± 0.9) on Day 1, however a significant decrease was found in the BF group between Day 1 (4.6 ± 2.5) and Day 4 (2.4 ± 1.7; P < 0.05).
Conclusion: Daytime clenching was reduced in the short-term with the help of an EMG biofeedback system under natural circumstances. Further research is needed to confirm a long-lasting effect.

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Purpose: The aim of this pilot study was to consider evaluation of the psychological effects of dental prosthetic treatments using ESAM.
Method: We examined gum chewing with and without an occlusal interference device that simulated a negative change in oral sensation in four subjects. First, we analyzed the temporal components of mandibular movement trajectories as indices for evaluating the degree to which chewing is actually impaired by occlusal interference. Subsequently, we measured brain activity before and after chewing for each of the two conditions (with or without the occlusal interference device). For brain activity, we used the four emotional indices of stress, sadness, joy and relaxation based on ESAM to estimate psychological states before and after chewing, and made a comparison between the two conditions. Statistical analyses were performed with Mann–Whitney's U-test (p < 0.05).
Results: The opening phase and chewing cycle were shorter when wearing the occlusal interference device in every subject. There was a significant difference for all subjects (p < 0.05) in the closing cycle. Therefore, because a significant difference occurred for at least one temporal component of the mandibular movement trajectory for every subject, we concluded that normal chewing in subjects was impaired by wearing the occlusal interference device. Similarly, in ESAM analyses using EEG, stress tended to increase due to occlusal interference in every subject. In addition, relaxation decreased due to occlusal interference in three subjects.
Conclusion: The results suggested the potential for evaluating the psychological effects of dental prostheses using emotional indices based on ESAM.

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Purpose: We used functional magnetic resonance imaging (fMRI) to investigate the change in brain regional activity during gum chewing when edentulous subjects switched from mandibular complete dentures to implant-supported removable overdentures.
Methods: Four edentulous patients (3 males and 1 female, aged 64 to 79 years) participated in the study. All subjects received a set of new maxillary and mandibular complete dentures (CD), followed by a maxillary complete denture and a new mandibular implant-supported removable overdentures (IOD). A 3-T fMRI scanner produced images of the regional brain activity for each subject that showed changes in the blood-oxygenation-level-dependent (BOLD) contrast in the axial orientation during gum-chewing with CD and IOD.
Results: Region-of-interest analysis showed that IOD treatment significantly suppressed chewing-induced brain activity in the prefrontal cortex. The chewing-induced brain activities in the primary sensorimotor cortex and cerebellum tended to decrease with IOD treatment, however they did not reach to significance level. There was no change in brain activity in the supplementary motor area, thalamus and insula between gum chewing with CD and IOD. Group comparison using statistical parametrical mapping further showed that, within the prefrontal cortex, the neural activity of the frontal pole significantly decreased during gum-chewing with IOD when compared to that with CD (P < 0.05).
Conclusion: Despite the limitation of a small sample size, these results suggest that the gum-chewing task in elderly edentulous patients resulted in differential neural activity in the frontal pole within the prefrontal cortex between the 2 prosthodontic therapies—mandibular CD and IOD.

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Purpose: The aim of this study was to determine the importance of each morphological factor of edentulous alveolar ridges according to its influence on the movement of complete dentures.
Methods: The shapes of casts and waxed complete dentures were digitized. The determined shapes of the ridges were uniformly divided circumferentially and radially. Principal component (PC) analysis was performed using the coordinates of the points on the grid as the variables (morphological PC). The denture movement under bilateral and unilateral loads was analyzed using a finite element (FE) model constructed from the digitized shape, following PC analysis of the displacement of representative points on the denture (displacement PC). The effects of the morphological PCs were evaluated by means of stepwise multiple regression analysis with displacement PC as a dependent variable.
Results: The ridge height, clearance between the ridge and the occlusal plane, and various inclinations, were significantly selected as independent variables where the dependent variable was the displacement PC under a bilateral load. Under a unilateral load, the displacement PC was mainly influenced by the ridge height. The influence of morphological PCs of the non-loaded side tended to be larger than that of loaded side.
Conclusion: Under a bilateral load, ridge height, clearance to the occlusal plane, and inclination of the ridge are considered to account for denture movement. To evaluate the effect of the ridge morphology on denture movement under a unilateral load, it is effective to determine the partitioned shape together with the height in general.

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Purpose: Bone regeneration stimulated by two different shapes of interconnected porous calcium hydroxyapatite (IP-CHA) granules was evaluated in the mandibles of 3 beagle dogs.
Methods: Deferent shapes of IP-CHA were used, spherical (spherical shaped IP-CHA granules) and irregular shapes (irregularly shaped IP-CHA granules). Two bone sockets (3 mm in diameter and 5 mm in depth) were prepared in the right edentulous mandible of each animal where right premolars had been extracted and sites healed for 3 months. The two types of IP-CHA were filled into the sockets to stimulate bone regeneration. New bone formation was evaluated histologically at 4, 8 and 12 weeks after filling.
Results: At 4 weeks, little bone formation was apparent in any of the bony sockets. At 8 weeks, newly formed bone was detected between the granules but not in the pores. In contrast, at 12 weeks, bone formation was clearly observed not only between the granules but also inside the granule pores. Comparing the two sites at 8 and 12 weeks, more bone formation was detected in sites receiving irregularly shaped IP-CHA than in sites receiving spherical IP-CHA.
Conclusion: These results indicate that use of irregularly shaped IP-CHA may enhance bone regeneration. The results of this preliminary study suggest that irregularly shaped IP-CHA granules may have more possible usefulness than spherically shaped granules as a scaffold for bone regeneration.

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Purpose: The purpose of this study was to compare microshear bond strength of three different luting resins using a new microshear method closely simulating clinical condition.
Methods: Thirty 1-mm-thick slices of intact human first molars and thirty 0.8-mm-diameter feldspathic porcelain rods were etched by 37% phosphoric acid for enamels and 9.5% hydrofluoric acid for porcelains. Adhesive (Margin bond) was applied on both silaned porcelain and enamel surfaces. Three luting agents were used as follows: (1) dual polymerized cement (DP) (Variolink II refill), (2) light polymerized cement (LP) (Variolink II base), and (3) flow composite (FC) (Tetrick flow). Porcelain rods were attached to flat enamel surfaces followed by cementation. The specimens were thermal cycled for 500 cycles between 5 and 55 °C, and microshear test was then performed with wire and loop method using Dillon Quantrol. Modes of failure were identified by stereomicroscope, and one sample of each group was observed with SEM. finally collected data were statistically analyzed using one-way ANOVA (P < .05).
Results: The mean microshear bond strengths were 21.48 (DP), 23.92 (LP) and 24.57 (FC) in MPa units. Most cohesive failures occurred in groups LP and FC, whereas most adhesive failures were observed in group DP.
Conclusion: Bond strength of feldspathic porcelain to enamel with studied luting resins were not significantly different among the groups based on current method (P < .05).

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The prosthodontic treatment of a patient who had undergone brain surgery to resect a brain stem astrocytoma has been described. Since the motor innervation to the oral muscles was impaired, the new neutral zone was recorded by using a tissue conditioner material. The teeth and polished surfaces of the mandibular partial denture fitted to the functional cheek anatomy of the surrounding tissue helped in the stability of the denture and to avoid the end tongue biting.

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Background and aim: One of the major problems of all ceramic restorations is their probable fracture against the occlusal force. The aim of the present in vitro study is to compare the effect of two marginal designs (shoulder and chamfer) on the fracture resistance of all ceramic restorations, INCERAM.
Materials and methods: On an extracted first maxillary premolar 50 in. chamfer margin (0.7 mm) was prepared. Ten impressions were taken using a polyvinylsiloxane. The impressions were poured with epoxy resin to fabricate dies. The same tooth was retrieved and 50 in. chamfer was converted into 90 in. shoulder (1 mm). Ten impressions were taken and ten more epoxy resin dies were fabricated. Impressions of each epoxy resin die were taken using polyvinylsiloxane impression material and poured with die stone. Alumina cores with 0.5 mm thickness fabricated on the stone dies in a dental laboratory. The alumina cores were then cemented on the epoxy resin dies and underwent a fracture test with a universal testing machine and samples were investigated from the point of view of the origin of the failure.
Result: The mean value of fracture resistance for the chamfer samples were 610.18 ± 58.79 N and 502.72 ± 105.83 N for the shoulder samples. The Student's t-test revealed a statistically significant difference between groups.
Conclusion: The result of this study indicates a relationship between the marginal design of the alumina cores and their fracture resistance. A chamfer margin could improve the biomechanical performance of posterior single crown alumina restorations. This may be because of the strong unity in the chamfer margin.

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